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Dirvi, Gulzar Ahmad. "Wheat/beans interactions in mixed cropping systems." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264278.
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Chim, Bee Khim. "Alternative and Improved Cropping Systems for Virginia." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/79721.
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Feed grain consumption in Virginia and the mid-Atlantic region is more than double the total production. Producing more feed grains in this region could generate more profit for grain growers and lower costs for end-users. Increased feed grain production in this region will necessitate improved corn (Zea mays L.) management techniques and adoption of alternative feed grains such as grain sorghum (Sorghum bicolor L.). In order to achieve our overall objective of increased corn and grain sorghum production in the region, experiments were conducted to assess tools with the ability to increase the efficiency of sidedress nitrogen (N) application for corn and to test the performance of grain sorghum in both full season and double-crop rotations in this region.
For the corn studies, seven field experiments were established in 2012-2014 with four replications in a randomized complete block design. Treatments included a complete factorial of four different preplant N rate (0, 45, 90, 134 kg ha-1) with three different approach simulation model-prescribed rates (Virginia Corn Algorithm, Maize-N, Nutrient Expert-Maize) and the standard Virginia yield-goal based approach. No differences in corn yield were found between the different simulation model and preplant N rate, however the prescribed sidedress N rate varied significantly due to the simulation model, preplant N rate and the interaction between them. The nitrogen use efficiency (NUE) was estimated based on partial factor productivity (PFP) of nitrogen. The greatest PFP resulted from use of the Virginia Corn Algorithm (VCA), which produced 68 kg grain kg N-1 compared with 49 kg grain kg N-1 for the yield-goal based approach. While the VCA shows promise as a tool for improving NUE of sidedress applications in corn, more research is needed to validate performance.
Soybean (Glycine max L.) is often double-cropped after small grain in the mid-Atlantic region. Growing grain sorghum in this niche in the cropping system instead could result in greater overall feed grain production. In order to assess the performance of grain sorghum as an alternative in common cropping systems, four field experiments were established at the Southern Piedmont Agriculture Research and Extension Center (SPAREC) and Tidewater Agriculture Research and Extension Center (TAREC), near Blackstone and Holland, Virginia, respectively. The experiments were conducted using a split plot design with four replications and fourteen treatments. Main plot was winter small grain crop; either barley (Hordeum vulgare L.), triticale (x Triticosecale.), wheat (Triticum aetivum L.) or winter-fallow and the subplot either soybean or sorghum. In three of four instances, full season sorghum yields were greater than double-cropped sorghum after small grain. At two locations, sorghum yields following triticale were lower than when following barley, possibly indicating an antagonistic or allelopathic effect of triticale. The most profitable cropping system was wheat-soybean based on the price assumptions and measure yields in this experiment. Among the sorghum cropping system, the most profitable system was also wheat-sorghum. Sorghum can be successfully grown in both full-season and double-crop systems and offers good potential to increase feed grain production in this region.Ph. D.
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Swoish, Michael Joseph. "Technological Innovations for Mid-Atlantic Cropping Systems." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/104449.
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Greater projected demand for food, fuel, and fiber will require substantial increases in global agricultural production over the next three decades. Climate change is also forecasted to make weather events more extreme and variable. Efficiency will become more important as demand for food products increases and the availability of fertilizer and land decreases. Technology may be of paramount importance for pushing the boundaries of production while remaining sustainable for generations to come. The first chapter of this dissertation investigated the importance of rate and timing of the plant growth regulator trinexapac-ethyl to malting barley in Virginia. Plant growth regulators can help plants remain upright during strong winds, thereby preserving grain quality and yield. However, this study demonstrated that risks of plant injury also exist. Application should be restricted to fields with greater risk of lodging and made only after the barley crop has broken dormancy and a substantial increase in air temperature is not forecasted in the week following application. Chapter two compared the efficacy of eight vegetation indices calculated from three satellites (Landsat 8, Sentinel 2, and Planet) for estimating cover crop biomass. Cover crops can have beneficial effects on agricultural land as well as groundwater and surface water, but only when adequate biomass is established to reduce erosion and nutrient leaching. Satellite imagery was able to estimate multi-species cover crop biomass more accurately than field-based sensors, although the most accurate vegetation index was dependent upon which satellite was being tested. Chapter three investigated the potential of Arabidopsis thaliana ipk1-, a loss-of-function mutant which exhibits decreased growth at elevated phosphorus concentration, for serving as in indicator of plant available phosphorus. An indicator crop could provide greater spatial resolution compared to soil testing, as well as represent plant available nutrients as opposed to chemically extracted nutrient estimations. Plant response exhibited a quadratic relationship with media P concentration in the range of fertilizer decision making for maize, providing valuable insight for potential yield response in agricultural fields below 'very high' phosphorus concentration.Doctor of Philosophy
Climate change, increased demand for locally sourced ingredients, and elevated pressure for environmentally responsible practices will make meeting the growing demand for food difficult for farmers to achieve over the next few decades. Similar to many other industries, implementation of advanced technology may be necessary to keep up with agricultural demand. Plant growth regulators are one such technology which when applied to plants can cause them to remain short, decreasing the chance of blowing over during windstorms. However, chapter one of this dissertation concluded that risks of plant injury also exist when applying plant growth regulator on malting barley (for brewing or distilling). Application should be restricted to fields with greater risk of wind damage (e.g. taller barley) and made only after the barley crop begins spring growth and a decrease in air temperature is not forecasted in the week following application. Chapter two compared eight spectral vegetation indices across three satellites with different image resolution for their ability to estimate cover crop biomass. Cover crops protect groundwater and surface water quality, but only when adequate growth is achieved. Satellite imagery was able to estimate multi-species cover crop biomass more accurately than field-based sensors, although the most accurate vegetation index was dependent upon which satellite was being tested. Chapter three investigated the potential of Arabidopsis thaliana ipk1-, a loss-of-function mutant which exhibits decreased growth at elevated phosphorus concentration, as in indicator of plant available phosphorus in soil. An indicator crop could help determine which areas of a field are likely to have increased crop yield if fertilized and which are not. The mutant tested could be useful as an indicator crop given its response to phosphorus concentration, warranting further research with other plant species more appropriate for field use.
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Rezaei, Rashti Mehran. "Nitrous Oxide Emissions from Vegetable Cropping Systems." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/365552.
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Agricultural manipulation of the soil nitrogen (N) cycle has caused a significant increase in nitrous oxide (N2O) emissions during the past five decades. Nitrous oxide is one of the major greenhouse gases with potent and long-lasting global warming effects [298 times higher than carbon dioxide (CO2) over a time period of 100 years]. The major biogenic processes responsible for N2O production in agricultural soils are identified as nitrification which is the oxidation of ammonium (NH4+) to nitrite (NO2-) and nitrate (NO3-) and denitrification that is the anaerobic reduction of NO2- and NO3- to gaseous nitric oxide (NO), N2O or N2. Although the current concentration of N2O in the atmosphere is relatively lower than other greenhouse gases, it is annually increasing at a rate of 0.25%. Vegetable cropping systems, a major agricultural activity worldwide, generally comprise intensive cultivation and high rates of N application. However, the N recovery from intensively cultivated vegetable fields is reported to be only 20 - 50% of the applied N fertiliser, suggesting large amounts of N loss from these fields. In Australia, horticulture represents less than 1% of land used for agriculture, but accounts for 6-12% of N fertiliser use in agriculture and its contribution to national N2O emissions is significant.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Li, Yuxia. "Traffic and tillage effects on dryland cropping systems in north-east Australia /." [St. Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16335.pdf.
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Bosshard, Christina. "Nitrogen dynamics in conventional and organic cropping systems /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17329.
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Blade, Stanford F. (Stanford Fred). "Evaluation of cowpea lines in Nigerian cropping systems." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70310.
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The primary hypothesis of this research was that improved cowpea genotypes (selected under sole crop) could yield well in several Nigerian cropping systems, and that there were cowpea characteristics that improved overall system productivity. Cowpea lines were identified which were high yielding and stable in several management systems. Practices such as not applying insecticide and intercropping both reduced cowpea grain yield significantly. Land equivalent ratios were greater than one for all tested intercrop systems: cassava-cowpea (1.21-2.35), maize-cowpea (1.31-4.23), maize-cassava-cowpea (1.63-3.40) and millet-cowpea (1.13-6.88). Nitrogen nutrition of component crops was investigated. Line influenced both maize grain (12.5-28.4 kg ha-1) and total biomass (48.7-69.0 kg ha-1) nitrogen yield. Evidence from pot and field experiments (including $ sp{15}$N-dilution studies) indicated same-season nitrogen transfer. Light interception studies also indicated the increased light harvesting ability of early sole cowpea lines compared to early intercropped lines systems.
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Heggenstaller, Andrew Howard. "Productivity and nutrient cycling in bioenergy cropping systems." [Ames, Iowa : Iowa State University], 2008.
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Halbach, Rachel Beverly. "Weed growth in conventional and low-input cropping systems." [Ames, Iowa : Iowa State University], 2010. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1475925.
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Vongsaroj, Prasan. "Agronomy and weed control for rice-soybean cropping systems." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46596.
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Asada, Haruhisa. "Climate and Rice Cropping Systems in the Brahmaputra Basin." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/147382.
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Chiwindo, Privata Simon. "Economics of Mono-Cropping and Agroforestry Systems in Tanzania." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469175239.
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Parenti, Andrea <1988>. "Modelling new sustainable cropping systems for advanced biofuel production." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9298/1/PhD%20Thesis%20Andrea%20Parenti.pdf.
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Through the re-use of empirical functions and new model development, this study aims at contributing to the development of advanced biofuels in Europe. Four lignocellulosic crops were selected and tested in stand-alone (sunn hemp – Crotalaria juncea L.) and rotation system (sunn hemp, biomass sorghum - Sorghum bicolor x Sorghum sudangrass, kenaf - Hibiscus cannabinus L. and industrial hemp - Cannabis sativa L.) in different European environments. The first Chapter deals with a new model development (SunnGro) to reproduce sunn hemp, an interesting summer crop for advanced biofuels in Europe; in the second Chapter, the same model was used to simulate 20-year sunn hemp productivity across Europe. The SunnGro model reproduces sunn hemp development and growth, while providing a detailed description of leaf/branch size heterogeneity and its evolution during the vegetative season, depending on thermal time accumulation (GDD), sowing time (ST) and density (SD). The model was calibrated and evaluated using 20 sunn hemp field datasets collected in Greece, Spain and Italy. Interesting correlations were found between simulated and measured values of branch and leaf number (0.80
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Kanwar, John. "Smart cropping tools with help of machine learning." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74827.
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Machine learning has been around for a long time, the applications range from a big variety of different subjects, everything from self driving cars to data mining. When a person takes a picture with its mobile phone it easily happens that the photo is a little bit crooked. It does also happen that people takes spontaneous photos with help of their phones, which can result in something irrelevant ending up in the corner of the image. This thesis combines machine learning with photo editing tools. It will explore the possibilities how machine learning can be used to automatically crop images in an aesthetically pleasing way and how machine learning can be used to create a portrait cropping tool. It will also go through how a straighten out function can be implemented with help of machine learning. At last, it is going to compare this tools with other software automatic cropping tools.Maskinlärning har funnits en lång tid. Deras jobb varierar från flera olika ämnen. Allting från självkörande bilar till data mining. När en person tar en bild med en mobiltelefon händer det lätt att bilden är lite sned. Det händer också att en tar spontana bilder med sin mobil, vilket kan leda till att det kommer med något i kanten av bilden som inte bör vara där. Det här examensarbetet kombinerar maskinlärning med fotoredigeringsverktyg. Det kommer att utforska möjligheterna hur maskinlärning kan användas för att automatiskt beskära bilder estetsikt tilltalande samt hur maskinlärning kan användas för att skapa ett porträttbeskärningsverktyg. Det kommer även att gå igenom hur en räta-till-funktion kan bli implementerad med hjälp av maskinlärning. Till sist kommer det att jämföra dessa verktyg med andra programs automatiska beskärningsverktyg.
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Lacroix, Mireille 1958. "Cropping to suppress yellow nutsedge (Cyperus esculentus L.)." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65450.
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ARAYAPHONG, SUPISRA. "Cost – Benefit Analysis of Different Rice Cropping systems in Thailand." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-180974.
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System of Rice Intensification (SRI) has been introduced and practiced throughout Thailand. However, the conventional transplanting system is well-accepted among Thai farmers over the country. This paper quantifies and compares costs and benefits of SRI and the conventional system of rice cultivation in Thailand to find the best system for a farmer, the environment and a society. The scope of this paper includes a farmer’s profit, the environmental damages and a society’s net benefits categorized in clay soil and sandy loam conditions. The farmer’s profit consists of a production cost and income. The amount of fertilizer application, level of lethal dose and climate change cost are regarded as environmental damage components. The society has concerned over the farmer’s profit and the environmental cost in a decision. The study uses cost-benefit analysis to investigate mean and variation of profit and cost in monetary term. Monte Carlo simulation is utilized for quantifying risk in each scenario. The study finds that SRI saves the production input and increases yield gain significantly. The most impressive results are a reduction in water consumption and number of seeds. Also, the environmental damage caused by this system is lower due to less amount of chemical fertilizer and pesticide applications as well as a low rate of methane gas emission. Sensitivity analysis shows that SRI has better performance under best and worst case scenarios for both types of soil (clay soil and sandy loam). However, the system contains the highest risk of the farmer’s profit. In conclusion, SRI is more beneficial and efficient than conventional system. Still, risk aspects should be considered in decision making. This study can be employed as a framework for government or any parties, who are interested or have willingness to conduct a field study of SRI and the conventional rice cropping system or for the further study about the integrated system (a combination between SRI and conventional system).
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Rick, Terry Lynn. "Phosphorus fertility in Northern Great Plains dryland organic cropping systems." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2008/rick/RickT1208.pdf.
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Maintaining phosphorus (P) fertility in northern Great Plains (NGP) dryland organic cropping systems is a challenge due to high pH, calcareous soils that limit P bioavailability. Organic P fertilizers, including rock phosphate (RP) and bone meal (BM) are sparingly soluble in higher pH soils. Certain crops species have demonstrated an ability to mobilize sparingly soluble P sources. Objectives of this project were to 1) evaluate the effect of green manure (GM) crops and organic P fertilizers on the P nutrition of subsequent crops, and 2) investigate P fertility differences between organic and non-organic cropping systems. A two-year cropping sequence was conducted on an organic farm in north-central Montana (mean pH=6.6; Olsen P=16 mg kgâ»Â¹). Spring pea (Pisum sativum L), buckwheat (Fagopyrum esculentum L.), yellow mustard (Sinapis alba L.) and tilled fallow were fertilized with 0, 3.1 and 7.7 kg P haâ»Â¹ as RP, grown to flat pod stage and terminated with tillage. Winter wheat (Triticum aestivum L.) was grown on these plots in year two. Phosphorus uptake of winter wheat was enhanced (P>0.05) by RP following buckwheat only (P=0.02) at 7.7 kg P haâ»Â¹ compared to 0 P. Results indicate buckwheat can enhance P in a subsequent crop. A greenhouse pot experiment in a low P soil (Olsen P=4 mg kgâ»Â¹) consisted of four green manures; buckwheat, spring pea, wheat, and a non-crop control fertilized with 7.0 and 17.5 kg available P haâ»Â¹ as RP, 13.0 and 32.5 kg available P haâ»Â¹ as BM and 10 and 25 kg available P haâ»Â¹ as monocalcium phosphate (MCP). Green manures were harvested, dried, analyzed for nutrient content, and returned to pots. Pots were seeded with wheat. Phosphorus uptake in wheat following all crops was enhanced by MCP (P<0.05). Phosphorus uptake of wheat following buckwheat was enhanced by all P sources over the control. Buckwheat demonstrates the capacity to increase the availability of organic P fertilizers. Soil sampling of organic and non-organic no-tillage (NT) cropping systems was conducted in two separate studies to determine differences in P availability between management systems. Soil analysis determined available P tends to be lower in non-fertilized systems.
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Kaluli, J. Wambua. "Water table management and cropping systems for intensive corn production." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40155.
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The use of agricultural chemicals, such as nitrogen fertilizers in corn production, often results in water pollution. This research, comprising three parts, was designed to investigate the effects of nitrogen fertilizer application rates, water table management, and corn cropping systems on drainage water quality. The first part was a field study, to investigate the impact of two cropping systems and water table management on nitrate loss through tile drainage. The considered water table treatments were free drainage, and subirrigation with target water table depths at 0.5 m or 0.75 M below the soil surface. Corn (Zea mays L.) monoculture and corn intercropped with annual ryegrass (Lolium multiflorum Lam.) were investigated. The highest annual tile drainage losses of 21.9 kg N/ha were measured in monocropped, freely draining plots. Subirrigation with a water table depth of 0.5 m reduced tile drainage loss of N by over 70%, and intercropping corn with ryegrass under free drainage reduced leaching losses by 50%.The second part of the research was a simulation study with the water quality model, DRAINMOD-N. The water quality impact of fertilizer application rate under free drainage, subirrigation and controlled drainage was evaluated. Leaching losses, denitrification and N accumulation in the soil profile were investigated. Using data obtained from the field experiment, the performance of DRAINMOD-N was evaluated. DRAINMOD-N assumes that denitrification follows first order kinetics, contrary to field measurements which showed little correlation between denitrification rate and NO$ sb3 sp-$-N concentration. Therefore, DRAINMOD-N was modified by replacing the original denitrification function with the Michaelis-Menten relationship. In so doing, denitrification is expressed as a first order process when NO$ sb3 sp-$-N concentration limits denitrification, and as a zero order process for non-limiting NO$ sb3 sp-$-N concentration.
For denitrification to be a decision making criterion of water table management, inexpensive but reliable measurement techniques are required. Thus, the purpose of the final part of this research was to formulate a technique for measuring real-time denitrification rate. Denitrification rate could be expressed as a function of soil redox potential (Eh) and temperature. Laboratory and field studies showed that factors such as soil nitrate and organic carbon had negligible effect on denitrification rate. Therefore, it can be concluded that for most agricultural soil, Eh and soil temperature will satisfactorily describe denitrification variation.
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Hossain, Mohamed Faruque. "The nitrogen economy of rice based cropping systems in Bangladesh." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248241.
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Miller, Robert Neil Gerard. "The characterization of Ganoderma populations in oil palm cropping systems." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283672.
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Gomes, Maryjane Diniz de AraÃjo. "Sustainability of organic and conventional family based irrigated cropping systems." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14187.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoFamily farming has contributed to social development because through millions of small producers it has been a growing industry of entire relevance for the development of the country. Despite the high current production efficiency in agriculture it has been observed many environmental and social impacts, such as: soil erosion, contamination of surface and groundwater, loss of biodiversity, loss of traditional knowledge associated with economic dependence, reducing of job opportunities and income as well as rural exodus and social exclusion. For this reason, in the past few years it has been giving very strong focus on ecological benefits from cultivation of organic products. The general objective of this research is to comparatively analyze, based on indicators of economic, social and environmental indicators, two irrigated cultivation systems of organic and conventional production. The value of production and income of the farmer were respectively evaluated as variables associated to social and economic dimensions. The microbial activity of the soil was used as an environmental variable and the statistical analysis was performed using the program "ASSISTAT 7.5 BETA". The generation of direct jobs per area unit in the conventional tillage system corresponds to the reference values. Nevertheless, the organic system provides a generation of direct jobs that may reach three times the average capacity of employment generation per area unit of irrigated agriculture in the Brazilian semi-arid region, thus creating in a sustainable way, maintenance conditions for peasants. The organic system has a lower risk associated with the economic dimension compared to conventional tillage system. Current useful agricultural areas of the two production units allow them to remain in agricultural activity ensuring the social reproduction of farmers in a scenario with funding from the Pronaf. The results of the evaluated environmental variables demonstrate that production unit with organic farming has higher environmental sustainability, since the soil has good physical and chemical conditions that are more satisfactory to the development of microorganisms.
A agricultura familiar vem contribuindo para o desenvolvimento social, pois atravÃs de seus milhÃes de pequenos produtores à um setor em crescimento e de inteira relevÃncia para o desenvolvimento do paÃs. Apesar da elevada eficiÃncia produtiva atual na agricultura, tem se observado diversos impactos ambientais e sociais, tais como erosÃo dos solos, contaminaÃÃo das Ãguas superficiais e subterrÃneas, reduÃÃo da biodiversidade e perda de saberes tradicionais associados, dependÃncia econÃmica, reduÃÃo das oportunidades de trabalho e renda, Ãxodo rural e exclusÃo social. Por este motivo, nos Ãltimos tempos, tem se dado Ãnfase aos benefÃcios ecolÃgicos provenientes do cultivo de produtos orgÃnicos. A pesquisa tem como objetivo geral analisar comparativamente, a partir de indicadores de sustentabilidade econÃmica, social e ambiental, dois sistemas irrigados de produÃÃo, um orgÃnico o outro convencional. O valor da produÃÃo e da renda do agricultor foram avaliados como variÃveis associadas com dimensÃes sociais e econÃmicas, respectivamente. A anÃlise estatÃstica dos dados ambientais foi realizada atravÃs do programa âASSISTAT 7.5 BETAâ submetidos à anÃlise de variÃncia e as mÃdias comparadas pelo teste de Tukey. A geraÃÃo de empregos diretos por unidade de Ãrea no sistema de cultivo convencional corresponde aos valores de referÃncia. Jà o sistema de cultivo orgÃnico proporciona uma geraÃÃo de empregos diretos que chega a corresponder trÃs vezes à mÃdia da capacidade de geraÃÃo de emprego por unidade de Ãrea da agricultura irrigada na regiÃo do semiÃrido brasileiro, criando assim de forma sustentÃvel, condiÃÃes de permanÃncia do homem no campo. O sistema de cultivo orgÃnico apresenta um menor risco associado à dimensÃo econÃmica comparativamente ao sistema de cultivo convencional. As superfÃcies agrÃcolas Ãteis atuais das duas unidades de produÃÃo permitem que as mesmas se mantenham na atividade agropecuÃria assegurando a reproduÃÃo social dos agricultores num cenÃrio com financiamento do Pronaf. Os resultados das variÃveis ambientais avaliadas demonstram que a unidade de produÃÃo com cultivo orgÃnico apresenta maior sustentabilidade ambiental, uma vez que o solo encontra-se em condiÃÃes fÃsicas e quÃmicas mais satisfatÃrias para o desenvolvimento dos microrganismos.
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Akley, Korbla Edwin. "Impacts of cropping systems on soil health and microbial ecology." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20357.
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Master of ScienceDepartment of Agronomy
Charles W. Rice
Declining soil health is the underlying cause of decreasing agricultural productivity and environmental degradation. To address this challenge, research was conducted to determine how: (1) cover crops affect soil health in Kansas, USA and (2) direct seeding mulch–based cropping (DMC) systems affect soil health in Nyankpala, Ghana. Soil health indicators assessed include: biomass yield (kg ha[superscript]-1), soil microbial respiration (SMR), soil microbial C and N (MBC & MBN), potentially mineralizable N (PMN), dissolved organic carbon (DOC), soil organic C (SOC), soil total nitrogen (TN), phospholipid fatty acid analysis (PLFA), water stable aggregate (WSA), bulk density, pH, N, P, K, Ca and Mg. DMC systems from Ghana yielded significantly greater biomass compared to the control. High biomass produced by DMC systems did not increase SOC and PMN relative to the control. Fertilizer application had a significant impact on biomass production, which resulted in a significant increase in SOC and PMN in the 0-5 cm soil layer. Soil pH was significantly reduced by cropping systems and fertilizer in the 0-5 cm soil layer. Microbial biomass N, TN, SMR, N, P, Ca and Mg were not affected by the DMC cropping systems. Application of mineral fertilizer increased SMR, MBN, TN, N, and P. Soil K was also significantly affected by cropping systems and mineral fertilizer. The combination of mineral fertilizer and plant residues would be needed to improve soil health and increase crop productivity in the Guinea Savanna Zone of Ghana. Liming would be required to address low soil pH. In the USA, of all the soil health indicators examined, actinomycetes, gram-positive bacteria, fungi-bacteria ratio (F:B), SMR, MBN and WSA, were those significantly influenced by cover crops. The interactive effect of cover cops and N fertilizer also affected gram-positive bacteria, total PLFA, MBN, F:B ratio and WSA. Cover crop residues contributed to the observed differences in these indicators. The low response of soil health indicators suggest further evaluations are needed to determine the effectiveness of the indicators.
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Matlaletsa, Tsoelipe Samuel. "Simulating nitrogen dynamics in sugarcane cropping systems using DSSAT-Canegro." Diss., University of Pretoria, 2016. http://hdl.handle.net/2263/53523.
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Sugarcane is a high-biomass producing crop and often requires substantial amounts of
nitrogen (N) fertiliser to achieve optimal yields. Nitrogen fertiliser represents a significant
input cost for the sugar industry. This nutrient is highly challenging to manage due to its
susceptibility to various kinds of losses following application, for example, leaching and
denitrification. In addition to reduced profitability, N losses potentially lead to
environmental degradation, for example, through eutrophication of water bodies. As a
result of the complexities of N dynamics in sugarcane cropping systems, mechanistic
crop models are now more commonly being used to help understand these various N inand
outflows, and to inform better management practices. These models first require
extensive calibration, testing and validation with measured data in order to gain
confidence in their performance, however. In this study, a historical dataset from a
fertigation trial conducted in Komatipoort, Mpumalanga, was firstly used to assess the
ability of DSSAT-Canegro (with a newly included N subroutine) to simulate cane and
sucrose yields as well as aboveground N mass in response to different N fertiliser rates
over five consecutive seasons (2003-2007). Cane and sucrose yields, as well as
aboveground N mass were adequately simulated in response to various N rates under
drip irrigation. In addition to this, cane yield, aboveground N mass and soil water N
concentrations were monitored for model testing purposes as part of this study in trials
conducted in Pongola (irrigated), Mount Edgecombe (rainfed), and Inanda (rainfed), all
in KwaZulu Natal. For the Mount Edgecombe trial, N fertiliser treatments that took soil N
levels into account before deciding when to fertilise were included, and the potentially
reduced leaching loads were investigated by the model. In most cases, the DSSATCanegro
model simulated N dynamics and cane yield adequately under both irrigated and rainfed conditions. The model was also observed to perform well under contrasting
environmental conditions, such as during periods of drought versus high rainfall. In a
number of cases, significant differences in cane yield between treatments receiving
different rates of N were not observed in the measured data, indicating that the crop
was able to acquire sufficient N from organic matter mineralisation and fertiliser N from
previous seasons applications or the different N rates were all more than the required
amount. Based on the potential implications of reduced cane yield following water stress
and/or N stress, and unwanted N exports to the environment, it is concluded that
DSSAT-Canegro is a useful tool to improve our knowledge of N dynamics in sugarcane
ropping systems and to develop best management practices.Dissertation (MSc)--University of Pretoria, 2016.
Plant Production and Soil Science
MSc
Unrestricted
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Stecker, John A. "Evaluation of residual starter phosphorus bands for no-till cropping systems /." free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9901287.
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Kage, Henning. "Simulation modelling for improving nitrogen use efficiency in intensive cropping systems." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=977957020.
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Rahman, Md Rashedur. "Shrimp Based Rice Cropping Systems in the Coastal Area of Bangladesh." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188853.
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Bourguignon, Emmanuel. "Ecology and diversity of indigenous Trichoderma species in vegetable cropping systems." Lincoln University, 2008. http://hdl.handle.net/10182/641.
Full textAbstract:
The overall aim of this research was to improve the understanding of the ecology and diversity of Trichoderma species within the soil and rhizosphere of onion (Allium cepa L.) and potato (Solanum tuberosum L.) under intensive management in New Zealand. The indigenous Trichoderma population was measured in a field trial at Pukekohe over a three year period under six different crop rotation treatments. The treatments included two continuous onion and potato rotations (intensive), two onion/potato mixed rotation (conventional), and two green manure rotations (sustainable). Results showed that Trichoderma populations were stable in both the rhizosphere and bulk soil (1.5 x 10² to 8.5 x 10³ CFU g⁻¹ ODS). The planting and incorporation of an oat (Avena sativa L.) green manure in the sustainable rotations positively increased Trichoderma colony forming unit (CFU) numbers in the rhizosphere soil from 3.4 x 10² to 2.5 x 10³ g⁻¹ ODS. A Trichoderma species identification method was developed based on colony morphology. Representative isolates were verified using restriction fragment length polymorphism (RFLP) and DNA sequencing. The method allowed for rapid and reliable identification of isolated Trichoderma species. Five species were identified in the Pukekohe soil: T. asperellum, T. atroviride, T. hamatum, T. harzianum and T. koningii. Results showed identical species diversity between the rhizosphere, rhizoplane and bulk soil. The species did not strongly compete between each other for the rhizosphere ecological niche and differences in species proportions seemed to be caused by environmental factors rather than the rotation treatments. The incorporation of oat green manure in pots did not significantly promote the indigenous Trichoderma population size and diversity in the rhizosphere of onion plants up to 4 months old. The identified species were the same as in the field trial. The incorporation of onion scale residues was shown to result in low Trichoderma and high Penicillium CFU numbers and a reduction in plant size. Additionally, the presence of high levels (6.0 x 10⁵ CFU g⁻¹ ODS) of Penicillium CFU was negatively correlated with the presence of Trichoderma CFU. The effect of oat incorporation on Trichoderma saprophytic growth was also investigated in a soil sandwich assay and revealed no significant differences. A series of experiments indicated that onion extract obtained from dry onion scale residues had no antifungal activity against either Trichoderma or Penicillium and instead tended to promote their hyphal growth and sporulation. It also showed that competition between Penicillium and Trichoderma isolates was limited despite the ability of Penicillium to produce a wide range of inhibitory substances. Four indigenous Trichoderma species (T. atroviride, T. hamatum, T. harzianum and T. koningii) were shown to be rhizosphere competent in a split tube experiment over a 6 week period. The results of this experiment revealed that, the Trichoderma species clearly displayed differences in their ability to colonise the rhizosphere of young onion seedlings. Species such as T. koningii had the greatest rhizosphere colonising ability regardless of soil depth while T. harzianum displayed the weakest ability. Results also indicated that when inoculated as a mixture the four species competed with one another to colonise the rhizosphere. Overall, this research indicated that the studied crop rotation treatments and the use of oat as a green manure did not strongly promote indigenous Trichoderma populations. Species diversity was constant throughout the research with T. hamatum and T. koningii being the most frequently isolated species.
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Aronsson, Helena. "Nitrogen turnover and leaching in cropping systems with ryegrass catch crops /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/a214.pdf.
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Postlethwaite, Yvonne L. "Sustainability of dryland cropping systems in the Wimmera region of Victoria /." Title page, contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09AFP/09afpp858.pdf.
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Vizard, Catherine. "Soil organic matter quality and nitrogen dynamics in sustainable cropping systems." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289279.
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Tewoldemedhin, Yared Tesfai. "Characterisation of Rhizoctonia in cropping systems in the Western Cape Province." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/2269.
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Thesis (MScAgric (Plant Pathology))--University of Stellenbosch, 2005.The genus Rhizoctonia includes important soilborne plant pathogens that can cause severe economic losses on a wide range of crops including cereal, canola, pasture and grain legume crops. Limited information is available on specific anastomosis groups (AGs), nuclear status, pathogenicity and cross-pathogenicity of Rhizoctonia isolates associated with each of these crops in the Western Cape province. Therefore, these aspects were investigated in this study, since information in this regard is crucial for the development of Rhizoctonia disease management practices.
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Sequeira, Cleiton Henrique. "Soil Organic Matter Dynamics in Cropping Systems of Virginia's Valley Region." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/37381.
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Soil organic matter (SOM) is a well known indicator of soil quality due to its direct influence on soil properties such as structure, soil stability, water availability, cation exchange capacity, nutrient cycling, and pH buffering and amelioration. Study sites were selected in the Valley region of Virginia with the study objectives to: i) compare the efficiency of density solutions used in recovering free-light fraction (FLF) organic matter; ii) compare different soil organic fractions as sensitive indices of short-term changes in SOM due to management practices; iii) investigate on-farm effects of tillage management on soil organic carbon (SOC) and soil organic nitrogen (SON) stocks; and iv) evaluate the role of SOM in controlling soil available nitrogen (N) for corn uptake. The efficiency of the density solutions sodium iodide (NaI) and sodium polytungstate (SPT) in recovering FLF was the same at densities of 1.6 and 1.8 g cm⁻³, with both chemicals presenting less variability at 1.8 g cm⁻³. The sensitivity of SOM fractions in response to crop and soil management depended on the variable tested with particulate organic matter (POM) being the most sensitive when only tillage was tested, and FLF being the most sensitive when crop rotation and cover crop management were added. The on-farm investigation of tillage management on stocks of SOC and total soil N (TSN) indicated significant increases at 0–15 cm depth by increasing the duration (0 to 10 years) of no-tillage (NT) management (0.59 ± 0.14 Mg C ha⁻¹ yr⁻¹ and 0.05 ± 0.02 Mg N ha⁻¹ yr⁻¹). However, duration of NT had no significant effect on SOC and TSN stocks at 0–60 cm depth. Soil available N as controlled by SOM was modeled using corn (Zea mays L.) plant uptake as response and several soil N fractions as explanatory variables. The final model developed for 0–30 cm depth had 6 regressors representing the different SOM pools (active, intermediate, and stable) and a 𝑅² value of 65%. In summary, this study provides information about on-farm management affects on SOM levels; measurement of such effects in the short-term; and estimation of soil available N as related to different soil organic fractions.Ph. D.
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Moe, Swe Yee. "Analysis of Dynamics of Cropping Systems in the Dry Zone, Myanmar." Kyoto University, 2015. http://hdl.handle.net/2433/199368.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19044号
農博第2122号
新制||農||1032(附属図書館)
学位論文||H27||N4926(農学部図書室)
31995
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 縄田 栄治, 教授 舟川 晋也, 教授 白岩 立彦
学位規則第4条第1項該当
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Cruse, Michael James. "Fossil energy use in conventional and low-external-input cropping systems." [Ames, Iowa : Iowa State University], 2009.
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Sonder, Kai. "Soil erosion in andean cropping systems : the impact of rainfall erosivity." Hohenheim : Universität Hohenheim, Institut für Pflanzenproduktion und Agrarökologie in den Tropen und Subtropen, 2004. http://opus-ho.uni-stuttgart.de/hop/volltexte/2004/55/.
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Thierfelder, Christian. "Soil crusting and sealing in cropping systems of the Colombian Andes /." Stuttgart : Universität Hohenheim, 2003. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015376941&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Burgess, Macdonald Hugh. "Sustainable cropping systems for the Northern Great Plains: energetic and economic considerations." Diss., Montana State University, 2012. http://etd.lib.montana.edu/etd/2012/burgess/BurgessMH0512.pdf.
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Reliance on non-renewable resources is among the fundamental challenges to agricultural sustainability. Quantification of inputs in units of embodied fossil energy offers insight into sustainable use of these resources. Metrics of intensity, efficiency of non-renewable energy inputs to agriculture have been proposed for optimization in search of sustainability in the face of energy scarcity. Such analyses have found controversial results however, and further theoretical understanding is necessary. The research presented here focuses on approaches to sustainability targeting the semiarid northern Great Plains of North America. The 4 million ha of cropland fallowed in this region every year represent both a challenge to sustainability and an opportunity to address that challenge. Long identified as unsustainable when accomplished by tillage and without fertilizer input, the summerfallow-wheat crop production system is also energy-efficient by definitions that do not account for changes in soil fertility. It is shown here that accounting for lost soil N as an energy input to crop production partially resolves this paradox, but no strategy for energetic valuation of systems that build soil quality is apparent. Alternatives to summerfallow considered here include pulse crops (e.g. pea and lentil) grown for grain, forage, or as cover crops. In research conducted on farms already growing pulses, the largest effect on cropping system energy productivity was due to increased wheat yield rather than a reduction of inputs. In plot-scale research addressing a wider variety of production practices, neither system-level energy intensity nor productivity provided more insight into energy price exposure than basic economic analyses. 'Co-authored by Perry R. Miller and Clain A. Jones.'
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Omokanye, Akim Tunde, University of Western Sydney, of Science Technology and Environment College, and Centre for Horticulture and Plant Sciences. "Biological and economic evaluation of maize-based cropping systems for Nigerian smallholders." THESIS_CSTE_HPS_Omokanye_A.xml, 2004. http://handle.uws.edu.au:8081/1959.7/797.
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Indigenous African shifting cultivation production systems, that were developed over many generations and took into account production potential as well as the constraints imposed by natural resources, are no longer practicable for Nigerian smallholder farmers. These systems relied on long fallow for fertility restoration after a period of cropping. Overpopulation has resulted in lower per capita land availability, necessitating a shift to sedentary cultivation systems. In such systems, fallow is short term (months) compared to shifting systems, where it lasted several years. This shift has resulted in overexploitation of land resources and despite intensification of agricultural production methods, non-sustainable demand on the natural resource base has increased and crop and animal production has declined. This study examined the performance of five maize-based cropping systems consisting of cereal-legume, cereal-cereal and cereal bare fallow rotations, to identify systems that have potential for increased agricultural production in the subhumid and mid-altitude zones of Nigeria. The study was conducted at Richmond, near Sydney, in NSW, Australia from 2000 to 2003. The trial investigated the effects of the combined use of legumes and N fertilizer in CSs to maintain or improve soil fertility, maize crop and maize storage silage production and yield and quality of all crop residues. This study showed that inclusion of a legume in the rotation is an important production and income generating strategy. Owing to their potential for increased maize productivity, to build up N-rich systems and to improve small holder levels of farm income, cropping systems with legumes should therefore be given more research attention in NigeriaDoctor of Philosophy (PhD)
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Pachta, Christopher James. "Improving irrigated cropping systems on the high plains using crop simulation models." Thesis, Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/316.
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Maxwell-Benson, Kelli S. "Balancing biological and chemical nitrogen in irrigated Phaseolus vulgaris (L) cropping systems." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1313917301&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Jayasundara, H. P. S. "Productivity, dinitrogen fixation and nitrogen transfer in some legume based cropping systems." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386547.
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Smith, Hazel. "Improving the sustainability of water use in baby leaf salad cropping systems." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/354419/.
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Future food security is under threat from both climate change and human population growth. Water scarcity is a major limitation to crop production worldwide and the effects of climate change are likely to exacerbate this. Furthermore, an ever increasing human population is driving our demand for food, fuel and fibre. In combination, climate change and population growth, and their interaction, creates a complex problem with regards to improving plant productivity with which to maintain food security. If crop production can be made more efficient, agricultural intensification can be achieved without the need to expand the world’s cropped area, which is unfeasible. Leafy salad crops are of significant nutritional value and are eaten globally, thus making them an exciting target for improving resource use efficiency in agriculture. This research focuses on water as a resource and takes two complementary approaches. Firstly, to improve the crop genetically so it produces more ‘crop per drop’ without a detrimental impact on yield. Secondly, the aim was to improve irrigation management in a commercial setting in order to use water more efficiently while attaining optimal crop yield and quality. Candidate SNPs within the lettuce genome have been elucidated which control both fresh weight and water use efficiency and these can now be used to inform a marker assisted selection breeding program. This breeding will produce a more water use efficient lettuce crop, which is not compromised in its ability to produce biomass, while also retaining the favoured traits of currently used commercial crops. Furthermore, it has been demonstrated using thermal imagery that water savings of almost 20% can be made in a commercial setting without any impact on crop yield or quality. The water savings which we have provided, if extended commercially, will confer significant savings in terms of water, waste and money.
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D'Attilio, DeAnna Rae. "Optimizing nitrogen fertilization practices under intensive vineyard cover cropping floor management systems." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/56614.
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Under-trellis cover crops have become more prevalent in East Coast grape growing regions through either intentional planting or adoption of native vegetation, to minimize the potential for erosion and to help regulate grapevine size and vigor. These companion crops, however, have sometimes resulted in increased competition for soil nitrogen, leading to decreased vine nitrogen status and berry yeast assimilable nitrogen (YAN). The aim of this study was to determine the effects of different nitrogen fertilization methods applied at varying doses and different times, on vine and berry nitrogen parameters of cover cropped grapevines. The research described herein involved Sauvignon blanc, Merlot, and Petit Manseng grapevines (Vitis vinifera L.) subjected to different sets of nitrogen treatments, and was primarily conducted over two years. There were very few differences in pruning weights, canopy architecture, components of yield, and primary fruit chemistry amongst nitrogen treatments. Sauvignon blanc petiole nitrogen concentration, season-long chlorophyll content index (CCI) values, and berry YAN were most affected by the highest rate of soil nitrogen treatment (60 kg N/ha total split between two calcium nitrate applications at bloom and six weeks post bloom) and foliar fertilization (40 kg N/ha split over seven to nine urea applications); however, the foliar fertilization was most effective at increasing the concentration of certain individual amino acids. Petit Manseng berry YAN at harvest was increased in response to post-véraison foliar applications (10 kg N/ha split between two urea applications), corresponding to an increased concentration of nine amino acids. Merlot berry YAN, petiole nitrogen concentration, and season-long CCI values were most affected by a high rate of soil nitrogen treatment (60 kg N/ha total split between two calcium nitrate applications at bloom and six weeks post bloom) and establishing clover as the under-trellis cover crop. This study identified nitrogen treatments that improved berry nitrogen concentration and content in cover cropped sites.Master of Science
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Minoli, Sara. "Managing phenology for agronomic adaptation of global cropping systems to climate change." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21965.
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Der Klimawandel fordert die Anbausysteme heraus, um das derzeitige Produktionsniveau zu verbessern oder sogar aufrechtzuerhalten. Es wird erwartet, dass zukünftige Trends bei Temperatur und Niederschlag die Ernteproduktivität beeinträchtigen. Es ist daher notwendig, möglicher Lösungen zur Anpassung der Anbausysteme an den Klimawandel zu untersuchen.
Ziel dieser Arbeit ist es, das Wissen über die Anpassung von weltweit relevanten Getreidepflanzen an den Klimawandel zu erweitern. Die zentrale Fragestellung ist, ob globale Anbausysteme an den Klimawandel angepasst werden können, indem die Phänologie der Kulturpflanzen durch Anpassung von Wachstumsperioden und Sorten gesteuert wird.
Die Phänologie und die Ertragsreaktionen sowohl auf den Temperaturanstieg als auch auf die Sortenselektion werden zunächst anhand eines Ensembles von “Global Gridded Crop Models” bewertet. Anschließend wird die Komplexität der Anpassung durch phänologisches Management analysiert, insbesondere unter Berücksichtigung der bestehenden großen Wissenslücken bei der Auswahl von Pflanzensorten. Das Ergebnis der Analyse ist ein regelbasierter Algorithmus, der phänologische Zyklen der Kulturpflanzen auswählt, um die Zeit für die Ertragsbildung zu maximieren und Temperatur- und Wasserbelastungen während der Wachstumszyklen der Kulturpflanzen zu minimieren. Die berechneten Aussaatdaten und Wachstumsperioden werden verwendet, um globale Muster von Sorten zu parametrisieren, die an aktuelle und zukünftige Klimaszenarien angepasst sind.
Diese Arbeit zeigt, dass die Auswirkungen des Klimawandels auf die Pflanzenproduktivität erheblich variieren können, je nachdem, welche Annahmen für das agronomische Management getroffen werden. Änderungen im Management zu vernachlässigen, liefert die pessimistischste Prognose für die zukünftige Pflanzenproduktion. Relativ einfache Ansätze zur Berechnung angepasster Aussaatdaten und Sorten bieten eine Grundlage für die Berücksichtigung autonomer Anpassungsschemata als integraler Bestandteil globaler Modellierungsrahmen.Climate change is challenging cropping systems to enhance or even maintain current production levels. Future trends in temperature and precipitation are expected to negatively impact crop productivity. It is therefore necessary to explore adaptation options of cropping systems to changing climate. The aim of this thesis is to advance knowledge on adaptation of world-wide relevant grain crops to climate change. The central research question is whether global cropping systems can be adapted to climate change by managing crop phenology through adjusting growing periods and cultivars. Phenology and yield responses to both temperature increase and cultivar selection are first assessed making use of an ensemble of Global Gridded Crop Models. Then, the complexity of adaptation through phenological management is analysed, particularly addressing the existing large knowledge gaps on crop cultivar choice. The outcome of the analysis is a rule-based algorithm that selects crop phenological cycles aiming at maximizing the time for yield formation and minimizing temperature and water stresses during the crop growth cycles. The computed sowing dates and growing periods are used to parametrize global patterns of cultivars adapted to present and future climate scenarios. This thesis demonstrates that the impacts of climate change on crop productivity can vary substantially depending on which assumptions are made on agronomic management. Neglecting any changes in management return the most pessimistic projection on future crop production. Relatively simple approaches to compute adapted sowing dates and cultivars provide a base for considering autonomous adaptation schemes as an integral component of global scale modelling frameworks.
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Roslon, Ewa. "Relay cropping of spring barley and winter wheat /." Uppsala : Dept. of Ecology and Crop Production Science, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a427-ab.html.
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Li, Ru. "Exploring bacterial communities and their functions for soil health under different cropping systems." PLoS ONE, 2012. http://hdl.handle.net/1993/19948.
Full textAbstract:
Rhizosphere and soil bacteria are important drivers in nearly all biochemical cycles in terrestrial ecosystems and participate in maintaining health and productivity of soil in agriculturally managed systems. However, the effect of agricultural management systems on bacterial communities is still poorly understood. In this study, cultural methods and advanced molecular methods (terminal restriction fragment length polymorphism (TRFLP) and 454- pyrosequencing) were used to identify shifts in soil and rhizosphere bacterial diversity, community composition, and functions under different cropping systems in Manitoba, Canada. This included monoculture vs. rotation, zero tillage vs. conventional tillage, and organic farming vs. conventional farming.
Results showed that: (1) different cropping systems did not significantly influence the diversity of bacterial communities. However, a significant variation in relative abundances of bacterial communities at both the phylum and genus level was observed among different cropping systems. Compared to conventional farming systems, organic farming system had a higher percentage of the phylum Proteobacteria (many Plant Growth Promoting Rhizosbacteria) and a lower percentage of the phylum Actinobacteria. When canola monoculture was compared to wheat-oat-canola-pea rotation, a significantly higher percentage of Proteobacteria and a lower percentage of Actinobacteria were found in the rotational system. Wheat monoculture shared similar bacterial communities with wheat-oat-canola-pea rotation. Zero tillage did not change bacterial community profiles except for an increase in Firmicutes (many PGPR), compared to conventional tillage. At the genus level, significant differences were found for the dominant genera Pseudomonas, Rhizobium, Stenotrophomonas, Brevundimonas, Burkholderia, Marmoricola, Microlunatus, and Solirubrobacter. The bacterial distribution was strongly associated with soil pH. (2) The cropping systems also influenced the antibiotic-producing Pseudomonas populations determined through PCR-based screening for the detection of genes involved in the biosynthesis of antibiotics. It was found that pyrrolnitrin- and phenazine- producing Pseudomonas spp. were more prevalent in the soil under zero tillage and organic farming systems, while 2,4-DAPG and pyoluteorin-producing strains were not found in this study.
This comprehensive study provided fundamental information on how different cropping systems affect soil and rhizosphere bacterial communities, which can be used to guide Manitoba farmers to choose proper farming systems to maintain soil health and increase PGPR populations in soil.
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Li, Ru. "Exploring bacterial communities and their function for soil health under different cropping systems." PLoS ONE, 2012. http://hdl.handle.net/1993/19948.
Full textAbstract:
Rhizosphere and soil bacteria are important drivers in nearly all biochemical cycles in terrestrial ecosystems and participate in maintaining health and productivity of soil in agriculturally managed systems. However, the effect of agricultural management systems on bacterial communities is still poorly understood. In this study, cultural methods and advanced molecular methods (terminal restriction fragment length polymorphism (TRFLP) and 454- pyrosequencing) were used to identify shifts in soil and rhizosphere bacterial diversity, community composition, and functions under different cropping systems in Manitoba, Canada. This included monoculture vs. rotation, zero tillage vs. conventional tillage, and organic farming vs. conventional farming.
Results showed that: (1) different cropping systems did not significantly influence the diversity of bacterial communities. However, a significant variation in relative abundances of bacterial communities at both the phylum and genus level was observed among different cropping systems. Compared to conventional farming systems, organic farming system had a higher percentage of the phylum Proteobacteria (many Plant Growth Promoting Rhizosbacteria) and a lower percentage of the phylum Actinobacteria. When canola monoculture was compared to wheat-oat-canola-pea rotation, a significantly higher percentage of Proteobacteria and a lower percentage of Actinobacteria were found in the rotational system. Wheat monoculture shared similar bacterial communities with wheat-oat-canola-pea rotation. Zero tillage did not change bacterial community profiles except for an increase in Firmicutes (many PGPR), compared to conventional tillage. At the genus level, significant differences were found for the dominant genera Pseudomonas, Rhizobium, Stenotrophomonas, Brevundimonas, Burkholderia, Marmoricola, Microlunatus, and Solirubrobacter. The bacterial distribution was strongly associated with soil pH. (2) The cropping systems also influenced the antibiotic-producing Pseudomonas populations determined through PCR-based screening for the detection of genes involved in the biosynthesis of antibiotics. It was found that pyrrolnitrin- and phenazine- producing Pseudomonas spp. were more prevalent in the soil under zero tillage and organic farming systems, while 2,4-DAPG and pyoluteorin-producing strains were not found in this study.
This comprehensive study provided fundamental information on how different cropping systems affect soil and rhizosphere bacterial communities, which can be used to guide Manitoba farmers to choose proper farming systems to maintain soil health and increase PGPR populations in soil.
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Kravchenko, Anatoliy G. "Overcoming the rotational antagonism of corn following wheat in high residue cropping systems." Diss., Connect to online resource - MSU authorized users, 2006.
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Thesis (M. S.)--Michigan State University. Dept. of Crop and Soil Sciences, 2006.Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references (p. 94-99). Also issued in print.
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Holland, Jonathan Eddison. "Changes in soil physical properties under raised bed cropping /." Connect to thesis, 2006. http://eprints.unimelb.edu.au/archive/00002537.
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Ess, Daniel R. "Energetics of low-input corn production." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-06082009-171129/.
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