Dissertations / Theses: 'Crop rotations'

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Arnet, Kevin Broc. "Cover crops in no-tillage crop rotations in eastern and western Kansas." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4086.

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Paton, Lewis William. "A robust Bayesian land use model for crop rotations." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11484/.

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Often, in dynamical systems, such as farmers’ crop choices, the dynamics are driven by external non-stationary factors, such as rainfall and agricultural input and output prices. Such dynamics can be modelled by a non-stationary stochastic process, where the transition probabilities are functions of such external factors. We propose using a multinomial logit model for these transition probabilities, and investigate the problem of estimating the parameters of this model from data. We adapt the work of Chen and Ibrahim to propose a conjugate prior distribution for the parameters of the multinomial logit model. Inspired by the imprecise Dirichlet model, we will perform a robust Bayesian analysis by proposing a fairly broad class of prior distributions, in order to accommodate scarcity of data and lack of strong prior expert opinion. We discuss the computation of bounds for the posterior transition probabilities, using a variety of calculation methods. These sets of posterior transition probabilities mean that our land use model consists of a non-stationary imprecise stochastic process. We discuss computation of future events in this process. Finally, we use our novel land use model to investigate real-world data. We investigate the impact of external variables on the posterior transition probabilities, and investigate a scenario for future crop growth. We also use our model to solve a hypothetical yet realistic policy problem.

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Sciarresi, Cintia Soledad. "OPTIMIZING COVER CROP ROTATIONS FOR WATER, NITROGEN AND WEED MANAGEMENT." UKnowledge, 2019. https://uknowledge.uky.edu/pss_etds/122.

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Winter cover crops grown in rotation with grain crops can be an efficient integrated pest management tool (IPM). However, cover crop biomass production and thus successful provisioning of ecosystem services depend on a timely planting and cover crop establishment after harvest of a cash crop in the fall. One potential management adaptation is the use of short-season soybeans to advance cover crop planting date in the fall. Cover crops planted earlier in the fall may provide a greater percentage of ground cover early in the season because of higher biomass accumulation that may improve weed suppression. However, adapting to short-season soybeans could have a yield penalty compared to full-season soybeans. In addition, it is unclear if further increasing cover crop growing season and biomass production under environmental conditions in Kentucky could limit nitrogen and water availability for the next cash crop. This thesis combines the use of field trials and a crop simulation model to address the research questions posed. In Chapter 1, field trials evaluating yield and harvest date of soybean maturity group (MG) cultivars from 0 to 4 in 13 site-years across KY, NE, and OH, were used to calibrate and evaluate the DSSAT crop modeling software (v 4.7). The subsequent modeling analysis showed that planting shorter soybean maturity groups (MG) would advance date of harvest maturity (R8) by 6.6 to 11 days per unit decrease in MG for May planting or by 1 to 7.3 days for July planting. The earliest MG cultivar that maximized yield ranged from MG 0 to 3 depending on the location, allowing a winter-killed cover crop to accumulate between 257 to 270 growing degree days (GDD) before the first freeze occurrence when soybean was planted in May, and between 280 to 296 GDD when soybean was planted in July. Winter-hardy cover crops could accumulate 701 to 802 GDD following soybean planted in May and 329 to 416 GDD after soybean planted in July. In Chapter 2, a two-year field trial was conducted at Lexington, KY to evaluate the effect of a soybean – cover crop rotation with soybean cultivars MG 1, 2, 3 or 4 on cover crop biomass and canopy cover, and on weed biomass in the fall and the following spring. Results showed that having cover crops was an efficient management strategy to reduce weed biomass in the fall and spring compared to no cover treatment. Planting cover crops earlier in the fall after a short-season soybean increased cover crop biomass production and percentage of ground cover in the fall, but not the following spring. Planting cover crop earlier after a short-season soybean did not improve weed suppression in the fall or spring compared to a fallow control with full-season soybean. Having a fall herbicide application improved weed control when there was a high pressure of winter annual weeds. By the spring, delaying cover crop termination increased cover crop biomass but also did weed biomass. In Chapter 3, a soybean – cover crop – corn rotation was simulated to evaluate the effect of different soybean MG and cover crop termination, as well as year to year variability on water and nitrogen availability for the next corn crop in Lexington, KY. Simulations showed that when cover crops were terminated early, they did not reduced soil available water at corn planting. However, introducing a non-legume cover crop reduced total inorganic nitrogen content in the soil profile by 21 to 34 kg ha-1 implying 15 to 30 kg ha-1 less in corn nitrogen uptake. Cover crop management that was able to maintain similar available water values than fallow treatment while minimizing nitrogen uptake differences was cover crops planted after soybean MG 4 with an early termination. However, the best management strategies that will maximize ecosystem services from cover crops as well as cash crop productivity may need to be tailored to each environment, soil type, irrigation management, and must consider year-to-year variability.

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McLaughlin, Michael John. "Phosphorus cycling in soil under wheat-pasture rotations /." Title page, contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phm1615.pdf.

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Bhogaraju, Prabhakar V. "A Case-Based Reasoner for Evaluating Crop Rotations in Whole-Farm Planning." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/36817.

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I have worked on a Case-Based Reasoning (CBR) system that evaluates crop rotations for their soil erosion and risk of insect pest problems. The purpose of this system is to provide decision support for an automated whole-farm planner (CROPS). CROPS (Buick et al., 1992) generates crop rotation plans that can address some of the environmental, economic and legislative pressures facing natural resource managers. To generate and recommend a crop rotation plan CROPS requires estimates on the soil erosion risks and pesticide pollution potential of the crop rotation. In this research I have designed and prototyped a system that can assist CROPS in the process of whole-farm planning by providing information required for determining the soil erosion risks and the pesticide pollution potential of crop rotations. Inputs for the system include: a crop rotation, its tillage and residue management practices, and field conditions. Soil erosion risk is quantified using the C-value. Pest risks are likelihood of pest outbreaks that require control in a crop rotation. CBR was the chosen methodology for system implementation. In CBR, solutions to new problem situations are derived from retrieving and adapting solutions to similar problem situations experienced in the past. The system was prototyped using Esteemâ ¢, a CBR development shell, and runs on a PC under the MS. Windowsâ ¢, operating system. Master of Science

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Eleki, Krisztina. "Soil management, crop rotations, and biomass removal effects on soil organic matter content." [Ames, Iowa : Iowa State University], 2007.

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Meiss, Helmut. "Diversifying crop rotations with temporary grasslands : potentials for weed mangement and farmland biodiversity." Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00575607.

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Crop rotation may be used to prevent the continuous selection of particular weed species adapted to one crop type. This might be useful for weed management, economy in herbicide applications and promoting biodiversity. Common simple crop sequences might be diversified by introducing perennial forage crops. Impacts of such perennial crops on weeds were studied with four approaches : 1) Large-scale weed surveys in 632 fields in western France showed that weed species composition differed most strongly between perennial alfalfa crops and annual crops. Comparisons of fields before, during and after perennial alfalfa suggested that community composition varies in a cyclic way during such crop rotations. Several weed species problematic in annual crops were suppressed during and after perennial crops, but the appearance of other species led to equal or even higher plant diversities. 2) A 3-year field experiment with contrasting crop management options allowed an investigation of the underlying mechanisms for this: The absence of soil tillage reduced weed emergence but increased the survival of established plants. The permanent vegetation cover and frequent hay cuttings reduced weed growth, plant survival and seed production. 3) Greenhouse experiments testing the regrowth ability of individual plants after cutting showed strong differences between species and functional groups. An two-factorial experiment suggested that the negative impacts of cutting and competition on weed growth were mainly additive. 4) Special measurements of weed seed predation in the field experiment showed positive correlations with vegetation cover, indicating that this ecosystem service may be particularly fostered by perennial crops. Consistent preferences of seed predators for certain weed species indicates that seed predation may be another cause of the observed weed community shifts.

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Abreu, Daniel Carneiro de. "Whole-farm modeling approach to evaluate different crop rotations in organic dairy systems." Universidade Federal de Viçosa, 2014. http://www.locus.ufv.br/handle/123456789/6596.

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Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2015-11-09T15:34:52Z No. of bitstreams: 1 texto completo.pdf: 492609 bytes, checksum: 66747ed601f7421b79e4e7f037a223b9 (MD5) Made available in DSpace on 2015-11-09T15:34:52Z (GMT). No. of bitstreams: 1 texto completo.pdf: 492609 bytes, checksum: 66747ed601f7421b79e4e7f037a223b9 (MD5) Previous issue date: 2014-09-25 Fundação de Amparo à Pesquisa do Estado de Minas Gerais O mercado de trigo (Triticum aestivum L.) orgânico para produção de pão cresceu em grande magnitude na região da Nova Inglaterra, nos Estados Unidos. Este nicho de mercado representa uma alternativa de renda para os produtores de leite orgânico abastecerem este mercado através do cultivo e colheita de grãos em rotação de cultura na própria fazenda. Objetivou-se com este estudo determinar a sustentabilidade de oito sequências de rotação de cultura (três anos de rotação) durante o período de 25 anos em uma propriedade produtora de leite orgânica bem manejada. Uma fazenda média foi simulada utilizando o modelo computacional Integrated Farm System Model (versão 3.6) para avaliar o efeito da rotação de cultura no desempenho da cultura, impacto ambiental e rentabilidade. As estratégias de rotação incluíram pasto contínuo (azevém e trigo), milho (Zea mays L.) colhido cedo seguido de trigo de inverno (milho-trigo de inverno- pasto), milho seguido de trigo de primavera (milho-trigo de primavera-pasto), pasto em rotação com trigo de inverno (azevém/trigo - trigo de inverno - azevém/trigo), pasto em rotação com trigo de primavera (azevém/trigo - trigo de primavera - azevém/trigo), soja [Glycine max (L.) Merr.] em rotação por trigo de inverno (soja - trigo de inverno - azevém/trigo) e primavera (soja - trigo de primavera - azevém/trigo), milho em cultivo consecutivo (milho - milho - azevém/trigo) e soja seguida de milho (soja - milho - azevém/trigo). O trigo foi colhido em grão e comercializado a preço premium em todos os anos simulados. Em todas as simulações foram cultivados azevém e trigo (Lolium perenne / Trifolium pratense) consorciados no terceiro ano. Em geral, não houve benefício econômico e ambiental na rotação de cultura em comparação o pasto contínuo (monocultivo). Entretanto, entre as rotações de cultura, o cultivo de trigo de inverno deve ser incentivado, particularmente em rotação com a soja, para reduzir o impacto ambiental e aumentar rentabilidade da fazenda. The market for high-quality organic bread wheat (Triticum aestivum L.) is increasing in New England. This economic niche represents one alternative income for organic dairy producers (if they include wheat in their crop rotation) to supply this market by raising wheat as a cash crop. Our objective was to determine the sustainability to eight crop rotation sequences of 3-yr rotations in a long-term (25-yr) well-managed organic dairy farm. A medium-sized organic dairy farm was simulated with the Integrated Farm System Model (IFSM, version 3.6) to evaluate crop rotation (management) effects on crop performance, environmental impacts and profitability. The cropping strategies included continuous ryegrass/red clover (continuous grass), corn (Zea mays L.) harvested early followed by winter wheat (corn-wwheat-grass), corn followed by spring wheat (corn-swheat-grass), ryegrass/red clover rotated with winter wheat (grass-wwheat-grass), ryegrass/red clover in rotation with spring wheat (grass-swheat-grass), soybean [Glycine max (L.) Merr.] rotated by both winter wheat (soybean-wwheat-grass) and spring wheat (soybean- swheat-grass), corn double cropped (corn-corn-grass) and soybean followed by corn (soybean- corn-grass). Wheat was harvested as a cash crop in all simulated years and sold at a premium price. All rotations were in long rotation with perennial ryegrass/red clover (Lolium perenne / Trifolium pratense) over the 3-yr. In general, there was no economic and environmental benefit to shifting land from continues grass-based production to specified cropping rotations. However, under crop rotation, use of winter wheat should be encouraged, particularly soybean replaced with cash crop wheat, to reduce environmental impact and improve farm profitability.

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Latta, Roy A. "Improving medic pastures in pasture-wheat rotations in the Mallee district of North-Western Victoria /." Title page, contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09A/09al364.pdf.

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Bilek, Meredith K. "Winter annual rye cover crops in no-till grain crop rotations impacts on soil physical properties and organic matter /." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7268.

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Thesis (M.S.) -- University of Maryland, College Park, 2007. Thesis research directed by: Dept. of Natural Resource Sciences and Landscape Architecture. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Hariharan, Janani. "Predictive Functional Profiling of Soil Microbes under Different Tillages and Crop Rotations in Ohio." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1435856176.

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Daniel, John Sathiaseelan. "Strategies for the management of root-knot nematodes with biocontrol agents and crop rotations for vegetable crops in small farms." Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402591.

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Petrosino, Justin Scott. "Response of weeds to the intensification of Kansas No-Till crop rotations with cover cropping." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4095.

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Swiegelaar, Nina Antionette. "Evaluating the effect of crop rotations and tillage practices on soil water balances of selected soils and crop performances in the Western Cape." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86237.

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Thesis (MScAgric)--Stellenbosch University, 2014. ENGLISH ABSTRACT: The aim of this study was to investigate the influence of crop rotation and soil tillage on the soil water balance and water use efficiency of wheat, canola, lupin and medics in the Swartland sub region of the Western Cape. This trail was conducted as a component study within a long-term crop rotation/tillage trial during 2012 and 2013 at the Langgewens Research Farm (33016’42.33” S; 18042’11.62” E; 191m) of the Western Cape Department of Agriculture near Moorreesburg. The experiment was laid out as a randomized complete block, with a split-plot treatment design and replicated four times. Three crop rotation systems, continues wheat (WWWW), wheat/medic/wheat/medic (WMcWMc) and wheat/canola/wheat/lupin (WCWL) were allocated to main plots. . Each main plot was subdivided into four sub-plots allocated to four tillage treatments namely: zero-till (soil left undisturbed and planted with zero-till planter), no-till (soil left undisturbed until planting and then planted with a tined no-till planter), minimum-till (soil scarified March/April and then planted with a no-till planter) and conventional tillage (soil scarified late March/early April, then ploughed and planted with a no-till planter). All straw, chaff and stubble remained on the soil surface and no-grazing was allowed on all tillage treatments. Three replicates were included in this current study. Only the no-till (NT) and conventional till (CT) were included in this current study as main tillage treatments. The volumetric soil water content was monitored at weekly intervals during the active growing season (May-October) and once a month during the fallow period (November-April) using a Diviner 2000 soil moisture meter. The Diviner 2000 was used to record the soil water content at every 100 mm depth increment up to the maximum depth of the profile. At the end of the growing season the total biomass, grain yield and quality parameters were determined. The soil water balance data calculated from the 2012 season were found to be inconclusive due to too shallow installation of soil water monitoring tubes and big variations in the depth complicating any attempt in comparing data from treatments and cropping systems. Soil water monitoring tubes was installed to a depth of 900 mm in the 2013 season. Complications during planting in the 2013 season resulted in very poor emergence in the CT sites. Weed counts revealed that only 38 % of CT sites were covered by crop, 31 % with weeds and 31 % were completely bare. The NT sites had 40 % crop coverage, 50.5 % grass weed coverage and only 9.5% bare surface. As a consequences crop rotation had no effect on the soil water balance, while the tillage treatments showed a response. The effect that tillage had on the soil water balance was clearly shown in the 2013 season, in which 79 mm more rainfall occurred than the long-term average. NT retained more soil water in the profile in the drier first half of the season when only 30 % of the total rainfall in the 2013 season occurred. There was no real difference in the soil water retention in the second half of the season where 70 % of the total rainfall in the 2013 season occurred. Crop rotation did have a positive effect on grain yield. Wheat monoculture was out performed by legume based cropping systems. This trend was also observed in the biomass production. No significant difference between tillage treatments were recorded when comparing grain yield data. However wheat mono culture was again out-performed by the McWMcW, CWLW and LWCW systems producing on average significantly higher biomass. The data from both seasons suggest that in seasons where more rainfall than the long term average occurs, there is no difference in the RUE between cropping systems or tillage practices.. This study highlighted the major effect that the prevailing weather conditions have and that the expected advantages associated with NT most likely only come into play in dry conditions when plant water availability is limited. AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die invloed van grondbewerking en gewasproduksiestelsels op die grondwaterbalans en doeltreffendheid van watergebruik te ondersoek in die koringproduserende gebied van Malmesbury. Hierdie eksperiment is uitgevoer as 'n komponentstudie binne 'n langtermyn grondbewerking/gewasrotasieproef gedurende 2012 en 2013 op die Langgewens Navorsingsplaas (33016'42 .33 'S; 18042'11 0,62' E, 191m) van die Wes-Kaapse Departement van Landbou naby Moorreesburg. Die eksperiment is uitgelê as 'n volledige ewekansige blok, met 'n gesplete perseel behandelingsontwerp met vier herhalings. Drie gewasproduksiestelsels naamlik, koring monokultuur (WWWW), koring/medic/koring/medic (WMcWMc) en koring/canola/ koring/lupiene (WKWL) is elk toegeken aan persele en vier keer herhaal. Elke hoofperseel is onderverdeel in vier subpersele en bewerkingsbehandelings is soos volg toegeken: Konvensionele bewerking (CT) - grond gebreek in Maart/April, en daarna geploeg en geplant met geen bewerkingsplanter. Minimum bewerking (MT) - grond gebreek in Maart/April en daarna geplant met 'n geen bewerkingsplanter. Geen bewerking (NT) - grond is heeltemal onversteur gelaat tot planttyd en daarna geplant met 'n geen bewerkingsplanter. Zero bewerking (ZT) - grond tot planttyd met rus gelaat en dan geplant met 'n sterwielplanter. Alle strooi, kaf en stoppels het op die grondoppervlak gebly en geen beweiding is toegelaat nie. Slegs drie herhalings is ingesluit in die huidige studie en slegs die geen bewerking (NT) en konvensionele bewerking (CT) is in die huidige studie as hoof bewerkingbehandelings ingesluit. Die volumetriese grondwaterinhoud is weekliks gemonitor tydens die aktiewe groeiseisoen (Mei - Oktober) en een keer 'n maand gedurende die braaktydperk (November - April) met behulp van 'n Diviner 2000 grondvogmeter. Die Diviner 2000 is gebruik om die grondwaterinhoud by elke 100 mm diepte tot die maksimum diepte van die profiel te bepaal. Aan die einde van die seisoen is die totale biomassa, graanopbrengs en kwaliteitparameters bepaal. Die data vir grondwaterbalans van die 2012-seisoen is buite rekening gelaat weens te vlak installering van moniteringsbuise en groot variasie in die dieptelesings wat enige poging om vergelykende data van rotasie en behandelings te verkry, bemoeilik het. Moniteringsbuise vir grondwater is geïnstalleer tot op 'n diepte van 900 mm in die 2013-seisoen. Komplikasies tydens die plantaksie in die 2013-seisoen het gelei tot 'n baie swak opkoms in die CT-persele. Slegs 38 % van die CT-persele was bedek deur die gewas en 31 % met onkruid, terwyl 31 % van die oppervlak onder CT-behandeling heeltemal kaal was. Die NT-persele het 40 % gewasbedekking, 50.5 % grasbedekking en slegs 9.5 % kaal oppervlak gehad. Dit het die poging, om die effek van wisselboustelsels op die grondwaterbalans, in die wiele gery. Alhoewel wisselbou skynbaar geen effek op die grondwaterbalans gehad het nie, het die tipe bewerking egter wel ‘n effek gehad. Die effek van grondbewerking op die grondwaterbalans het duidelik na vore gekom in die 2013-seisoen. In hierdie seisoen het 79 mm meer reën geval as die langtermyngemiddelde. Geen bewerking het meer grondwater in die droër eerste helfte van die seisoen in die profiel behou, toe slegs 30% van die totale reënval in die 2013 geval het. Daar was geen beduidende verskil in die grondwaterretensie in die tweede helfte van die seisoen toe 70% van die totale reënval in die 2013 geval het nie. Wisselbou het egter 'n positiewe uitwerking op die graanopbrengs gehad. Koring monokultuur is in opbrengsyfers geklop deur stelsels met peulplante as komponent. Hierdie tendens is ook waargeneem in die biomassaproduksie. Bewerkingsbehandelings het geen beduidende verskil in graanopbrengste tot gevolg gehad nie, hoewel die biomassaproduksie van koring monokultuur weer geklop is deur die McWMcW-, CWLW- en LWCW-stelsels. Die data van beide seisoene dui daarop dat in seisoene waar meer reën as die langtermyn gemiddelde voorkom, daar geen verskil in die RUE tussen verbouingstelsels of bewerkingspraktykes was nie. Hierdie studie beklemtoon die groot invloed wat die heersende klimaat speel en dat die verwagte voordele wat verband hou met NT waarskynlik slegs ‘n rol speel in droër jare.

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Hoang, Fagerström Minh Ha. "Agroforestry systems in northern Vietnam with Tephrosia candida as an alternative to short-fallow crop rotations /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5737-8.pdf.

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Almadni, Mftah Alhusen Alhadi. "Impact of agricultural management on risks of nitrate leaching in crop rotations with potatoes and cereals." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2713.

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There is concern about increased nitrate levels in drinking water due to potential impacts on human health. At the same time there are also concerns about the environmental impact of increased levels of nitrate in surface water systems; the increased amount of nitrate in surface water can cause eutrophication. It has become almost axiomatic that nitrate which comes from agriculture soils is one of the main drivers of the increased nitrate levels in water. Arable agriculture is considered to be one of the main sources of nitrate due to high rates of nitrogen fertiliser or manure application, non-synchronous application of fertiliser with crop demand and inappropriate management of soil and water. Therefore minimise nitrate losses from agriculture soils could help to reduce nitrate level in ground and surface waters. This PhD study aims to improve the recommendations that are available to farmers to minimise nitrate leaching from arable rotations under UK conditions by investigating the impact of typical agricultural management practices on the risks of nitrate leaching in crop rotations with potatoes and cereals. In the conclusion, the achievements of this PhD study are evaluated with reference to the original aims and objectives. Then recommendations for further work to develop the understanding of nitrate leaching in arable rotations are made.

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Fagerström, Minh Ha Hoang. "Agroforestry systems in Northern Vietnam with Tephrosia candida as an alternative to short-fallow crop rotations /." Uppsala : Swedish University of Agricultural Sciences, 2000. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=009004572&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

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Zou, Congming. "SOIL MANAGEMENT AND NITROGEN DYNAMICS IN BURLEY TOBACCO ROTATIONS." UKnowledge, 2015. http://uknowledge.uky.edu/pss_etds/64.

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Agronomic practices, including tillage, crop rotation and N fertilization, have been developed to efficiently manage soil N dynamics and crop N nutrition. These practices can affect soil organic carbon (SOC) and soil total nitrogen (STN) sequestration, and consequently influence soil nitrogen mineralization (SNM) and crop N nutrition. However, little research has been systematically and simultaneously conducted to examine the effect of agronomic management on (1) SOC and STN stocks; (2) SNM; and (3) crop N nutrition. Burley tobacco (Nicotiana tobacum L.) is a N demanding crop and subject to inefficiency in N fertilization. Moreover, conservation tillage and rotation have been integrated into traditionally tillage intensive tobacco cropping systems. Thus, a tobacco tillage and rotation study was used to test how agronomic practices can affect N dynamics and crop N status in a series of sequential experiments. Firstly, different tobacco production systems were utilized to investigate the effects of tillage and rotation on soil aggregate stabilization and associated SOM sequestration. No-tillage and rotation management enhanced SOC and STN stocks, mainly by increasing the proportion of macroaggregates and SOC and STN concentrations. Secondly, a series of studies were conducted on SNM, including: (1) comparison of laboratory and in situ resin-core methods in estimating SNM; (2) evaluation of the influence of N fertilizer application on SNM; and (3) comparison of chemical indices for predicting SNM across management treatments over time. Laboratory method had different results relative to in situ method due to sample pretreatments. Fertilizer N application had a priming effect on SNM, but priming depended on both the N fertilizer rate and the background SOM level. The effect of rotation/tillage treatments on SNM was stable across years and SOC appeared to be the best indicator of SNM among other soil carbon and N estimates. Thirdly, a N fertilizer study for different tillage systems was conducted in 2012 and 2013. Crop parameters and plant available N (PAN) were collected to investigate the impact of tillage on tobacco production. Crop parameters showed that no-tillage can result in N deficiency in dry years. Similar PAN for both tillage methods suggested N deficiency in no-till tobacco was due to the crop’s lower N uptake capacity. In 2014, tobacco root analysis confirmed that no-tillage can result in less root exploration of the soil volume than conventional tillage.

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Gonzalez-Maldonado, Noelymar. "Evaluating the Effects of Long-Term No-Till and Crop Rotations in Soil Health and Corn Productivity." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1557142156675221.

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Koomson, Eric [Verfasser], and Georg [Akademischer Betreuer] Cadisch. "Benefits and trade-offs of legume-led crop rotations on crop performance and soil erosion at various scales in SW Kenya / Eric Koomson ; Betreuer: Georg Cadisch." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2021. http://d-nb.info/1239729413/34.

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El-Kholei, Ahmed Mohammed Salah. "Evaluating the impact of economic agricultural policies during the reform era for major crops and crop rotations in Egypt : a policy analysis matrix approach." Thesis, University of Nottingham, 2003. http://eprints.nottingham.ac.uk/13346/.

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In 1986, Egypt implemented a succession of comprehensive economic reforms both in the agriculture sector and more generally such as the Economic Reform and Structural Adjustment Program (ERSAP) of 1991. Since then, the agricultural sector has been gradually transformed from one characterised by central planning and governmental controls to one that is more free market oriented. This study employs the Policy Analysis Matrix technique to evaluate the impacts of reform policies on eleven major crops (wheat, maize, sugar cane, soy bean, broad bean, cotton, rice, tomatoes, potatoes, long and short berseem) and their associated crop rotations (crop mix) during the period 1986-2000. The PAM offers six tools of economic indicators. The first (private Cost Ratio) is used to identify the competitiveness of crops domestically. The second (Domestic Resource Cost) is employed in an attempt to identify those commodities in which Egypt has a comparative advantage/disadvantage. The third (Nominal Protection Coefficient for inputs and outputs) is used to measure the divergences between the domestic and international prices for inputs and output. The fourth (Effective Protection Coefficient) reflects the complete pattern of incentives to farmers in the tradable commodities markets, combining the separate influences of polices represented by the NPCO and NPCI measures. The fifth and sixth (profitability Coefficient and Subsidy Ratio to Producers) estimates the net protection effects afforded to each of the major sectors by the whole range of policy intervention. The most important findings are that: (1) The Egyptian pricing policy in the reform era is still encouraging domestic production of importable products (by setting their prices above world prices) while export products are taxed relative to their equivalent world prices. (2) Cotton, the main historical export commodity, is shown to be grown with a comparative disadvantage since it receives the highest levels of subsidy. (3) On the other hand, wheat showed a remarkably positive example for the high response from farmers to the reformed pricing policies with an increase in its area and its productivity by 83% and 60% respectively. (4) There is a high response of change in planted area to water charges. The conclusion of these analyses is that the impact of policy changes has indeed been positive, especially in relation to areas of crop production. But many remains to be done, for example, growers' still face problems in marketing, accessing to inputs, processing and trade.

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Hall, G. S. "A study of the microbial association with root senescence in winter wheat following various long-established crop rotations." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355006.

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Weeks, James Michael Jr. "Perennial Grass Based Crop Rotations in Virginia: Effects on Soil Quality, Disease Incidence, and Cotton and Peanut Growth." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/35394.

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In 2003 eight peanut and cotton crop rotations were established in southeastern Virginia, 4 of which included 2 or 3 years of tall fescue or orchardgrass grown as high-value hay crops. Each crop rotation was evaluated for changes in soil quality indicators including soil carbon and nitrogen, water stable soil aggregates, plant available water content, bulk density, cone index values, and soil moisture. Cotton and peanut growth and yield were also observed to evaluate changes in crop growth associated with differences in soil quality. Soilborne plant pathogens including root-knot nematode, stubby root nematode, ring nematode, stunt nematode, and Cylindrocladium parasiticum microsclerotia were measured in the spring and fall of each year to determine differences associated with crop rotations. Water stable soil aggregates in 2007 were higher in rotations with 3 years of either perennial grass. Soil moisture tended to be the highest at depths 30 - 60 cm in the 3-year tall fescue rotation in August and September 2007. Cotton in 2006 and peanut in 2007 had higher growth and yield where the annual crop directly followed a perennial grass. Root-knot nematode tended to decrease in all rotations over time. Stubby root nematode populations tended to increase in rotations with either duration of orchardgrass. Including perennial grasses in cotton and peanut rotations has the potential to increase growth and yield as demonstrated in this research. Master of Science

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Prater, Jacob. "Long term effects of phosphorus and conservation tillage management on crop yield and soil phosphorus in corn-soybean rotations." [Ames, Iowa : Iowa State University], 2007.

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Krato, Christoph [Verfasser], and Roland [Akademischer Betreuer] Gerhards. "Consequences for weed management in crop rotations by introducing imidazolinone-tolerant oilseed rape varieties / Christoph Krato. Betreuer: Roland Gerhards." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2013. http://d-nb.info/1029506744/34.

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Rached, E. M. "The effects of fertilization and crop rotations on rainfed barley development, growth and yields, in a semi-arid mediterranean-type climate /." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74366.

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A study was conducted for two growing seasons in northeastern Syria to evaluate the effect of N and P fertilizers and previous crops--i.e. vetch (Vicia sativa L.), barley (Hordeum vulgare L. cv. Beecher) or fallow--on water consumption, development, growth and yields of barley in a semi-arid, Mediterranean-type climate. The two seasons contrasted in rainfall and temperature which affected soil N, water use and yields. Fertilizer addition and residual P were the major determinants in barley yield increases. Rotation effects were significant only when fertilizers were added. Fallowing was an inefficient way of storing water, but stored water was used most efficiently by subsequent barley crops when fertilized. Fertilizers did not increase total evapotranspiration. Water use efficiency was related to dry matter production at stem elongation (DMse). Grain weight was a stable component of grain yields. Grain number was related to crop growth rates during the three week pre-anthesis period and to DMse, in turn affected by temperature, nutrient and moisture conditions. Vetch yields were in the order of 2.5 t.ha$ sp{-1}$ in the wetter season (1982/83). Results showed that substantial barley yield increases can be obtained with innovative crop rotations and appropriate use of fertilizers in semi-arid environments.

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Angeletti, Carlo. "Long term and short term effects of crop rotations in organic farming on soil organic matter content and stabilization dynamics." Doctoral thesis, Università Politecnica delle Marche, 2016. http://hdl.handle.net/11566/243104.

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La gestione del suolo in agricoltura puo’ contribuire significativamente ad accrescere la qualita’ dei suoli. Pratiche quali le lavorazioni minime, l’applicazione di ammendanti organici e la coltivazione di colture di copertura costituiscono delle valide strategie per accrescere il contenuto di sostanza organica nei suoli agricoli e squestrare CO2 dall’atmosfera, riducendo l’impatto ambientale dell’attivita’ agricola. Il contenuto di carbonio organico (OC) nel suolo e’ controllato dall’entita’ degli input di materiale organico che giungono al suolo in seguito alla coltivazione, e dalla resistenza offerta dalla sostanza organica alla degradazione microbica. Lo studio dei meccanismi che presiedono la stabilizzazione della sostanza organica del suolo (SOM) e’ quindi di primaria importanza. La resistenza offerta dalla SOM alla degradazione microbica dipende dalle sue proprieta’ chimiche e, in maggior misura, dalle interazioni che si stabiliscono fra le molecole organiche e la matrice del suolo. Rivestono particolare importanza l’occlusione dei residui organici grossolani all’interno degli aggregati e le interazioni che si stabiliscono fra molecole organiche e superfici delle particelle minerali. La coltivazione influenza in maniera profonda questi meccanismi, determinando la quantita’ di input organici che giungono al suolo ad ogni ciclo colturale e disturbando la formazione degli aggregati tramite le lavorazioni. Lo scopo di questa ricerca e’ stato quello di analizzare come le rotazioni colturali influenzano i processi che si trovano alla base della stabilizzazione della SOM nei suoli agricoli. Lo studio ha preso in esame due rotazioni colturali svolte in un arco temporale di 13 anni. Una delle due rotazioni e’ stata caratterizzata da lavorazioni del suolo poco frequenti e dalla presenza di residui colturali ricchi in N (ALF), mentre l’altra rispondeva alle esigenze di un’agricoltura piu’ intensiva, con lavorazioni frequenti e prevalenza di colture sfruttanti (CON). I due campi sperimentali sono stati coltivati con grano duro e cece in due successive stagioni colturali e gli effetti delle rotazioni colturali effettuate nei 13 anni precedenti l’inizio dell’esperimento, cosi’ come quelli relativi alla coltivazione di grano e cece nei due campi, sono stati analizzati approfonditamente. Il primo esperimento ha preso in considerazione gli effetti delle pratiche sopra citate sulla composizione chimica della sostanza organica. Un frazionamento chimico sequenziale e’ stato applicato ai campioni di suolo, in modo da ottenere un pool di SOM labile, composto dalla frazione leggera (LF) e dal carbonio organico solubile (WSOC), e un pool recalcitrante costituito dalla frazione umica, ulteriormente divisa in acidi umici (HAs) e acidi fulvici (FAs). Il secondo esperimento ha avuto come oggetto l’analisi degli effetti delle stesse pratiche colturali sull’occlusione della sostanza organica negli aggregati e sulla formazione di complessi organo-minerali. Durante il secondo esperimento sono state isolate, mediante frazionamento per classi di aggregati e per densita’il contenuto e la composizione chimica delle particelle organiche grossolane libere (fPOM) e di quelle occluse in aggregati di diverse dimensioni, cosi’ come della frazione organica intimamente legata alle superfici dei minerali. I risultati ottenuti hanno evidenziato che la stabilizzazione della SOM e’ influenzata sia dalla intensita’ delle lavorazioni, sia dalla composizione chimica dei residui colturali, principalmente attraverso l’influenza che questi due fattori esercitano sulla formazione degli aggregati e sull’interazione fra molecole organiche e superfici dei minerali. Le lavorazioni hanno esercitato un’azione dirompente sugli aggregati, particolarmente evidente nella classe dei macro-aggregati (>200 μm). Di conseguenza, la quantita’ di macro aggregati in ALF era significativamente maggiore che in CON all’inizio dell’esperimento. Le lavorazioni svolte durante la coltivazione del grano e del cece, sebbene abbiano causato una diminuzione del contenuto di macro-aggregati in ALF, non hanno determinato una riduzione del contenuto di sostanza organica occlusa all’interno degli aggregati, probabilmente a causa della forte azione cementante svolta dal carbonato di calcio (CaCO3) sugli aggregati. I continui input di materiale organico avvenuti in ALF durante i 13 anni precedenti l’inizio dell’esperimento, hanno favorito le attivita’ della comunita’ microbica, che a sua volta ha determinato un’alta capacita’ di mineralizzare la fPOM. La composizione chimica della sostanza organica e’ cambiata significativamente nei due suoli in seguito alla coltivazione di grano e cece, come si evince dai risultati emersi in entrambi gli esperimenti. Il frazionamento chimico sequenziale ha messo in luce un aumento del contenuto di acidi umici e fulvici in entrambi i suoli in seguito alla coltivazione del cece. Il frazionamento dei suoli per classi di aggregati e per densita’ ha meso in luce un pattern piu’ complesso. In ALF l’aumento dell’intensita’ delle pratiche agricole ha determinato il rimescolamento della fPOM grossolana con parte della fPOM piu’ fine e degradata, probabilmente a causa dell’interruzione della continuita’ degli input di residui organici. Il contenuto di OC nei macro aggregati e’ diminuito, mentre e’ aumentato il ternore di OC nelle particelle non aggreagate piu’ fini. In CON la coltivazione di grano, e soprattutto del cece, ha determinato l’arrivo al suolo di residui ricchi in N. Questo ha fatto si’ che il conteuto di OC e N aumentasse nelle particelle minerali piu’ fini. L’accresciuta attivita’ microbica avvenuta in CON durante la prova di campo, e’ probabilmente alla base dell’accumulo di materiale organico relativamente “fresco” avvenuto all’interno degli aggregati. Questa ricerca ha mostrato come gli effetti delle rotazioni colturali non dipendono solamente dall’azione di disturbo alla formazione degli aggregati esercitata dalle lavorazioni del suolo, ma anche dalla qualita’ degli input organici e da processi mediati dalla comunita’ microbica, i quali influenzano l’occlusione della SOM negli aggregati e l’interazione della sostanza organica con le particell minerali. Soil management can contribute significantly to increasing agricultural soil quality. Practices such as reduced tillage, organic amendments application and cover cropping are all recognized as valuable ways to restore the depleted SOM pools and sequester CO2 from the atmosphere, hence reducing the environmental impact of farming. The amount of organic carbon (OC) in the soil is controlled by the amount of OC returning to the soil during cultivation, and the decomposition rate, i.e. stability, of the organic input. Therefore, it is of key importance to understand the mechanisms that allow SOM to stabilize within the soil matrix. Soil organic matter (SOM) resistance to degradation depends on its chemical properties and, more importantly, on the interactions between organic molecules and the soil matrix i.e. occlusion within soil aggregates and interaction with mineral particles surfaces. Cultivation has a profound effect on of these mechanisms, as it determines the amount and chemical composition of the organic inputs that reach the soil, and includes tillage practices that disrupt soil aggregates, decreasing SOM stability. The aim of this research was to provide a scientific contribution to the understanding of how crop rotations affect the processes that underlie SOM accumulation within cropland soils. The study examined the effects of two long term (13 y) crop rotations, one characterized by low tillage intensity and N rich crop residues (ALF) and the other by higher tillage intensity and lower N input from plant residues (CON), on SOM stabilization. The effects of the introduction of a cereal-legume cropping sequence in the two fields were also observed on SOM amount and chemical composition. This experimental design allowed gaining an insight on both the long term and the short term consequences of cultivation on soil organic matter stabilization dynamics. In a first experiment, a sequential chemical fractionation was conducted on soil samples from ALF and CON in order to isolate: light fraction (LF), water soluble organic carbon (WSOC), fulvic acids (FAs) and humic acids (HAs). In a second experiment the same soil samples were subjected to a combined aggregate size and density fractionation, in order to isolate fPOM, oPOM from macro and micro-aggregates, and mineral associated organic matter in macro-aggregates, micro-aggregates and in silt and clay size particles. Our results showed that cultivation intensity and plant residues chemical composition both affected the extent to which SOM stabilizes within the soil profile, mostly via occlusion within soil aggregates and association with mineral particles. Tillage exerted a disrupting action against soil aggregates, which allowed more coarse aggregates to form in ALF, as compared to CON. Nevertheless, tillage operations conducted during the cultivation of winter wheat and chickpea, despite affecting negatively the amount of macro-aggregates in ALF, did not determine the mineralization of occluded POM, due to high level of inorganic C which acted as a cementing agent for soil aggregates. The continuous input of organic material which occurred in ALF during the 13 years before the beginning of the experiment, determined high levels of microbial activity, which determined in turn a high capacity to mineralize fPOM once the continuity of the organic input was interrupted. SOM chemical composition changed significantly in the two soils following the cultivation of winter wheat and chickpea, as it emerged from both the chemical fractionation experiment and the combined aggregate size and density fractionation experiment. In the former, we observed a consistent increase of HAs and FAs content in both the soils at 0-10 following the cultivation of chickpea. In the latter this corresponded to a complex pattern of changes occurring in the two soils across different aggregate and density fractions. In ALF, the conversion to the more intensive cropping system caused coarse fPOM to mix with finer and more degraded fPOM, as a consequence of the interruption of the continuous OC inputs. SOC content decreased in the macro-aggregates and relocated towards the silt and clay size particles, as an effect of the total macro-aggregates mass lost. The cultivation of winter wheat and chickpea in CON determined the introduction of fresh N rich plant residues. This in turn allowed for OC and N to accumulate in close association with silt and clay size particles. In addition, the cereal-legume cropping sequence caused new SOM to accumulate within soil aggregates, possibly as an effect of microbial mediated reactions. Our study showed that the effect of crop rotations on SOM accumulation and stability is not determined only by tillage disrupting action towards soil aggregates, as organic inputs quality and microbial mediated processes affect the mechanisms that allow for SOM protection via spatial inaccessibility and interaction with mineral surfaces.

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Stubbs, Victoria. "The use of Tagetes erecta and Pasteuria penetrans within crop rotations for the control of Meloidogyne spp. in microplots in Zimbabwe." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312561.

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Boglaienko, Daria. "Buckwheat as a Cover Crop in Florida: Mycorrhizal Status, Soil Analysis, and Economic Assessment." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/921.

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This thesis analyses buckwheat as a cover crop in Florida. The study was designed to demonstrate: soil enrichment with nutrients, mycorrhizal arbuscular fungi interactions, growth in different soil types, temperature limitations in Florida, and economic benefits for farmers. Buckwheat was planted at the FIU organic garden (Miami, FL) in early November and harvested in middle December. After incorporation of buckwheat residues, soil analyses indicated the ability of buckwheat to enrich soil with major nutrients, in particular, phosphorus. Symbiosis with arbuscular mycorrhizal fungi increased inorganic phosphorus uptake and plant growth. Regression analysis on aboveground buckwheat biomass weight and soil characteristics showed that high soil pH was the major limiting factor that affected buckwheat growth. Spatial analysis illustrated that buckwheat could be planted in South Florida throughout the year but might not be planted in North and Central Florida in winter. An economic assessment proved buckwheat to be a profitable cover crop.

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Götze, Philipp [Verfasser]. "Impact of specialised sugar beet crop rotations on soil fertility parameters and on yield and yield stability of sugar beet / Philipp Götze." Halle, 2017. http://d-nb.info/1137867655/34.

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Pichardo, Sergio Tomás. "Occurrence of diseases and insect pests in select soybean (Glycine max (L.) Merr.) and sorghum (Sorghum bicolor (L.) Moench) rotations in Mississippi." Diss., Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-09242007-142233.

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Jasionė, Vaidutė. "Sėjomainų ir tarpinių pasėlių įtaka dirvos piktžolėtumui ir fermentų aktyvumui ekologinėje žemdirbystėje." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110603_114217-63789.

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Tyrimai atlikti 2008–2009 m. Lietuvos žemės ūkio universiteto Bandymų stotyje. Dirvožemis – karbonatingas sekliai glėjiškas išplautžemis (Calc(ar)i-Epihypogleyic Luvisol). Tyrimo A veiksnys – 4 septynių narių sėjomainų rotacijos su nevienoda azotą fiksuojančių augalų dalimi: I – 43 proc. (daugiametės žolės → daugiametės žolės → žieminiai kviečiai → vasariniai miežiai → žirniai → žieminiai kviečiai → miežiai), II – 43 proc. (daugiametės žolės → žieminiai kviečiai → žirniai → vasariniai miežiai su įsėliu → daugiametės žolės → žieminiai kviečiai → miežiai), III – 29 proc. (daugiametės žolės → bulvės → belukštės avižos → vasariniai miežiai → žirniai → žieminiai kviečiai → miežiai), IV – 14 proc. (daugiametės žolės → žieminiai kviečiai → bulvės → vasariniai miežiai → žieminiai rapsai → žieminiai kviečiai → miežiai). Veiksnys B – tarpinis pasėlis žaliajai trąšai: 1) be tarpinio pasėlio, 2) tarpinis pasėlis žaliajai trąšai. Nustatyta, kad sėjomainos piktžolių sėklų atsargoms dirvoje esminės įtakos neturėjo. Tarpinis pasėlis žaliajai trąšai, lyginant su jo nenaudojimu, turėjo tendenciją mažinti nuo 5,4 iki 44,2 proc. piktžolių sėklų atsargas dirvoje. Piktžolės pasiskirstė į 4 ekologines grupes pagal poreikį dirvožemio pH, azotui ir drėgnumui. Didžiausias sėklų kiekis dirvoje nustatytas indiferentiškų pagal poreikį dirvožemio pH ir drėgnumui, mažo rūgštumo ir silpnai šarminių dirvožemių piktžolių rūšių, azoto turtinguose dirvožemiuose augančių dažniau negu neturtinguose bei... [toliau žr. visą tekstą] Field experiments were carried out in 2008 and 2009 at the Experimental Station of Lithuanian University of Agriculture. The objective of this investigation was to determine the influence of crop rotations and catch crops for green manure on weed seed-bank and soil enzymes urease and saccharase activity in the organic farming. Soil – Calc(ar)i-Epihypogleyic Luvisol. Factor A of the experiment – crop rotations with a different ratio of nitrogen fixing crops: I – 43% (grass-clover→grass-clover→winter wheat→spring barley→peas→winter wheat→spring barley), II – 43% (grass-clover→winter wheat→peas→spring barley→grass-clover→winter wheat→spring barley), III – 29% (grass-clover→potato→oat→spring barley→peas→winter wheat→spring barley), IV – 14% (grass-clover→winter wheat→potato→spring barley→winter rape→winter wheat→spring barley). Factor B – catch crop: 1) without catch crop, 2) with catch crop. Crop rotations had no significant effect on weed seed-bank. Catch crop for green manure, compared to without catch crop, decreased from 5.4 to 44.2% the amount of weed seeds. Weeds distributed into 4 ecological groups according to soil pH, nitrogen and soil moisture demand. The highest amount of weed seeds belonged to indifferent to soil pH and moisture, slightly acid and slightly alkaline soil, more frequent on nitrogen rich soil than on poor and moderately nitrogen rich soil and very nitrogen rich soil, dry and moderately moist soil weed species. Qualitative distribution of weeds into... [to full text]

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Knott, Stuart Charles. "An analysis of the financial implications of different tillage systems within different crop rotations in the Swartland area of the Western Cape, South Africa." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96855.

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Thesis (MScAgric)--Stellenbosch University, 2015. ENGLISH ABSTRACT: The pressure on the world’s natural resources is increased by an expanding global population. The majority of the growth is expected to take place in Africa and Asia. This creates the need for sustainable agricultural practices. To sustain food security, the limited natural resources must be utilised efficiently to optimise agricultural productivity. Conservation agriculture (CA) is one of the most holistic sustainable agricultural practices yet. It reduces environmental degradation, and concurrently it could enhance farm profitability. The practice of CA is able to improve food security while sustaining the environment for the benefit of future generations of both consumers and producers. A large proportion of the commercial grain producers in the Western Cape have adopted CA to varying degrees. A purer form of CA practice is continually pursued to realise its full benefits. Adoption has taken place in the absence of any policy support framework directed to CA, and thus, has been market driven. The reasons for and rates of CA adoption in other regions of the world differed, but was mostly successful, which highlights the driving forces behind adoption of CA in the Middle Swartland. The physical/biological benefits of CA are well known. The financial implications of the various systems within CA, at farm-level are still unknown. This study implements trial data from Langgewens experimental farm to evaluate the financial implications of various farming systems over an extended period. Farm systems are complex, consisting of numerous interrelated components. A whole-farm budget model is developed within a systems approach to compare various farming systems designed within CA principles. A trustworthy whole-farm model providing an accurate representation of a real life farm requires insight across many scientific disciplines. Multidisciplinary group discussions are used to bridge the gap between scientific knowledge. To serve as a basis for comparison, the whole-farm model was based on a typical farm within the Middle Swartland relative homogeneous farming area. Trial data on crop rotations and tillage systems from Langgewens experimental farm served as starting point for the research. The data was fitted for use in financial analysis and as input to the typical farm model. A key role of the inter-disciplinary expert group was to ensure that data and the model design accurately reflect the underlying physical/biological processes of CA. The financial evaluation of the various farming systems showed that conventional agricultural practices of monoculture and deep tillage are financially unsustainable. Farming systems under conventional tillage returned negative net present values (NPV) and an internal rate of return on capital investment (IRR) lower than the real interest rate. This implies that investment in conventional tillage will ultimately lead to financial losses. The financial benefits of CA are directly related to improved soil health, lower weed and pest stress and improved yields. The CA farming systems were less susceptible to variations in external factors, highlighting the resilience of the system that incorporates crop rotation and no-till. The farming systems operated under conventional practices are expected to be unsustainable over a long-term period of 20 years. AFRIKAANSE OPSOMMING: Opsomming Die druk op die aarde se natuurlike hulpbronne word verhoog deur ŉ groeiende wêreld populasie. Die meeste van die groei word verwag in Afrika en Asië. Dit skep die nodigheid vir volhoubare landboupraktyke. Om voedselsekerheid te volhou moet die beperkte natuurlike hulpbronne doeltreffend benut word om landbouproduksie te optimeer. Bewaringslandbou is die mees holistiese volhoubare landboupraktyk tot op hede. Dit verminder omgewingsdegradasie terwyl boerderywinsgewendheid kan verbeter. Die praktyk van bewaringslandbou is in staat om voedselsekuriteit te verbeter terwyl die omgewing onderhou word tot voordeel van toekomstige generasies van beide produsente en verbruikers. ŉ Groot gedeelte van kommersiële graanprodusente in die Wes-Kaap het bewaringslandbou teen verskillende intensiteit aangeneem. ŉ Suiwer vorm van bewaringslandbou word deurlopend nagejaag om die volle voordeel daarvan te benut. Die aanneming van bewaringsboerdery het sonder regeringsbeleid plaasgevind en was dus markgedrewe. Bewaringsboerdery is in ander wêrelddele vir verskillende redes aangeneem, maar was meestal suksesvol. Dit beklemtoon die beweegrede vir die aanneming van bewaringslandbou in die Middel Swartland. Die fisies/biologiese voordele van bewaringslandbou is wel bekend. Die finansiële implikasies van verskillende stelsels binne bewaringslandbou op plaasvlak is nog nie bekend nie. Hierdie studie gebruik proefdata van Langgewensproefplaas om die finansiële implikasies van verskillende boerderystelsels oor die langtermyn te evalueer. Boerderystelsels is kompleks en bestaan uit interafhanklike komponente. ŉ Geheelplaas begrotingsmodel is binne ŉ stelselsraamwerk ontwikkel om verskillende stelsels wat binne bewaringslandboubeginsels ontwerp is, te evalueer. ŉ Geloofwaardige geheelplaasmodel wat ŉ akkurate weerspieëling van realiteit verskaf benodig insig van verskeie wetenskaplike dissiplines. Multidissiplinêre groepbesprekings is gebruik om die gaping tussen die verskillende dissiplines te oorbrug. Die basis vir vergelyking wat gebruik is, is ŉ tipiese plaas in die relatief homogene boerderygebied van die Middel Swartland. Proefdata van verskillende gewasrotasie- en bewerkingstelsels is as die vertrekpunt vir die studie gebruik. Die data is pasgemaak vir finansiële ontledings en om te dien as inset vir die geheelplaasmodelle. ŉ Kern rol van die interdissiplinêre ekspert groep was om te verseker dat die data en die model-ontwerp die onderliggende beginsels van bewaringslandbou reflekteer. Die finansiële evaluasie van die verskillende boerderystelsels wys dat konvensionele landboupraktyke met monokultuur en diepbewerking nie finansieel volhoubaar is nie. Boerdery stelsels onder konvensionele bewerking genereer ŉ negatiewe netto huidige waarde en ŉ opbrengs op kapitaal investering wat laer as die inflasie vlak is. Dit beteken dat investering in konvensionele uiteindelik tot finansiële verlies kan lei. Die finansiële voordele van bewaringslandbou is direk geassosieer met verbeterde grondgesondheid, laer onkruid en plaag-druk en beter opbrengste. Die bewaringslandbou boerderystelsels is ook minder blootgestel aan veranderinge in eksterne faktore wat die gehardheid van die stelsels wat gewas-wisselbou en geenbewerking inkorporeer, beklemtoon. Die boerderystelsel onder konvensionele praktyke sal na verwagting nie volhoubaar wees oor ŉ langer periode van 20 jaar nie.

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Rembon, Fransiscus Suramas. "Impact of no-tillage versus conventional tillage, soybean-corn rotations, and fertilizer N rates on soil N levels and grain yields in two Eastern Canadian soils." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22794.

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Corn (Zea mays L.) production under monoculture and conventional-tillage management may cause soil degradation and nitrate (NO$ sb3 sp-)$ pollution. This study was conducted from 1991 to 1993 to evaluate the impact of conventional-tillage (CT) and no-tillage (NT) practices under corn-soybean (Glycine max L. Merill) rotations (C-S-C and S-C-S), continuous corn (C-C-C) and continuous soybean (S-S-S) systems on optimum N fertilization rates, yield and soil residual N levels. Field experiments were carried out on a Ste. Rosalie clay (Humic Gleysol) and an Ormstown silty clay loam (Humic Gleysol). Overall, tillage had little effect on soil and crop N levels or grain yields. Residual soil NO$ sb3$-N in the fall was related to fertilizer N rates in C-C-C, but not with S-S-S or soybean in rotation. Residual NO$ sb3$-N values after soybean were high and at zero added N were equivalent to 90 kg N with C-C-C. Consequently, soybean contributed the equivalent of 90 kg N ha$ sp{-1}$ to subsequent corn. Corn yields following soybean were higher than following corn, and less fertilizer N was required following soybean than following corn.

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Potter, Mark. "Biochemical studies of tissue glucosinolates for improvement of canola (Brassica napus) as a disease break within the southern Australian cereal rotation /." Title page, contents and summary only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09php8678.pdf.

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Thesis (Ph.D) -- University of Adelaide, Depts. of Plant Science and Crop Protection, 1998. Thesis (Ph.D.)--University of Adelaide, Depts. of Plant Science and Crop Protection, 1999? Bibliographical references: leaves 112-125.

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Doole, Graeme John. "Value of perennial pasture phases in dryland agricultural systems of the eastern-central wheat belt of Western Australia." University of Western Australia. School of Agricultural and Resource Economics, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0213.

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Over the past thirty years, price relativities and technological development have motivated an increase in the area of land allocated to cropping, as opposed to pasture production, throughout the central wheat belt of Western Australia. Nevertheless, reducing the proportion of pasture in these rotations has challenged the future productivity of farming systems in this area. First, the frequent application of selective herbicides for weed control in extended cropping rotations has promoted the development of herbicide resistance in a number of major agricultural weeds. Second, the primary use of annual plants has promoted the development of soil salinisation by allowing a significant proportion of rainfall to recharge saline water tables. The inclusion of perennial pasture phases between extended periods of cropping may mitigate or delay these constraints to production through (a) allowing the use of costeffective forms of non-selective weed control, and (b) through creating a buffer of dry soil that absorbs leakage occurring beneath subsequent crops. This study consequently explores the value of including perennial pasture phases in dryland agricultural systems in the eastern-central wheat belt of Western Australia, accounting for benefits related to herbicide resistance and water table management. A novel computational algorithm for the solution of multiple-phase optimal control problems is developed and used to conduct a conceptual analysis of the value of lucerne (Medicago sativa L.) pasture for managing annual ryegrass (Lolium rigidum Gaudin), the primary weed in wheat belt cropping systems. The competitiveness and fecundity of annual ryegrass provide strong economic incentives to maintain a low weed population, irrespective of herbicide-resistance status. Consequently, the ineffectiveness of selective herbicides primarily reduces the profitability of cropping by motivating the adoption of more costly non-selective forms of weed control. The inclusion of lucerne in land-use rotations is only optimal in the presence of severe herbicide resistance given (a) the low efficiency of alternative weed-management practices available during the pasture phase, relative to selective-herbicide application; (b) the significant cost of establishing this perennial pasture; and (c) the high relative profitability of cereal production in the absence of resistance. The value of lucerne, relative to annual pastures, for weed management is explored in greater detail through the use of compressed annealing to optimise a sophisticated simulation model. The profitability of candidate rotations is also manipulated to account for the long-term production losses accruing to the recharge of saline groundwaters that occurs beneath them. Sequences incorporating lucerne are only more profitable than those that include annual pasture at the standard set of parameter values if (a) annual ryegrass is resistant to all selective herbicides, (b) the water table is so shallow (approximately less than 3.5 m deep) that frequent rotation with perennials is required to avert soil salinisation, or (c) sheep production is highly profitable. The value of perennial pasture is sufficient under these circumstances to overcome its high establishment cost. Consistent with intuition, these benefits are reinforced by lower discount rates and higher rates of leakage occurring beneath annual-based systems. Formulation of an effective communication strategy to report these results to producers is justified given the complexity involved in determining the true magnitude of these intertemporal benefits through alternative means, such as field trials.

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Barbieri, Pietro. "Can the availability of mineral nutrient be an obstacle to the development of organic agriculture at the global scale ?" Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0432.

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L’agriculture biologique (AB) est souvent présentée comme une alternative prometteuse à l’agriculture conventionnelle, permettant des systèmes alimentaires durables tout en minimisant les impacts environnementaux. La capacité de l’AB à satisfaire la demande alimentaire mondiale reste néanmoins fortement débattue. Plusieurs études ont conclu que l’AB pourrait satisfaire la demande alimentaire globale à condition de réduire simultanément la consommation de produits animaux et les gaspillages. Cependant, ces études n’ont pas pleinement pris en compte les changements d’assolement et de choix d’espèces lorsque les systèmes conventionnels sont convertis en AB. Surtout, ils ont ignoré le rôle clé de la disponibilité en azote (N) dans le maintien des rendements en AB. Dans cette étude, nous avons d’abord réalisé une méta-analyse comparant les rotations de cultures en agriculture biologique et conventionnelle à l’échelle mondiale. Sur la base de ces résultats, nous avons développé une cartographie des espèces cultivées à l’échelle globale sous un scénario de fort développement de l’AB. Nous avons ensuite estimé la production alimentaire grâce au développement de GOANIM (Global Organic Agriculture NItrogen Model), un modèle biophysique et spatialement explicite d’optimisation linéaire simulant le cycle de l’azote (N) et ses effets sur la production alimentaire globale. GOANIM est adapté au cas de l’AB et simule les flux d'azote entre les terres cultivées, les animaux d'élevage et les prairies permanentes, ainsi qu’entre les systèmes agricoles biologiques et conventionnels. Le modèle optimise les populations d’élevage à l’échelle locale afin de maximiser l’approvisionnement en N provenant du fumier, ce qui maximise la production issue des terres cultivées, tout en minimisant la concurrence exercée par les animaux pour les ressources alimentaires. GOANIM a été utilisé pour simuler l’offre alimentaire sous plusieurs scénarios de conversion à l’AB. Ces résultats ont été comparés à différentes estimations de la demande alimentaire mondiale. Nous montrons que la carence en N risque d’être un facteur limitant majeur de la production en AB, entraînant une réduction de -37% de la disponibilité alimentaire à l’échelle globale sous un scénario de conversion à l’AB de 100%. Nous montrons que des taux de conversions inférieurs (jusqu'à 60% des terres agricoles), en coexistence avec l'agriculture conventionnelle, permettent de satisfaire la demande alimentaire mondiale si cette conversion est associée à une évolution conjointe de la demande, telle que la réduction de l'apport énergétique par individu ou du gaspillage alimentaire. Ces travaux contribuent de manière substantielle à mieux comprendre le rôle que l’AB peut jouer dans la transition vers des systèmes alimentaires équitables et durables. Ils indiquent également des voies à suivre pour parvenir à la sécurité alimentaire mondiale Organic agriculture is often proposed as a promising approach to achieve sustainable food systems while minimizing environmental impacts. Its capacity to meet the global food demand remains, however, debatable. Some studies have investigated this question and have concluded that organic farming could satisfy the global food demand provided that animal product consumption and food waste are reduced. However, these studies have not fully considered the changes in the type of crops grown that occur when conventional farming systems are converted to organic farming. Most importantly, they also have missed a critical ecological phenomenon by not considering the key role that nitrogen (N) cycling plays in sustaining crop yields in organic farming. In this study, we first carried out a global meta-analysis comparing organic vs conventional crop rotations. Based on these results, we developed global spatial explicit maps of the type of crop grown if organic farming was to drastically expand. We then estimated organic global food production using GOANIM (Global Organic Agriculture NItrogen Model), a spatially explicit, biophysical and linear optimization model simulating N cycling in organically managed croplands and its feedback effects on food production. GOANIM explores N flows between croplands, livestock animals and permanent grasslands, and with conventional farming systems. The model optimizes livestock populations at the local scale in order to maximize N supply from livestock manure – hence maximizing cropland production –, while minimizing the animals’ competition for grain food resources. We used GOANIM to simulate several supply-side scenarios of global conversion to organic farming. We then compared the outcomes of these scenarios with different estimates of the global demand, thus leading to complete exploration of the global production-demand options space. We show N deficiency would be a major limiting factor to organic production in a full organic world, leading to an overall -37% reduction in global food availability. Nevertheless, we also show that lower conversion shares (up to 60%) would be feasible in coexistence with conventional farming when coupled with demand-side solutions, such as reduction of the per capita energy intake or food wastage. This work substantially contributes to advancing our understanding of the role that organic farming may play to reach fair and sustainable food systems, and it indicates future pathways for achieving global food security

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Galiano, Norma Graciela. "Soil nitrate and ammonia levels as affected by no-till and conventional tillage, monoculture corn and soybean, corn-soybean and corn- soybean-alfalfa rotations, and added N." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27319.

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Corn (Zea mays L.) production under monoculture and conventional tillage systems may land to soil degradation and nitrate (NO$ sb3 sp-$) pollution of surface and groundwater. This study evaluated the impact of no-till and conventional tillage, monoculture corn and soybean, corn-soybean rotations and corn-soybean-alfalfa rotations, and three fertilizer N rates applied to monoculture corn or soybean, and corn in rotation, on soil NO$ sb3$-N and NH$ sb4$-N levels. Experimental sites were a Ste-Rosalie clay (Humic Gleysol) and an Ormstown silty clay loam (Humic Gleysol). Results obtained from fall 1992 to spring 1995 showed that tillage had no effect on soil N levels under corn. Soil N levels under corn showed a linear response to added N, specially in the fall. Soil N levels under corn did not change considerably during the non-growing season. Higher spring NO$ sb3$-N levels, particularly in plots under conventional tillage and alfalfa or soybean, compared to fall values indicated greater nitrification and/or mineralization than denitrification, immobilization or leaching. Low NH$ sb4$-N levels indicated that nitrification processes were active. No consistent estimation could be made of fertilizer N credits for corn from either soybean or alfalfa based on NO$ sb3$-N levels in soil.

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39

Isaac, Gura. "Crop rotation and crop residue management effects under no till on the soil quality of two ecotopes in the Eastern Cape, South Africa." Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/2934.

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The degradation of soil quality due to undesirable farming practices has reached alarming scales in the Eastern Cape and this has had negative repercussions on soil productivity and the environment in general. There is growing evidence that conservation agriculture (CA) practices involving minimal mechanical disturbance, maintaining permanent surface cover and embracing diverse crop rotations increase soil organic carbon (SOC) and therefore has potential to mitigate soil quality deterioration. A study was carried out at two sites located in two ecotopes to investigate the effects of crop residue retention and crop rotations in a no till system on overall soil quality using the Soil Management Assessment Framework (SMAF) as the soil quality assessment tool. The CA study trials were laid out in 2012 at two different locations, one at the Phandulwazi Agricultural High school within the Phandulwazi Jozini ecotope and the other one at University of Fort Hare Research Farm within the Alice Jozini ecotope. The experiment was laid out as a split-split plot arrangement in a randomized complete block design with three replicates. Tillage treatments were applied on the main plots while crop rotation treatments were applied as subplots. Crop residue retention treatments were applied as sub-sub plots. The rotational treatments were maize-fallow-maize (MFM), maize-fallow-soybean (MFS), maize-wheat-maize (MWM) and maize-wheat-soybean (MWS). The initial assessment of the overall soil quality of the two ecotopes using the SMAF soil quality index (SQI) revealed that the soils at the Alice site were functioning at 80% while the soils at the Phandulwazi site were functioning at 79 percent of their optimum capacity. The slight difference in the soil quality of the two ecotopes could be attributed to their different soil organic C contents where the Alice Jozini ecotope had significantly higher soil organic C contents than the Phandulwazi Jozini ecotope. After 3 years of continuous treatment application, crop residue retention significantly improved most of the measured soil quality parameters. Generally across the sites, more soil organic C, microbial biomass C (MBC), ß-glucosidase (BG) activity, mineral N, extractable P and K, Cu, Zn, Mn, Fe, and macro-aggregates were recorded in treatments where crop residues were retained. Crop rotations alone did not have a significant impact on most of the measured soil quality indicators. The crop rotations influenced significantly the availability of mineral N across the two sites, highlighting the importance of using a legume in rotations on available N for the subsequent crops. Most of the measured soil attributes were not significantly influenced after 3 years of continuously applying combined treatment of CA components. Mineral N (NO3 + NH4), K, Zn and Fe were significantly impacted on by the interactions of CA components at the Phandulwazi site, while N, Cu, Zn and Mn were significantly increased at the Alice site. Low response of SOC to combined CA treatments in the short-term prompted the need to examine treatment effects on individual soil carbon fractions. The interaction of crop rotation and residue management techniques were significant on the fine particulate organic matter – C fractions and microbially respired C. These soil C fractions were more sensitive to short-term treatments of combined CA components than SOC and MBC, therefore they can be used as short-term indicators of CA effects on SOM. Soil organic carbon, MBC, extractable P and K, soil pH, EC, b, AGS (aggregate stability) and BG activity were measured and the Soil Management Assessment Framework (SMAF) used to calculate soil quality index (SQI) values for each treatment. The combination of the crop rotations with crop residue retention showed the potential to significantly improve SQI values in the long term. The highest soil quality improvement at both sites was achieved by the maize-wheat-soybean (MWS) rotation with crop residue retention.

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40

Castellazzi, M. S. "Spatio-temporal modelling of crop co-existence in European agricultural landscapes." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/3747.

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The environmental risk of growing genetically modified (GM) crops and particularly the spreading of GM genes to related non-GM crops is currently a concern in European agriculture. Because the risks of contamination are linked to the spatial and temporal arrangements of crops within the landscape, scenarios of crop arrangement are required to investigate the risks and potential coexistence measures. However, until recently, only manual methods were available to create scenarios. This thesis aims to provide a flexible referenced tool to create such scenarios. The model, called LandSFACTS, is a scientific research tool which allocates crops into fields, to meet user-defined crop spatio-temporal arrangements, using an empirical and statistical approach. The control of the crop arrangements is divided into two main sections: (i) the temporal arrangement of crops: encompassing crop rotations as transition matrices (specifically-developed methodology), temporal constraints (return period of crops, forbidden crop sequences), initial crops in fields regulated by temporal patterns (specifically-developed statistical analyses) and yearly crop proportions; and (ii) the spatial arrangements of crops: encompassing possible crops in fields, crop rotation in fields regulated by spatial patterns (specifically-developed statistical analyses), and spatial constraints (separation distances between crops). The limitations imposed by the model include the size of the smallest spatial and temporal unit: only one crop is allocated per field and per year. The model has been designed to be used by researchers with agronomic knowledge of the landscape. An assessment of the model did not lead to the detection of any significant flaws and therefore the model is considered valid for the stated specifications. Following this evaluation, the model is being used to fill incomplete datasets, build up and compare scenarios of crop allocations. Within the GM coexistence context, the model could provide useful support to investigate the impact of crop arrangement and potential coexistence measures on the risk of GM contamination of crops. More informed advice could therefore be provided to decision makers on the feasibility and efficiency of coexistence measures for GM cultivation.

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41

Shakoor, Arif. "Crop rotation planning using simulated annealing." Master's thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-02232010-020018/.

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42

Balnytė, Skirmantė. "Agroecosystem Optimization by Crop Rotation, Catch Crop and Manure in Organic Farming." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20110902_143932-39161.

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To analyse the influence of crop rotations with a different ratio of nitrogen-fixing crops, catch crops and fertilisation with organic fertilisers on the following: 1. Soil enzyme activity; 2. Agrochemical properties of the soil and nitrogen balance; 3. Weed response; 4. Weed seed bank in the soil; 5. Crop yield and productivity. Agroekosistemų optimizavimo augalų kaita, tarpiniais pasėliais ir organinėmis trąšomis ekologinėje žemdirbystėje tyrimai vykdyti 2004–2009 m., Lietuvos žemės ūkio universiteto Bandymų stotyje, sertifikuotame ekologinės žemdirbystės lauke, karbonatingame sekliai glėjiškame išplautžemyje (IDg8-k) – Calcari-Epihypogleyic Luvisol (LVg-p-w-cc). Tyrimų hipotezė. Optimizuoti agroekosistemas ekologinėje žemdirbystėje galima taikant priemonių kompleksą: parenkant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius bei tręšiant organinėmis trąšomis. Tyrimų tikslas – įvertinti agroekosistemų optimizavimo galimybes ekologinėje žemdirbystėje derinant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius ir tręšiant organinėmis trąšomis. Tyrimų uždaviniai: Ištirti sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių ir tręšimo organinėmis trąšomis įtaką: 1. dirvožemio fermentų aktyvumui; 2. dirvožemio agrocheminėms savybėms ir azoto balansui; 3. pasėlių piktžolėtumui; 4. dirvožemio armens užteršimui piktžolių sėklomis; 5. augalų derlingumui ir bendrosios energijos kiekiui. Mokslinio darbo naujumas. Ekologinės žemdirbystės sąlygomis kompleksiškai įvertintas sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių bei tręšimo organinėmis trąšomis poveikis agroekosistemoms. Tai suteikia naujų žinių apie potencialaus dirvožemio derlingumo palaikymo, pasėlių ir dirvos piktžolėtumo kontrolės... [toliau žr. visą tekstą]

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43

Umeda, Kai, and B. Deeter. "Sandea Herbicide Rotational Crop Replant Study." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2003. http://hdl.handle.net/10150/214976.

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Broccoli and red table beets emerged and established a stand in Sandea treated plots at 0.5 or 1.0 oz product/A. Table beets planted into the beds treated with Sandea did not exhibit significantly different rates of emergence and stand establishment relative to the untreated check. The broccoli that emerged and established a stand did not show any significant differences or numerical trends between the untreated check and the two Sandea treatments during any of the observation dates. Spinach, the third indicator crop, did not emerge adequately in the test site.

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Alexander, Peter Mark William. "Modelling the UK perennial energy crop market." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9645.

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Biomass produced from perennial energy crops, Miscanthus and willow or poplar grown as short-rotation coppice, is expected to contribute to UK renewable energy targets and reduce the carbon intensity of energy production. The UK Government has had incentives in place, targeting farmers and power plant investors to develop this market, but growth has been slower than anticipated. Market expansion requires farmers to select to grow these crops, and the construction of facilities, such as biomass power plants, to consume them. Farmer behaviour and preferences, including risk-aversion, are believed to be important to crop selection decisions. Existing research estimating the total potential resource has either only simplistically considered the farmer decision-making and opportunity costs, or has not considered spatial variability. No previous work has modelled the contingent interaction of farmers’ decisions with the construction of biomass facilities. This thesis provides an improved understanding of the behaviour of the perennial energy crop market in the UK, by addressing these limitations, to understand the spatial and temporal dynamics of energy crop adoption. It attempts to determine the factors that govern the rate and level of adoption, to quantify the greenhouse gas abatement potential, and to assess the cost effectiveness of policy mechanisms. A farm-scale mathematical programming model was implemented to represent the crop selection of a risk-averse farmer. This was applied using spatially specific data to produce maps and cost curves economic supply, for the UK. To represent the contingent interaction of supply and demand within the market, an agent-based model was then developed. The results indicate that perennial energy crop supply may be substantially lower than previously predicted, due to the time lags caused by the spatial diffusion of farmer adoption. The model shows time lags of 20 years, which is supported empirically by the analogue of oilseed rape adoption. Results from integrating a greenhouse gas emissions balance shows that directly supporting farmers, via establishment grants, can increase both the carbon equivalent emissions abatement potential and cost effectiveness of policy measure. Results also show a minimum cost of carbon abatement is produced from scenarios with an intermediate level of electricity generation subsidy. This suggests that there is a level of support for electricity generated from energy crops that reduces emissions in the most cost effective manner.

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Umeda, K., and B. Munda. "Evaluation of Summer Cover Crops for Rotations with Vegetable Crops." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/221500.

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Five different crops were evaluated in exploratory and observational field studies for potential use as a summer cover crop in a rotation with commonly grown vegetable and field crops. Sesbania ( Sesbania exaltata), cowpea (ViRna unguiculata), sunnhemp (Crotalaria iuncea var. Tropic Sun), sudangrass (Sorghum sudanense cv. Piper), and kenaf (Hibiscus cannabinus) were drill seeded and grown with 2-3 irrigations during the summer months in two field tests. In one test, fresh weight yields were: 7,794 lb/A for sesbania; 10,551 lb/A for sunnhemp; 5,184 lb/A for cowpea; 19,816 lb/A for sudangrass; and 2,390 lb/A for kenaf General observations indicated that adult whiteflies were attracted to sunnhemp at one test site but not at the other. Broccoli, cabbage, and barley were planted in the fall following the cover crops and general observations indicated that sudangrass significantly reduced all of the crops' stand and measurable responses were not evident where the other cover crops were planted.

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Atallah, Therese. "Studies on the effects of organic amendments on nutrient recycling and nitrogen supply in a biological approach to crop production." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364054.

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Humble, Shauna Marie. "Weeds and ground beetles (Coleoptera: Carabidae) as influenced by crop rotation type and crop input management." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62758.pdf.

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48

Herzog, Craig. "Canola Production as Influenced by Previous Crop and Tillage System." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1967998321&sid=7&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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Seibutis, Vytautas. "Trumpų sėjomainos rotacijų agrobiologinis įvertinimas." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050929_115234-56584.

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Lithuania’s agricultural reform resulted in significant changes in land use, i.e. in the emergence of small individual farms. As a result, the formerly most popular 7, 8, 9-course crop rotations, or even 5-6-course crop rotations became inapplicable on small farms, especially on those not involved in animal production and cultivation of grass forage. Multiple-course crop rotations would disperse the same crops over several places, and the fields would not be unacceptably small. This is especially problematic for market farms, where it is intended to have 1-2-3 main crops and adequately alternate them. In foreign countries short rotations are a common practice in similar cases. However, in Lithuania short rotations have hardly been investigated, except for the sporadic research cases, therefore it is rather complicated to judge the feasibility of market crops growing in short rotations. When the area of cereals is increased in a crop rotation, it is more difficult to choose preceding crops, and continuous growing of crops becomes inevitable. It is of special relevance here to maintain soil fertility, moreover, the adverse effects of crops concentration manifest themselves much more severely than in any other system, namely, heavy occurrence of weeds, diseases and pests, soil depletion and fatigue. On cultivated Central Lithuania’s soils shortening of rotations and proper choice of preceding crops make it feasible to produce profitable, high quality agricultural production... [to full text]

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Mupambwa, Hupenyu Allan. "Winter rotational cover crops effects on soil strength, aggregate stability and water conservation of a hardsetting cambisol in Eastern Cape Province, South Africa." Thesis, University of Fort Hare, 2012. http://hdl.handle.net/10353/453.

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Winter rotational cover crops (WRCC) are often used to boost soil fertility and plant nutrition. However, selection and use of WRCC for soil physical improvement is usually overlooked. The objective of this study was to determine the effects of WRCC on soil strength, aggregate stability and water conservation of a hardsetting soil. The soil physical properties were determined after four rotations of growing monocultures of vetch (Vicia dasycarpa cv. Max), lupin (Lupinus angustifolius cv. Tanjil) and oats (Avena sativa cv. Sederberg) and after two rotations of growing bicultures of oats (Avena sativa cv. Pallinup) and vetch (Vicia dasycarpa cv. Max) across two soil layers, 0 to 15 cm and 15 to 30 cm. The individual WRCC and a weedy fallow constituted the treatments in the monoculture study whilst in the biculture study the various combinations of WRCC namely; 90% oat plus 10% vetch (O90V10); 70% oat plus 30% vetch (O70V30) and 50% oat plus 50% vetch (O50V50) and a weedy fallow constituted the treatments. After four rotations with cover crop monocultures, oats significantly (P ≤ 0.05) reduced penetration resistance (PR) whilst vetch increased PR in both soil layers compared to the weedy fallow control. The effect of the biculture treatments was only experienced within the 15 to 30 cm depth. The treatments O50V50 and O70V30 increased the PR compared to the control. The WRCC in monoculture significantly increased the soil aggregate stability relative to the control in both soil layers. Vetch, lupin and oats resulted in a 41.7%; 20.4% and 15.7% increase in MWD in the 0 to 15 cm soil layer and 47.2%; 44.2% and 39.7% in the 15 to 30 cm depth, respectively. An increase in aggregate stability was associated with increased macro-aggregation. Under the biculture, WRCC slightly increased, non- significantly, the aggregate stability. Both hot water and dilute acid extractable polysaccharides showed no significant correlation with aggregate stability in the two studies. Oats monoculture resulted in a significant difference (P ≤ 0.05) on cumulative infiltration compared to the control. However, after 2 h vetch and lupin showed no significant difference from the control on cumulative infiltration. Oats resulted in a 7.8% increase in final infiltration rate (FIR) whilst vetch and lupin reduced FIR by 9% and 16.7% respectively, compared to the control. Bicultures of oats and vetch significantly (P ≤ 0.05) increased cumulative infiltration compared to the weedy fallow control. A similar significant increase in FIR was also observed under bicultures. The treatments O50V50; O90V10 and O70V30 resulted in a 163.3%; 113.3% and 105.4% increase in FIR respectively, compared to the control. Cover crop monocultures significantly (P ≤ 0.05) increased plant available water (PAW) compared to the weedy fallow, with vetch, oats and lupin resulting in a 28.3%; 22% and 23.9% increase respectively, in PAW. However, no significant differences were observed on PAW after two rotations with bicultures. Compared with winter weedy fallow, WRCC improved most of the soil physical properties under study, with the most suitable results expected under bicultures compared to monocultures. Under CA, selection of WRCC like oats, vetch and lupin, one should therefore take into consideration their effects on soil physical properties as a selection criterion and not biomass and fertility alone.

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Dissertations / Theses on the topic 'Crop rotations'

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