Dissertations / Theses: 'Soil fertility Fertilizers Soils'

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Knowles, Tim C., Paul Artz, and Chip Sherrill. "Preplant Micronutrient Fertilizers for Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/197269.

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Micronutrient fertilizers including zinc, boron, copper, and manganese in their sulfate forms were broadcast applied and incorporated preplant to determine their effects on lint yield of upland cotton.

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Dupuis, Eartha M. "Poultry manure and inorganic fertiliser effects on soil fertility and microbial communities in wheat and corn agroecosystems." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97946.

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Many producers in North America are finding it profitable to make the transition from conventional farming to organic agriculture. Organic fertilisers may affect crop production and soil quality differently than inorganic fertilisers. The objectives of this study conducted in Ste.-Anne-de-Bellevue. Quebec were to examine crop yield, grain quality, soil fertility and microbial community parameters in wheat and corn agroecosystems receiving poultry manure or inorganic fertiliser. Wheat grain yield declined and corn grain yield did not increase with higher N rates, suggesting that increased N supply did not encourage grain production. Soil analyses demonstrated high inherent soil fertility at the study site, and fertilisation led to an environmentally undesirable increase in residual soil NO3 concentrations. Microbial biomass and respiration in corn agroecosystems were greater with poultry manure amendments than inorganic fertiliser, but not in wheat agroecosystems due to significant variation among field replicates. Phospholipid fatty acid analysis revealed significant differences between wheat and corn soil microbial community composition, but differences due to fertilisation were less evident. Further work is needed to uncover the relationships among N fertilisation, crop nutrition and soil microbiology in organic agroecosystems.

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Al-Ghawas, Samir A. "Some fertility problems associated with Kuwaiti calcareous soil and brackish irrigation water." Thesis, Bangor University, 1994. https://research.bangor.ac.uk/portal/en/theses/some-fertility-problems-associated-with-kuwaiti-calcareous-soil-and-brackish-irrigation-water(d3c74d9d-cf4e-452a-8c2c-73d98636cffe).html.

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The study was undertaken to improve phosphorus (P), iron (Fe), zinc (Zn) and manganese (Mn) availability and crop uptake in Kuwaiti calcareous soils. Field, glass-house and laboratory studies investigated the effectiveness of i) pyrophosphate (PP) mixed with orthophosphate (OP) fertilizers and ii) elemental sulphur (S') as a soil acidulent. In the field PP was incorporated with OP at a PP: OP P ratio of 0: 100,5: 95 and 10: 90 and applied at recommended agronomic P rates to Zea mays (corn) and Triticum spp (wheat) with micronutrients as subtreatments. Crop yields did not differ for all treatments receiving P probably due to high P residual levels in the soil but plant P uptake and P-tissue concentrations were significantly higher with PP treatment and Zn-tissue concentrations increased above the control treatments by 17% and 34% for the corn and wheat respectively, whereas with OP only treatments there was a slight decline in Zntissue concentrations. A further two experiments were conducted in the glass-house utilising a similar soil and experimental design to grow Zea mays and Avena sativa (oat) under distilled or brackish water irrigation regimes. PP amended treatments increased plant yields in the glass-house experiments by 15-18% and 20-25% for the corn and oats, respectively, while plant P-uptake increased by 83% and 32% when PP was incorporated with OP for the corn and oats respectively. Similarly, PP treatments stimulated higher plant Zn-uptake. In the glass-house Zn concentrations in plant tissues were higher by 24-40% for treatments with PP than with OP only. These findings were supported by NaHC03 P and DTPA-Zn soil extraction, where levels moved from "marginal" to "adequate" ranges with the inclusion of PP with OP. Generally there were no significant improvements when PP/OP ratio increased from 5 to 10%. Furthermore, brackish water irrigation had no direct influence on PP soil reaction or hydrolysis. Elemental sulphur (S') was applied in quantities that could theoretically neutralise 0,25,50,100 and 200% of the soil CaCO3 with two rates of P and micronutrient combinations in a split-split plot design. In the field experiment corn and wheat were grown as test crops, while in the glass-house corn was grown with distilled or brackish water after the soil/S' mixture was incubated at 30'C and approximate field moisture capacity for six months. The oxidation of S' to H 2SO4 did not proceed in a linear fashion; there were lower rates of S' oxidation at the high S' application, better monitored by the generated SO42 than the decline in either soil pH or CaCO3 content. Soil pH decline was moderate until soil CaCO3 content dipped below 6%. At these levels soils became acidic. The dissolution of soil CaCO3 was proportional to the S' applied, but its effective size distribution changed from coarse clay/fine silt to that of coarse silt/fine sand with the highest S' rates. This would have profound effects on its surface area and activity. The S' treatment also resulted in higher soil salinity; EC increased from 3-4 to as high as 12 dSm-1. Simultaneously there was a build up of gypsum which under SEM examination revealed that soil particle surfaces were shielded by gypsum crystals. Plants did not respond favourably to S' inclusion, and yield declined by 35% with the highest S' rates. However, at moderate rates the yield was similar to the control. Soil-P increased (NaHCO3 P extraction) at moderate levels of S' and then declined at higher rates. Extractable soil-Fe (DTPA) significantly increased only at higher S' rates, while Zn (DTPA) did not have a clear response and DTPA-Mn steadily increased even with the lowest S' rate. Plant tissue concentration and element uptake were difficult to assess in the light of declining plant growth and changed soil nutrient availability. Nevertheless S' treatment equivalent to 25% CaCO3 neutralisation maintained yield, P and Zn uptake while significantly increasing Fe and Mn uptake by 63 and 12% respectively for the field grown wheat. In none of the studies was there consistent response to micronutrient fertilisation. Furthermore, brackish irrigation did not interfere with the soil nutrient extractions or plant uptake.

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Rethwisch, M. D., R. Suffle, M. Reay, and R. Murphey. "Effects of AuxiGro® WP and Fertilizers on Upland Cotton in the Palo Verde Valley, 2002." College of Agriculture, University of Arizona (Tucson, AZ), 2003. http://hdl.handle.net/10150/197913.

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A field experiment was conducted to obtain data from upland cotton grown under low desert conditions to document of the effects of AuxiGro® WP and treatments consisting of AuxiGro® WP plus various foliar fertilizers on cotton yield and quality. Treatments were applied the morning of July 6, 2002, to DPL 655BR cotton that had begun bloom approximately June 28. Yields and quality data were obtained and economics calculated. AuxiGro by itself did not result in a yield increase, but did so in combination with various fertilizers. Highest quality resulted in the 8 oz/acre rate of AuxiGro + Foliar Pride fertilizer, but highest yields were documented from the 4 oz./acre rate of AuxiGro + CalMax. All treatments increased harvested value of cotton/acre when compared with the untreated check, with the treatment consisting of 4 oz./acre rate of AuxiGro + CalMax worth almost $200/acre more than the untreated check.

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Pasquini, Margaret. "Soil fertility management strategies in irrigated peri-urban agriculture around Jos, Nigeria : an interdisciplinary approach." Thesis, Durham University, 2002. http://etheses.dur.ac.uk/3970/.

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This thesis examines soil fertility management strategies in dry season irrigated vegetable production (DSIVP) in peri-urban areas of Jos, Nigeria. Farmers have developed a complex strategy of mixing inorganic fertilisers with organic manure and town refuse ash (produced by open burning, and sorting for non-combustible components). The thesis aimed to gain insights into the sustainability (in terms of nutrient supply) of the local agricultural system, acquire an understanding of past and present fertiliser practices and the rationale behind them, provide an appreciation of the role played by urban waste ash and the risks attached to its use, and place the problem of soil fertility in a wider context of farming problems. An inter-disciplinary approach was adopted so the methods used are: chemical analysis of soil and inputs (i.e. refuse ash), questionnaire surveys, semi-structured interviews (with farmers and PADP, JMDB, FUA etc.) and participant observation. The thesis observed that farmers have in-depth, but informal, empirically-derived knowledge about fertiliser application, which explains their past success in soil fertility maintenance. The tremendous increase in DSIVP in the last decade, though, has brought about a scarcity of organic amendments; farmers are increasingly reliant on inorganic fertilisers, probably over-applying them. Although this is not an immediate threat to the stability of the system, it may lead to soil acidification in the near future. Urban waste ash can counteract soil acidification (high pH and base cations), but certain batches can be contaminated by heavy metals, and indeed there is some indication of accumulation in the crops of the study farms. The problem of soil fertility needs to be addressed, however, farmers' short-term concerns (particularly access to credit facilities) need to be solved first. It is imperative that the Nigerian Government should take note of these issues and rapidly take steps to solve them.

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Rethwisch, M. D., E. Duran, J. Seiler, J. Nelson, and P. Hayden. "Effects of Foliar Fertilizers Containing Calcium on Early June Planted Cotton in the Palo Verde Valley, 2000." College of Agriculture, University of Arizona (Tucson, AZ), 2003. http://hdl.handle.net/10150/197912.

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Three foliar fertilizers containing calcium were applied at first bloom to evaluate effects on late planted (June 1) cotton in the Palo Verde Valley. Application of Calcium Metalosate resulted in increased retention percentages when compared with other foliar fertilizers at 21 days post treatment as well as more nodes/plant and calculated fruiting structures/plant. Yields did not reflect these differences however, as highest overall yields were from the untreated check, which yielded about 100 lbs. of lint/acre more than foliar fertilizer treatments. Foliar treatments did result in numerically lower micronaire and longer fibers from first pick cotton. Cotton from the first pick Calcium Metalosate treatment was strongest, but similar to other treatments. Foliar treatments did result in increased cotton value/acre by $65-95/acre, but differences noted were not consistent across field. Increased value noted for fertilizers was associated with areas of field with lowest retention rates in the untreated check at three weeks post application, and further reduction in lint quality value of untreated cotton, due perhaps to crop stresses.

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Turmel, Marie-Soleil. "Soil properties and the response of rice production to water regime and fertilizer source in low fertility soils of the Republic of Panama." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103713.

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The System of Rice Intensification (SRI) is a resource-conserving rice production system that uses intermittent flooding and organic fertilization. The SRI is emerging as an alternative to conventional rice production systems that use continuous flooding and mineral fertilizer only, however yield improvements with SRI have been highly variable. The objective of this research was to determine if soil properties control the yield improvements with SRI and, if so, the underlying chemical and biological mechanisms. A meta-analysis of 72 SRI vs. conventional system trials from 16 countries found a significant yield response to SRI in low fertility soils (P<0.0001), but no difference between SRI and the conventional system in moderate and high fertility soils. These results were validated in a greenhouse study. Soils with low P availability (≤7.1 mg P kg-1) responded positively to intermittent flooding and organic fertilizer by increasing plant biomass, plant P uptake, available soil P and microbial P concentrations, compared to soils under continuous flooding and amended with mineral NPK fertilizer only. A field study investigating the interactive effects of water regime and fertilizer source found that, under conditions of P limitation, yields were greater with NPK + composted cow manure (compost) than NPK fertilizer alone in the intermittently flooded (6.6 t ha-1 vs. 4.9 t ha-1) and continuously flooded (6.8 t ha-1 vs. 6.2 t ha-1) soils. The available soil P concentration was significantly increased by compost and was correlated with yield (P=0.007). When N was the most limiting nutrient, according to the Diagnostic and Recommendation Integrated System (DRIS) analysis, yields were greater in the continuously flooded (5.2 t ha-1) than intermittently flooded (2.7 t ha-1) soils receiving NPK fertilizer only, but showed no difference when compost was applied. Compost had a positive effect on the crop nutrient balance according to DRIS analysis (P=0.0007). On-farm trials of SRI at 10 locations in Panama showed an average yield increase of 47% and 86% less water use. SRI is recommended as a rice production system to conserve water and improve rice yields under conditions of P limitation. Organic fertilization is recommended to improve crop nutrient balance and yield under intermittently flooded soil conditions.
Le Système de Riziculture Intensive (SRI) est un système de production du riz qui préserve les ressources naturelles en utilisant l'irrigation intermittente et la fertilisation organique. SRI apparait comme une alternative aux systèmes de production de riz conventionnels qui utilisent l'irrigation continue et seulement des engrais minéraux; cependant les améliorations de rendement avec le SRI ont été très variables. L'objectif de cette recherche a été de déterminer si les améliorations de rendement dépendent des propriétés du sol avec SRI et quels sont les mécanismes chimiques et biologiques sous-jacents. Une méta-analyse de 72 tests SRI vs systèmes traditionnels dans 16 pays a révélé une réponse significative du rendement au SRI sur sols à faible fertilité (P<0.0001) mais pas de différence sur des sols à moyenne et forte fertilité. Ces résultats ont été validés par une étude en serre. Des sols bas en P (≤7.1 mg P kg-¹) ont réagis positivement à l'irrigation intermittente et aux engrais organiques en augmentant la biomasse de la plante, l'assimilation P, la disponibilité du P du sol, les concentrations microbiennes de P, comparativement aux sols avec irrigation continue et modifiés avec des engrais minéraux NPK seulement. Une étude de terrain investiguant les interactions des types d'alimentation en eau et des types d'engrais a démontré que dans les conditions de limitation de P, les rendements étaient plus importants avec NPK + fumier de vache (compost) qu'avec l'engrais NPK seul sur sols irrigués par intermittence (6.6 t ha-¹ vs 4.9 t ha-¹) et sur sols irrigués en continue (6.8 t ha-¹ vs 6.2 t ha-¹). La concentration P a été augmentée de façon significative par le compost et corrélée au rendement (P=0.007). Selon l'analyse du Système Intégré de Diagnostic et Recommandation (DRIS), lorsque l'N était la substance nutritive la plus limitée, les rendements étaient meilleurs sur des sols à irrigation continue (5.2 t ha-¹) que sur sols à irrigation intermittente (2.7 t ha-¹) en utilisant l'engrais NPK seulement, mais les rendements n'étaient pas différents quand le compost était utilisé. Le compost avait un effet positif sur l'équilibre des substances nutritives de la récolte selon l'analyse de DRIS (P=0.0007). Des essais du SRI dans les fermes à différents endroits du Panama ont montré une augmentation moyenne du rendement de 47% et ont utilisé 86% de moins d'eau. SRI est recommandé en tant que système de production du riz pour préserver l'eau et pour augmenter les rendements de production du riz dans les conditions de limitation du P. La fertilisation organique est recommandée pour améliorer l'équilibre des substances nutritives de la récolte et du rendement dans les conditions de sols irrigués par intermittence.

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Sika, Makhosazana Princess. "Effect of biochar on chemistry, nutrient uptake and fertilizer mobility in sandy soil." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20272.

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Thesis (MScAgric)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Biochar is a carbon-rich solid material produced during pyrolysis, which is the thermal degradation of biomass under oxygen limited conditions. Biochar can be used as a soil amendment to increase the agronomic productivity of low potential soils. The aim of this study was to investigate the effect of applying locally-produced biochar on the fertility of low-nutrient holding, sandy soil from the Western Cape, and to determine the optimum biochar application level. Furthermore, this study investigates the effect of biochar on the leaching of an inorganic nitrogen fertilizer and a multi-element fertilizer from the sandy soil. The biochar used in this study was produced from pinewood sawmill waste using slow pyrolysis (450 °C). The soil used was a leached, acidic, sandy soil from Brackenfell, Western Cape. In the first study, the sandy soil mixed with five different levels of biochar (0, 0.05, 0.5, 0.5 and 10.0 % w/w) was chemically characterised. Total carbon and nitrogen, pH, CEC and plant-available nutrients and toxins were determined. The application of biochar resulted in a significant increase in soil pH, exchangeable basic cations, phosphorus and water holding capacity. A wheat pot trial using the biochar-amended soil was carried out for 12 weeks and to maturity (reached at 22 weeks). The trial was conducted with and without the addition of a water-soluble broad spectrum fertilizer. Results showed that biochar improved wheat biomass production when added at low levels. The optimum biochar application level in the wheat pot trial was 0.5 % (approximately 10 t ha-1 to a depth of 15 cm) for the fertilized treatments (21 % biomass increase), and 2.5 % (approximately 50 t ha-1 to a depth of 15 cm) for unfertilized treatments (29 % biomass increase). Since most biochars are alkaline and have a high C:N ratio, caution should be taken when applying it on poorly buffered sandy soil or without the addition of sufficient nitrogen to prevent nutrient deficiencies. In the second study, leaching columns packed with sandy soil and biochar (0, 0.5, 2.5 and 10.0 % w/w) were set up to determine the effect of biochar on inorganic nitrogen fertilizer leaching over a period of 6 weeks. It was found that biochar (0.5, 2.5, and 10.0 % w/w) significantly reduced the leaching of ammonium (12, 50 and 86 % respectively) and nitrate (26, 42 and 95 % respectively) fertilizer from the sandy soil. Moreover, biochar (0.5 %) significantly reduced the leaching of basic cations, phosphorus and certain micronutrients. This study demonstrated the potential of biochar as an amendment of acidic, sandy soils. Our findings suggest that an application rate of 10 t ha-1 should not be exceeded when applying biochar on these soils. Furthermore, biochar application can significantly reduce nutrient leaching in sandy agricultural soils.
AFRIKAANSE OPSOMMING: Biochar is ŉ koolstof-ryke, soliede materiaal geproduseer gedurende pirolise, wat die termiese degradasie van biomassa onder suurstof-beperkte omstandighede behels. Biochar kan gebruik word as ŉ grondverbeterings middel om die agronomiese produktiwiteit van grond te verhoog. Die doel van hierdie studie was om die effek van plaaslike vervaardigde biochar op die vrugbaarheid van die sanderige grond van die Wes-Kaap te ondersoek, en om die optimale biochar toedieningsvlak te bepaal. Verder, het hierdie studie die effek van biochar op die loging van anorganiese stikstof kunsmis en ‘n multi-elementkunsmis op sanderige grond ondersoek. Die biochar wat in hierdie studie gebruik is, is van dennehout saagmeul afval vervaardig d.m.v. stadige pirolise (450 °C). Die grond wat in hierdie studie gebruik is, is ‘n geloogde, suur, sanderige grond van Brackenfell, Wes-Kaap. In die eerste studie, is ‘n chemiesie ondersoek van die sanderige grond wat vermeng met is met vyf verskillende vlakke van biochar (0, 0.05, 0.5 en 10.0 % w/w) uitgevoer. Totale koolstof en stikstof, pH, KUK, en plant-beskikbare voedingstowwe en toksiene is in die grondmengsels bepaal. Die toediening van biochar het ‘n veroorsaak dat die grond pH, uitruilbare basiese katione, fosfor en waterhouvermoë beduidend toegeneem het. ‘n Koringpotproef was uitgevoer vir 12 weke en ook tot volwassenheid (wat op 22 weke bereik was) om die effek van die biochar op die sanderige grond teen die vyf verskillende toedieningsvlakke te bepaal. Daar was behandelings met en sonder die bykomstige toediening van ‘n wateroplosbare breë-spektrumkunsmis. Resultate toon dat die toediening van biochar teen lae vlakke koringbiomassa produksie verbeter. Die optimale biochar toedieningsvlak in die koringpotproef is 0.5 % (omtrent 10 t ha-1 tot ‘n diepte van 15 cm) vir die bemeste behandeling (21 % biomassa toename), en 2.5 % (omtrent 50 t ha-1 na ‘n diepte van 15 cm) vir onbemeste behandelings (29 % biomassa toename). Aangesien die meeste biochars alkalies is en ‘n hoë C:N verhouding besit, moet sorg gedra word wanneer dit op swak-gebufferde of lae N-houdende sanderige gronde toegedien word. Die resultate het aangedui dat die biochar versigtig aangewend moet word om grond oorbekalking te voorkom. In die tweede studie, was kolomme gepak met 2.0 kg van die sanderige grond gemeng met biochar (0, 0.05, 0.5, 2.5 en 10.0 % w/w) om die effek van biochar op die loging die anorganiese stikstof kunsmis oor ‘n tydperk van 6 weke om vas te stel. Daar is gevind dat biochar (0.5, 2.5 en 10.0 % w/w) die loging van ammonium (12, 50 en 86 % onderskeidelik) en nitraat (26, 42 en 95 % onderskeidelik) op sanderige grond aansienliek verminder. Verder, het biochar (0.5 %) die loging van basiese katione, fosfor en mikrovoedingstowwe aansienlik verminder. Hierdie studie het die potensiaal van biochar as verbeteringmiddel van suur, sanderige grond gedemonstreer. Ons bevindinge dui daarop aan dat ‘n toepassing vlak van 10 t ha-1 moet nie oorskry word nie wanneer biochar op hierdie gronde toegedien word. Die toediening van biochar op sanderige grond kan die loging van voedingstowwe aansienlik verlaag.

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Dube, Ernest. "Soil fertility enhancement through appropriate fertilizer management on winter cover crops in a conservation agriculture system." Thesis, University of Fort Hare, 2012. http://hdl.handle.net/10353/d1001044.

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A study was carried out to determine the effects of oat (Avena sativa) and grazing vetch (Vicia darsycapa) winter cover crops and fertilizer application on SOM, phosphorus (P) pools, nutrient availability, nutrient uptake, maize yield and seedbanks of problematic weeds in an irrigated maize-based conservation agriculture (CA) system. A separate experiment was carried out to investigate the effects of the winter cover crops on nitrogen (N) management, N use efficiency and profitability. After four years of continuous rotation, the winter cover crops significantly (p<0.05) increased particulate SOM and hot water soluble carbon in the 0 – 5 and 5 – 20 cm soil depths. When fertilized, oat was better able to support SOM sequestration in water stable aggregates at 0 – 20 cm whilst grazing vetch was more effective at 20 – 50 cm. Where no fertilizer was invested, there were significant (p<0.01) reductions in biomass input and SOM on oat-maize and weedy fallow-maize rotations whereas vetch-maize rotations did not respond, both at 0 – 5 and 5 – 20 cm. Targeting fertilizer to the winter cover crop required less fertilizer, and yet gave a similar SOM response as targeting the fertilizer to the maize crop. In addition to increasing SOM in the surface soil (0 – 5 cm), the winter cover crops significantly (p<0.05) increased labile pools of P, including microbial P. The cover crops also significantly (p<0.05) increased maize P concentration during early growth, extractable soil P, Cu, Mn, and Zn but had no effect on Ca and K. Grazing vetch increased soil mineral N but reduced extractable soil Mg. Without fertilizer, there were sharp declines in maize grain yield on oat and weedy fallow rotations over the four year period, but less so, on the grazing vetch. Grazing vetch increased maize growth, grain yield response to N fertilizer, nitrogen use efficiency (NUE) and profitability for fertilizer rates below 180 kg N ha-1. Oat effects however on maize yield and NUE were generally similar to weedy fallow. Based on the partial factor productivity of N, the highest efficiencies in utilization of fertilizer N for maize yield improvement under grazing vetch and oat are obtained at 60 kg N ha-1 and would decline thereafter with any increases in fertilizer application rate. Grazing vetch gave N fertilizer replacement values of up to 120 kg N ha-1 as well as the highest marginal rates of return to increasing N fertilizer rate. The cover crops were more effective than the weedy fallow in reducing seedbank density of Digitaria sanguinalis, Eleusine indica, Amaranthus retroflexus and Datura stramonium at 0 – 5 cm soil depth, causing weed seed reductions of 30 - 70%. The winter cover crops however, selectively allowed emergence of the narrow leafed weeds; Cyperus esculentus and Digitaria sanguinalis in the maize crop. The findings of this study suggested that grazing vetch is suited for SOM improvement in low fertilizer input systems and that fertilizer is better invested on winter cover crops as opposed to maize crops. Oat, on the other hand, when fertilized, would be ideal for C sequestration in water stable aggregates of the surface soil. Grazing vetch is ideal for resource poor farmers who cannot afford mineral fertilizers as it gives grain yield improvement and high fertilizer replacement value. Grazing vetch can produce enough maize yield response to pay its way in the maize-based systems and oat may not require additional N than that applied to the weedy fallow. Phosphorus and Zn are some of the major limiting essential plant nutrients on South African soils and the winter cover crops could make a contribution. The cover crops also hasten depletion of some problematic weeds from seedbanks, leading to reduced weed pressure during maize growth.

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Röing, Kristina. "Soil nitrogen fluxes in Swedish and Nigerian agricultural systems /." Uppsala : Dept. of Soil Sciences, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200557.pdf.

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Hedlund, Anna. "Nutrient management in smallholder peri-urban farming systems : a case study in southern Vietnam /." Uppsala : Dept. of Soil Sciences, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/9212291.pdf.

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Mpabanga, Nkosi. "The effect of phosphorus fertilizer application on growth, biomass and nutritive value of Pigeon pea (Cajanus cajan (L.) Millsp.) varieties in Alice, South Africa." Thesis, University of Fort Hare, 2017. http://hdl.handle.net/10353/6180.

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Low soil fertility has been identified to be among the major causes of low pasture quantity and quality. Scarcity of high quality forage mainly during the dry season threatens animal productivity in some areas of South Africa, thus the need for identifying livestock feed alternatives. Pigeon pea is a woody legume that has continually been an important shrub in agroforestry and can provide protein-rich livestock feed during times of shortage. Soil fertility to support the production of pigeon pea can be enhanced by application of fertilisers. Therefore, this study was carried out firstly, to determine the effect of phosphorus fertiliser on the growth performance and biomass production of three pigeon pea varieties, and secondly, to investigate the influence of phosphorus application on the nutrient and anti-nutrient content of three pigeon pea varieties. The field experiment was done at the University of Fort Hare research farm in Alice, South Africa. The factors investigated were three pigeon pea varieties namely Chitedze 1, Chitedze 2 and CIMMYT 1 and three phosphorus fertiliser application rates of 0, 40 and 60 kg P/ha. The study was a 3× 3 factorial experiment set up in a randomised complete block design and was replicated three times. The growth performance attributes evaluated in this study include the number of branches, plant height and root collar diameter. Root collar diameter was not significantly (p>0.05) different among the pigeon pea varieties and phosphorus levels. Likewise, the application of phosphorus was not significant (p>0.05) on plant height and the number of branches of all the varieties. However, when P level was varied, there were significant differences among the varieties, and so were the interaction (p<0.05) between variety and phosphorus on plant height and the number of branches. There was no significant (p>0.05) difference among the phosphorus levels on the fresh leaf yield of Chitedze 1 and Chitedze 2, but phosphorus application at 40 kg P/ha increased the fresh leaf yield of CIMMYT 1. Phosphorus application at 60 kg P/ha increased (p<0.05) the dry matter content of Chitedze 1 and Chitedze 2. Furthermore, the results of the trial show that the application of 40 kg P/ha and 60 kg P/ha increased (p<0.05) the dry matter yield of the varieties CIMMYT 1 and Chitedze 2, respectively. The effects of phosphorus application on the nutrient composition of the three pigeon pea varieties varied. The composition of hemicellulose of all the varieties was significantly (p<0.05) increased by the application of 40 kg P/ha. Conversely, the concentration of crude protein, phosphorus, copper and iron, and the calcium to phosphorus ratio of all the pigeon pea varieties was not significantly (p>0.05) affected by phosphorus application and there was no interactive effect of variety and phosphorus. The proximate compositions of fat, total non-structural carbohydrates, ash, neutral detergent fibre, acid detergent fibre, cellulose, neutral detergent insoluble nitrogen, acid detergent insoluble nitrogen of the pigeon pea varieties varied significantly (p<0.05) at different phosphorus application levels. There was an interactive (p<0.05) effect of variety and the level of phosphorus on the concentration of calcium (Ca), potassium (K), magnesium (Mg), sodium, zinc, manganese, and the K/(Ca+Mg) ratio. The digestible dry matter, dry matter intake and the relative feed value were significantly (p<0.05) different among the pigeon pea varieties at varying phosphorus levels. The anti-nutrient composition of Chitedze 2 was not significantly (p>0.05) affected by phosphorus application but the concentration of phenols and saponins of Chitedze 1 was significantly (p<0.05) increased when 60 kg P/ha was applied, but these anti-nutrients were reduced (p<0.05) for CIMMYT 1 at 60 kg P/ha. It can be concluded that phosphorus application influences the biomass production and chemical composition while the optimum phosphorus level vary among the pigeon pea varieties.

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Spankie, Heather A. (Heather Anne). "Fertilization effects on soil and foliar nutrient status in relation to declining sugar maple (Acer saccharum Marsh.)." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59435.

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Eight fertilization treatments were applied in May 1987 to two sugar maple stands. This was followed by soil and foliar sampling and decline evaluation in mid-summer 1987 and foliar sampling and decline evaluation in mid-summer 1988.
Trees selected for sampling purposes on average showed evidence of light to moderate decline. Foliar nutrient status was found to be poor at both sites, with Ca, Mg, K and P at or very near to deficiency levels although foliar molar ratios for Ca/K, Ca/Mg and Ca/Al were well within their respective critical ranges.
Fertilization had significant effects on several elemental concentrations of the soil and foliage at the Entrelacs sites. Effects in general showed an increase in base cation concentrations when those elements were supplied in high enough quantities in the fertilizers. Fertilization had no significant effect on decline levels.
Positive correlations were obtained between soil B horizon levels and foliar Ca, Mg and K and between soil FH horizon levels and foliar K and Al.

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Liu, Ge 1961. "Effects of soil fertility and time on the leaf physiology of sugar maple in relation to forest decline." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61218.

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Two studies were conducted to assess physiological responses of declining sugar maple (Acer saccharum Marsh.) in southern Quebec to wet acidic precipitation and increased soil fertility. Leaves of sugar maple were relatively acidic, had low external neutralization capacity (ENC = 5.1 $ mu$equiv. H$ sp{+} rm g sp{-1}$) and buffering capacity index (BCI = 103 $ mu$equiv. H$ sp{+} rm g sp{-1}$), and higher ENC/BCI compared to three other tree species. Deciduous species showed a higher BCI and a lower ENC in August. Our results suggest that sugar maple may be relatively sensitive to wet acidic deposition and that leaf buffering capacity is related to photosynthesis potential and seasonal change in foliar Ca concentration. Foliar analyses revealed that fertilization with a mixture of K, Ca, and Mg had significant effects on leaf concentrations of K, free amino acids (FAA) and the ratios of N to K, and FAA to N after two growing seasons. Our results suggest that base cation fertilization improved the N and K status of sugar maple and that leaf carbon partitioning appeared to be more dynamic in fertilized trees.

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15

Magnusson, Margareta. "Soil pH and nutrient uptake in cauliflower (Brassica oleracea L. var botrytis) and Broccoli (Brassica oleracea L. var. italica) in northern Sweden : multielement studies by means of plant and soil analyses /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5750-5.pdf.

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16

Gnankambary, Zacharia. "Compost and fertilizer mineralization effects on soil and harvest in parkland agroforestry systems in the south-Sudanese zone of Burkina Faso /." Umeå : Dept. of Forest Ecology and Management, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/2007129.pdf.

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17

Sinak, Sokrat. "Influence comparée de la pédogenèse et des pratiques agricoles sur la fertilité phosphorique des sols." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL108N.

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La fertilité phosphorique des sols agricoles dépend de facteurs naturels et anthropiques dont l'influence respective est mal connue. Ce travail était destiné à identifier, à différentes échelles (pays, région, parcelle, profil et interface sol-racine), les facteurs déterminant la fertilité phosphorique. L'Albanie a servi de support expérimental en raison des grandes diversités pédologiques (roche mère, relief et type de sol) et de pratiques culturales (fertilisation minérale ou organique et type d'exploitation) rencontrées. La fertilité P de 256 échantillons de terre a été caractérisée par la méthode des échanges isotopiques et par extraction Olsen, Machigin et résine cl#. L'évolution de la fertilité à l'interface sol-racine a été étudiée en présence de deux engrais phosphates insolubles dans l'eau (phosphate naturel et scories de déphosphoration) en présence de Zea mays. Les données ont permis de cartographier la fertilité P de l'Albanie en fonction des facteurs intensité, quantité et capacité ainsi que des paramètres cinétiques décrivant le flux moyen des ions phosphate entre la phase solide et liquide du sol. La pédogenèse a une influence nettement plus importante que l'intensification agricole. A l'échelle de la parcelle, la position du profil dans la toposéquence détermine sa fertilité. La fertilité P est surtout portée par la fraction argileuse et l'organisation structurale détermine l'accessibilité des ions phosphate. Au voisinage de la racine, la fertilité P est rapidement modifiée par un épuisement local et une nouvelle répartition du P à l'intérieur des compartiments du sol. L'altération des engrais P dépend de leur nature physico-chimique, du type de sol et de l'activité racinaire. En conclusion, la fertilité P est fortement liée à la composition minéralogique du sol (fraction argileuse, oxydes de fer) et des facteurs susceptibles de la modifier (érosion, terrassement). L'activité biologique (racines) peut altérer fortement mais localement et temporairement la biodisponibilité du phosphore. La prévision de l'évolution de la fertilité phosphorique des sols agricoles nécessite de raisonner en terme de flux

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18

Gama, Marcos André Piedade. "Dinâmica do fósforo em solo submetido a sistemas de preparo alternativos ao de corte e queima no nordeste paraense." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-02082002-171225/.

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Na Amazônia, o sistema de cultivo predominante é o da agricultura de corte-queima, desenvolvido pelos pequenos agricultores que trabalham exclusivamente com mão-de-obra familiar e que são responsáveis pela maior parte da produção agrícola regional. Esse sistema, no entanto, deixa de ser sustentável quando desenvolvido em áreas como a do nordeste paraense, onde a densidade populacional é crescente e a dispo-nibilidade de terra aos agricultores é pequena, sendo por isso, considerado como uma das causas do crescente desmatamento florestal e degradação dos solos. Além disso, outros fatores contribuem para o insucesso da agricultura de corte-queima, como por exemplo, a generalizada deficiência de fósforo (P), comum nos solos da região tropical e que possuem alta capacidade de retenção desse elemento. Esta pesquisa foi realizada na região nordeste paraense com o objetivo de avaliar as alterações na fertilidade do solo, no teor de P orgânico (Po) e na adsorção de fósforo em duas áreas submetidas a diferentes tempos de pousio (quatro anosVS4a; e dez anosVS10a) e a diferentes métodos de preparo do solo. Os tratamentos, em número de cinco, consistiram de duas formas de preparo da terra (1- corte e queima da vegetação; e 2- Corte, trituração e deposição da vegetação de pousio sobre o solo, como cobertura morta ou "mulching") combinadas com aplicação ou não de fertilizante NPK. O quinto tratamento (testemunha) consistiu de uma área na qual se manteve a vegetação de pousio. Amostras de solo foram coleta-das em quatro períodos: antes do preparo inicial da área (outubro de 1994); no início (janeiro de 1997) e no final do segundo ciclo de cultivo (julho de 1998); e próximo ao final do segundo período de pousio (julho de 2000). Para todos os métodos de preparo do solo houve manutenção ou aumentos no nível de fertilidade do solo, avaliada pela matéria orgânica, P-resina, pH em CaCl2, saturação por bases e por alumínio trocável, bem como redução da capacidade de adsorção de P. O método de preparo do solo que não utiliza a queima da vegetação (mulching) mostrou-se superior ao método tradicional de corte-queima, uma vez que não degradou a fertilidade do solo, reduziu a capacidade de adsorção de P e aumentou a quantidade de P orgânico total. A utilização do fertilizante NPK contribuiu para manter o teor de P-resina e de P orgânico total do solo ao longo dos seis anos de estudo, independentemente da utilização ou não do fogo no preparo do solo. A sustentabilidade do sistema foi maior na área com tempo de pousio de 10 anos e com maior quantidade de biomassa vegetal do que na área com 4 anos de pousio.
In Amazonia, Brazil, the most important cultivation system is the slash and burn agriculture or shifting agriculture. This system was developed by small farmers that use exclusively family labor and are responsible for most of the agricultural production in the region. However, this system is unsustainable when developed in areas such as the northeast of the State of Pará, where population is growing and land availability to farmers is small; such facts have been considered to be among the causes of the increasing deforested areas and degraded soils. In addition, other factors contribute to the failure of the shifting agriculture, as the widespread phosphorus deficiency (P), common in the tropical soils with high capacity of phosphorus retention. This research was carried out in the northeast of the State of Pará, Brazil, to study alterations in the soil fertility, in the organic P (Po) content and in the phosphorus adsorption in two areas submitted to different fallow periods (four years - VS4a; ten years - VS10a) and different methods of soil preparation. Treatments, in a number of five, consisted of two methods of soil preparation (1- slash and burn of the vegetation; and 2- slash, chop and deposition of the fallow vegetation on the ground to act as a mulch), combined with application or not of NPK fertilizer. The fifth treatment (control) consisted of an area in which the fallow vegetation was maintained. Soil samples were collected in four periods: before the preparation of the area (October of 1994); at the beginning (January of 1997) and end of the second cultivation cycle (July of 1998); and almost at the end of the second fallow period (July of 2000). All soil preparation methods maintained or increased the soil fertility, evaluated by the content of organic matter and resin-P, pH in CaCl2, soil base saturation and exchangeable Al content, as well as decreased phosphorus adsorption in the soil. Clearing the soil without burning was superior to the traditional slash and burn method, since soil fertility was not affected, phosphorous adsorption decreased and the amount of organic P increased. The application of NPK fertilizer helped in maintaining the content of resin-P and total organic P in the soil during the study period of six years, whether or not fire was used in the soil clearing process. System sustainability was higher in the area submitted to a fallow period of 10 years and containing a larger amount of plant biomass than in the area where the fallow period was only 4 years.

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Teklay, Tesfay. "Organic inputs from agroforestry trees on farms for improving soil quality and crop productivity in Ethiopia /." Umeå : Dept. of Forest Ecology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/2005122.pdf.

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20

Otto, Rafael. "Desenvolvimento radicular e produtividade da cana-de-açúcar relacionados à mineralização do N do solo e à adubação nitrogenada." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-23032012-171851/.

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A cana-de-açúcar têm despertado o interesse mundial como fonte alternativa de energia renovável. Para que a cultura se estabeleça globalmente como alternativa à produção de bioenergia, questões de sustentabilidade devem ser consideradas. Nesse sentido, a fertilização nitrogenada desempenha papel fundamental, pois influencia a produtividade do canavial e, por outro lado, pode ocasionar impactos ao ambiente se manejada inadequadamente. O objetivo deste estudo foi elucidar questões recentemente levantadas a respeito do manejo da cana-de-açúcar em áreas colhidas sem queima, tais como (i) a colheita mecanizada sucessiva poderá ocasionar degradação física do solo que comprometerá o desenvolvimento do sistema radicular da cultura? (ii) a aplicação de elevadas doses de N sobre a palha e sem o cultivo das soqueiras irá alterar a arquitetura radicular da cana-de-açúcar? e (iii) é possível desenvolver métodos diagnósticos de N do solo para dar suporte ao manejo da adubação nitrogenada da cana-de-açúcar? Três estudos foram desenvolvidos para elucidar as questões acima descritas. Do primeiro capítulo conclui-se que a colheita mecanizada sucessiva do canavial, sem o cultivo da soqueira, altera as propriedades físicas da camada superficial do solo, com efeito negativo na densidade radicular da cultura. Valores de resistência à penetração (RP) inferiores a 0,75 MPa não comprometem o crescimento radicular da cana, porém RP entre 0,75 a 2,0 MPa diminui a densidade radicular e, a partir de 2,0 MPa, há restrição severa ao crescimento radicular. O segundo capítulo apresentou a variação no crescimeno radicular da cana-de-açúcar no ciclo de primeira soqueira, em duas áreas (Usina Santa Adélia, USA e São Martinho, USM) e em função de doses de N aplicadas no plantio (0 ou 120 kg ha-1 N) e na soqueira (0 e 150 kg ha-1 N). O efeito da adubação nitrogenada no crescimento de raízes da cana-de-açúcar variou entre as áreas. Em ambos experimentos, a variação na biomassa de raízes durante o ciclo foi mais influenciada pelas propriedades dos solos do que pelas doses de N. Na área da USM a adubação nitrogenada de soqueira aumentou a densidade de raízes na camada superficial (0-0,2 m) e próximo às plantas (<0,3 m), enquanto que no experimento da USA nenhum efeito foi observado. Não houve efeito residual da adubação nitrogenada de plantio na biomassa e no acúmulo de N nas raízes e na parte aérea. A aplicação de altas doses de N na superfície do solo e sobre a palha não alterou significativamente a arquitetura do sistema radicular da cultura. O terceiro capítulo avaliou a resposta à adubação nitrogenada de soqueira em dez experimentos de campo no Estado de São Paulo. Os solos foram divididos em altamente responsivo, moderadamente responsivos e não responsivos. Estudos subsequentes em laboratório mostraram que os solos diferiram quanto à capacidade de fornecimento de N. A mineralização bruta separou adequadamente os solos quanto à responsividade ao N, enquanto o testes químicos Illinois Soil Nitrogen Test e Destilação a Vapor Direta apresentaram resultados promissores, podendo ser realizados em laboratórios de rotina de análise de solo em um dia de serviço. Estudos adicionais devem ser realizados para verificar a viabilidade de testes de N no solo para melhorar o manejo da adubação nitrogenada da cana-de-açúcar.
Sugarcane has been a promissing crop for renewable energy production around the world. In order to establish sugarcane as a globally alternative for bioenergy production, sustainability issues should be considered. Synthetic nitrogen (N) fertilizers plays a key role in sugarcane production but, if used improperly, causes environmental threats. The goal of this study was to elucidate current questions about sugarcane management in unburned areas, as follows (i) the sucessive mechanical harvesting could decrease the soil physical quality and thus compromise root system development? (ii) applying high N rates over the sugarcane straw, without further cultivation would modify the sugarcane root architecture? and (iii) is it possible to use soil N mineralization indexes in order to improve the N management of sugarcane? Three studies were carried out in order to elucidate the aforementioned issues. The findings of the first study is that successive mechanical harvesting without further soil cultivation modify the physical properties of the superficial soil layer, with negative effects on root density. No limitations on root growth occurs when penetration resistance (PR) is lower than 0,75 MPa, but PR from 0,75 to 2,0 MPa decreases root density and PR higher than 2,0 MPa causes severe restriction to root growth. The second study shows the variation in sugarcane root growth over the first ratoon cycle in two trials (Santa Adelia Mill, USA and Sao Martinho Mill, USM) as related to N rates applied at planting (0 or 120 kg ha-1 N) and to the ratoon (0 and 150 kg ha-1N). The effect of N fertilizer addition in sugarcane rooting varied between sites. In both trials, the variation in root biomass was more influencied by soil properties than by N supply. At USM site, ratoon N fertilization increased root density in the superficial soil layer (0-0,2 m) and close to the plants (<0,3 m), while at the SA site no effect of N was observed. There was no carry over effect from N applied at planting in the evaluated parameters (root and shoot biomass and N accumullation). Applying high N rates over the sugarcane straw does not affect significantly the sugarcane root architecture. The third study assess the N fertilizer response of sugarcane in ten field trials at Sao Paulo State. The soils were categorized in highly responsive, moderately responsive and non-responsives to N fertilization. Further studies developed under laboratory conditions showed differences in the soil\'s N supplying power. The gross mineralization succesfully identified the soils responsiveness to N, and the chemical tests Illinois Soil Nitrogen Test and Direct Steam Distilation showed promising results and can be performed in routine soil analysis in one work day. Further studies are warranted to assess the feasibility in using soil N tests to improve N fertilizer management in sugarcane.

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Mariano, Eduardo. "Mineralização e disponibilidade de nitrogênio em solos cultivados com cana-de-açúcar." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-20012011-034436/.

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A colheita sem queima da cana-de-açúcar favorece o acúmulo de resíduos na superfície, aumentando os teores de C e N no solo. A quantificação do N mineralizado é de grande interesse, pois a matéria orgânica do solo (MOS) é o principal reservatório de N para as plantas. Embora a mineralização da MOS forneça quantidades apreciáveis de N mineral, a fertilização nitrogenada se faz necessária para a manutenção de produtividades elevadas na cultura. Devido à espessa camada de palha, a aplicação dos fertilizantes nitrogenados é realizada geralmente sobre o solo, intensificando o processo de volatilização de NH3 quando a uréia é utilizada. A primeira parte deste estudo avaliou e comparou métodos biológicos para estimativa do N mineralizável em solos cultivados com cana-de-açúcar. Foram utilizadas amostras de cinco solos, coletadas nas profundidades de 0-20, 20-40 e 40-60 cm. As amostras de solo foram incubadas aerobiamente a 35°C, durante 32 semanas, e anaerobiamente (waterlogged) a 40°C, por 7 dias. Os teores de areia, silte e argila foram os melhores índices para estimar o N mineralizável do solo. Na incubação aeróbia de longa duração, o N mineralizado acumulado apresentou maior sensibilidade em relação N potencialmente mineralizável para a predição da mineralização líquida de N. A incubação anaeróbia de curta duração pode ser utilizada em rotina de laboratórios. A manutenção do N-NH4+ pré-existente nas amostras proporcionou melhores estimativas do N mineralizável do solo com o método da incubação anaeróbia. O segundo experimento avaliou a variação temporal do N inorgânico em um LATOSSOLO VERMELHO distrófico (LVd) e LATOSSOLO VERMELHO-AMARELO eutrófico (LVAe) relacionada à fertilização nitrogenada em soqueiras de cana-de-açúcar. Os tratamentos constaram das fontes: Ajifer®, cloreto de amônio, nitrato de amônio, uréia e YaraBela NitromagTM, na dose de 100 kg ha-1 de N; uréia nas doses: 50, 100, 150 e 200 kg ha-1 de N e uma testemunha. No LVd, o Ajifer® e YaraBela NitromagTM inicialmente aumentaram os teores de N-NH4+ na camada de 0-20 cm, enquanto que a aplicação de YaraBela NitromagTM, nitrato de amônio, Ajifer® e as doses de 150 e 200 kg ha-1 de N-uréia incrementaram a quantidade de N-NO3- nas profundidades de 0-20 e 20-40 cm. Após 44 dias, o N mineral do solo decresceu abruptamente devido à absorção pelas plantas e imobilização microbiana. A aplicação de N no LVAe não modificou a disponibilidade do nutriente no solo. O terceiro ensaio avaliou a eficiência de um coletor aberto na quantificação do N-NH3 volatilizado da uréia aplicada sobre a palhada de cana-de-açúcar. As perdas de N-NH3 foram estimadas pelo coletor semi-aberto estático (CSA) e coletor aberto com absorvedor envolto em película de politetrafluoroetileno (CA). A uréia foi aplicada superficialmente e em faixa, em tratamentos que corresponderam às doses de 50, 100, 150 e 200 kg ha-1 de N. O CA não alterou a quantidade de N-NH3 volatilizada em relação ao CSA. A eficiência do CA variou de forma não-linear, em função da taxa de N-NH3 volatilizado, com valor médio de 58,4% na faixa de 100 a 200 kg ha-1 de N-uréia.
Harvesting sugarcane without burning favors the straw surface accumulation and C and N storage. Quantification of N mineralization is of great importance because soil organic matter (SOM) is the major N pool for plants. Although SOM mineralization provide appreciable amounts of mineral N, the fertilization is necessary for maintaining high yields. Due to the thick straw layer, the N fertilizer is applied normally above the residue, enhancing the NH3 volatilization process when urea is used. The first part of this study evaluated and compared biological methods to estimate N mineralization in soils cropped with sugarcane. Five soils samples were collected at 0-20, 20-40 and 40-60 cm depths. The soil samples were incubated aerobically at 35°C for 32 weeks, and anaerobic (waterlogged) at 40°C for 7 days for determination of net soil N mineralization. The sand, silt and clay fractions were the best indices for estimating soil N mineralization. The mineralized N accumulated in the long-term aerobic incubation showed higher sensitivity towards N mineralization potential to predict net N mineralization. The short-term anaerobic incubation can be used in laboratories routine. Maintaining the pre-existing NH4+-N of samples was advantageous to improve the mineralizable soil N estimation with the anaerobic incubation method. The second experiment evaluated the temporal inorganic N variation in a Typic Hapludox (TH) and Typic Eutrustox (TE), related to N fertilization of a sugarcane ratoon. The treatments were the sources: Ajifer®, ammonium chloride, ammonium nitrate, urea and YaraBela NitromagTM, at 100 kg ha-1 N dose; urea rates: 50, 100, 150 and 200 kg ha-1 N and a control. In TH, the Ajifer® and YaraBela NitromagTM initially increased the levels of NH4+-N at the 0-20 cm depth, while Ajifer®, ammonium nitrate, YaraBela NitromagTM and rates of 150 and 200 kg ha-1 urea-N raised the amount of NO3--N at 0-20 and 20-40 cm depths. After 44 days, mineral N decreased sharply due to the N uptake by plants and microbial immobilization. The N sources and N-urea rates in TE did not change the soil N availability. The third trial evaluated the effectiveness of an open collector for quantification of NH3-N volatilized from urea applied on sugarcane trash blankets. The NH3-N losses were estimated by semi-open static collector (SOC) and open collector absorber wrapped in polytetrafluoroethylene film (OC). Urea was applied in band on soil surface at rates of 50, 100, 150 and 200 kg ha-1 N. The OC did not alter the amount of NH3-N in relation to SOC. The OC effectiveness ranged non-linearly with the NH3-N rate and showed an average of 58.4% on the range of 100 to 200 kg ha-1 urea-N.

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Fischer, Peter. "The degree of phosphorus saturation of agricultural soils in Brazil and Germany: New approaches for risk assessment of diffuse phosphorus losses and soil phosphorus management." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19589.

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Diffuse Phosphor (P)-Austräge aus der Landwirtschaft tragen zur Gewässereutrophierung bei. Der Phosphorsättigungsgrad (DPS) ist ein etablierter Parameter, um das P-Austragsrisiko aus Böden zu erfassen. Ein bodentypunabhängiger Ansatz, der die Abschätzung des DPS durch eine einfache Standardmethode wasserlöslichen P (WSP) ermöglicht (WSP-DPS-Ansatz), wurde an europäischen Böden entwickelt. In der Dissertation wurde dieser Ansatz erstmalig: i) an tropischen Böden getestet und ii) dazu verwendet P-Austragsrisiken von Boden-P-Monitoringdaten und von landwirtschaftlichen Institutionen empfohlenen P-Gehalten abzuleiten. Neben dem DPS wurde der Einfluss der in Brasilien gängigen anorganischen Oberflächendüngung auf das Austragsrisiko mittels Laboranalysen und Feldstudien erfasst. Die Bodentypunabhängigkeit des WSP-DPS-Ansatzes wurde für Böden Brasiliens bestätigt. Infrarotspektroskopische Analysen lieferten eine Erklärung für relativ niedrige gelöste P-Konzentrationen im Oberflächenabfluss von Oxisols. Pedotransferfunktionen zwischen WSP und Methoden, die in Brasilien und Deutschland zur Abschätzung pflanzenverfügbaren P verwendet werden, ermöglichten die Berechnung von DPS-Werten aus Monitoringdaten. Erste DPS-Karten zeigten relative geringe Austragsrisiken für das Untersuchungsgebiet in Brasilien und hohe Risiken für Deutschland, die teilweise durch unterschiedliche empfohlene Boden-P-Gehalte erklärbar waren. Um mit einer einfachen und kosteneffizienten Methode sowohl die landwirtschaftliche Produktion als auch den Gewässerschutz zu berücksichtigen, wurden die Wasser- und CaCl2-Methode zur Abschätzung von pflanzenverfügbarem P mit dem WSP-DPS-Ansatz kombiniert. Dieser Ansatz könnte helfen die Herausforderungen zu lösen mit denen die Menschheit in den nächsten Jahrzehnten bezüglich P in der Landwirtschaft konfrontiert sein wird: Einer effizienten Nutzung der limitierten Ressource P und dem Schutz der Gewässer vor diffusen P-Einträgen.
Diffuse phosphorus (P) losses from agriculture contribute to the eutrophication of surface waters. The degree of P saturation (DPS) is an established parameter for assessing the risk of P loss from agricultural soils. A soil type-independent approach for estimating the DPS by a simple standard method of water-soluble phosphorus (WSP; the WSP-DPS approach) was developed on European soils. In the thesis, the WSP-DPS approach was for the first time: i) tested on tropical soils and ii) used to derive P loss risks from soil P monitoring data and from recommended soil P levels by agricultural institutions. In addition to DPS, laboratory analyses and field studies were combined to assess the risk of P loss associated with the superficial application of inorganic fertilizer, which is commonly used in Brazil. The soil type-independency of the WSP-DPS approach was confirmed for soils of Brazil. Infrared spectroscopic analyses provided an explanation for the relatively low dissolved P concentrations in the surface runoff of Oxisols. Pedotransfer functions were determined between WSP and methods used to estimate plant-available P in Brazil and Germany and allowed for the transformation of soil P monitoring data into DPS values. The first DPS maps revealed relatively low P loss risks for the investigation area in Brazil and high risks for Germany. This difference was partly explainable by the recommended soil P levels in the two countries. To consider both agricultural production and the protection of surface waters in soil P management with a simple and cost-effective method, the soil test methods of using water and CaCl2 to estimate plant-available P and the WSP-DPS approach were combined. This approach could help to solve the challenges humanity faces regarding P in agriculture in the coming decades: An efficient use of the limited resource P and the protection of surface waters from diffuse P losses.

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23

Knowles, Tim C., Jack Watson, and Vic Wakimoto. "Late Season Nitrogen Fertilizer for Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/197237.

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Field experiments were conducted during the 1996 and 1997 growing seasons in Mohave Valley to determine the effect of late season nitrogen (N) fertilizer applications on top crop yield potential of upland cotton. A long season production system utilizing late season nitrogen (N) applications through peak bloom (August) was compared to a short season production system in which N was applied through mid-bloom (June). Mid-season N applications were based on UA guidelines utilizing plant mapping and petiole nitrate data for the short season production system.

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Silvertooth, J. C., E. R. Norton, and S. E. Ozuna. "Foliar Fertilizer Evaluation on Upland Cotton, 1997." College of Agriculture, University of Arizona (Tucson, AZ), 1998. http://hdl.handle.net/10150/210383.

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A single field experiment was conducted in 1997 at the University of Arizona Yuma Valley Agricultural Center. The purpose of the experiment was to evaluate foliar applications of Macro Sorb (L form amino acids) and KeyPlex (chelated micronutrients and alpha keto amino acids) foliar fertilization materials on Upland cotton. Treatments consisted of various rates and times of application of the foliar materials based upon manufacturer recommendations. Results from this single experiment revealed no differences among treatments with respect to in-season plant measurements, tissue N concentrations, or lint yield.

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Navarro, J. C., J. C. Silvertooth, and A. Galadima. "Fertilizer Nitrogen Recovery in Irrigated Upland Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/211129.

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Field studies were carried out for the purpose of evaluating fertilizer nitrogen (N) recovery of upland cotton by use of the difference technique. The treatments under study included : i) check (no fertilizer N applied), ii) standard approach (preplant and sidedress), iii) feedback approach (based upon soil and plant factors), and iv) 2X feedback approach. The studies were carried out at two locations Maricopa (MAC) and Marana (MAR). MAC is a low elevation location with a coarser textured soil compared to the MAR location. 'DPL-20' was the variety used in both locations, except for the early years at MAC where 'DPL-90' was used. The sources of fertilizer N were urea and ammonium sulphate, which were sidedress and split applied. In general, for the MAC location the final N fertilizer rates (NFR) applied were higher than for MAR due to higher yield potentials. The total N uptake increased as the NFR increased. The N use efficiency (NUE) values were reduced as NFR increased. The N fertilizer uptake (NFU) showed a decreasing pattern in the first years, and then an increasing trend; which was coupled with rather high amounts of N taken up in the check plot (soil N mineralized). When the N uptake in the check plot was high, NFU values were low, and vice versa. At MAC the N uptake in the check plot, apparently due to mineralized soil N revealed a slight increasing trend during the first years and then, after the fourth year, a rapid reduction of the mineralized soil N (check plot). A similar pattern was observed for MAR, although the total amount of N taken up was smaller compared to the MAC location.

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Souza, Richard Matos de. "Eficiência agronômica de fosfatos de rocha, via adubação corretiva, em um cambissolo cultivado com milho no Estado de Sergipe." Pós-Graduação em Agroecossistemas, 2013. https://ri.ufs.br/handle/riufs/6567.

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In the last decade, the adoption of technologies in corn crop provided a significant productivity and yield increase in Sergipe State, Brazil. In this state, soils classified as Inceptisols are very adequate for corn cropping. The only limitation presented by those soils is the low levels of available P for plants. Fertilization to increase soil P level through rock phosphates should be considered in order to increase P response to annual P fertilization in the row, which is related to the crop requirement. On the other hand, direct application of rock phosphates in soils which have pH (H2O) above 5,5 and a high calcium content, like those above mentioned, has not been recommended because they could slow down the dissolution of rock phosphates. A strip split plot in a complete randomized blocks design with four replications experiment, was set up in order to study the agronomic effectiveness of Bayóvar and Itafós rock phosphates applied for soil P correction in an Inceptisol with pH 6,0 and high calcium content. Rock phosphates and triple superphosphate, used as a reference source, were broadcasted in the main plots and incorporated by disk plowing. A main plot without soil P correction also was included in the study. In the subplots annual P application at rates of 0, 60 e 120 kg.ha-1 as triple superphosphate were accomplished in the planting rows. Corn was grown in the raining seasons of 2011 and 2012. Yield and P leaf content indicated that less P from annual application was needed in treatments corrected by those sources with higher P solubility. Mehlich-1 and mixed resin method removed more soil P from rock phosphates plots than the reference TSP plot. The relative agronomic effectiveness (RAE) of Bayóvar and Itafós rock phosphates were 77,19% and 45,66%, respectively, calculated based on two years.
Na última década, a modernização da tecnologia de cultivo do milho no Estado de Sergipe proporcionou significativos aumentos de produção e produtividade. Neste sentido, as áreas de Cambissolos vêm se destacando por serem muito adequadas a esta cultura, apresentando limitações somente quanto aos níveis de P. Uma das formas para contornar a baixa disponibilidade deste nutriente no solo pode ser a realização de uma adubação corretiva através de fontes fosfatadas alternativas de baixo custo e/ou solubilidade. Esta prática visa elevar o teor de P disponível no solo com a finalidade de propiciar uma melhor resposta da cultura às doses de P aplicadas no sulco de plantio. Desta forma, foi conduzido um experimento de dois anos para avaliar a eficiência agronômica dos fosfatos de Bayovar e Itafós, como fontes corretivas de P, em um Cambissolo Háplico Ta Eutrófico vertissólico, de elevado teor de cálcio trocável e pH em torno de 6. O delineamento experimental utilizado foi em blocos ao acaso, com parcelas subdivididas em faixas, e quatro repetições. As parcelas consistiam das adubações corretivas realizadas no primeiro ano com as fontes Fosfato Natural Reativo de Bayóvar, Fosfato de Rocha Itafós e superfosfato triplo (fonte de referência), na dose de 200 kg ha-1 de P2O5, e um tratamento sem correção. As subparcelas foram compostas pelos três níveis de adubação de manutenção, no sulco de plantio, aplicados anualmente através de superfosfato triplo, nas doses de 0, 60 e 120 kg.ha-1 de P2O5. No período avaliado, a produtividade de grãos e o teor de P na folha do milho indicaram menores necessidades de reposição de P para as plantas, conforme maior era a solubilidade da fonte corretiva aplicada ao solo. Com relação à determinação de P disponível no solo, tanto Mehlich-1 quanto a Resina de Troca Iônica removeram mais P do solo dos tratamentos em que os fosfatos naturais foram aplicados. O índice de eficiência agronômica médio dos fosfatos para os dois anos foi de 77,19 % e 45,66 % para o Bayóvar e Itafós, respectivamente.

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Ranko, Čabilovski. "Примена органских ђубрива у производњи јагоде." Phd thesis, Univerzitet u Novom Sadu, Poljoprivredni fakultet u Novom Sadu, 2015. https://www.cris.uns.ac.rs/record.jsf?recordId=90309&source=NDLTD&language=en.

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Органска ђубрива садрже готово све неопходне хранљиве елементе за гајене биљке, али имају значајно мању ефикасност од синтетичких ђубрива јер је садржај хранива неупоредиво нижи у односу на синтетичка, а облици у којима се налазе нису директно приступачни гајеним биљкама. Циљ истраживања био је да се испита утицај примене различитих органских ђубрива биљног и животињског порекла, као и течних ђубрива на хемијска својства земљишта, принос и квалитет јагоде у оквиру два система производње (малчирања земљишта). Пољски оглед је постављен као двофакторијални по методи/плану подељених парцела (Split/plot), са случајним распоредом третмана. Оглед се састојао од две главне парцеле на којима је испитан утицај два различита начина покривања земљишта (малч од сламе и црна полиетиленска фолија), док је на основним парцелама испитан утицај 13 различитих третмана ђубрења (контрола – без примене ђубрива, Ø; говеђи стајњак, С; говеђи стајњак + гуано (фолијарно), С+Г; говеђи стајњак + екстакт глистењака (фолијарно), С+ЕГ; глистењак, ГЛ; глистењак + гуано (фолијарно), ГЛ+Г; глистењак + екстракт глистењака (фолијарно), ГЛ+ЕГ; компост из производње печурака, К; компост из производње печурака + гуано (фолијарно), К+Г; компост из производње печурака + екстракт глистењака, К+ЕГ; гуано (фертигација + фолијарно), Г; екстракт глистењака (фертигација + фолијарно), ЕГ; стандардни програм ђубрења са минералним NPK ђубривима, NPK). У узорцима земљишта одређен је садржај минералних облика N, приступачних облика P, K, Ca, Mg, Fe, Mn, Cu, Zn и pH вредност земљишта. Поред параметара приноса јагоде (број цветова, прој плодова, просечна маса плода) у све три године плодоношења одређени су садржај макро и микроелемената у листу и плоду јагоде, и параметри квалитета плода јагоде (укупан садржај растворљиве суве материје, укупан садржај киселина, садржај укупних антоцијана, антиоксидативна активност, обојеност и чврстина плода). Резултати истраживања су показали да се продужено дејство примене чврстих и течних органских ђубрива на садржај хранљивих елемената у земљишту значајно разликује у зависности од елемента који се посматра. Примена чврстих органских ђубрива имала је највећи утицај на садржај приступачних облика фосфора, затим калијума, док је најмањи утицај имала на садржај минералних облика азота у земљишту. Изузев стајњака, примена органских ђубрива, у количини еквивалентној 170 kg N ha-1, није имала утицај на концентрацију приступачних облика секундарних макроелемената и микроелемената у земљишту. Земљиште покривено црном ПЕ фолијом одликовало се вишим садржајем минералних облика азота и приступачних облика Fe, Mn, Zn и Cu у односу на земљиште покривено сламом, у свим терминима мерења. Примена чврстих органских ђубрива приликом садње јагоде довела је до значајног повећања приноса, у односу на контролу, само у првој години плодоношења, док је у другој и трећој години плодоношења највиши принос јагоде остварен на третманима где су примењена NPK ђубрива и течни гуано. Третмани ђубрења имали су значајан утицај на минерални састав, садржај растворљиве суве материје, садржај киселина, садржај антоцијана, антиоксидативну активност и обојеност плода. Примена црне полиетиленске фолије, поред позитивног утицаја на садржај хранљивих елемената у земљишту, довела је до вишег приноса и квалитета плода јагоде у односу на примену сламе као малча. Rезултати показују да се применом црне фолије може значајно повећати ефикасност ђубрива чиме се смањује ризик од загађења животне средине и остварује већа економска добит у производњи јагоде.
Organska đubriva sadrže gotovo sve neophodne hranljive elemente za gajene biljke, ali imaju značajno manju efikasnost od sintetičkih đubriva jer je sadržaj hraniva neuporedivo niži u odnosu na sintetička, a oblici u kojima se nalaze nisu direktno pristupačni gajenim biljkama. Cilj istraživanja bio je da se ispita uticaj primene različitih organskih đubriva biljnog i životinjskog porekla, kao i tečnih đubriva na hemijska svojstva zemljišta, prinos i kvalitet jagode u okviru dva sistema proizvodnje (malčiranja zemljišta). Poljski ogled je postavljen kao dvofaktorijalni po metodi/planu podeljenih parcela (Split/plot), sa slučajnim rasporedom tretmana. Ogled se sastojao od dve glavne parcele na kojima je ispitan uticaj dva različita načina pokrivanja zemljišta (malč od slame i crna polietilenska folija), dok je na osnovnim parcelama ispitan uticaj 13 različitih tretmana đubrenja (kontrola – bez primene đubriva, Ø; goveđi stajnjak, S; goveđi stajnjak + guano (folijarno), S+G; goveđi stajnjak + ekstakt glistenjaka (folijarno), S+EG; glistenjak, GL; glistenjak + guano (folijarno), GL+G; glistenjak + ekstrakt glistenjaka (folijarno), GL+EG; kompost iz proizvodnje pečuraka, K; kompost iz proizvodnje pečuraka + guano (folijarno), K+G; kompost iz proizvodnje pečuraka + ekstrakt glistenjaka, K+EG; guano (fertigacija + folijarno), G; ekstrakt glistenjaka (fertigacija + folijarno), EG; standardni program đubrenja sa mineralnim NPK đubrivima, NPK). U uzorcima zemljišta određen je sadržaj mineralnih oblika N, pristupačnih oblika P, K, Ca, Mg, Fe, Mn, Cu, Zn i pH vrednost zemljišta. Pored parametara prinosa jagode (broj cvetova, proj plodova, prosečna masa ploda) u sve tri godine plodonošenja određeni su sadržaj makro i mikroelemenata u listu i plodu jagode, i parametri kvaliteta ploda jagode (ukupan sadržaj rastvorljive suve materije, ukupan sadržaj kiselina, sadržaj ukupnih antocijana, antioksidativna aktivnost, obojenost i čvrstina ploda). Rezultati istraživanja su pokazali da se produženo dejstvo primene čvrstih i tečnih organskih đubriva na sadržaj hranljivih elemenata u zemljištu značajno razlikuje u zavisnosti od elementa koji se posmatra. Primena čvrstih organskih đubriva imala je najveći uticaj na sadržaj pristupačnih oblika fosfora, zatim kalijuma, dok je najmanji uticaj imala na sadržaj mineralnih oblika azota u zemljištu. Izuzev stajnjaka, primena organskih đubriva, u količini ekvivalentnoj 170 kg N ha-1, nije imala uticaj na koncentraciju pristupačnih oblika sekundarnih makroelemenata i mikroelemenata u zemljištu. Zemljište pokriveno crnom PE folijom odlikovalo se višim sadržajem mineralnih oblika azota i pristupačnih oblika Fe, Mn, Zn i Cu u odnosu na zemljište pokriveno slamom, u svim terminima merenja. Primena čvrstih organskih đubriva prilikom sadnje jagode dovela je do značajnog povećanja prinosa, u odnosu na kontrolu, samo u prvoj godini plodonošenja, dok je u drugoj i trećoj godini plodonošenja najviši prinos jagode ostvaren na tretmanima gde su primenjena NPK đubriva i tečni guano. Tretmani đubrenja imali su značajan uticaj na mineralni sastav, sadržaj rastvorljive suve materije, sadržaj kiselina, sadržaj antocijana, antioksidativnu aktivnost i obojenost ploda. Primena crne polietilenske folije, pored pozitivnog uticaja na sadržaj hranljivih elemenata u zemljištu, dovela je do višeg prinosa i kvaliteta ploda jagode u odnosu na primenu slame kao malča. Rezultati pokazuju da se primenom crne folije može značajno povećati efikasnost đubriva čime se smanjuje rizik od zagađenja životne sredine i ostvaruje veća ekonomska dobit u proizvodnji jagode.
Organic fertilizers contain almost all the necessary nutritional elements for cultivated plants, but they have a significantly lower efficiency compared to synthetic fertilizers due to lower nutrient content and the forms of nutrients in which they are not directly accessible to the cultivated plants. The aim of this study was to quantify the effect of the application of different plant and animal origin organic fertilizer, as well as liquid fertilizers, on soil chemical properties, yield and quality of strawberries in two production systems (soil mulching). The field experiment was conducted using a 2-factorial split-plot completely randomized design, with ground cover management (mulch) as main-plot factor and fertilization treatments in sub-plot. On the main plots we examined the influence of two different mulches (straw and black polyethylene sheet), while on sub-plots the effect of 13 different treatments of fertilization was examined (control - no fertilization, Ø; dairy manure, С; dairy manure + guano (foliar application), С+Г; dairy manure + vermicompost leachate (foliar application), С+ЕГ; vermicompost, ГЛ; vermicompost leachate + guano (foliar application), ГЛ+Г; vermicompost + vermicompost leachate (foliar application), ГЛ+ЕГ; spent mushroom compost, К; spent mushroom compost + guano (foliar application), К+Г; spent mushroom compost + vermicompost leachate, К+ЕГ; guano (fertigation + foliar application), Г; vermicompost leachate (fertigation + foliar application), ЕГ; standard fertilization with mineral NPK fertilizers, NPK). The soil samples were analysed to determine the content of mineral forms of N, available forms of P, K, Ca, Mg, Fe, Mn, Cu, Zn and soil pH value. Beside parameters of strawberry yield (number of flowers, number of fruits, average fruit weight) in all three fruiting years we determined the content of macro- and microelements in the leaves and fruits, as well as fruit quality parameters (total soluble solids, total acidity, total anthocyanins, antioxidant activity, coloring and fruit firmness). The results showed that application of solid and liquid organic fertilizers had a different residual effect on concentration of macro- and micro elements in the soil. Application of solid organic fertilizer had the greatest influence on the content of available forms of phosphorus, than potassium, while the least impact had on the content of mineral forms of nitrogen in the soil. Except for dairy manure, the application of organic fertilizers, in amount equivalent to 170 kg N ha-1, had no effect on concentration of available forms of secondary macroelements and microelements in the soil. Soil covered with black polyethylene mulch had higher content of mineral forms of nitrogen and available forms of Fe, Mn, Zn and Cu, compared to soil covered with straw mulch, in all terms of measuring. The application of solid organic fertilizers led to a significant increase in yield compared to the control in the first fruiting year, while in the second and third fruiting years the highest yields were achieved on the treatments where NPK fertilizer and liquid guano were applied. Fertilization treatments had a significant effect on the mineral composition, content of soluble solids, titrible acidity, content of anthocyanins, antioxidant activity and color of the strawberry fruits. Black polyethylene mulch had positive impact on concentration of macro- and microelements in soil and led to higher yield and quality of strawberry fruits compared to straw mulch. The results shows that the black polyethylene mulch can significantly increase fertilizer efficiency, which reduce the risk of environmental pollution and may result in greater economic gain in strawberry production.

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Rethwisch, Michael D., Mark Reay, Aron Quist, Tim Cox, Jessica Grudovich, and Jessica Wellman. "Comparison of Potassium Fertilizer Products and Amounts on DPL555BR Cotton, 2003." College of Agriculture, University of Arizona (Tucson, AZ), 2004. http://hdl.handle.net/10150/198132.

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Norton, E. R., L. J. Clark, and H. Borrego. "Evaluation of Variable Rate Fertilizer Applications in an Arizona Cotton Production System." College of Agriculture, University of Arizona (Tucson, AZ), 2005. http://hdl.handle.net/10150/198174.

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A project was initiated in the 2004 cotton (Gossypium hirsutum) growing season in an effort to accomplish two major objectives. The first was to continue with phosphorus (P) fertilization evaluations that have taken place in the Upper Gila River Valley for the past four seasons by continuing to document the effects of P fertilization on crop yield and fiber quality. The second objective was to investigate the feasibility of utilizing a Global Positioning Systems (GPS) and Geographic Information Systems (GIS) technology for making variable rate (VR) applications of P fertilizers based upon yield data from the previous cropping season. Yield maps from a cotton picker mounted yield monitoring system were collected from the 2003 growing season and used to develop prescription applications of P fertilizers in the 2004 season. The project was established with four treatments including a control (Treatment 1 - 0 P fertilizer applied); a VR application treatment (Treatment 2 - received 52 lbs P/acre on average); a high Uniform Rate (UR) application (Treatment 3 - 75 lbs P/acre); and a low UR application (Treatment 4 - 45 lbs P/acre). These treatments were arranged in a randomized complete block design with four replications. The size of each experimental unit was 0.7 acres. Lint yield results indicated a positive response to applied P fertilizers with treatments 2, 3, and 4 producing significantly higher yields than the control. Lint yield was not significantly affected by fertilizer application technique. Yield differences among the treatments receiving P fertilizer were minimal, particularly among treatments 2 and 3. However, it is important to note that the amount of P fertilizer used in treatment 2 was reduced by 27% with the use of the VR application technique. This produces an approximate $7/acre savings to the grower. This project will be continued in the 2005 growing season and will be expanded to investigate VR application technology in nitrogen (N) fertilization also.

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Silvertooth, J. C., J. C. Navarro, E. R. Norton, and A. Galadima. "Soil and Plant Recovery of Labeled Fertilizer Nitrogen in Irrigated Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 2001. http://hdl.handle.net/10150/211318.

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Proper timing of fertilizer N applications in relation to crop uptake can serve to improve fertilizer efficiency in irrigated cotton. Earlier research has identified an optimum application window extending from the formation of first pinhead squares to peak bloom, which corresponds well with maximum crop uptake and utilization. Field experiments were conducted at the University of Arizona Marana Agricultural Center (Grabe clay loam soil) utilizing sidedress applications of ammonium sulfate with 5-atom % 15-N at pinhead square, early bloom, and peak bloom at a rate of 56 kg N/ha. The objective was to compare relative efficiencies in terms of fertilizer N uptake and recovery among these three times of application. Results indicate that all treatments averaged approximately 80% total fertilizer N recovery. Of the fertilizer N that was recovered, approximately 40 % was taken up by the plants and 60 % recovered in the soil, primarily in the top 60 cm of the soil profile.

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Silvertooth, J. C., S. H. Husman, J. E. Malcuit, and T. A. Doerge. "Upland Cotton Resposne to Soil and Foliar Applies Potassium Fertilizer, 1991." College of Agriculture, University of Arizona (Tucson, AZ), 1992. http://hdl.handle.net/10150/208656.

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A single field experiment was conducted near Gila Bend, Arizona in 1991 to evaluate the effects of both soil and foliar applied potassium (K) fertilizersto Upland (Gossvpium hirsutum L.) cotton to a soil testing 315 ppm K (high). Soil applied K fertilizer at rates of 0, 75,150, and 225 lbs. K₂O/acre as K₂SO₄ were broadcast and preplant incorporated before listing. Foliar applications were made in all combinations with the various soil applied K treatments and consisted of four applications of 4.6 lbs. K₂O /acre as KNO₃ (10 lbs. KNO₃ /acre) over the first fruiting cycle, by a ground applicator with approximately 25 gallons per acre as carrier. No differences among treatments were detected by any plant growth measurement taken, plant tissue analyses, lint yield or lint quality determinations which were made over this experiment. Conclusions (preliminary) based upon these results indicate that K fertilization was not warranted under the conditions characterized in this single field experiment.

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Silvertooth, J. C., T. A. Doerge, G. W. Thacker, S. W. Stedman, and J. E. Malcuit. "Effects of Banded Phosphorus Fertilizer on Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/204814.

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Four field experiments were established in 1988 in Arizona to evaluate the effects of banded phosphorus (P) fertilizers on cotton. 2 sites involved upland cotton (Gossypium hirsutum L.) and 2 sites with pima (G. barbadense L. var Pima S-6), with 1 of each located near Marana, AZ (Vinton Anthony sandy loam). A site with 1 of each kinds was also located near Coolidge, AZ (Mohall sandy loam). At the Marana studies, P was applied 6 inches directly below the zone of seed placement at the time of listing and at the Coolidge sites, P was applied 6 inches below and 2 inches to the side of the zone of seed placement after listing but before planting. In all cases, the P source was 10-34-0 at rates of 0, 30, and 65 lb. P₂O₅ acre⁻¹. At the Marana location, a treatment of banded 10-34-0 at 30 lb. P₂O₅ acre⁻¹ plus a foliar application of 10 lb. P₂O₅ acre⁻¹ (early bloom) as 10-34-0 was included in both the upland and the pima experiments. Plant measurements for plant height, flower numbers, node numbers, boll numbers, and nodes to first fruiting branch were taken to evaluate plant response throughout the season. Plant tissue samples were also taken for leaf petiole PO₄-P and leaf blade total P analysis. Lint yield measurements were also taken. No statistically significant (P < 0.05) differences were found among any of the treatments for any of the measured parameters, except in the petiole PO₄-P levels from the upland study at Coolidge on the second sampling date.

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Bomeisl, Lauren. "Residual Soil Phosphorus in Tropical Oxisols: An Opportunity to Enhance Fertilizer Use Efficiency?" ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/1159.

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Phosphorus (P) is essential to life on Earth and often the limiting nutrient in agricultural systems. P fertilizer is thus an essential resource to maintain food security. In the last half century, agricultural intensification has led to an increase in P fertilizer consumption from 4.6 to 17.5 Tg of P/year to meet rising global food demand. Mineral P (i.e., phosphate rock) is a non-renewable resource in the context of the Anthropocene, and its price is vulnerable to global market fluctuations. Increased efficiency of P use on farms is considered the most effective strategy to conserve P. The soybean industry demands 9.7% of global P use, of which Brazil’s soy industry consumes the most, accounting for 5.8% of the world’s P2O5 use in 2014. This global source of soy production is challenged by the unique tendency of weathered tropical soils, such as Oxisols, to retain (i.e., fix) P in forms that are unavailable to crops. The accumulation of soil P due to years of P fertilization in excess of harvested P is referred to as “residual” or “legacy” P. Historical hotspots for crop production in the US and Europe have relied on residual soil P stocks to maintain yields despite reduced P inputs. Whether Brazil will be able to utilize the same strategy depends on the accessibility of residual soil P stocks when applied fertilizer P is reduced. Field research on this topic remains relatively scarce for cultivated Oxisols in tropical climates. I conducted a field trial at Tanguro Ranch in Mato Grosso, Brazil on a field that has been fertilized at standard high rates for 10 years to test whether residual soil P can be accessed by soy crops. Soy yield response differed significantly (p < 0.05) based on the interaction between fertilization treatment (0%, 50%, or 100% of standard P fertilization) and soil texture. My results highlight opportunities to enhance P fertilizer use efficiency in intensive tropical agriculture.

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Silvertooth, J. C., G. W. Thacker, J. E. Malcuit, T. A. Doerge, and S. H. Husman. "Upland and Pima Cotton Response to Banded Fertilizer Applications, 1990." College of Agriculture, University of Arizona (Tucson, AZ), 1991. http://hdl.handle.net/10150/208629.

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Two field experiments were established in Arizona in 1990 to evaluate the effects of banded phosphorus (P) fertilizer on cotton. Experiments involved both Upland (Gossvpium ltirsutum, L.) and American Pima (Q. barbadense L.). Banded applications of P fertilizerwere made with placement of the concentrated band of fertilizer 6 in. below and 3-6 in. to the side of the zone of seed placement. The P₂O₅ was supplied from 10-34-0. Rates of applied P ranged from 0 to 160 lb P₂O₅ /acre. In one experiment, treatments consisting of 5 to 10 lbs. Zn/acre were included in all possible combinations with the P₂O₅ treatments. In all cases, treatments in the field were arranged in a randomized complete block design with four replications. Plant measurements for plant height, flower numbers per unit area, number of mainstem nodes, and nodes to the first fruiting branch were initiated by the fifth true leaf stage to evaluate plant response in terms of growth and development. Plant tissue samples were also taken at several stages of growth from each experiment throughout the growing season. Tissue samples consisted of petioles from the uppermost fully - developed leaves. Petioles were analyzed for extractable PO₄-P. Lint yield measurements also were taken. No statistically significant differences (P ≤ 0.05) were found among any treatments for any of the plant growth parameters. The same was true with regard to petiole PO₄-P levels measured. No significant differences were detected among Upland or Pima cotton lint yields in response to the applications of P fertilizers.

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Unrah, B. L., J. C. Silvertooth, D. M. Hendricks, and J. E. Malcuit. "Potassium Fertility of Several Arizona Soils." College of Agriculture, University of Arizona (Tucson, AZ), 1993. http://hdl.handle.net/10150/209581.

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Potassium (K) fertility requirements for cotton ( Gossypium spp) have been a matter of concern due to increasing interest and emphasis on fiber quality and numerous reports of K deficiencies in various cotton producing regions. To address this matter appropriately, a thorough understanding of the chemical, physical, and mineralogical composition of the soils in question is in order. Soil samples were collected from ten sites across southern Arizona that are representative of the common agricultural soils of the region. At all locations soils were sampled to a depth of 120 cm in 30 cm increments. All soils were characterized with respect to chemical composition by the following parameters: exchangeable K, total K, cation exchange capacity and particle size analysis. With the exception of one soil (a soil not commonly employed in cotton production), none of the chemically characterized soils contained less than 150 mg K kg⁻¹ of extractable K in the surface 90 cm of soil. All of the soils contained K- bearing mica and none of the soils contained any K- fixing vermiculite. From the initial chemical and mineralogical information, K fertilization is not likely for similar situations in Arizona. Further research is under way to quantify the K-fixing ability of each soil in this survey and additional field studies are also being conducted to evaluate K fertilization in both Upland (G. hirsutum L.) and Pima (G. barbadense L.) cotton.

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Thompson, Ashley A. "The Effects of Rootstock Selection and Carbon-based Fertility Amendments on Apple Orchard Productivity and Soil Community Ecology." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/83441.

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In apple (Malus domestica Borkh.) orchards, rootstock genotype, and soil fertility management practices impact soil fertility, plant associated soil microbial communities, and orchard productivity. Apple growers select rootstocks to confer beneficial traits, including size control, precocity, and pest and disease resistance. Rootstock genotype may also influence microbial communities, resulting in changes that affect tree health and productivity. Many apple growers apply synthetic nitrogen fertilizers to improve fruit yield and quality. In excess of tree requirements, nitrogen fertilizers may reduce crop yield and quality, as well as contribute to water pollution. The addition of carbon-based amendments, such as yardwaste, chicken litter composts, and biochar, may potentially reduce nitrogen and water loss, while improving soil structure and mineral nutrient availability. Orchard and pot-in-pot experiments were designed to study the following objectives: 1) determine the effects of integrated carbon-based fertilizer amendments on tree growth, productivity, and orchard soil fertility, 2) assess the effects of biochar on tree growth, leaf mineral nutrition, soil physiochemistry, and microbial community structure and activity, and 3) understand how rootstocks and fertilizers alter soil microbial communities. Applications of composts, integrated compost-calcium nitrate fertilizers, and biochar increased soil carbon, organic matter, cation exchange capacity and microbial respiration. In the orchard study, nitrogen fertilizer application did not increase tree growth, fruit quality, or leaf nitrogen concentration. Biochar applied at high rates with nitrogen fertigation increased tree growth and leaf nitrogen concentration similar to nitrogen fertigation. In the pot-in-pot compost study, chicken litter compost increased tree growth, and integrated compost-calcium nitrate fertilizer applications increased leaf N concentration. Analysis of the microbial community structure of bulk soil samples from the biochar and compost pot-in-pot experiments determined that the community structure was similar for all treatments during the three-year study. Metagenomic sequencing of the rhizosphere bacterial community indicated that compost applications altered community diversity and evenness, and that compost treatments were more similar to each other than to the calcium nitrate treatment. Data from my dissertation research suggests that compost can be used to increase orchard soil fertility, tree growth, and leaf nutrition, and that compost applications increase soil microbial community diversity and activity.
Ph. D.

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Junior, João de Deus Gomes dos Santos. "Fertilidade do solo no acúmulo de forragem e nutrição do capim-tanzânia sob pastejo na região dos cerrados." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-08062005-155015/.

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O número de sistemas intensivos de produção de bovinos a pasto no Brasil tem crescido nos anos mais recentes em razão do esmero do setor pecuário em se aprimorar como uma atividade economicamente viável e capaz de competir no mercado externo. Dentre os fatores de intensificação da produção de carne a pasto destaca-se o papel primordial do manejo da fertilidade do solo, desde que acompanhada de eficiente utilização da forragem produzida e posterior conversão em produto animal. Um experimento foi conduzido na Embrapa Gado de Corte, localizada em Campo Grande-MS, com o objetivo de avaliar o efeito de quatro condições de fertilidade do solo na produção de forragem, concentração e acúmulo de macronutrientes em capim-Tanzânia (Panicum maximum cv. Tanzânia) ao longo de ciclos de pastejo no verão e outono. O delineamento experimental foi o de blocos completos ao acaso, em parcelas subdivididas, com três repetições. Os tratamentos consistiram da combinação entre duas doses de calcário, fósforo e potássio (CPK1 e CPK2) e duas doses de nitrogênio (N1 e N2), assim dispostas: a) CPK1: aplicação de fósforo de 30 kg ha-1 ano-1 e de potássio de 50 kg ha-1ano-1, associado à calagem para elevar a porcentagem de saturação por bases a 50%; b) CPK2: aplicação de fósforo e potássio de 60 e 100 kg ha-1 ano-1, respectivamente, associado à calagem para elevar a porcentagem de saturação por bases a 70%; c) N1: dose de nitrogênio de 150 kg ha-1 ano-1; d) N2: dose de nitrogênio de 300 kg ha-1 ano-1. Amostragens foram realizadas nos tempos de rebrotação de 0, 12, 19, 26, 34 e 40 dias, no ciclo de pastejo de verão, e aos 0, 10, 18, 25 e 31 dias, no ciclo de outono. Em cada tempo de rebrotação foram descritos a altura e o índice de área foliar do dossel (IAF), como atributos que caracterizam a pastagem do ponto de vista de sua estrutura. Ao final do período de crescimento do verão (aos 40 dias) foram obtidas produções de lâminas foliares de 4616 e 3292 kg ha-1 nas doses de nitrogênio N2 e N1, respectivamente. Tornou-se evidente o aumento da proporção de folhas em relação à de colmos+bainhas pelas doses de nitrogênio, bem como o expressivo efeito das doses de calcário, fósforo e potássio na produção de colmos+bainhas, indicando a necessidade de mais estudos do efeito de nutrientes na plasticidade morfológica do capim-Tanzânia. Quanto ao acúmulo de macronutrientes pelo capim-Tanzânia foi observado expressivo efeito da massa seca de forragem, mesmo em situações onde o efeito de diluição foi acentuado como verificado para o nitrogênio, fósforo, potássio e enxofre. Em ambos os ciclos de pastejo o acúmulo de macronutrientes foi em ordem decrescente: K>N>Ca>Mg>P>S. No crescimento de verão, a taxa de acúmulo de nitrogênio da parte aérea das plantas foi devida ao acúmulo do nutriente nas lâminas foliares, sendo observados os valores de 1,3 e 2,6 kg ha-1 dia-1, nas doses de nitrogênio N1 e N2, respectivamente. As doses de nitrogênio diferiram quanto ao acúmulo de nitrogênio na parte aérea a partir dos 19 dias, o qual esteve associado à altura de 87 e 89 cm e IAF de 2,2 e 3,2 nas doses de nitrogênio N1 e N2, respectivamente. As doses de calcário, fósforo e potássio alteraram significativamente os teores de cálcio e magnésio no solo, principalmente nas camadas superficiais. Por outro lado, as doses de nitrogênio foram mais efetivas em favorecer o acúmulo de cálcio e magnésio na parte aérea do capim, os quais estiveram relacionados com o expressivo aumento da massa seca, e às variações nas concentrações desses nutrientes ao longo do período de crescimento. As condições de fertilidade do solo CPK1N1 e CPK1N2 supriram as necessidades nutricionais do capim-Tanzânia para sustentar produções significativas de lâminas foliares no ciclo de pastejo de verão. Também, atenderam as necessidades nutricionais no ciclo de outono, onde a produção vegetal foi limitada por aspectos climáticos.
The number of systems of intensive pasture use in Brazil has been increase in recent years in an attempt to improve the animal husbandry as a feasible economic activity and capable of competing in the international market. Among the factors that increase meet yield, the management of soil fertility conditions stand out by its effects in promoting forage yield, that must be accomplished with an efficient utilization and conversion into animal product. An experiment was carried out at Embrapa Gado de Corte located in Campo Grande-MS, with the objective of evaluating the effect of four soil fertility conditions in the forage yield, macronutrients concentrations and accumulations in Tanzania-grass (Panicum maximum cv. Tanzânia) along the summer and fall growing seasons. The experiment was a split-plot in randomized complete block design, with three replications. The treatments consisted of the combinations of two rates of limestone, phosphorus, and potassium (CPK1 and CPK2) and two rates of nitrogen (N1 and N2) as follows: a) CPK1: application of 30 kg ha-1 year-1 of phosphorus and 50 kg ha-1 year-1 of potassium associated to liming to increase the base saturation percentage to 50%; b) CPK2: application of 60 kg ha-1 year-1 of phosphorus and 100 kg ha-1 year-1 of potassium associated to liming to increase the base saturation percentage to 70%; c) N1: 150 kg ha-1 year-1 of nitrogen; d) N2: 300 kg ha-1 year-1 of nitrogen. Samplings were carried out at regrowth periods of 0, 12, 19, 26, 34, and 40 days during summer growing season, and at 0, 10, 18, 25, and 31 days during fall growing season. For each regrowth period plant height and the leaf area index (LAI) were described as attributes that characterize the pasture in its structural point of view. At the end of summer growing season (at 40 days) leaf blade yields of 4616 and 3292 kg ha-1 were obtained for N1 and N2 rates, respectively. The yield responses to nitrogen were higher for leaf blades than for stems+sheaths, while the responses to limestone, phosphorus and potassium were higher for stems+sheaths. This results indicated the need of more studies about the effect of nutrients in the morphological plasticity of Tanzânia-grass. Concerning the macronutrients accumulations in Tanzânia-grass it was observed that the effect of the amount of forage dry matter was more significant than the dilution effect of nitrogen, phosphorus, potassium and sulfur. Concerning both growing seasons, the macronutrients accumulations were in decreasing order: K>N>Ca>Mg>P>S. In the summer growing season, the aboveground nitrogen accumulation rate was almost exclusively due to the accumulation of the nutrient in the leaf blades, with values of 1.3 and 2.6 kg ha-1 day-1 observed for leaf blade at nitrogen rates N1 and N2, respectively. Responses to nitrogen rates were different regarding the accumulation of aboveground nitrogen after 19 days, which was associated to height of 87 cm and 89 cm, and LAI of 2.2 and 3.2 for rates of nitrogen N1 and N2, respectively. The rates of limestone, phosphorus, and potassium significantly changed the exchangeable of calcium and magnesium concentrations in the soil, particularly in the top layers. On the other hand, rates of nitrogen were more effective in promoting the accumulation of calcium and magnesium in the plant and the variation in concentrations of these nutrients along the growing season, which were related to the expressive increase in forage dry matter. Soil fertilities conditions CPK1N1 and CPK1N2 support the leaf blades yields observed in the summer growing season. Likewise, these soil fertilizations supplied the nutritional needs during the fall growing season when it was observed that the forage yield was limited by climatic conditions.

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Silvertooth, J. C., E. R. Norton, and A. Galadima. "Evaluation of Potassium and Phosphorus Fertility in Arizona Soils." College of Agriculture, University of Arizona (Tucson, AZ), 2001. http://hdl.handle.net/10150/211298.

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Two field experiments were conducted during the 2000 growing season to address fertility recommendations for fertilizer phosphorus (P) and potassium (K). A K fertility study was conducted near Tonopah, AZ consisting of two treatments, an untreated control and a treatment receiving a total of 20 gallons of K-Sul/acre. No significant differences were observed in leaf blade K concentrations between treatments. Plant growth and development estimates revealed that fruit retention (FR) levels remained consistently higher in the untreated control versus the treated plots. A second study involved treatments consisting of both P and K fertilizers was conducted near Cibola, AZ. Four treatments in this experiment included an untreated control plus treatments of 11-52-0, 0-0-60, and 4-17-40 at 100, 200, and 300 lbs. fertilizer/acre respectively. Plant growth and development estimates were similar among treatments during the season. At the end of the season the untreated control had a slightly higher FR level than the other treatments, which also produced a significantly higher yield. No other differences in yield among the fertilized treatments were observed.

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Pearson, William W. "Residual soil nitrogen and nitrogen response of corn after alfalfa on sandy loam soil /." View abstract (PDF format), 2002. http://epapers.uwsp.edu/abstracts/2002/Pearson.pdf.

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40

Fisher, Scott E. "The Effects of Different Soil Amendments on Fertility and Productivity in Organic Farming Systems." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1319737408.

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41

Jenkins, Anthony Blaine. "Organic carbon and fertility of forest soils on the Allegheny Plateau of West Virginia." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2486.

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Thesis (M.S.)--West Virginia University, 2002.
Title from document title page. Document formatted into pages; contains x, 282 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

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42

Heinzlmaier, Franz. "Pflanzennährstoffe in Österreichs Böden : räumliche und zeitliche Variationen sowie Wechselwirkungen mit Bodenparametern /." Wien [u.a.] : Guthmann-Peterson, 2007. http://deposit.d-nb.de/cgi-bin/dokserv?id=2971532&prov=M&dok_var=1&dok_ext=htm.

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43

Katseanes, Chelsea Kae. "Soil Fertility Status and Degradation of 2, 4, 6-Trinitrotoluene Contaminated Soils." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5517.

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Current models for predicting the environmental fate of munitions constituents (MC) in soils are based mostly on chemical distribution parameters and neglect the larger considerations of other soil parameters. We are working towards a new approach based on the whole soil activity for predicting the long-term residence time and fate of MC in soils with connection to agronomic soil fertility concepts. These relationships are demonstrated by correlating experiments involving full physical and chemical characterization of eight taxonomically distinct soils, with batch reactor studies determining MC degradation potential. Soils were incubated in a slurry for 10 days in a closed reactor system with temperature, pH, and Eh readings recorded every 24 h. Air and slurry samples were taken eight times within the 168 h incubation period. Carbon dioxide, TNT, and nutrient solution concentrations were assessed to obtain a full picture of soil chemistry changes associated with microbial activity in response to additions of TNT. Multivariate analysis was used to determine the main factors impacting degradation rate. Principle Components Analysis (PCA) statistically classified the soils based on the variance of their soil property data. Partial Least Squares Analysis (PLS) showed that TNT degradation was possibly correlated with soil fertility characteristics. Although this is an exploratory study, results show promise in moving towards a more effective way of predicting TNT environmental fate in soils.

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Silvertooth, J. C., A. Galadima, and E. R. Norton. "Residual Soil Nitrogen Evaluations in Irrigated Desert Soils, 2003." College of Agriculture, University of Arizona (Tucson, AZ), 2004. http://hdl.handle.net/10150/198133.

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Field experiments aimed at investigating N fertilizer management in irrigated cotton production have been conducted for the past 16 seasons at three University of Arizona Agricultural Centers (Maricopa, MAC; Marana, MAR; and Safford, SAC). In 2003, residual N studies were conducted at two of these locations (MAC and MAR). The MAC and SAC experiments have been conducted each season since 1989 and the Marana site was initiated in 1994. Original purposes of the experiments were to test nitrogen (N) fertilization strategies and to validate and refine N fertilization recommendations for Upland (Gossypium hirsutum L.) and American Pima (G. barbadense L.) cotton. Each experiment has utilized N management tools such as pre-season soil tests for NO₃⁻-N, in-season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between fruit retention levels and N needs of the crop. This pattern was further reflected in the final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive N application regimes did not consistently benefit yields at any location. Generally, the more conservative, feedback approach to N management provided optimum yields at all locations. In 2001, a transition project evaluating residual N effects associated with each treatment regime was initiated with no N fertilizer applied. Therefore, all N taken-up by the crop was derived from residual soil N. In 2001, 2002, and even 2003 there were no significant differences among the original fertilizer N regimes in terms of residual soil NO₃⁻-N concentrations, crop growth, development, lint yield, or fiber properties. Lint yields were very uniform at each location in 1991 and averaged 1500, 1100, and 850 lbs. lint/acre for MAC, MAR, and SAC, respectively. In 2002, results were very similar and yields averaged 1473 and 1060 lbs. lint/acre for MAC and MAR locations respectively. The results for 2003 were similar to the results of the prior two years with yields at 1322 and 1237 lbs. lint/acre for MAC and MAR, respectively. Trends associated with residual fertilizer N effects are not evident at either location following three consecutive seasons of N fertilizer treatments.

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Silvertooth, J. C., A. Galadima, and E. R. Norton. "Residual Soil Nitrogen Evaluations in Irrigated Desert Soils, 2004." College of Agriculture, University of Arizona (Tucson, AZ), 2005. http://hdl.handle.net/10150/198175.

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Field experiments aimed at investigating N fertilizer management in irrigated cotton production have been conducted for the past 16 seasons at three Arizona locations on University of Arizona Agricultural Centers (Maricopa, MAC; Marana, MAR; and Safford, SAC). In 2004, residual N studies were conducted at two of these locations (MAC and MAR). The MAC and SAC experiments have been conducted each season since 1989 and the Marana site was initiated in 1994. The original purposes of the experiments were to test nitrogen (N) fertilization strategies and to validate and refine N fertilization recommendations for Upland (Gossypium hirsutum L.) and American Pima (G. barbadense L.) cotton. The experiments have each utilized N management tools such as pre-season soil tests for NO₃⁻-N, in-season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location reveal a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive N application regimes did not consistently increase yields at any location. Generally, the more conservative, feedback approach to N management provided optimum yields at all locations. In 2001, a transition project evaluating the residual N effects associated with each treatment regime was initiated and no fertilizer N was applied. Therefore, all N taken-up by the crop was derived from residual soil N. In 2001, 2002, 2003 and even 2004 there were no significant differences among the original fertilizer N regimes in terms of residual soil NO₃⁻-N concentrations, crop growth, development, lint yield, or fiber properties. The lint yields were very uniform at each location in 1991 and averaged 1500, 1100, and 850 lbs. lint/acre for MAC, MAR, and SAC, respectively. In 2002, results were very similar and yields averaged at 1473 and 1060 lbs. lint/acre for MAC and MAR locations respectively. The 2003 results were not different from the prior two years of results and yields averaged at 1322 and 1237 lbs. lint/acre for MAC and MAR respectively. In 2004, yields averaged 828 and 1075 lbs. lint/acre. Trends associated with residual fertilizer N effects are not evident at either location four seasons following N fertilizer applications.

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46

Silvertooth, J. C., A. Galadima, and E. R. Norton. "Residual Soil Nitrogen Evaluations in Irrigated Desert Soils, 2001." College of Agriculture, University of Arizona (Tucson, AZ), 2002. http://hdl.handle.net/10150/197713.

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Field experiments were conducted in Arizona in 2001 at three locations (Maricopa, Marana, and Safford). The Maricopa and Safford experiments have been conducted for14 consecutive seasons and the Marana site was initiated in 1994. The original purposes of the experiments were to test nitrogen (N) fertilization strategies and to validate and refine N fertilization recommendations for Upland (Gossypium hirsutum L.) and American Pima (G. barbadense L.) cotton. The experiments have each utilized N management tools such as pre-season soil tests for NO₃⁻-N, in-season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive, N application regimes did not benefit yields at any location. Generally, the more conservative, feedback approach to N management provided optimum yields at all locations. In 2001, a transition project evaluating the residual N effects associated with each treatment regime was initiated and no fertilizer N was applied. Therefore, all N taken-up by the crop was derived from residual soil N. In 2001 there were no significant differences among the original fertilizer N regimes in terms of residual soil NO₃⁻-N concentrations, crop growth, development, lint yield, or fiber properties. The lint yields were very uniform at each location and averaged 1500, 1100, and 850 lbs. lint/acre for Maricopa, Marana, and Safford, respectively.

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47

Silvertooth, J. C., A. Galadima, and E. R. Norton. "Residual Soil Nitrogen Evaluations in Irrigated Desert Soils, 2002." College of Agriculture, University of Arizona (Tucson, AZ), 2003. http://hdl.handle.net/10150/197911.

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Field experiments investigating N fertilizer management in irrigated cotton production have been conducted for the past 15 seasons at three Arizona locations on University of Arizona Agricultural Centers (Maricopa, MAC; Marana, MAR; and Safford, SAC). In 2002, residual N studies were conducted at two of these locations (MAC and MAR). The MAC and SAC experiments have been conducted each season since 1989 and the Marana site was initiated in 1994. The original purposes of the experiments were to test nitrogen (N) fertilization strategies and to validate and refine N fertilization recommendations for Upland (Gossypium hirsutum L.) and American Pima (G. barbadense L.) cotton. The experiments have each utilized N management tools such as pre-season soil tests for NO₃⁻-N, in-season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive N application regimes did not consistently benefit yields at any location. Generally, the more conservative, feedback approach to N management provided optimum yields at all locations. In 2001, a transition project evaluating the residual N effects associated with each treatment regime was initiated and no fertilizer N was applied. Therefore, all N taken-up by the crop was derived from residual soil N. In 2001, there were no significant differences among the original fertilizer N regimes in terms of residual soil NO₃⁻-N concentrations, crop growth, development, lint yield, or fiber properties. The lint yields were very uniform at each location and averaged 1500, 1100, and 850 lbs. lint/acre for MAC, MAR, and SAC, respectively. In 2002, results were very similar at the MAC and MAR locations. Trends associated with residual fertilizer N effects are not evident at either location just two seasons following N fertilizer applications.

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48

Gottschalk, Pia. "Modelling soil organic carbon dynamics under land use and climate change." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=186643.

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Soil organic matter (SOM) models simplify the complex turnover dynamics of organic matter in soils. Stabilization mechanisms are currently thought to play a dominant role in SOM turnover but they are not explicitly accounted for in most SOM models. One study addresses the implementation of an approach to account for the stabilization mechanism of physical protection in the SOC model RothC using 13C abundance measurements in conjunction with soil size fractionation data. SOM models are increasingly used to support policy decisions on carbon (C) mitigation and credibility of model predictions move into the focus of research. A site scale, Monte Carlo based model uncertainty analysis of a SOM model was carried out. One of the major results was that uncertainty and factor importance depend on the combination of external drivers. A different approach was used with the SOM ECOSSE model to estimate uncertainties in soil organic carbon (SOC) stock changes of mineral and organic soils in Scotland. The average statistical model error from site scale evaluation was transferred to regional scale uncertainty to give an indication of the uncertainty in national scale predictions. National scale simulations were carried out subsequently to quantify SOC stock changes differentiating between organic and mineral soils and land use change types. Organic soils turned out to be most vulnerable to SOC losses in the last decades. The final study of this thesis emplyed the RothC model to simulate possible futures of global SOC stock changes under land use change and ten different climate scenarios. Land use change turned out to be of minor importance. The regionally balance between soil C inputs and decomposition leads to a diverse map of regional C gains and losses with different degrees of certainty.

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Weill, Anne. "The effect of tillage reduction and fertilizer type on corn yield and soil properties /." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75685.

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An experiment was undertaken to determine the effect of tillage and fertilizer on silage and grain corn production and on soil properties as well as to develop a crop yield model. Conventional, reduced, and zero tillage treatments in combination with inorganic or organic (cattle dairy manure) fertilizer treatments were applied yearly on a clay and a sandy loam soil from 1982 to 1986. The best yields were obtained for the combination of zero or reduced-till and inorganic fertilizers. Zero-till resulted in increased soil density and soil water content and a slight accumulation of P and K in the surface layer of the clay soil. Manure improved soil physical properties especially when combined with zero-till, but resulted in lower N availability to the plants. The factors that limited plant yield in the clay site were plant population, soil nitrate content, bulk density and soil water content. Plant population was the only limiting factor in the sandy loam site. A simplified method for predicting corn yields under different management practices was developed.

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Isse, Abdullahi. "Capacity of cover crops to capture excess fertilizer and maintain soil efficiency." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0021/MQ37132.pdf.

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Dissertations / Theses on the topic 'Soil fertility Fertilizers Soils'

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