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1
Gomes, Carolyn. "Spatial distribution of B horizon properties in a pine flatwood landscape New Hanover County, NC /." View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-3/gomesc/carolyngomes.pdf.
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Simonsson, Magnus. "Mechanisms controlling the solubility of aluminium in B horizons of podzolized soils /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5711-4.pdf.
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Riggs, Katherine Sarah. "Soil chemical changes following limestone additions to acid soils." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315889.
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Cook, H. F. "Assessment of drought resistance in soils." Thesis, University of East Anglia, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374255.
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Baba, Hafeez Ullah. "Factors influencing frost heaving of soils." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335823.
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Stone, Kevin John Lindsay. "Modelling of rupture development in soils." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304434.
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Haque, S. M. Sirajul. "Afforestation effects on former agricultural soils." Thesis, University of Aberdeen, 1997. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU094706.
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Long-term changes in soil profile characteristics and important soil physical, chemical and biological properties were evaluated and compared at 4 paired sites in NE Scotland, 44-61 years after the afforestation of agricultural soils planted with either Norway spruce (Picea abies (L.)) or Scots pine (Pinus sylvestris (L.)). At each paired site five profiles were studied in the afforested and five in the control agricultural soils. Comparison made between various properties in the pairs of soils showed a number of significant changes, which are summarised in Tables 2.18-2.20. The surface (O) horizon of the afforested soil could be differentiated into L, F and H horizons. The O horizon was rich in organic matter, crumb structured, porous and well-drained and was differentiated from the A horizon below by an irregular boundary. The A horizon was moderately well to excessively well-drained with a subangular blocky to crumb structure. This horizon was differentiated from the B horizon below by an irregular boundary. The agricultural soil profile was characterised by compact O and A horizons with a subangular blocky structure; each horizon was separated from the one below by a gradual, smooth horizon boundary. Afforestation increased the combined thickness of the O and A horizon by 0.21 cm yr-1. It caused a significant decrease in bulk density and had no effect on particle size distribution. At most sites % organic matter, C, C/N ratio, CEC and NH4+ concentration were higher and extractable P concentration lower in the O horizon and most of the A horizons of forest soils, compared to the agricultural soil. The concentration of N increased significantly in the O horizon. Soil pH, exchangeable Ca, Mg and K and % base saturation decreased significantly in most forest soil horizons compared to the agriculated soils. Exchangeable Na concentration increased in the B horizon. Accumulation rates of each element since afforestation were also calculated.
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Obrycki, John F. "Managing Soils For Environmental Science And Public Health Applications." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469014282.
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Ahmad, A. R. "Coupled diffusion and oxidation reactions in soils." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375219.
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Boyce, Emma Elizabeth Ruth. "Modelling of transport processes in heterogeneous soils." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339466.
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Mwepu, Mireille K. M. "Attenuation of ionic pollutants in selected South African soils." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/2516.
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Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2007.Two–thirds of South Africa, including more than 280 towns and settlements are largely dependent on groundwater for their drinking water supply and development. However, groundwater resources in South Africa are limited both in terms of quantity and quality, especially in the semi–arid parts of the country (Sililo et al., 2001, p. i). Therefore, the importance of protecting groundwater resources from pollution has been recognized. The first objective of this research was to investigate the attenuation capacity of a selection of soil horizons and materials representing major types of diagnostic horizons and materials in the South African soil classification in order to validate their chemical attenuation ratings as provisionally specified by Sililo et al. (2001, p. 4.6). The second objective was to assess the pollutant attenuation capacity of South African soil horizons and materials as well as describe the diagnostic value of key chemical properties of soils for conveying information on their contaminant transport/attenuation potential. The third objective was to investigate whether it is possible to apply acid/base priming using H2SO4 and Ca(OH)2 to a bulk quantity of soil in order to reduce the mobility of contaminants.
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Dell'Olio, Laura Ashley. "Refining the Phosphorus Loss Assessment Tool for the Organic Soils of North Carolina." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-10262006-141107/.
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Phosphorus (P) runoff and leaching from agricultural fields have been identified as major environmental concerns for the health of aquatic ecosystems. North Carolina has responded by implementing the Phosphorus Loss Assessment Tool (PLAT). The goal of the PLAT is to determine relative P losses from agricultural fields based on several site factors and characteristics, including Mehlich-3 P (M3P) soil test values. Based on previous research, the current version of PLAT is programmed to predict greater soluble P losses from organic soils than from mineral soils with the same M3P values. However, recent research specific to North Carolina?s organic soils has indicated decreased soluble P release in the presence of high Al concentrations. Our objectives were to determine (i) the Al content of Typic Haplosaprists and Terric Haplosaprists of North Carolina?s Lower Coastal Plain, and (ii) how the Al in these soils affects P retention. We sampled four organic soil series and determined M3P, Mehlich-3 Al (M3Al), Mehlich-3 Fe (M3Fe), water-soluble P (WSP), total P, pH, particle size distribution, and the organic matter content (OM). Water-soluble P and M3P were also measured in a 21-d incubation study in which P was added at a rate equivalent to 150 kg P ha-1. Total CuCl2 extractable Al and inorganic soil P fractions were identified in an Al and inorganic P fractionation study, respectively. According to the results of the incubation, multiple regression, and fractionation studies, Al was the main cation responsible for P retention; the mean topsoil M3Al concentrations (1926 mg kg-1) in these organic soils were much higher than those observed in another study of mostly mineral NC soils. The concentration of M3Fe was low in every series and was not correlated to any P characteristics. Mehlich-3 P was not consistently correlated to P retention and WSP; however, OM, M3Al, and total CuCl2 extractable Al were correlated with P retention. In the incubation study, the percentage of applied P that was adsorbed was greater in soils with lower OM and/or higher M3Al. Increased OM was associated with increased WSP and lower total P, as well as decreased P retention. The opposite effect was observed with increasing M3Al concentrations; however, the ratio of OM to M3Al showed increased correlation to P retention and WSP than when OM and Al were used alone. These results indicate that soils with higher OM and lower Al did not retain P as well as soils with lower OM and higher Al contents. Furthermore, as more Al bound P was extracted by M3P (causing higher M3P/Al-P %), WSP increased, and coincided with decreased total CuCl2 Al. The results from this study show that in high OM soils, the concentration of extractable Al controlled the solubility of P. North Carolina?s PLAT could be modified to include M3Al concentrations to more accurately predict P losses in the organic soils of the lower coastal plain, thus potentially reducing P runoff and leaching into our aquatic ecosystems.
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Hoyle, Frances Carmen. "The effect of soluble organic carbon substrates, and environmental modulators on soil microbial function and diversity /." Connect to this title, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0050.
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Bagour, Mohammed Hussien. "Measuring and predicting steady state infiltration rates for Arizona irrigated soils." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279790.
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Five methods to measure the saturated hydraulic conductivity of Arizona irrigated soils were evaluated using the in-situ single ring, double ring, compact constant head permeameter methods, and with tempe cells (soil cores) in the laboratory. Ten Arizona irrigated soils were studied, and the textures of these soils ranged from sand to silty clay. Three water qualities were evaluated, namely the local water, gypsum in local water, and gypsum water (0.005M CaSO₄ · 2H₂O solution). Sites were selected to provide soils having a wide range of soil characteristics and detailed laboratory and field morphology data were measured including soil texture, bulk density, soil aggregation, stickiness, plasticity, moisture retention at various tensions, ECₑ, and pHₑ. The results showed that the double ring method was the better in-situ method. The relationships between soil properties and K(sat) were evaluated, and soil properties were examined as predictor variables for K(sat) in stepwise multiple-regression. Stepwise multiple-regression criteria were set at a probability of F to enter ≤ 0.5 and probability of F to remove ≥ 0.1. Six models are presented that can be used in predicting K(sat). Each model has a subset of field and laboratory predictor variables selected based on stepwise multiple-regression criteria, and with some personal judgment. Casewise diagnostics were used to test model performances.
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Coetzee, Marina Elda. "Chemical characterisation of the soils of East Central Namibia." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/4068.
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Thesis (MScAgric (Soil Science)--University of Stellenbosch, 2009.ENGLISH ABSTRACT: A number of chemical and physical features of Namibian soils in a 22 790 km2, two degree-square block between 17 – 19 oE and 22 – 23 oS in eastern central Namibia, had been investigated, and the fertility status established. In 80 % of samples the nitrate, nitrite, and sulfate concentrations of the saturated paste extract are 0 – 54.6 mg l-1 NO3 -, 0 – 24.7 mg l-1 NO2 -, and 5.4 – 20.9 mg l-1 SO4 2- respectively. In 90 % of samples the plantavailable phosphorus is below 12 mg kg-1, which is low for a soil under natural grassland, but in line with the prevailing semi-arid climate and low biomass production of the study area. In 80 % of samples the extractable calcium, magnesium, potassium, and sodium concentrations are 0.61 – 5.73 cmolckg-1 Ca (122 – 1 146 mg kg-1 Ca), 0.12 – 2.28 cmolckg-1 Mg (15 – 278 mg kg-1 Mg), 0.13 – 0.54 cmolckg-1 K (51 – 213 mg kg-1 K) and 0.05 – 0.38 cmolckg-1 Na (11 – 87 mg kg-1 Na) respectively, while the exchangeable calcium, magnesium, potassium, and sodium concentrations are 0.21 – 6.02 cmolckg-1 Ca, 0.12 – 2.01 cmolckg-1 Mg, 0.12 – 0.49 cmolckg-1 K and 0 – 0.13 cmolckg-1 Na respectively. The mean ± 1 standard deviation is 3.57 ± 3.57 cmolckg-1 for cation exchange capacity, 3.48 ± 3.61 for sum of exchangeable bases and 4.53 ± 4.39 for sum of extractable bases. The cation exchange capacity and the sum of exchangeable bases are virtually identical, which indicate the almost complete absence of exchangeable H+ and Al3+ in the soils of the study area, as expected from a semi-arid climate. None of the profiles were classified as saline or sodic. In 80 % of samples the plant-available iron, manganese, zinc and copper concentrations are 7.2 – 32.8 mg kg-1 Fe, 13.6 – 207.5 mg kg-1 Mn, 0 – 1.80 mg kg-1 Zn and 0 – 4.0 mg kg-1 Cu respectively. Soil organic matter content of the study area soils ranges between 0.05 – 2.00 %, with most (80 % of samples) containing 0.25 – 1.20 % organic matter. This is considerably lower than values reported in literature, even for other southern African countries. The reason lies with the hot, semi-arid climate. The pH distribution is close to normal, with 80 % of samples having pH (H2O) of 5.54 – 8.18, namely moderately acid to moderately alkaline. Sand, silt and clay content of most (80 %) samples varies between 60.3 – 89.7 % sand, 4.6 – 25.2 % silt and 3.5 – 19.1 % clay. The soils of the study area are mainly sandy, sandy loam and loamy sand. In 80 % of samples the coarse sand fraction ranges from 3.5 – 34.5 %, the medium sand fraction from 20.5 – 37.3 %, the fine sand fraction from 38.7 – 54.5 % and the very fine sand fraction from 0.0 – 12.9 % of all sand. The fine sand fraction, thus, dominates, with very fine sand being least abundant. The topsoil contains relatively more coarse sand and less very fine sand than the subsoil. Instances of sealing, crusting and hardening occur sporadically in the study area. Cracking is only found in pans, while self-mulching is not evident. No highly instable soils were encountered in the study area. The water-holding capacity is generally low, with depth limitations in the western highlands, the Khomas Hochland, and texture limitations in the eastern Kalahari sands. The central area has soils with a somewhat better water-holding capacity, but it is still very low when compared to arable soils of temperate, sub-humid and humid zones elsewhere in southern Africa. Soil characteristics are perceptibly correlated with climate, parent material, topography, degree of dissection of the landscape and position in the landscape. The most obvious differences are between soils formed in schistose parent material of the Khomas Hochland in the west and those of the Kalahari sands in the east. The soils of the study area are unsuitable to marginally suitable for rainfed crop production, due to low iv fertility. The study area is climatologically unsuited for rainfed crop production, so the present major land use is extensive livestock production on large farms. The natural vegetation is well adapted to the prevailing conditions. The methodology followed to delineate terrain units, with a combination of procedures involving digital elevation data and satellite imagery, seems to work well in the Namibian landscape. This study thus served as a successful proof-of-concept for the methodology, which can in future be rolled out for the remainder of the country. The site and analytical information is available in digital format as spreadsheets and in a geographical information system, as well as in a variety of digital and printed maps.
AFRIKAANSE OPSOMMING: ‘n Aantal chemiese en fisiese eienskappe van Namibiese gronde in ‘n 22 790 km2, 1o x 2o blok tussen 17 – 19 o Oos en 22– 23 o Suid in oostelike sentraal-Namibië is ondersoek en die grondvrugbaarheidstatus bepaal. In 80 % van monsters is die nitraat-, nitriet- en sulfaatkonsentrasies van die versadigde pasta ekstrak 0.0 – 54.6 mg l-1 NO3 -, 0.0 – 24.7 mg l-1 NO2 -, en 5.4 – 20.9 mg l-1 SO4 2-onderskeidelik. In 90 % van monsters is die plant-beskikbare fosfor minder as 12 mg kg-1, wat laag is vir gronde onder natuurlike grasveld, maar dit is verklaarbaar deur die heersende semi-ariede klimaat en lae biomassa produksie in die studiegebied. In 80 % van monsters is die konsentrasies van ekstraheerbare kalsium, magnesium, kalium en natrium 0.61 – 5.73 cmolckg-1 Ca (122 – 1 146 mg kg-1 Ca), 0.12 – 2.28 cmolckg-1 Mg (15 – 278 mg kg-1 Mg), 0.13 – 0.54 cmolc kg-1 K (51 – 213 mg kg-1 K) en 0.05 – 0.38 cmolckg-1 Na (11 – 87 mg kg-1 Na) onderskeidelik, terwyl die uitruilbare kalsium, magnesium, kalium en natrium konsentrasies onderskeidelik 0.21 – 6.02 cmolckg-1 Ca, 0.12 – 2.01 cmolckg-1 Mg, 0.12 – 0.49 cmolckg-1 K and 0.0 – 0.13 cmolckg-1 Na is. Die gemiddelde ± 1 standaardafwyking is 3.57 ± 3.57 cmolckg-1 vir katioonuitruilvermoë, 3.48 ± 3.61 vir die som van uitruilbare basisse en 4.53 ± 4.39 vir die som van ekstraheerbare basisse. Die katioonuitruilvermoë en som van uitruilbare basisse is feitlik identies, wat ‘n feitlik algehele afwesigheid van uitruilbare H+ and Al3+ in die gronde van die studiegebied aandui, soos verwag word weens die semi-ariede klimaat. Geeneen van die profiele is geklassifiseer as soutbrak of natriumbrak nie. In 80 % van monsters is die plant-beskikbare yster, mangaan, sink en koper konsentrasies onderskeidelik 7.2 – 32.8 mg kg-1 Fe, 13.6 – 207.5 mg kg-1 Mn, 0.0 – 1.80 mg kg-1 Zn en 0.0 – 4.0 mg kg-1 Cu. Grond organiese material inhoud in die studiegebied wissel tussen 0.05 – 2.00 %, met 80 % van monsters wat 0.25 – 1.20 % organiese material bevat. Dit is aansienlik laer as die waardes gevind in literatuur, selfs vir ander Suider-Afrikaanse lande. Die oorsaak is die warm, semiariede klimaat. Die pH verspreiding is feitlik normaal, met 80 % van monsters wat pH (H2O) van 5.54 – 8.18 het, met ander woorde matig suur tot matig alkalies. Sand, slik en klei inhoud van die meeste (80 %) monsters varieer tussen 60.3 – 89.7 % sand, 4.6 – 25.2 % slik en 3.5 – 19.1 % klei. Die gronde van die studiegebied is hoofsaaklik sand, sand-leem en leem-sand. In 80 % van monsters beslaan die growwe sandfraksie 3.5 – 34.5 %, die medium sandfraksie 20.5 – 37.3 %, die fyn sandfraksie 38.7 – 54.5 % en die baie fyn sandfraksie 0.0 – 12.9 % van die totale sandfraksie. Die fyn sandfraksie is dus dominant, terwyl die baie fyn sandfraksie die skaarsste is. Die bogronde bevat relatief meer growwe sand en minder baie fyn sand as die ondergronde. Gevalle van verseëling, korsvorming en verharding kom sporadies in die studiegebied voor. Krake kom net in panne voor en self-omkering is nie opgemerk nie. Geen hoogsonstabiele gronde is in die studiegebied gevind nie. Die waterhouvermoë is in die algemeen laag, met dieptebeperkinge in die westelike hooglande, die Khomas Hochland, en tekstuurbeperkinge in die oostelike Kalahari sande. Die sentrale gedeelte het gronde met ‘n ietwat beter waterhouvermoë, maar dis steeds baie laag in vergelyking met akkerbougronde van gematigde, sub-humiede en humiede sones elders in Suider- Afrika. Grondeienskappe is ooglopend verwant aan klimaat, moedermateriale, topografie, graad van gebrokenheid van die landskap en posisie in die landskap. Die duidelikste verskille kom voor in die gronde wat van vi skisagtige moedermateriaal van die Khomas Hochland in die weste en dié wat in die Kalahari sande in die ooste gevorm het. Die gronde van die studiegebied is ongeskik tot marginaal geskik vir droëland akkerbou, weens die lae vrugbaarheid. Aangesien die studiegebied klimatologies ongeskik is vir droëland akkerbou, is die huidige hoof landgebruik ekstensiewe veeproduksie op groot plase. Die natuurlike plantegroei is goed by die heersende omstandighede aangepas. Die metodiek wat gevolg is om terreineenhede af te baken, wat ‘n kombinasie van prosedures met digitale hoogtedata en satellietbeelde is, blyk goed te werk vir die Namibiese landskap. Hierdie studie dien dus as ‘n suksesvolle bewys-van-konsep van die metodiek, wat in die toekoms uitgebrei kan word na die res van die land. Die veld- en ontledingsinligting is beskikbaar in digitale formaat, in ‘n geografiese inligtingstelsel en ‘n verskeidenheid digitale- en gedrukte kaarte.
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Ron, Vaz Maria Dolores. "Characterization of phosphorus in solutions from temperate soils." Thesis, University of Aberdeen, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261327.
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An analytical protocol for the determination of various soluble P fractions, namely: total dissolved P (TDP), dissolved reactive P (DRP), dissolved organic P (DOP) and dissolved condensed P (DCP) has been developed. The determination of DOP in soil solutions and water extracts was achieved by an improved automated photo-oxidation procedure, in which possible interferences caused by aluminium have been overcome. Partitioning of TDP into DRP, DOP and DCP fractions increased our understanding of P cycling in temperate soils. A combination of field and laboratory studies indicated that management factors such as soil acidity and fertiliser P additions greatly influenced the amount and distribution of soluble P between fractions. Natural climatic processes such as freeze/thaw and wetting/drying cycles have been shown to greatly affect soil P cycling. Fractionation of TDP into DRP, DOP and DCP components highlighted the problems associated with attributing the `freezing and drying effect' to any single process. The significance of these observations are discussed in terms of plant nutrition and possible contribution to P leaching and surface water quality.
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Tarkalson, David Dale. "PHOSPHORUS LOSS IN SURFACE RUNOFF FROM PIEDMONT SOILS RECEIVING ANIMAL MANURE AND FERTILIZER ADDITIONS." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010926-002603.
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The purpose of this research was to measure P losses in runoff from agricultural land in the Piedmont region of the southeastern U.S. with varying soil P levels and receiving broiler litter and inorganic P fertilizers. The experimental results will be helpful for the development of the P Loss Assessment Tool in North Carolina and other P Index approaches in states with similar soil characteristics and crop management practices. A net influx of P into many areas due to high animal populations has resulted in increased potential P losses to sensitive surface waters. A typical North Carolina broiler farm and dairy farm were found to have annual P surpluses of 65 kg P/ha and 20 kg P/ha respectively. The use of low phytic acid corn varieties and phytase enzyme has the potential to reduce the P surplus on broiler farms by 25 to 58%. Phosphorus losses in runoff from Piedmont conventional till (CT) and no-till (NT) soils with varying soil P concentrations and from soils currently receiving broiler litter and fertilizer P applications were assessed. In these studies, rainfall simulation at rates of 6 and 7.6 cm/hr were utilized to collect runoff samples from crop land with a range of initial P concentrations and from plots with varying fertilizer P and broiler litter application rates, both incorporated and broadcast. Runoff samples were collected at 5-min intervals for 30 min and analyzed for reactive P (RP), algal-available (AAP), and total P (TP). Concentration of RP in runoff from CT and NT plots was positively correlated with Mehlich-3 extractable P (r2 = 0.61 and 0.7 respectively) and oxalate extractable degree of P saturation (DPS) (r2 = 0.6 and 0.61 respectively). However, only TP mass loss (kg TP/ha) in runoff from CT was correlated with DPS (r2 = 0.57). A Mehlich 3 extractable P concentration of 350 mg P/kg and a DPS of 84% corresponded to 1 mg RP/L in runoff. Incorporation of broiler litter and inorganic P fertilizer into the soil at all P application rates virtually eliminated P runoff loses and had similar P losses in runoff as the unfertilized control. Surface application of broiler litter resulted in runoff containing between 2.9 and 24.5 mg RP/L for application rates of 8 to 82 kg P/ha respectively. Mass loss of TP in runoff from surface-applied broiler litter ranged from 1.3 to 8.5 kg P/ha over the same application rates. There was no significant relationship between surface applied inorganic P application rate and RP concentrations or TP mass losses in runoff. However, there was a trend for increased RP concentrations and TP mass losses in runoff with increasing application rate. Concentration of RP and mass loss of TP in runoff from surface applied inorganic P averaged 4.9 mg RP/L and 1.1 kg P/ha over all application rates. There was no significant difference between P losses in runoff from plots receiving surface applied conventional broiler litter and broiler litter derived from birds fed a low phytic acid corn (High Available P corn).
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Brown, Aaron D. "Chemical Weathering of Pyrite in Soils." DigitalCommons@USU, 1985. https://digitalcommons.usu.edu/etd/4345.
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The products of pyrite oxidation, including solution phase Fe2+, Fe3+, S2O32-, S4O62-, SO32- and SO42- and solid phase Fe(OH)3, were measured under controlled conditions in order to investigate the behavior of pyrite in calcareous and alkaline soils.
The distribution of sulfur oxidation products is pH dependent and can be interpreted in terms of metastable equilibrium among thiosulfate, disulfane disulfonate and sulfite. Thisulfate and sulfite predominate in the pH range greater than about pH 7 or 8. Sulfane disulfonates are more predominant at more acid pH.
Solution concentration data were consistent with the presence of Fe(OH)3. Concentrations of thiosulfate and sulfane disulfonate were consistent with a redox equilibrium among solution iron and sulfure species at pH 6 to 9.
Linear or zero-order kinetics were found to be sufficient for description of pyrite oxidation in this study. Linear kinetics were observed as electrical conductivity, solution sulfur products and solution plus solid phase iron products. The measurement of solution iron plus solid-phase iron oxide is a more rigorous approach to the extent of reaction than the measurement of sulfate.
The rate of pyrite oxidation is pH dependent, increasing from 10-20 pmol(Fe) m-2 s-1 to 40-60 pmol(Fe) m-2 s-1 between pH 5 and 9. This is consistent with an oxidation mechanism involving the reoxidation of solution Fe2+ via a reaction between an iron hydroxide complex and hydrated oxygen as the rate-determining step. The effect o background electrolytes on oxidation rates at low pH also supports this interpretation.
Pyrite oxidation rates in the presence of calcium carbonate, sodium bicarbonate, sodium thiosulfate and calcium-saturated bentonite can be related to the pH effect. Sodium thiosulfate and DTPA appeared to have specific inhibitory effects.
Column studies show that the disposal of pyritic mine spoils or tailings by mixing with calcareous material may produce thiosulfate, a good reducing agent for toxic metals. Burial of lime below pyritic materials may protect groundwater quality more effectively than application of lime to the surface.
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Jia, Xinhua. "Electrokinetic management of nitrate movement in drip irrigated soils." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280615.
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Nitrate contamination of surface and groundwater has become a serious concern in many agricultural areas throughout the world. The major source of nitrate contamination is believed to be nitrogen fertilizer from agricultural fields. Best Management Practices have been developed to guide fertilizer use and minimize nitrogen losses, but do not address control of nitrate movement from the crop root zone. It is proposed that an in-situ method, electrokinetics (EK), could be used to control nitrate movement, retaining it near the root zone. Lysimeter experiments were conducted to evaluate the effect of parallel electrodes on pH and nitrate distribution in field soils subjected to an electrical input. However, the expected results, increased nitrate retention, reduced sodium and calcium concentration and lower pH values near the anode, were not attained consistently in the test soils with and without Sudan grass. Small scale experiments in a vertical, partially saturated sandy soil column (25 cm height by 14 cm diameter) were conducted to evaluate the optimal EK parameters. After 80 mA current for 6 h the nitrate was retained near the anode, with the highest measured nitrate concentration of 7155 mg/L within 5 mm of the anode. The nitrate concentration at the cathode was 1/5 of the inflow solute concentration (221 mg/L). The pH was 11 near the cathode, 3.5 near the anode, and showed little changes in intermediate layers. The results demonstrate that in sandy soils nitrate can be strongly retained near the anode, even against gravity effect. As the percentage of illite clay in the soil increased, the EK effect decreased; due to the increase of fine clay particles both the transports of ions and the water were inhibited. The loam soil showed some increase in the nitrate concentration near the anode, but the clay soil showed no change. An increase of pH near the cathode was seen in all soils. The electrical potential analysis showed the sandy soil required the highest electrical potential 97.23 V, loam soil was 18.24 V and clay soil was 14.22 V.
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Jopony, Marcus. "The solubility of lead and cadmium in contaminated soils." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292700.
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Uygur, Veli. "Zn sorption/desorption chemistry in calcareous soils from Turkey." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388131.
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Nawar, Niman K. "Reclamation of saline-sodic soils by poly (vinyl alcohol)." Thesis, University of Salford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258170.
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Abu, Bakar Rosenani. "Nitrate losses from agricultural soils - the role of identification." Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238688.
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Gibson, Richard W. "The characterisation of soluble organic matter from forest soils." Thesis, University of Aberdeen, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295565.
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The characteristics of water-soluble organic material in soil solutions has been studied extensively 'in situ'. Relatively little attention has focused on isolation of such material, particularly when comparison of a number of samples has been attempted. In this study the water-soluble organic acids leached from the soil horizons beneath eight different tree species were isolated by adsorption onto macroporous resins. Amberlite XAD-8 and XAD-4 resins were used in series therefore two samples, labelled as 'hydrophobic' and 'hydrophilic' acids were obtained. Practical amounts of free organic acids for characterisation purposes were isolated from each resin. Elemental analysis (carbon, nitrogen and sulphur) and acidity (measured by potentiometric titration) reflected the probable state of oxidation of the material. Lower molecular weight material was more abundant with depth. Copper binding ability correlated well with the acidity generally but a group of samples isolated from similar horizons and resin showed high acidity and poor metal binding ability. This was probably due to the inability of the acidic sites to be involved in chelation reactions. Metal binding was measured using gel filtration, dialysis and an ion-exchange method. Chromatography in gel filtration was monitored by direct feed of column effluent into an atomic absorption spectrophotometer, a technique attempted but not used successfully before. The method measured directly metal bound and required only 0.2 mg of sample per determination. For these reasons this method was used for routine analysis whereas dialysis and ion-exchange were only used for comparison purposes. As expected the samples isolated on each resin were very different. Comparison of samples from the horizons showed clearly the increased state of oxidation with depth. It was possible to establish differences in the organic material in the soil horizons on the basis of whether the stands were coniferous or deciduous trees but the similarities between the samples were perhaps equally striking.
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Cook, Simon Ernest. "Amendment of agricultural peat soils with pulverised fuel ash." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317763.
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Lee, Say Yong. "Centrifuge modelling of cone penetration testing in cohesionless soils." Thesis, University of Cambridge, 1990. https://www.repository.cam.ac.uk/handle/1810/250983.
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Bernard, Marie-Eve. "Nitrous oxide emissions and denitrification potential of fertilized grassland soils in Western Norway." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104860.
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In Norway, 65% of agricultural soils are under grassland that receives high N inputs from manure and mineral fertilizers each year and are expected to be an important source of N₂O from denitrification. The objectives of this thesis were to quantify the N₂O emissions, denitrification potential and N₂O:(N₂+N₂O) ratio of grassland soils from Western Norway and to relate these measures of N₂O production to soil physico-chemical properties and climate. During a two-year field experiment, there was relatively little N₂O emitted (fluxes did not exceed 200 μg N₂O-N m-2 h-1) from grassland receiving manure and mineral fertilizers. The N₂O fluxes were positively correlated (p < 0.001) with soil mineral N (r= 0.29) and air temperature (r= 0.31) in both years, but negatively correlated with WFPS (r= -0.44) in 2009 only. Cumulative N₂O losses were from 1.5 to 2.1 kg N₂O-N ha-1 in 2009 and 0.2 to 0.7 kg N₂O-N ha-1 in 2010. Year-to-year variation in N₂O loss was attributed to the N fertilizer regime prior to 2009 and higher N mineralization rates in 2009 than in 2010. Dry matter yield and the cumulative N₂O losses were negatively correlated in 2009 and positively correlated in 2010, probably due to differences in climatic conditions and grassland productivity. Laboratory incubations with soil from eight grasslands gave N₂O:(N₂+N₂O) ratios from 0.14 to 0.74, which were negatively correlated (p< 0.05) with soil organic C (Corg) and soil pH. Higher N₂O:(N₂+N₂O) ratios from soils washed with a 5mM KNO₃ solution imply that N₂O production by denitrifiers was limited by NO₃ availability. Denitrification potential was from 0.42 to 9.38 μg N₂O-N gdwsoil-1 h-1, with the lowest value in the forest soil, intermediate values in the mineral soils and the highest value in the peat soil. The denitrification potential was correlated with soil Corg (r= 0.95, p < 0.01) and soil pH (r=0.46, p < 0.05). We propose that grassland soil be limed more frequently to increase soil pH and therefore reduce the N₂O emissions associated with low soil pH. Furthermore, the low NO₃ availability in Norwegian grasslands due to the efficient N use by plants indicates that these agroecosystems should have low N₂O emissions.En Norvège, 65% des terres agricoles sont cultivées en fourrage et reçoivent de grandes quantités d'engrais organique et minéral, représentant donc des sources potentielles de N₂O par la dénitrification. Les objectifs de ce mémoire étaient de quantifier les émissions de N₂O, le potentiel de dénitrification et le ratio N₂O:(N₂+N₂O) de sols de prairies agricoles de l'ouest de la Norvège et de relier ces mesures de production de N₂O aux propriétés physiques et chimiques du sol et aux variations climatiques. Lors des deux années de l'expérience au champ, il y a eu relativement peu de N₂O émis (les flux n'ont jamais excédé 200 μg N₂O-N m-2 h-1) par la prairie ayant reçu du lisier et des engrais minéraux. Les flux de N₂O étaient positivement corrélés (p < 0.001) avec l'azote minéral du sol (r= 0.29) et la température de l'air (r= 0.31) durant les deux années, mais négativement corrélés avec le contenu du sol en eau (r= -0.44) en 2009. Les pertes cumulatives de N₂O ont varié de 1,5 à 2,1 kg N₂O-N ha-1 en 2009 et de 0,2 à 0,7 kg N₂O-N ha-1 en 2010. La variation inter-annuelle est attribuée à un effet résiduel de la fertilisation avant 2009 et par un taux de minéralisation de l'azote supérieur en 2009 qu'en 2010. Le rendement en matière sèche et les pertes cumulatives en N₂O étaient corrélés négativement en 2009 mais positivement en 2010, probablement dû à des différences climatiques et à la productivité de la prairie. Des expériences d'incubation au laboratoire avec huit sols de prairies ont donné des ratios N₂O:(N₂+N₂O) entre 0.14 et 0.74, et ces ratios étaient négativement corrélés (p< 0.05) avec le contenu du sol en carbone organique et le pH du sol. Le ratio N₂O:(N₂+N₂O) plus élevé dans les sols ayant reçu du KNO₃ (5 mM) indique que la production de N₂O par les dénitrifiants était limité par le NO₃. Le potentiel de dénitrification se situait entre 0,42 μg N₂O-N g sol-1 h-1 et 9,38 μg N₂O-N g sol-1 h-1, avec la plus petite valeur dans le sol forestier, les values intermédiaires dans les sols minéraux et le plus élevé dans le sol organique. Le potentiel de dénitrification était significativement corrélé avec le contenu du sol en carbone organique (r= 0.95, p < 0.01) et le pH du sol (r=0.46, p < 0.05). Nous suggérons que les prairies soient chaulées plus fréquemment pour augmenter le pH du sol afin de réduire les émissions de N₂O dû au faible pH du sol. De plus, la faible disponibilité des NO₃ dans les prairies de l'ouest de la Norvège dû à l'efficacité des plantes à utiliser l'azote indique que ces agro-écosystèmes devraient émettre de petites quantités de N₂O.
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Syan, Harvinder. "Fate and transport of herbicides used in growing transgenic canola in Quebec soils." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114603.
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Canola is the second most important oilseed crop after soybean. More than 90% of the canola crop grown in the world is transgenic. Before this crop is grown more extensively in Quebec, there is a need to assess environmental risks associated with genetically engineered canola, mainly Roundup Ready (glyphosate- resistant) and Liberty Link (glufosinate-resistant) varieties. We have conducted a field study to compare and contrast the fate and transport of glyphosate and glufosinate herbicides in soil (used in transgenic canola production), with trifluralin, a herbicide commonly used with non-transgenic (conventional) canola cultivars. Yield data were also collected in each test plot. Three treatments were assigned (type of transgenic canola, variety, and plant stage at which herbicide application was made), in quadruplicate, in a completely randomized block design set up at two sites: Emile A. Lods Agronomy Research Centre in the Macdonald Campus of McGill University and the Normandin site of Agriculture and Agri food Canada. Soil samples were collected from two depths, 0-0.15 m and 0.15-0.30 m, at different times (1, 7 and 20 days) after herbicide application, during the growing season. Non-significant yield differences were observed between herbicide-resistant and conventional canola grown in Quebec. Glufosinate was found to be the least persistent herbicide (half-life = 7 days), while trifluralin was found to have the longest persistence in the soil (half-life = 54 days). The overall order of persistence was Trifluralin > Glyphosate > Glufosinate. Negligible leaching was observed in case of glyphosate and glufosinate to a depth of 0.30 m. Since glyphosate was found to be highly adsorbed on to the topsoil at the Lods site, herbicide concentrations were recalculated for the top 2 mm of soil, as per published literature, and they were very high, thus heightening concerns for polluted surface runoff. Trifluralin was found at the lower depth (0.15-0.30 cm) at 7 and 20 days after herbicide application, with higher (relative to each herbicide's level in the soil one day after application) residual concentrations than herbicides used in herbicide resistant (HR) canola.Le canola est au deuxième rang mondial, après le soja, comme culture oléagineuse. Plus de 90% de la récolte de canola provident de variétés transgéniques. Avant que cette culture prenne sa place au Québec il est nécessaire d'évaluer les risqué environnementaux associés au canola transgénique, en particulier les variétés Roundup Ready (tolérant au glyphosate) et Liberty Link (tolérant au glufosinate). Une étude au champ, nous a permis de comparer et mettre en contraste le devenir et le transport d'herbicides à base de glyphosate and glufosinate, utilisées dans la production de canola transgénique, dans le sol, avec la trifluraline, un herbicide servant au contrôle des mauvais herbes dans le canola non-transgénique (conventionnel). Le rendement fut évalue pour chaque parcelle. Trois traitements furent imposes (type de canola transgénique, variété, et étape de développement de la culture lors de l'application d'herbicide), avec 4 répétitions, dans un protocole complètement aléatoire et plans en blocs aléatoires complets, mis en place à deux sites: la Ferme Lods sur le campus Macdonald de l'université McGill, et au site Normandin d'Agriculture et Agroalimentaire Canada. Des échantillons de sol furent prélevés à deux profondeurs (0-0.15 m et 0.15-0.30 m), à différent moments (1, 7 et 20 jours) après l'application d'herbicide. Des différences non-significatives furent notées entre le rendement des variétés de canola résistantes aux herbicides et le canola conventionnel, cultivées au Québec. Le glufosinate se montra l'herbicide le moins persistant dans le sol (demi vie = 7 jours), tandis que la trifluraline se montra le plus persistant (demi-vie = 54 jours). Globalement, la persistance de ces herbicides suit l'ordre Trifluraline > Glyphosate > Glufosinate. Un niveau négligeable de lessivage jusqu'à une profondeur de 0.30 m fut observe pour le glyphosate et le glufosinate. Etant donné la forte liaison du glyphosate aux sols du site Lods, les concentrations recalculées pour the 2 mm en surface furent très élevées, représentant ainsi un certain risque de perte par ruissèlement. La trifluralin fut détectée dans la zone du sol la plus profonde (0.15-0.30 m) 7 et 20 jours après l'application d'herbicide application, et présenta des concentrations résiduelles plus élevés à 7 et 20 jours, sur une base relative aux niveaux présents dans le sol un jour après l'application des herbicides, que les herbicide appliqués aux variétés de canola résistantes aux herbicides.
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Herselman, Jacoba Elizabeth. "The concentration of selected trace metals in South African soils." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/1390.
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Thesis (PhD (Soil Science))--University of Stellenbosch, 2007.Trace elements occur naturally in soils, usually at low concentrations (<0.1% or <1000 mg kg-1 of the earth’s crust), as a result of weathering and pedogenic processes acting on the rock fragments from which soil develops (parent material). Since about 98% of human food is produced on land, soil is the primary source supplying these elements to the food chain. Although cases of trace element deficiency and toxicity have been documented in many parts of South Africa, no comprehensive description of trace element concentration has yet been attempted for South Africa as a whole. The Natural Resources Land Type mapping project, initiated in the mid-1970s, has provided a collection of samples (approximately 4500) from soil profiles selected to represent the main soil forms in each land type and therefore to provide representative coverage of most of the soils of South Africa. These archived samples have now been analysed for a spectrum of trace elements, in terms of both available and total concentrations as well as other soil properties. Although detailed information is available on a wide range of trace metals, the seven trace metals considered to be of most interest in a South African context due to natural geological occurrences were selected for this study, including Cd, Co, Cr, Cu, Pb, Ni and Zn. This data was used to: • determine baseline concentrations in SA soils; • determining threshold values for South African agricultural soils receiving sewage sludge at agronomic rates; • determining the influence of certain soil properties on the baseline concentrations of these trace elements in SA soils; and • development of a bioavailable trace element distribution map for SA. The range, the mean and standard deviation (both arithmetic and geometric), and the median were used to summarize the data statistically. The baseline concentration range was calculated using the quotient and product of the geometric mean and the square of the geometric standard deviation, including data below the instrument detection limit. The upper limit of the baseline concentration range was set at the 0.975 percentile value of the population in order to minimize the influence of contamination and the lower limit at the 0.025 percentile value to minimize problems that might be associated with analytical uncertainty near the lower limit of detection. The quantile regression statistical approach was followed to illustrate the relationship between soil properties and trace element concentrations in soils. The soil properties that showed the strongest relation were CEC, clay content, pH (H2O) and S value (base status). The soils were then divided into different classes according to these soil properties and baseline concentrations were derived for the different classes. Soils with low clay contents have lower trace element concentrations than soils with higher clay contents, soils with low or high pH levels have lower trace element contents than soils with intermediate pH values and mesotrophic soils have higher trace element concentrations than dystrophic soils. This information is useful for the compilation of trace element distribution maps for South Africa where different soil forms and series/families could be classified into different classes to determine areas of potential deficiencies as well as toxicities. South Africa, with its diverse geology, has areas of both trace element toxicities and deficiencies and for decision-making purposes it is necessary to identify these areas. Mapping of trace element levels based on soil samples would provide valuable information, which cannot be obtained from geological or geographical maps. Statistical analyses of the data (clay %, base status, pH (H2O) and NH4EDTA extractable trace element concentrations) indicated that soils could be divided into five trace element classes based on their clay content, pH and base status (dystrophic, mesotrophic and eutrophic). The soil series according to the binomial soil classification system for South Africa were then divided into these different classes. The geometric means for each clay class were determined and the baseline concentration range for each class was calculated. The land type maps were used as basis for the distribution maps. A general trace element distribution map for South Africa was derived from this data as well as Cu and Zn distribution maps. A random selection of 500 soil samples across the country was used to verify the accuracy of the distribution map. The general trace element distribution map indicate, with a confidence level between 89 and 96%, where the potentially available trace element content of South African soils are low (deficient) too moderately high, excluding rocky areas and areas with limited soil. The Cu and Zn maps indicate the distribution and expected baseline concentrations of these specific elements in South African soils. The same methodology could be applied to derive risk maps for all the individual trace elements to indicate the distribution and expected baseline concentrations of the elements in South Africa. This presentation of baseline concentrations, reflecting likely natural ranges in South African soils, is the first quantitative report on the spatial extent and intensity of Zn, Cu and Co deficiency in South African soils. The proposal of new threshold values for trace elements in agricultural soils will be valuable in setting more realistic norms for environmental contamination that accommodate the geochemical peculiarities of the region, one example being rather high Cr and Ni concentrations with low bio-availability. This information should be of value not only in environmental pollution studies but also in health, agriculture, forestry and wildlife management. The following recommendations are made: • The baseline concentrations could be used to determine site specific threshold values based on soil properties and soil type. Soils with lower pH, clay content and CEC would require more protection than soils with high pH, clay content and CEC and therefore the threshold levels for these soils should be lower. • Although the distribution maps can be used to indicate broad areas of trace element deficiencies and toxicities, more detailed investigations are recommended for areas where problems are experienced. The same methodology could be applied on smaller scale to increase the value of the map and to add more value on a regional scale. The maps could be used for regional soil quality assessment especially in areas where trace element deficiencies or toxicities could result in negative effects on plants and animals.
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roberts, john christopher. "Impact of Manure and Soil Test Phosphorus on Phosphorus Runoff from Soils Subjected to Simulated Rainfall." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-06162005-123000/.
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Runoff from agricultural fields amended with animal manure or fertilizer is a source of phosphorus (P) pollution to surface waters, which can have harmful effects such as eutrophication. The objectives of this study were to evaluate the impact of soil P status and the P composition of manure sources on P in runoff, characterize the effects of manure sources on mass loss of dissolved reactive P (DRP), total dissolved P (TDP), algal available P (AAP) and total P (TP) in runoff, and enhance the PLAT database with respect to soluble P attenuating factor (SPAF) and non-soluble P attenuating factor (NSPAF) values. Soil boxes set at 5% slopes received 7.5 cm hr-1 of simulated rainfall. Study soils included a Kenansville loamy sand (loamy siliceous subactive thermic Arenic Hapludults, a Coastal Plain soil) and a Davidson silt loam (kaolinitic thermic Rhodic Kandiudults, a Piedmont soil). Soil test P concentrations ranged from 16 to 283 mg P kg-1. Sources of P included broiler litter (BRL), breeder manure (BRD), breeder manure treated with three rates of alum (Al2(SO4)3) BRD0-0 kg m-2, BRDL-3.9 kg m-2, and BRDH-7.8 kg m-2 and DAP along with an unamended control. All manure sources were applied at 66 kg P ha-1. Water extractable P (WEP) represented an average of 10 ?b 6% total P in manure. Runoff samples were taken over a 30-min period. Piedmont soil contained greater amounts of clay, Al and Fe concentrations, and higher P sorption capacities that produced significantly lower DRP, TDP, AAP, and TP losses than the Coastal Plain soil. Runoff P loss did not differ for low and high STP soils of same taxonomy with the exception of AAP mass losses for Coastal Plain soil samples. Water extractable P in manures accounted for all DRP lost in runoff with DRP correlating strongly with WEP concentration (0.9961). A weak relationship between DRP in runoff and WEP applied to soil boxes was observed (R2=0.6547) and increased when a possible outlying manure treatment, BRL, was omitted from regression data (0.9927). Overall, manures containing the highest WEP concentrations supplied the largest losses of DRP in runoff. Manure treated with 3.9 and 7.8 kg m-2 of Al2(SO4)3 (alum) decreased DRP in runoff by 29%. Values calculated for PLAT SPAF and NSPAF coefficients were higher for Coastal Plain soil than Piedmont soil and overall higher than default values in PLAT. Management based on these results should help minimize harmful effects of P in runoff.
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Wimaladasa, G. D. "Some aspects of the chemistry and mineralogy of soil potassium in Sri Lankan acid tea soils and Scottish soils under a range of crops." Thesis, University of Aberdeen, 1989. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU020940.
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The Sri Lankan acid tea soils, collected from six different agro-ecological regions and from the long-term field experiments in St. Coombs, were subjected to a detailed mineralogical investigation with particular reference to the understanding of the chemistry of soil potassium and K fertiliser applications. These extremely weathered soils contained predominantly kaolinite, Al-chlorite, gibbsite and goethite, but K-fixing minerals like smectite and vermiculite were absent. Small quantities of micaceous minerals were only found in the fine and coarse sand fractions of these soils, except in the Hantana soil which contained substantial quantities of micaceous minerals in the clay, silt and sand fractions. The clay and silt fractions of the Scottish soils of the Countesswells and Foudland soil series comprised 60% to 70% of mica and mica-weathered products of interstratified mica/vermiculite and vermiculite/chlorite. The rate of transformation of the micaceous minerals and the concentration of hydroxy-Al 'islands' in the Countesswells soil series increased with decreasing soil pH. The Foudland soil contained more weatherable micaceous minerals, and spring barley, winter wheat, potatoes and ryegrass/clover in a crop rotation field experiment produced optimum crop yields in the absence of K fertilisers, due to the release of substantial amounts of non-exchangeable K. The Countesswells soil was unable to supply sufficient non-exchangeable K for ryegrass/clover growth in order to achieve the same yield as that with K fertiliser. A mixed NH4- and Cl- ion exchange resin method for extraction of soil K was developed, which was capable of estimating the amounts of short-, medium- and long-term K reserves that are available to ryegrass, grown in different soil types covering a wide range of soil pH and K-bearing minerals, without destroying the mineral matrix, but K-bearing minerals in both soils and pure minerals were found to either transform or dissolve progresively as mineralogical changes took place at the soil/root interface. A new perspex cell was constructed to hold a 4mm layer of soil or mineral, for in situ studies of root morphology, and for study of the mineralogical changes in soils or pure K-bearing minerals, due to the uptake of both exchangeable and non-exchangeable K by ryegrass, within a 2mm radius of the root surface. This study showed that there were more total, primary and lateral ryegrass roots growing in a soil of higher K status, compared with one of lower K status. The numbers of dead or decomposed roots were greater in the lower K status soil. Interstratified smectite, mica/vermiculite and vermiculite/chlorite minerals were formed in the soil within a 2mm radius of the root surface, due to K uptake by ryegrass. These mineralogical changes were not observed in the same soil under intensive cropping with ryegrass in the glasshouse in bigger cylindrical pots or after 21 years of continuous growth of ryegrass in the field. Dissolution of the 2:1 layer silicate mineral structure occurred in soils and vermiculite in the perspex cells, due to the production of H3O- ions, particularly where root growth was greatest. This dissolution mechanism may override the diffusion mechanism of K release to plant roots within a 2mm radius of the root surface, and may help explain the wide range of diffusion coefficients of soil K, (10-10 to 10-23)cm2 sec-1, which appear in the literature. The new techniques of extraction of soil K by use of a mixed NH4- and C1- ion exchange resin and of studying root growth in a perspex cell, which were developed in this thesis, merit further investigation.
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Townsend, Geoffrey Stephen. "Rate processes in aluminium mobilization from soils to surface waters." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315123.
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Alcock, Ruth Elizabeth. "The role of soils in the global cycling of PCBs." Thesis, Lancaster University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240505.
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Staunton, M. B. S. "The diffusion and reaction of ions in naturally aggregated soils." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375294.
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Haider, Abdul Rahman A. M. "Phosphate and micronutrient behaviour in some calcareous soils of Yemen." Thesis, Bangor University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254036.
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Osei, Benjamin Appiah. "Mineralogy, potassium status, and colloidal chemistry of some Ghanaian soils." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363900.
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Mbakwe, Ikenna. "An evaluation of the effectiveness of coal ash as an amendment for acid soils." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/1897.
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Kreinberg, Allison J. "The Sorption and Transformation of Tylosin and Progesterone by Soils." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1341590774.
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Warren, G. P. "Available nitrogen in relation to fractions of soil nitrogen in grassland soils." Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370367.
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Davis, Karen Melissa. "Using Apparent Electrical Conductivity (ECa) via Electromagnetic Induction (EMI) to Characterize Soils and the Stratigraphy for Wetland Restoration." NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-04302007-204731/.
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Wetland restoration can be difficult due to the time consuming efforts it requires to evaluate the soils and vegetation within the area being considered. The objective of this study was to determine whether apparent soil electrical conductivity (ECa) measured via electromagnetic induction (EMI) (a non-contact method) could be used to identify soil particle size distribution, map units, and selected chemical properties at a Carolina bay wetland restoration site, Juniper Bay. Surveys of ECa were performed at Juniper Bay in December 2000, June 2001, October 2005, and December 2005 using the EM38, GEM-2, and GEM-300 in the horizontal and vertical dipole positions. Cores were dug to depths of 6.1 and 15.2 m based on an equilateral triangle grid and adequate representative sampling of soil map units. Pits were dug to 1- and 1.5-m depths. Core and pit samples were analyzed for particle size distribution and soil chemical properties. Surficial samples were collected from 0- to 15-cm and 15- to 30-cm depths; chemical properties were evaluated on these samples. Correlations of ECa with soil particle size distribution and chemical properties were determined. Linear models were derived relating soil clay content and ECa. Soil ECa was compared with soil organic C and water table depth to determine if either property could be detected using EMI. Also, ECa from different survey dates were compared to determine whether there were short-term (within a day) and long-term (months to years) temporal changes in ECa. The ECa from the initial overall December 2000 survey was strongly correlated with soil core clay content at depths from 0.61 to 1.22 m and 2.74 to 3.96 m. The reason for this is unknown. Initial overall December 2000 ECa was also strongly correlated with pit clay content. No other soil core or pit particle size analysis properties had strong significant and consistent correlations with ECa for the December 2000 survey or for any of the other surveys. Few chemical properties were correlated with ECa; however, ECa was weakly correlated with pit organic C. Results showed that ECa could not be used to delineate soil map unit, but the map unit ECa means were different. However, ECa could not detect water table depth at Juniper Bay. Soil ECa was found to be temporally variable, and ECa surveyors should be conscious of potentially varying conditions from survey to survey. Along with ground-truthing, ECa modeling could be used to estimate clay content at certain depths and locations within Juniper Bay. This could aid wetland restoration by identifying locations of aquitards, which might have been penetrated by drainage ditches. Filling the ditches in the correct places could allow restoration to progress faster and more efficiently.
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St, Luce Mervin. "Labile organic nitrogen fractions: characteristics, dynamics and significance to soil nitrogen supply in agricultural soils." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117160.
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Short-term nitrogen (N) availability in agricultural soils is derived mostly from the labile organic N pool. A better understanding of N transformation processes that occur in key labile organic N fractions is necessary to recognize their role in N cycling and their relative contribution to N mineralization. The objectives of this thesis were to (1) examine, under field conditions, the influence of preceding legume and non-legume crops on microbial biomass N (MBN), water-extractable organic N (WEON), and particulate and light fraction organic matter N (POMN, LFOMN) across five sites and how these fractions supply N to canola (Brassica napus L.), as determined from N uptake and grain yield, and (2) investigate under controlled conditions, the incorporation and turnover of crop residue N through MBN, WEON, POMN and LFOMN. Labile organic N fractions were similar regardless of preceding crop but varied across sites due to soil and climatic conditions. The POMN was the best single predictor of soil N supply (R2 = 0.56 and R2 = 0.70 for yield and N uptake, respectively). Soil N supply was related to POMN, mineral N and sand content, which explained 68% of the variation in grain yield and 71% of the variation in N uptake. Sandy-loam and clay soils were incubated for 112 d with 15N-labelled faba bean (Vicia faba, C/N ratio = 29) and wheat (Triticum aestivum L, C/N ratio = 91) residues. After 3 d, most (17-30%) of the residue 15N was recovered in the POMN, with a greater proportion of the wheat than the faba bean residue recovered in the POMN fraction. The 15N recovered in the POMN fraction after 3 d was significantly related to mineral N released after 112 d (r = 0.78, P<0.001), with more 15N released as mineral N in sandy-loam than clay soil and from faba bean than wheat residue. Net N mineralization in whole soil (WS) + POM mixtures was better related to POM N concentration and less to soil mineral N, soil texture or pH, suggesting that the extent to which POM contributes to N mineralization depends on the crop residue chemistry from which it was derived. I conclude that the turnover of POMN is a major pathway through which mineral N is released in the short-term in agricultural soils. Current N fertilizer recommendations can be improved by considering POM and soil mineral N concentrations, soil texture and environmental conditions. This will help to minimize the negative impacts of N losses on the environment and make a significant step towards enhancing N-use efficiency in agroecosystems.La disponibilité à court terme de l'azote (N) dans les sols agricoles est essentiellement issue de la fraction labile du N organique. Une meilleure compréhension des processus de transformation de ces fractions est nécessaire pour connaitre leur rôle dans le cycle de l'azote et leur contribution relative à la minéralisation de N. Les objectifs de cette thèse étaient de (1) examiner, sous les conditions de champs, l'effet du précédent cultural (légumineuse vs non-légumineuse) sur la biomasse microbienne de l'azote (MBN), l'azote organique extrait à l'eau (WEON) et les fractions légère et particulaire de la matière organique (POMN, LFOMN) à travers cinq sites et comment ces fractions sont-elles liées à l'approvisionnement en N [canola (Brassica napus L.) prélèvement de N et rendement en grains] and (2) étudier, sous des conditions contrôlées, l'incorporation et le turnover de l'azote des résidus des cultures via MBN, WEON, POMN et LFOMN. Les fractions labiles du N organique étaient similaires quel que soit le précédent cultural mais varie avec les sites due aux sols et aux conditions climatiques. Le POMN était le meilleur indicateur de l'approvisionnement en N (R2 = 0,56 and R2 = 0,70 pour le rendement en grains et le prélèvement en N, respectivement). De plus, l'approvisionnement en N était premièrement relié à l'effet combiné de POMN, l'azote minéral et la teneur du sol en sable; ces paramètres expliquent 68% de la variation dans le rendement en grains et 71% de la variation dans le prélèvement en N .Deux sols, loam sableux et argileux, ont été incubés pendant 112 jours avec des résidus d'haricot (Vicia faba, C/N = 29) et du blé (Triticum aestivum L, C/N = 91) marqués à 15N. Après 3 jours, la majeure partie (17-30%) des résidus de 15N a été trouvée dans la fraction POMN par comparaison aux autres fractions. Une plus grande proportion de résidus de blé que de résidus d'haricot a été trouvée dans la fraction POMN. La forme minérale du 15N libérée a été plus élevée dans le sol laom-sableux que dans l'argile et avec l'incorporation de l'haricot comparée au blé. Le 15N incorporé au POMN après 3 jrs a été significativement relié à l'azote minéral libéré après 112 jrs (r = 0.78, P<0.001). La minéralisation nette dans le mélange au sol entier (WS) + POM est plus liée à la teneur en N du POM qu'à la teneur du sol en N minéral, sa texture et son pH. Ainsi, l'ampleur de la contribution de la fraction POM à la minéralisation de l'azote dépond de son origine. Dans l'ensemble, les résultats de cette étude suggèrent que le turnover de la fraction POMN est la principale voie par laquelle le N minéral est libéré dans les sols agricoles. Les recommandations actuellement utilisées en fertilisation azotée peuvent être améliorées en tenant compte des POMN, N minéral du sol, texture du sol et les conditions environnementales. Ces informations permettront de minimiser les impacts négatifs de la perte de N dans l'environnement and contribueront à l'amélioration de l'efficacité de l'utilisation de l'azote dans les agroécosystèmes.
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Lee, Jong-Sub. "High resolution geophysical techniques for small-scale soil model testing." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04052004-180045/unrestricted/lee%5Fjong-sub%5F200312%5Fphd.pdf.
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Hanafi, M. M. "Dissolution and plant availability of phosphate rock in acid Malaysian soils." Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386725.
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Aldhaheri, Salem M. "Analysis of trace elements in soils and their uptakes by plants." Thesis, University of Salford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280780.
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Ley, George J. "A study of hard-setting behaviour of structurally weak tropical soils." Thesis, University of Aberdeen, 1988. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU010493.
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Some soils set to a hard structureless mass on drying and this behaviour may limit crop productivity. The purpose of this study was to assess the extent to which soil management and soil properties influence hard-setting behaviour in order to identify those soil properties which are most appropriate to characterise the limitations to management and crop growth imposed by hard-setting. Five sites from four vegetation zones of Nigeria were investigated. Within each site soils were sampled from no-till or forested plots and these were contrasted with cleared (deforested) amd ploughed plots. Hard-setting behaviour was determined by measuring the unconfined compressive and tensile strengths of small undisturbed cores (minicores) which had been equilibrated at a range of matric potentials. Rooting potential was assessed both by measuring needle penetrometer resistance or cores equilibrated at potentials of -6 and -100 kPa; and also by measuring penetrometer resistance in the field at a range of moisture contents. Soil bulk density, organic matter concentration, soil friability, aggregate stability and amounts of water suspendable solids were also measured to assess soil properties that are likely to be diagnostic of hard-setting behaviour. The limitations imposed by hard-setting behaviour on rooting and yields of maize and cowpea were assessed at IITA. The minicore strengths increased as the moisture content decreased but the increase was much more marked for mechanized cleared or tilled soils than for the less disturbed treatments of forestry and a no-till system. For all soils the most pronounced effects of moisture content deplection on soil strength occurred at potentials of < -100 kPa. Theoretical considerations indicated that the effective stress accounted for over half of the strength of minicores at -100 kPa and more than accounted for the strength of minicores at -1 MPa. The greater strength in tilled soils was attributed to a decrease in organic matter content, wet aggregate stability and friability and to an increase in bulk density. Needle and field penetrometer resistance results indicated that rooting potential was reduced on hard-setting soils and actual root measurements supported this view. Consequently maize and cowpea yields were reduced.
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Sanger, Luke. "Acidic deposition effects on upland organic soils and their drainage water." Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU058910.
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The work presented in this thesis investigates the effects of precipitation chemistry on the chemical characteristics of upland organic soils in the UK and their associated drainage waters. It also describes effects on a number of microbially-mediated processes and concludes with a study on methods for the amelioration of peat acidification. Data presented in chapters 3, 5 and 6 have recently been published or accepted for publication (Sanger et al. 1993 a. 1993 b and 1993 c). The first chapter describes the nature of soil acidity and reviews the relevant literature on the effects of acidic deposition, with particular emphasis on upland organic soils and their drainage waters. Chapter 2 describes a field survey carried out in the UK which investigates relationships between the exchangeable and total element chemistry of peat and precipitation chemistry. The results showed that peat collected from areas receiving high concentrations of H+, NH4+, SO42- andNO3- in precipitation were characterised by high extractable NH4+ and total P. and low extractable NO3-, base saturation and exchangeable Ca2+ and Mg2+. TheNH4+ concentration in precipitation was strongly related to a number of soil chemical parameters and the results suggest that future changesin NH4+ inputsto peatscould significantlyeffect soil and drainage water chemistry. The results also show that (1) processes involved in the cycling of N and P may have been altered by precipitation chemistry (2) exchangeable Ca2+ and Mg2+ have been displaced by NH4+ and H+ in areas with high acidic deposition. Peat from areas with a high marine input in precipitation contained high concentrations of exchangeable N+ and K+. Laboratory simulation studies (chapter 3 and 4) using intact peat monoliths were carried out to complement the regional survey described in chapter 2. They were set up to examine element fluxes from peats in relation to precipitation chemistry.
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Salman, Talib H. "Triaxial behaviour of partially saturated granular soils at low stress levels." Thesis, University of Sheffield, 1995. http://etheses.whiterose.ac.uk/10232/.
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Granular soil is used as a backfilling material in trenches that are prepared for the installation, repair and replacement of service pipes. The soil is likely to be partially saturated and subjected to low stress levels (<100 kPa), as it exists at shallow depths (about 5m below the ground). A new double-wall triaxial cell has been designed for testing partially saturated granular specimens with height/diameter equal to 375mm/150mm, at low stress levels. The cell is able to make separate measurements and control of the pore air and pore water pressures. It was designed to make specimen stress and strain measurements internally. A conventional triaxial cell was modified to carry out tests on saturated granular specimens of the same dimensions at low stress levels. Two gradings of Limestone, fine and coarse, with maximum particle sizes of 5mm and 20mm respectively are used in the triaxial tests. The experimental results showed that the suction in the range 25 kPa to 75 kPa can have an effect on the volume, stiffness and shear strength of partially saturated granular soils at low stress levels. The results also showed that there is a linear relationship between q and (p-u_a) for the unsaturated soils or (p-u_w) for the saturated soils. And Fredlund's equation cannot be used to predict the shear strength of partially saturated granular soils at low stress levels, if the value of φ'is taken from tests carried out on saturated specimens. The results also showed that there was a relationship between q,(p-u_a), suction, specific volume and water content, all at failure.
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Montalvo, Grijalva Daniela Fernanda. "Nitrogen and Phosphorus Availability and Liming Effect of Poultry Layer Manures in North Carolina Coastal Plain and Piedmont Soils." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-09192008-165401/.
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Nutrient availability from poultry manures can be affected by soil types and manure processing. Estimates of nutrient release from manures are important when recommending their use. Three separate laboratory experiments were conducted to evaluate N and P availability, and liming value of poultry layer manures (fresh, composted, and pelleted) with surfaces samples of three NC soils: Belhaven (loamy, mixed, dysic, thermic Terric Haplosaprists), Cecil (fine, kaolinitic, thermic Typic Kanhapludults), and Lynchburg (fine-loamy, siliceous, semiactive, thermic Aeric Paleaquults). The N incubation compared N mineralization from poultry manures and urea, applied at a rate of 133 µg N cm-3 soil (200 kg ha-1) and incubated for 90 days. Net N mineralized from the manures was described by a single pool first order kinetic model. Potential available N, estimated as the proportion of applied N, was greater for the fresh and composted manures than for the pelleted source in the three soils investigated. Nitrogen availability in fresh, composted, and pelleted manures for the Belhaven soil was 57, 53, and 46 % of total N applied, respectively; 83, 73, and 61 % of total N applied in the Lynchburg soil; and 41, 33, and 25 % for the same order of manure sources in the Cecil soil. The 21 day lime incubation compared poultry manure rates of 1333 and 2667 µg cm-3 of soil (2 and 4 t ha-1) with multiple rates of CaCO3. Liming materials in all the manures were just as effective in neutralizing soil acidity as equivalent amounts of CaCO3. Nitrification of manure N, however, can reduce the net liming effect by the release of H+. The 21 day P incubation experiment compared available P from the manures applied at rates of 1333 and 2667 µg cm-3 of soil (2 and 4 t ha-1) with multiple rates of Ca(H2PO4)2. A linear relationship across all P sources and rates was the best estimator of the increase in Mehlich-3 extractable P per unit of P added. These results suggested that P from the manures behaved similar to inorganic P fertilizer. Treatments in a subsequent greenhouse experiment were designed to evaluate millet [Urochloa ramosa (L.) T. Q. Nguyen] response to N, P and lime supplied in manures. Plant available N from the manures, estimated from the urea-N fertilizer equivalence of plant N accumulation, followed the decreasing order of fresh > composted > pelleted. This ranking among manures is similar to that obtained in the N incubation study. Millet dry matter and nutrient accumulation at targeted levels of N supply and soil values of Mehlich-3 P and pH were similar between treatments of manure supplemented with P fertilizer and lime, and treatments receiving only inorganic fertilizers and lime. These results indicate that optimum plant growth in manure amended systems requires the appropriate identification and correction of soil N, P and/or acidity constraints. Type of manure processing affects total N availability, and soil properties such as texture and buffer capacity can influence N mineralization and soil available P.
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Smuts, Michiel Nicolaas. "Determination of the lime requirement of sandy, organic-rich, and structured, high Mg:Ca ratio soils by the Eksteen method." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/19866.
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Thesis (MScAgric)--Stellenbosch University, 2001.ENGLISH ABSTRACT: The Eksteen method of lime requirement determination, based on the ratio of Ca+Mg:H (R-value), is widely used in the Western Cape and has proven to be extremely accurate for most soils. However, the Eksteen method is known to give erroneous predictions of lime requirement for certain soil groups. These include sandy soils (notably pale coloured sandy soils), organic-rich topsoils and strongly structured, Mg-rich subsoils. The objective of this study was to examine the nature of the Eksteen RpH relationship for these problem soils, and to develop appropriate modifications to the Eksteen method, where possible. A population of both normal and problem soils was selected and analysed, the RpH relationships of the soils were determined, and various relationships were examined. The principal findings with regard to the nature of the Eksteen RpH relationship were as follows: 1. The lime requirements of pale coloured sandy soils can be most accurately determined on an equivalent basis relative to the total extractable acidity, after the total extractable acidity has been corrected for residual lime. 2. The previously observed and acknowledged inaccuracy of the Eksteen method on organic-rich soils stems from the pH-dependant acidity component of the organic matter. The accuracy with which the lime requirement of these soils is predicted by the Eksteen method can be greatly improved by the application of an organic matter correction factor (OMCF) to the total extractable acidity, which is the parameter on which the lime requirement is then based. 3. In structured, Mg-rich subsoils the pH-neutralising capacity of Mg is considerably lower than that of Ca, a factor which is not taken into account by the Eksteen method. The Eksteen method can nevertheless be corrected to overcome this discrepancy. The high levels of Mg in the structured, Mg-rich subsoils cannot be attributed to minerals in these subsoils containing brucite interlayers. 4. Toxic levels of AI may only be expected at soil pH values below approximately 4.7 as determined in 1M KC!. Soil organic matter and CEC have marked affects on AI extractability. In accordance with the objective that appropriate modifications to the Eksteen method should be developed if possible, theoretically-based correction factors were developed which will permit the use of the Eksteen method to be confidently extended to those soil groups (pale coloured sandy soils, organicrich topsoils and strongly structured, Mg-rich subsoils) for which it was formerly considered unreliable.
AFRIKAANSE OPSOMMING: Die Eksteen metode van kalkbehoeftebepaling, gebaseer op die verhouding van Ca+Mg:H (R-waarde), word oor die algemeen wyd in die Wes-Kaap gebruik en is baie akkuraat vir meeste gronde bewys. Dit is egter bekend dat die Eksteen metode verkeerde kalkbehoeftes vir sekere grondgroepe voorspel. Hierdie sluit sanderige grande (veral lig gekleurde sandgronde), organiesryke bogrande en sterk gestruktuurde, Mg-ryke ondergronde in. Die doel van hierdie studie was om die aard van die Eksteen R:pH verwantskap vir hierdie probleemgronde te bepaal, waar moontlik. 'n Populasie van beide normaal en probleemgrande is geselekteer en geanaliseer, die R:pH verwantskap van die grande is bepaal en verskeie verwantskappe is ondersoek. Die hoof bevindinge ten opsigte van die aard van die Eksteen R:pH verwantskap was as volg: 1. Die kalkbehoefte van lig gekleurde sandgronde kan akkuraat bepaal word op 'n ekwivalente basis, relatief tot die totale ekstraheerbare suurheid, nadat die totale ekstraheerbare suurheid gekorrigeer is vir residuele kalk. 2. Die voorheen bekende onakkuraatheid van die Eksteen metode op organiesryke gronde het sy oorsprong by die pH-afhanklike suurheid komponent van organiese material. Die akkuraatheid waarmee die kalkbehoefte van hierdie grande met behulp van die Eksteen metode voorspel kan word, kan noemenswaardig verbeter word deur die totale ekstraheerbare suurheid te korrigeer met behulp van 'n organiese materiaal korreksie faktor (OMKF). Die aangepaste totale ekstraheerbare suurheid is dan die parameter waarap die kallkbehoefte gebaseer word. 3. In gestruktuurde, Mg-ryke ondergrande is die pH-neutraliseringsvermoe van Mg aansienlik laer as die van Ca, 'n faktor wat seide in berekening gebring word by die Eksteen metode. Die Eksteen metode kan tog gekorrigeer word om hierdie tekortkoming te oorkom. Die hoe vlakke van Mg in gestruktuurde, Mg-ryke ondergrande kan nie aan die teenwoordigheid van minerale in die ondergrond, wat brusiet tussenlae bevat, toegeskryf word nie. 4. Toksiese AI vlakke sal alleenlik by grond pH waardes laer as ongeveer 4.7, soos bepaal in 1M KCI, verwag word. Grand organiese materiaal en KUK het 'n noemenswaardige effek op ekstraheerbare AI. In ooreenstemming met die doelwitte om toepaslike wysigings aan die Eksteen metode aan te bring, is teoreties gebaseerde korreksiefaktore ontwikkel, wat die gebruik van die Eksteen metode verder verbreed om daardie grondgraepe (lig gekleurde sanderige grande, organies-ryke bogrande en sterk gestruktuurde, Mg-ryke ondergrande) in te sluit waarvoor dit vantevore as onbetraubaar beskou is.
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Burgos, Hernández Tania D. "Investigating Soil Quality and Carbon Balance for Ohio State University Soils." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1577141132704637.
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