Dissertations / Theses on the topic 'Crop'
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Kufimfutu, Bakelana ba. "Crop planting pattern effects on crop and weed growth /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487778663287222.
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Åström, Petter. "Cash crops vs food crops : A case study of household's crop choices in Babati District." Thesis, Södertörn University College, School of Life Sciences, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-2605.
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According to earlier research farmer's crop orientation in developing countries mainly depends on farm size, large-scale farmers prefer cash crop while small-scale farmers prefer subsistence crops. The first aim of this study is to see if this hypothesis can be applied on six households in Babati District in rural Tanzania. The second aim is to investigate if other factors than farm size affect crop portfolio choice and the final aim is to see if those crop portfolio models can be improved. A case-study research design and qualitative interviews are used. The primary data is based on a fieldwork that took place from the 18th of February until the 7th of March 2009 in the study area.
From a theoretical perspective the underlying assumptions of the Marcel Fafchamp's model Crop portfolio choice under multivariate risks is discussed in connection to the result of the study.
Interviews were made with six households of different farm size. The result of the study indicates that both small-scale and large-scale farmers are using cash crops. The fact that all crops can be used for selling, gives also small-scale farmers in season with higher prices, an opportunity to sell a large share of their crops. It's thereby not possible to state that large-scale farmers devote a larger share of their land for cash crop than small-scale farmers do.
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Subedi-Chalise, Kopila. "Impacts of Crop Residue and Cover Crops on Soil Hydrological Properties, Soil Water Storage and Water Use Efficiency of Soybean Crop." Thesis, South Dakota State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10265200.
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Cover crops and crop residue play a multifunctional role in improving soil hydrological properties, soil water storage and water use efficiency (WUE). This study was conducted to better understand the role of crop residue and cover crop on soil properties and soil water dynamics. The study was conducted at the USDA-ARS North Central Agricultural Research Laboratory, located in Brookings, South Dakota. Two residue removal treatments that include low residue removal (LRR) and high residue removal (HRR) were established in 2000 with randomized complete block design under no-till corn (Zea mays L.) and soybean (Glycine max L.) rotation. In 2005, cover crop treatments which include cover crops (CC) and no cover crops (NCC) were integrated into the overall design. Soil samples were collected in 2014, 2015 and 2016. Data from this study showed that LRR treatment resulted in lower bulk density (BD) by 7 and 9% compared to HRR in 2015 and 2016, respectively, for 0-5 cm depth. Similarly, LRR treatment significantly reduced soil penetration resistance (SPR) by 25% in 0-5 cm depth compared with HRR treatment. In addition to this, LRR treatment significantly increased soil organic carbon (SOC) concentrations and total nitrogen (TN) by 22 and 17%, respectively, in 0-5 cm. Similarly, CC treatment resulted in lower BD and SPR by 7% and 23%, respectively, in 0-5 cm depth in 2015 compared with NCC treatment. The LRR significantly increased soil water infiltration by 66 and 22% compared to HRR in 2014 and 2015, respectively. Similarly, the CC treatment significantly increased infiltration by 82 and 22% compared to the NCC in 2014 and 2015, respectively. The significant impact of a crop residue was observed on soil water retention (SWR) in 2014 and 2015 for the 0-5 cm depth. The LRR and CC treatments increased the soil volumetric moisture content (VMC) and soil water storage (SWS) on the surface 0-5 cm depth. However, the trend was not always significant during the growing season. The CC treatment significantly impacted the soybean yield by 14% and WUE by 13% compared with NCC treatment. Some interaction of residue by cover crops was observed on BD, SPR, VMC, and SWS, which showed that the use of cover crops with LRR can be beneficial in improving the soil properties.
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Ramirez, Almeyda Jacqueline <1985>. "Lignocellulosic Crops in Europe: Integrating Crop Yield Potentials with Land Potentials." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/7854/1/Tesi_J.Ramirez_2017_Lignocellulosic%20crops%20potentials%20in%20EU.pdf.
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Given the ambitious EU targets to further decarbonise the economy, it can be expected that the demand for lignocellulosic biomass will continue to grow. Provisioning of part of this biomass by dedicated biomass crops becomes an option. This study presents integrated approach for crop allocation based on land availability and crop requirements. The model analysis to investigate the potential extension of unused land and its suitability for lignocellulosic crops was carried out in 37 European countries at the NUTS3 level. The CAPRI model predicts future land use changes and was used as a basic input to assess the agricultural biomass potentials in Europe. It was then identified the total land resource with a post-modeling assessment for three different potentials to the year 2020 and 2030, according to sustainability criteria formulated in the Renewable Energy directive (RED). Furthermore, crop-specific suitability maps were generated for each crop based on the variability of biophysical factors such as climate, soil properties and topographical aspects. The yields and cost levels that can be reached in Europe with different perennial crops in different climatic, soil and management situations. The AquaCrop model developed by FAO was used and fed with phenological parameters per crop and detailed weather data to simulate the crop growth in all European Nuts 3 regions. Yield levels were simulated for a maximum and a water-limited yield situation and further converted to match with low, medium and high input management systems. The costs production was assessed with an Activity Based Costing (ABC) model, developed to assess the roadside Net Present Value (NPV) cost of biomass. The yield, crop suitability and cost simulation results were then combined to identify the best performing crop-management mix per region.
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Murphy, Donal Patrick Lee. "Crop structure and crop productivity in winter barley, (Hordeum sativum)." Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262202.
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Perkins, Seth A. "Crop model review and sweet sorghum crop model parameter development." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14037.
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Master of ScienceDepartment of Biological and Agricultural Engineering
Kyle Douglas-Mankin
Opportunities for alternative biofuel feedstocks are widespread for a number of reasons: increased environmental and economic concerns over corn production and processing, limitations in the use of corn-based ethanol to 57 billion L (15 billion gal) by the Energy Independence and Security Act (US Congress, 2007), and target requirements of 136 billion L (36 billion gal) of renewable fuel production by 2022. The objective of this study was to select the most promising among currently available crop models that have the potential to model sweet sorghum biomass production in the central US, specifically Kansas, Oklahoma, and Texas, and to develop and test sweet sorghum crop parameters for this model. Five crop models were selected (CropSyst, CERE-Sorghum, APSIM, ALMANAC, and SORKAM), and the models were compared based on ease of use, model support, and availability of inputs and outputs from sweet sorghum biomass data and literature. After reviewing the five models, ALMANAC was selected as the best suited for the development and testing of sweet sorghum crop parameters. The results of the model comparison show that more data are needed about sweet sorghum physiological development stages and specific growth/development factors before the other models reviewed in this study can be readily used for sweet sorghum crop modeling. This study used a unique method to calibrate the sweet sorghum crop parameter development site. Ten years of crop performance data (Corn and Grain Sorghum) for Kansas Counties (Riley and Ellis) were used to select an optimum soil water (SW) estimation method (Saxton and Rawls, Ritchie et al., and a method that added 0.01 m m [superscript]-1 to the minimum SW value given in the SSURGO soil database) and evapotranspiration (ET) method (Penman-Montieth, Priestley-Taylor, and Hargraeves and Samani) combination for use in the sweet sorghum parameter development. ALMANAC general parameters for corn and grain sorghum were used for the calibration/selection of the SW/ET combination. Variations in the harvest indexes were used to simulate variations in geo-climate region grain yield. A step through comparison method was utilized to select the appropriate SW/ET combination. Once the SW/ET combination was selected the combination was used to develop the sweet sorghum crop parameters. Two main conclusions can be drawn from the sweet sorghum crop parameter development study. First, the combination of Saxton and Rawls (2006) and Priestley-Taylor (1972) (SR-PT) methods has the potential for wide applicability in the US Central Plains for simulating grain yields using ALMANAC. Secondly, from the development of the sweet sorghum crop model parameters, ALMANAC modeled biomass yields with reasonable accuracy; differences from observed biomass values ranged from 0.89 to 1.76 Mg ha [superscript]-1 (2.8 to 9.8%) in Kansas (Riley County), Oklahoma (Texas County), and Texas (Hale County). Future research for sweet sorghum physiology, Radiation Use Efficiency/Vapor Pressure Deficit relationships, and weather data integration would be useful in improving sweet sorghum biomass modeling.
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Schmitz, Austin. "Row crop navigation by autonomous ground vehicle for crop scouting." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/36237.
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Master of ScienceDepartment of Biological & Agricultural Engineering
Daniel Flippo
Robotic vehicles have the potential to play a key role in the future of agriculture. For this to happen designs that are cost effective, robust, and easy to use will be necessary. Robotic vehicles that can pest scout, monitor crop health, and potentially plant and harvest crops will provide new ways to increase production within agriculture. At this time, the use of robotic vehicles to plant and harvest crops poses many challenges including complexity and power consumption. The incorporation of small robotic vehicles for monitoring and scouting fields has the potential to allow for easier integration of robotic systems into current farming practices as the technology continues to develop. Benefits of using unmanned ground vehicles (UGVs) for crop scouting include higher resolution and real time mapping, measuring, and monitoring of pest location density, crop nutrient levels, and soil moisture levels. The focus of this research is the ability of a UGV to scout pest populations and pest patterns to complement existing scouting technology used on UAVs to capture information about nutrient and water levels. There are many challenges to integrating UGVs in conventionally planted fields of row crops including intra-row and inter-row maneuvering. For intra-row maneuvering; i.e. between two rows of corn, cost effective sensors will be needed to keep the UGV between straight rows, to follow contoured rows, and avoid local objects. Inter-row maneuvering involves navigating from long straight rows to the headlands by moving through the space between two plants in a row. Oftentimes headland rows are perpendicular to the row that the UGV is within and if the crop is corn, the spacing between plants can be as narrow as 5”. A vehicle design that minimizes or eliminates crop damage when inter-row maneuvering occurs will be very beneficial and allow for earlier integration of robotic crop scouting into conventional farming practices. Using three fixed HC-SR04 ultrasonic sensors with LabVIEW programming proved to be a cost effective, simple, solution for intra-row maneuvering of an unmanned ground vehicle through a simulated corn row. Inter-row maneuvering was accomplished by designing a transformable tracked vehicle with the two configurations of the tracks being parallel and linear. The robotic vehicle operates with tracks parallel to each other and skid steering being the method of control for traveling between rows of corn. When the robotic vehicle needs to move through narrow spaces or from one row to the next, two motors rotate the frame of the tracks to a linear configuration where one track follows the other track. In the linear configuration the vehicle has a width of 5 inches which allows it to move between corn plants in high population fields for minimally invasive maneuvers. Fleets of robotic vehicles will be required to perform scouting operations on large fields. Some robotic vehicle operations will require coordination between machines to complete the tasks assigned. Simulation of the path planning for coordination of multiple machines was studied within the context of a non-stationary traveling salesman problem to determine optimal path plans.
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Watt, J. "3D crop modelling." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1421425/.
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Crop models have become increasingly useful tools for understanding and implementing sus¬tainable agricultural techniques and as a way of accurately predicting crop yields for economists and policy decision makers. Using remotely sensed imagery can significantly reduce the effort required to obtain the in¬puts for crop models and can provide regular sets of observations throughout a growing season. Empirical models can be used to extract information regarding the crop from remotely sensed images but have well-documented limitations. Coupling a crop model with a radiative transfer model allows comparison between modelled and actual reflectance, across a range of potential crop model states. The potential difference observed can then allow for recalibration of the crop model. This technique enables the crop model to be updated throughout crop development and growth, increasing its accuracy at predicting the development of the crop. As the structure of the crop changes significantly during growth and development, affecting the remote sensing signal, a 3D structural model which can represent this change is required. This thesis presents work developing and re-parameterising an existing 3D crop model to make it more generic, as well as coupling it with a radiative transfer model. The crop model being re-parameterised is ADEL-wheat. Extensive field work spanning two growing seasons has been carried out to measure the phenological and structural differences that occurred during the growth and development of different genotypes of winter wheat. These observed differences, particularly in phenology, have been implemented within the model, and then used to test the impact on the remote sensing signal. The work shows that structural differences between genotypes tend to have a greater impact on the resulting modelled signal than phenological variation. The combined structural and radiative transfer modelling approach is shown to be very flexible and can be used to improve/augment existing crop modelling approaches.
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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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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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Ess, Daniel R. "Cover crop residue effects on machine-induced soil compaction." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164819/.
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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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Key, Georgina. "Cross-crop benefits : developing crop combinations to promote conservation biological pest control." Thesis, Lancaster University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658572.
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In agroecosystems, conservation biological control is often constrained by low availability of pollen and nectar. Although floral resources can be integrated into agricultural systems, this usually requires sacrifice of productive land. This thesis describes experiments which test the influence of floral resources provided by species which have marketable value in their own right as food or medicinal crops. Floralresource strips comprising such species were intercropped with Brassica crops at plot, field and commercial scales in replicated field experiments. The abundance and distribution of key Brassica crop pests a,nd their natural enemies in the presence of floral resources was examined. Parasitoids displayed distinct flower species preferences; Fagopyrum esculentum significantly increased parasitoid abundance. Parasitoids also responded to distance; their abundance significantly declined with increasing distance from floral strips, especially in F. esculentum, and parasitism levels declined significantly after 8 m. Borago offtcinalis also proved attractive to parasitoids and Tanacetum parthenium to Syrphidae. In addition, F. esculentum and B. offtcinalis were found to suppress the second generation of Pierid larvae at field scale. This evidence suggests that several flower species could be intercropped within a Brassica crop to promote biological pest control.
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Gayam, Narsi Reddy. "Risk in agriculture : a study of crop yield distributions and crop insurance." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35537.
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Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2006.Includes bibliographical references (leaves 52-53).
Agriculture is a business fraught with risk. Crop production depends on climatic, geographical, biological, political, and economic factors, which introduce risks that are quantifiable given the appropriate mathematical and statistical methodologies. Accurate information about the nature of historical crop yields is an important modeling input that helps farmers, agribusinesses, and governmental bodies in managing risk and establishing the proper policies for such things as crop insurance. Explicitly or implicitly, nearly all farm decisions relate in some way to the expectation of crop yield. Historically, crop yields are assumed to be normally distributed for a statistical population and for a sample within a crop year. This thesis examines the assumption of normality of crop yields using data collected from India involving sugarcane and soybeans. The null hypothesis (crop yields are normally distributed) was tested using the Lilliefors method combined with intensive qualitative analysis of the data. Results show that in all cases considered in this thesis, crop yields are not normally distributed.
(cont.) This result has important implications for managing risk involving sugarcane and soybeans grown in India. The last section of this thesis examines the impact of crop yield non normality on various insurance programs, which typically assume that all crop yields are normally distributed and that the probability of crop failure can be calculated given available data.
by Narsi Reddy Gayam.
M.Eng.in Logistics
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Lena, Bruno Patias. "Crop evapotranspiration and crop coefficient of jatropha from first to fourth year." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-06012017-111443/.
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The determination of crop coefficient (Kc) with adequate methodology is important to quantify regional water requirement. Jatropha (Jatropha curcas L.) Kc is still unknown and this information will be essential to provide reliable irrigation parameters, as well as for crop zoning. The objective of this study was to determine jatropha actual crop evapotranspiration (ETc) and Kc from 1st to 4th growing year, and correlate Kc with leaf area index (LAI) and cumulative thermal unit (CTU). The experiment was performed from March 2012 to August 2015 at \"Luiz de Queiroz\" College of Agriculture (ESALQ)/University of São Paulo (USP), at Piracicaba city, SP, Brazil. The experiment was divided into center pivot, drip, and rainfed treatments. Two large weighing lysimeters (12 m2 each lysimeter) per treatment were used to determine jatropha ETc (one plant per lysimeter). Reference evapotranspiration (ET0) was determined by Penman-Monteith method from a weather station data situated close to the treatments. Daily Kc was determined for the two irrigated treatments by the ration between ETc and ET0 (Kc=ETc/ET0). LAI was determined using the LAI-2200 plant canopy analyzer, which was previously calibrated for jatropha canopy type. In all growing years, LAI was almost zero at the beginning of vegetative stage, increasing until a maximum during productive stage, and decreasing to zero in the leaf senescence stage. Annual ETc trend during the three growing was very similar, which was explained by the different growing periods and the LAI variation. In the 1st year Kc was 0.47 for both treatments. In the 2nd, 3rd, and 4th years Kc ranged from 0.15 to 1.38 for center pivot treatment and from 0.15 to 1.25 for drip treatment. Kc average in 2nd, 3rd, and 4th years during vegetative and productive growing periods was 0.77, 0.93, and 0.82 for center pivot treatment, respectively, and 0.69, 0.79, and 0.74 for drip treatment, respectively. The relationship between Kc and LAI for the center pivot treatment was adjusted to a logarithmical equation with coefficient of determination (R2) and root mean square error (RMSE) of 0.7643 and 0.334, respectively. For the drip treatment R2 was 0.8443 and 0.2079, respectively. In all three years analyzed, Kc related to CTU by a 3rd degree polynomial equation for both treatments.A determinação de coeficiente de cultivo (Kc) com metodologia adequada é essencial para quantificar o consumo hídrico de cultivos em diferentes regiões. Valores de Kc do pinhão-manso (Jatropha curcas L.) ainda não foram determinados e essa informação é muito importante para auxiliar o manejo de irrigação de maneira adequada. O objetivo desse estudo foi determinar a evapotranspiração (ETc) e Kc do 1º ao 4º ano de cultivo do pinhão-manso, e correlacionar Kc com o índice de área foliar (IAF) e a soma da unidade térmica (SUT). O experimento foi realizado de março de 2012 à agosto de 2015 na Escola Superior de Agricultura \"Luiz de Queiroz\" (ESALQ)/Universidade de São Paulo (USP), na cidade de Piracicaba, SP, Brasil. O experimento foi divido nos tratamentos irrigados por pivô central, gotejamento e sem irrigação. Foram utilizados dois lisímetros de pesagem (12 m2 de superfície em cada lisímetro) por tratamento para realizar a determinação de ETc (uma planta por lisímetros). A evapotranspiração de referência (ET0) foi determinado pelo método de Penman-Monteith a partir de dados meteorológicos coletados na estação meteorológica localizada ao lado do experimento. Valores diários de Kc foram determinados nos tratamentos irrigados pela razão entre ETc e ET0 (Kc=ETc/ET0). IAF foi determinado utilizando o equipamento LAI-2200 Plant Canopy Analyzer, que foi previamente calibrado para adequar as características do dossel do pinhão-manso. Em todos os anos avaliados, o IAF foi quase zero durante o início do período vegetativo, aumentando os valores conforme a planta começou a se desenvolver até atingir valores máximos durante o período produtivo, decrescendo os valores até zero no estádio de desenvolvimento de senescência foliar. A variação anual de ETc no 2º, 3º e 4º ano foi muito similar, explicado pelos diferentes períodos de desenvolvimento da cultura e a variação de IAF no ano. No 1º ano, Kc foi 0,47 para os dois tratamentos irrigados. No 2º, 3º e 4º ano, Kc variou de 0,15 a 1,38 no tratamento irrigado por pivô central e de 0,15 a 1,15 no tratamento irrigado por gotejamento. A média dos valores de Kc no 2º, 3º e 4º ano durante os períodos vegetativos e produtivos foi de 0,77, 0,93 e 0,82 no tratamento irrigado por pivô central, respectivamente, e 0,69, 0,79 e 0,74 no tratamento irrigado por gotejamento, respectivamente. A relação entre Kc e IAF mostrou, para o tratamento irrigado por pivô central, um ajuste logaritmo com coeficiente de determinação (R2) e somatória do erro médio ao quadrado (SEMQ) de 0,7643 e 0,334, respectivamente, e 0,8443 e 0,2079 para o tratamento irrigado por gotejamento, respectivamente. Nos três anos analisados, Kc correlacionado com SUT mostrou o melhor ajuste à equação polinomial de 2ª ordem para os dois tratamentos.
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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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Myers, Brian. "Variable crop residue management." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/35271.
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Master of AgribusinessDepartment of Agricultural Economics
Jeffery R. Williams
Production agriculture is constantly evolving to become more efficient and productive. Crop residue serves as a valuable source of nutrients for the soil, but it is increasingly abundant with today’s enhanced crop genetics. If new technology can effectively provide a way to micro-manage crop residue levels within a field, the benefits will go beyond soil health. Surplus crop residue can be collected for secondary income while leaving the optimum amounts in the field to maintain the environment and soil health as well as promote future crop growth. The main objective of this study is to create a budget model that will determine the economic impact of crop residue removal on a controlled basis. The goals are to determine crop residue removal practices that are sustainable for the long-term, while also enhancing soil quality and increasing grain yield in future years. A sub-objective is to build a business case for producers to invest in variable crop residue management. The hypothesis presented in this study is that the increased complexity and price of a variable rate system is offset by more supplemental profits, increased crop yields, and better management of soil health and nutrients. The negative perceptions of crop residue removal include the fear of soil erosion or loss of soil organic matter. By developing a budget model that is easy to use, takes advantage of existing field data for inputs, and allows producers the ability to look at their operations on a sub-field level, this study aims to provide the necessary motivation to invest in new technology that will increase their productivity. By entering their site-specific crop residue return rate data into a budget model, along with prices and costs related to combine and auxiliary equipment, corn and corn stover, transportation and logistics, and nutrient replacement, they will come up with a return per acre for both constant rate and variable rate collection. The budget model determines whether it is economically viable to harvest crop residue from a continuous corn rotation at a variable rate across a field, rather than at a constant rate, using a producer’s own specific field data. To validate the concept, data from a joint study between John Deere and Iowa State is entered into the model. Prescriptions for corn stover return rates are provided from the study for pre-defined grid areas. Prescriptions are derived from a combination of data including grain yield, soil loss due to wind and water erosion, climate, topography, and soil sample data at time of planting (Nelson, et al. 2004). The average corn stover removal percentage was less for variable rate collection than constant rate collection, 26.05% to 31.85%. However, the assumption that grain yield and corn stover yield are positively correlated did not prove to be true in this case study. The variable rate plots had a lower average grain yield of 158.84 bushel/acre, compared to 160.46 for the constant rate plots, but they had more total corn stover available and therefore a higher return rate of 3.70 tons/acre, compared to 3.05 for the constant rate plots. This case study illustrates that less corn stover can be returned to the field through constant or variable rate collection while sustaining higher grain yields than a conventional harvest that would return all of the corn stover to the field. This case study demonstrates that variable rate collection can be more expensive than constant rate, but not in every situation. Every unique field site will require a specific crop residue management recommendation that is determined by both economic and environmental factors.
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Silvertooth, Jeffrey C. "Early Season Crop Management." College of Agriculture, University of Arizona (Tucson, AZ), 2015. http://hdl.handle.net/10150/558539.
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Revised 06/2015; Originally published: 02/20012 pp.
The approaches and techniques used to produce a cotton crop in Arizona can vary to some degree from county to county, or from farm to farm. However, one of the objectives that has become increasingly common across Arizona is that of achieving earliness with a crop.
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Watson, J., and M. Sheedy. "Crop Water Use Estimates." College of Agriculture, University of Arizona (Tucson, AZ), 1995. http://hdl.handle.net/10150/210312.
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Irrigation scheduling, by keeping track of irrigation applications, soil storage and crop water use, has been computerized by a number of different individuals. A key component of the computerized methods is the estimation of a reference crop evapotranspiration rate. Complaints about one such method, AZSCHED, led the authors to compare the reference crop evapotranspiration values calculated by AZSCHED with those calculated by a second procedure available used by AZMET. Results of the comparison indicated that no significant difference existed between methods, for either a traditionally "long season", or a contemporary "short season" growing period. AZSCHED did estimate crop water use to be about 5% - 8% more than AZMET, an amount that is not of importance considering the irrigation inefficiencies created by field non-uniformities. Experience by the authors indicates that inappropriate selection of irrigation efficiencies and/or soil water holding capacity may be the main cause of user complaints.
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Jones, Jennifer S., John C. Palumbo, and Peter C. Ellsworth. "Arizona Crop Information Site." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2004. http://hdl.handle.net/10150/215239.
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The Arizona Crop Information Site (ACIS) http://cals.arizona.edu/crops was launched by the University of Arizona in 2001. This site provides a one-stop resource for those seeking information on Arizona crop protection and production information. The site is the result of input and cooperation across Arizona’s agricultural community. The amount of information on the site continues to grow as does the site’s importance, usefulness and number of visitors.
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Mallory, Ellen B. "Crop/Livestock Integration Effects on Soil Quality, Crop Production, and Soil Nitrogen Dynamics." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/MalloryEB2007.pdf.
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Mditshwa, Sithembele. "Estimating maize grain yield from crop growth stages using remote sensing and GIS in the Free State Province, South Africa." Thesis, University of Fort Hare, 2017. http://hdl.handle.net/10353/6016.
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Early yield prediction of a maize crop is important for planning and policy decisions. Many countries, including South Africa use the conventional techniques of data collection for maize crop monitoring and yield estimation which are based on ground-based visits and reports. These methods are subjective, very costly and time consuming. Empirical models have been developed using weather data. These are also associated with a number of problems due to the limited spatial distribution of weather stations. Efforts are being made to improve the accuracy and timeliness of yield prediction methods. With the launching of satellites, satellite data are being used for maize crop monitoring and yield prediction. Many studies have revealed that there is a correlation between remotely sensed data (vegetation indices) and crop yields. The satellite based approaches are less expensive, save time, data acquisition covers large areas and can be used to estimate maize grain yields before harvest. This study applied Landsat 8 satellite based vegetation indices, Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI) and Moisture Stress Index (MSI) to predict maize crop yield. These vegetation indices were derived at different growth stages. The investigation was carried out in the Kopanong Local Municipality of the Free State Province, South Africa. Ground-based data (actual harvested maize yields) was collected from Department of Agriculture, Forestry and Fisheries (DAFF). Satellite images were acquired from Geoterra Image (Pty) Ltd and weather data was from the South African Weather Service (SAWS). Multilinear regression approaches were used to relate yields to the remotely sensed indices and meteorological data was used during the development of yield estimation models. The results showed that there are significant correlations between remotely sensed vegetation indices and maize grain yield; up to 63 percent maize yield was predicted from vegetation indices. The study also revealed that NDVI and SAVI are better yield predictors at reproductive growth stages of maize and MSI is a better index to estimate maize yield at both vegetative and reproductive growth stages. The results obtained in this study indicated that maize grain yields can be estimated using satellite indices at different maize growth stages.
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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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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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Zhen, Chen. "Celestial satellite and earthly crop yield: informational content of satellite-based crop yield forecasts." Thesis, Montana State University, 2001. http://etd.lib.montana.edu/etd/2001/zhen/ZhenC2001.pdf.
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Since the late 70s, burgeoning efforts have been allocated to study the potential of monitoring crop conditions and forecasting crop yields via remote sensing from the satellite. An overwhelming majority of these studies shows that remote sensing from the satellite express high predictive power in crop forecasting. In this thesis, using satellite images to forecast wheat yield from 1989 to 2000 in six Montana Crop Reporting Districts (CRD), several statistical improvements were achieved over extant crop forecasting models. First, different weights were allowed for satellite images obtained at different points of time, accounting for the likely heterogeneous contributions of various crop phenological stages to the final crop yield. Second, crop acreage information was directly modeled. This, to some extent, alleviates the low-resolution problem of existing satellite imagery. Third, jackknife out-of-sample forecasts were generated to formally measure the well-known instability problem of using satellite imagery in crop forecasting across seasons. In addition, the satellite-based crop yield forecasts were compared with those of the U.S. Department of Agriculture (USDA), whose forecasts were based on traditional methods. It is shown that although meaningful crop forecasts can be generated from the satellite imagery late season, the additional yield information that can be extracted from the satellite tends to be limited. Because in the major wheat producing CRDs, the USDA forecasts are already very accurate and little independent information is observed in the satellite-based forecasts. Results suggest the needs to pinpoint crop phenological stages and to calibrate region-specific crop forecasting model.
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Al-Shammari, Dhahi Turki Jadah. "Remote sensing applications for crop type mapping and crop yield prediction for digital agriculture." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29771.
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This thesis addresses important topics in agricultural modelling research. Chapter 1 describes the importance of land productivity and the pressure on the agricultural sector to provide food. In chapter 2, a summer crop type mapping model has been developed to map major cotton fields in-season in the Murray Darling Basin (MDB) in Australia. In chapter 3, a robust crop classification model has been designed to classify two major crops (cereals and canola) in the MDB in Australia. chapter 4 focused on exploring changes in prediction quality with changes in the spatial resolution of predictors and the predictions. More specifically, this study investigated whether inputs should be resampled prior to modelling, or the modelling implemented first with the aggregation of predictions happening as a final step. In chapter 5, a new vegetation index is proposed that exploits the three red-edge bands provided by the Sentinel-2 satellite to capture changes in the transition region between the photosynthetically affected region (red region) and the Near-Infrared region (NIR region) affected by cell structure and leaf layers. Chapter 6 was conducted to test the potential of integration of two mechanistic-type model products (biomass and soil moisture) in the DDMs models. Chapter 7 was dedicated to discussing each technique used in this thesis and the outcomes of each technique, and the relationships between these outcomes. This thesis addressed the topics and questioned asked at the beginning of this research and the outcomes are listed in each chapter.
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Dodds, Paul Edward. "Development of a crop model to examine crop management and climate change in Senegal." Thesis, University of Leeds, 2010. http://etheses.whiterose.ac.uk/1121/.
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Frequent droughts and sub-optimal crop management have been identified as the principal constraints on agricultural intensifcation in the Sahel. A new model, the Crop Model for Sahelian Adaptation Studies (CROMSAS), was developed to examine the influence of climatic variability, climate change and crop management strategies on millet yields. To improve the simulation of environmental stresses, several original features were implemented including a new leaf expansion methodology, semi-independent tillers, stress-dependent partitioning, and intercropping. CROMSAS was designed in a structured, accessible way to facilitate the use of the model by other researchers who want to examine climate change impacts in Africa. The influences of rainfall and crop management decisions over the period 1950{2009 were assessed for six locations in Senegal with average rainfall from 200mm to 1200 mm. Poor rainfall severely restricted yields in the north of the country in most years while having little impact in the more humid south. In the highly-populated groundnut basin, rainfall variability reduced the effectiveness and hence the profitability of fertiliser application. Current planting densities were found to lie within the optimal range but higher grain yields could have been produced, with lower risk of crop failure, by delaying planting by 2-3 weeks. The benefits of adapting crop management strategies according to the conditions in previous years were assessed. Using a fixed long-term strategy produced higher long-term yields and profits, at lower risk of crop failure, than frequently changing strategies. Projections from three GCMs for the period 2000-2100 were converted to daily weather data using a novel methodology and used to examine the impact of climate change on millet cultivation across Senegal. Grain yields were projected to be relatively unchanged for the SRES A2 and B1 scenarios, with losses due to temperature increases and higher vapour pressure deficits being balanced by CO2 fertilisation.
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Ping, Zhang. "The partitioning of water loss between crop transpiration and soil evaporation in potato crops." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303926.
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Christenson, Andi Marie. "Cover crops for horseweed [Conyza canadensis (L.)] control before and during a soybean crop." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/19230.
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Master of ScienceDepartment of Agronomy
J. Anita Dille
Kraig Roozeboom
Increasing numbers of herbicide-resistant weed species require alternative methods of weed suppression to be examined. This study quantified the interaction between various cover crop or herbicide systems and horseweed [Conyza canadensis (L.)] growth. Fall cover crops of winter wheat [Triticum aestivum (L.)], winter rye [Secale cereal (L.)], barley [Hordeum vulgare (L.)] and annual ryegrass [Lolium multiflorum (L.)] were seeded in November 2012 and 2013. Spring cover crop of oat [Avena sativa (L.)] was seeded in April 2013 or rye was seeded in March 2014. All cover crops were no-till seeded into grain sorghum stubble [Sorghum bicolor (L.) Moench]. Four herbicide treatments were fall or spring applied, with and without residual. The spring non-residual treatment was also applied to plots of winter rye. Cover crop plots were split and terminated with a roller crimper or glyphosate application prior to soybean [Glycine max (L.) Merr.] planting to determine the effect of termination method on treatment performance. Soybean was planted in June 2013 and May 2014 and mechanically harvested in October of both years. Horseweed density, biomass accumulation, and soybean yield data were quantified. Horseweed height, whole plant seed production, and seed subsamples were recorded in the untreated fallow control, winter wheat, and winter rye plots in 2014. Horseweed suppression by winter rye approached 90%, levels similar to suppression by herbicide systems. In both years, herbicide plots had less than half the horseweed biomass than any of the cover crop systems. In 2013, soybean yields in herbicide plots were at least 1,500 kg ha[superscript]-1, nearly more than double yields in cover crop plots. Soybean yields in 2014 were more consistent across treatments; barley and spring rye plots achieved yields equal to or greater than 2,000 kg ha[superscript]-1. Winter rye and winter wheat reduced horseweed seed production by 60% compared to the untreated fallow control, with no effect on individual seed weight. Seed production varied across plants, with the untreated control producing the greatest number of seeds. Cover crops were successful at reducing horseweed biomass, suppressing horseweed pressure, preserving soybean biomass, and protecting soybean yields when compared to a fallow untreated control.
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Addala, Venkata Krishna Raju. "Mining genes from crop genebanks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0015/MQ52868.pdf.
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Li, Bo. "Studies of weed-crop competition." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262269.
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Songjang, Khemika. "Peptides to inhibit crop predation." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428155.
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Endacott, Christopher John. "Studies on electrodynamic crop spraying." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47423.
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Herse, Maria. "Crop improvement using synthetic variation." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607892.
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Gelt, Joe. "Wanted: A Viable Biofuel Crop." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2007. http://hdl.handle.net/10150/622106.
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Munda, Bruce, Tim C. Knowles, Art Meen, Vic Wakimoto, and Bill Worthy. "Winter Forage Cover Crop Trials." College of Agriculture, University of Arizona (Tucson, AZ), 1998. http://hdl.handle.net/10150/208283.
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Several crops were evaluated at Worthy farms, near Marana, AZ, Wakimoto farms, Mohave Valley, near Bullhead City, AZ, and the Tucson Plant Materials Center for use as a winter cover crop following cotton with potential to reduce wind erosion and produce one to two hay cuttings. Hairy vetch (Vicia villosa), 'Lana' woolypod vetch (Vicia villosa ssp. varia), 'Papago' pea (Pisum sativum), and 'Biomaster' pea (Pisum sativum) were sown at the Tucson Plant Materials Center. Species sown at Worthy farm were: Papago pea, Lana vetch, and Biomaster pea. Species sown at Wakimoto farm were: Biomaster pea, Lana vetch, 'Seco' barley (Hordeum vulgare), and 'Multi-cut' berseem clover (Trifolium alexandrinum). Forage yield varied between locations due to sowning date, number of irrigations, and soil textures. Biomaster pea, Papago pea, and Lana vetch performed well at all three locations. However, Biomaster yields were more consistent and due to its shorter growing season may be the better choice as a winter cover between cotton crops. Additional trials are scheduled for the fall of 1998.
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Silvertooth, J. C., P. W. Brown, and J. E. Malcuit. "Basic Cotton Crop Development Patterns." College of Agriculture, University of Arizona (Tucson, AZ), 1991. http://hdl.handle.net/10150/208324.
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Summaries of cotton crop phenology, as a function of heat units (HU, 86/55°F limits) have been developed across a wide range of production conditions in Arizona. Optimum ranges in HU accumulations since January 1 are used to describe planting dates to maintain optimum yield potentials with full season varieties. Basic events such as the occurrence of pinhead squares, squares that are susceptible to pink bollworm, and first bloom are described in terms of HU accumulations since planting. Also, the expected ranges of HU's accumulated since planting that are required to accomplish crop cut -out are shown for three general maturity types of Upland cotton.
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Oppong-Konadu, Eden Y. "Evolution in genetically diverse populations of barley (Hordeum vulgare L.)." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336773.
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Wang, Dong. "Reducing the environmental risks and hazards of crop production by biosafe use of transgenic crops." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511191.
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Ödegaard, Knut. "Cash crop versus food crop production in Tanzania an assessment of the major post-colonial trends /." Lund : [Dept. of Economics, University of Lund], 1985. http://catalog.hathitrust.org/api/volumes/oclc/18958128.html.
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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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Atkinson, Ross G. "Molecular approaches to horticultural crop improvement." Thesis, University of Auckland, 1993. http://hdl.handle.net/2292/1911.
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Plant biotechnology and molecular biology are now being used to complement conventional breeding programmes in most of the world's important crop species. The aim of the research described in this thesis was to improve New Zealand's horticultural crop plants through application of similar molecular techniques. A) Gene transfer systems for apple, pepino and tamarillo Tissue culture systems were developed for micropropagation and regeneration of apple (cv Royal Gala), pepino (cv El Camino) and tamarillo (selection Oratia Red). In all three species, transient expression of the gusA reporter gene was observed and kanamycin resistant callus was produced, following inoculation with the pKIWI110 binary vector in the avirulent Agrobacterium strain LBA4404. No transgenic apple shoots were obtained. However, transgenic pepino and tamarillo plants expressing the gusA reporter gene, kanamycin resistance and herbicide tolerance were successfully regenerated. PCR and Southern analysis provided molecular evidence for integration of foreign DNA into the genomes of transgenic pepino and tamarillo plants, but indicated deletions of the integrated T-DNAs had occurred with high frequency. Inheritance of the transgenic phenotypes was demonstrated in the progeny of transgenic tamarillo plants. B) Characterisation of polygalacturonase genes A kiwifruit genomic clone with homology to a tomato cDNA clone for polygalacturonase (PG) was sequenced over an 8.1 kb region. The sequence revealed a gene divided into nine exons, with 58% overall identity to the tomato PG gene at the amino acid level. Significant homology was also noted to PG genes isolated from peach, Oenothera organensis and maize, particularly in several blocks of conserved amino acids believed to encode the active site of the enzyme. Analysis of the kiwifruit PG promoter revealed three 81 bp direct repeat sequences just upstream of the kiwifruit peptide start codon. These repeats were also conserved in a second kiwifruit PC genomic clone. Characterisation of partial cDNA clones indicated that at least two mRNAs for PG were expressed in ripe kiwifruit. Southern hybridisation detected the PG gene at low copy number in the genomes of kiwifruit, two other Actinidia species, apple and pepino. PCR was used to amplify a fragment of the apple PG gene for sequence analysis. PG sequences were also used to help define the genetic origin of kiwifruit. A region of the PG gene was amplified and sequenced from four Actinidia species: kiwifruit (A. deliciosa), A. chinensis, A. eriantha and A. chrysantha. These sequences were used to produce a phylogeny using PAUP (phylogenetic analysis using parsimony). Two distinct lineages of PG genes were observed in the genomes of A. deliciosa, A. chinensis and A. eriantha. Within both these lineages, A. deliciosa sequences were quite distinct to those found in the other three Actinidia species, with the exception of a single sequence that was identical to A. chinensis. These results suggest that hexaploid kiwifruit is an allopolyploid with A. chinensis and at least one other Actinidia species as likely progenitors.
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Jagbrant, Gustav. "Autonomous Crop Segmentation, Characterisation and Localisation." Thesis, Linköpings universitet, Institutionen för systemteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-97374.
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Orchards demand large areas of land, thus they are often situated far from major population centres. As a result it is often difficult to obtain the necessary personnel, limiting both growth and productivity. However, if autonomous robots could be integrated into the operation of the orchard, the manpower demand could be reduced. A key problem for any autonomous robot is localisation; how does the robot know where it is? In agriculture robots, the most common approach is to use GPS positioning. However, in an orchard environment, the dense and tall vegetation restricts the usage to large robots that reach above the surroundings. In order to enable the use of smaller robots, it is instead necessary to use a GPS independent system. However, due to the similarity of the environment and the lack of strong recognisable features, it appears unlikely that typical non-GPS solutions will prove successful. Therefore we present a GPS independent localisation system, specifically aimed for orchards, that utilises the inherent structure of the surroundings. Furthermore, we examine and individually evaluate three related sub-problems. The proposed system utilises a 3D point cloud created from a 2D LIDAR and the robot’s movement. First, we show how the data can be segmented into individual trees using a Hidden Semi-Markov Model. Second, we introduce a set of descriptors for describing the geometric characteristics of the individual trees. Third, we present a robust localisation method based on Hidden Markov Models. Finally, we propose a method for detecting segmentation errors when associating new tree measurements with previously measured trees. Evaluation shows that the proposed segmentation method is accurate and yields very few segmentation errors. Furthermore, the introduced descriptors are determined to be consistent and informative enough to allow localisation. Third, we show that the presented localisation method is robust both to noise and segmentation errors. Finally it is shown that a significant majority of all segmentation errors can be detected without falsely labeling correct segmentations as incorrect.Eftersom fruktodlingar kräver stora markområden är de ofta belägna långt från större befolkningscentra. Detta gör det svårt att finna tillräckligt med arbetskraft och begränsar expansionsmöjligheterna. Genom att integrera autonoma robotar i drivandet av odlingarna skulle arbetet kunna effektiviseras och behovet av arbetskraft minska. Ett nyckelproblem för alla autonoma robotar är lokalisering; hur vet roboten var den är? I jordbruksrobotar är standardlösningen att använda GPS-positionering. Detta är dock problematiskt i fruktodlingar, då den höga och täta vegetationen begränsar användandet till större robotar som når ovanför omgivningen. För att möjliggöra användandet av mindre robotar är det istället nödvändigt att använda ett GPS-oberoende lokaliseringssystem. Detta problematiseras dock av den likartade omgivningen och bristen på distinkta riktpunkter, varför det framstår som osannolikt att existerande standardlösningar kommer fungera i denna omgivning. Därför presenterar vi ett GPS-oberoende lokaliseringssystem, speciellt riktat mot fruktodlingar, som utnyttjar den naturliga strukturen hos omgivningen.Därutöver undersöker vi och utvärderar tre relaterade delproblem. Det föreslagna systemet använder ett 3D-punktmoln skapat av en 2D-LIDAR och robotens rörelse. Först visas hur en dold semi-markovmodell kan användas för att segmentera datasetet i enskilda träd. Därefter introducerar vi ett antal deskriptorer för att beskriva trädens geometriska form. Vi visar därefter hur detta kan kombineras med en dold markovmodell för att skapa ett robust lokaliseringssystem.Slutligen föreslår vi en metod för att detektera segmenteringsfel när nya mätningar av träd associeras med tidigare uppmätta träd. De föreslagna metoderna utvärderas individuellt och visar på goda resultat. Den föreslagna segmenteringsmetoden visas vara noggrann och ge upphov till få segmenteringsfel. Därutöver visas att de introducerade deskriptorerna är tillräckligt konsistenta och informativa för att möjliggöra lokalisering. Ytterligare visas att den presenterade lokaliseringsmetoden är robust både mot brus och segmenteringsfel. Slutligen visas att en signifikant majoritet av alla segmenteringsfel kan detekteras utan att felaktigt beteckna korrekta segmenteringar som inkorrekta.
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Artus, Sally. "VEGIGRO: a crop growth teaching model." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484201.
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Ashby, Alison Mary. "Agrobacterium tumefaciens : chemotaxis and crop protection." Thesis, Durham University, 1988. http://etheses.dur.ac.uk/6723/.
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Chemotaxis in Agrobacierium tumefaciens was studied. Several plant derived monocyclic phenolic compounds were analysed for their ability to act as chemoattractants for A. tumefaciens C58C (^1) and as inducers of the Ti-plasmid virulence operons. The results divided the phenolics into 4 groups. A strong correlation between vir- inducing ability and Ti-plasmid requirement for chemo taxis was established and chemical structure rules for vir induction and chemo taxis are outlined. Furthermore, virA and virG were found to be the Ti-plasmid virulence genes required for chemo taxis towards the monocyclic phenolic compound acetosyringone. Chemotaxis towards both monocotyledonous and dicotyledonous plant extracts was analysed. Undiluted shoot and root extracts from both sources elicited a response from both Ti-plasmid harbouring and cured A. tumefaciens C58C(^1) However, when diluted extracts of Wheat and Kalanchoe shoot homogenate were analysed, a distinct enhancement of chemotaxis was conferred by the Ti-plasmid, suggesting that recognition of, and attraction towards, susceptible plants is not the step blocked in monocot transformation. Analysis of cell wall material revealed that native cell wall components are not required for chemotaxis of A. tumefaciens C58C (^1) towards plant extracts. Results obtained on chemotaxis along with current knowledge of vir- induction allowed the development of a novel idea involving Agrobacterium as a biocontrol agent. A chitinase gene from Serratia marcescens was manipulated such that its promotor was removed. The promotorless cassette was linked to the virB pro-motor from an octopine Ti-plasmid and the construct introduced into Agrobacterium harbouring virA and virG. The potential benefit of this biocontrol system with respect to other existing biocontrol systems is that expression of the pesticidal gene is regulated by components of wound exudate and therefore is a conservative process, pesticide being produced only when a plant is wounded, at a time when it is most susceptible to attack by plant pathogens, and then exclusively in the microrhizosphere around the wound site.
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Afreh-Nuamah, K. "Spray distribution in a tree crop." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/38212.
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Al-Azri, Masoud. "Modelling crop diseases for food security." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/44777/.
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Global crop production is affected by seasonal and climatic variations in temperature, rainfall patterns or intensity and the occurrence of abiotic and biotic stresses. Climate change can alter pest and pathogen populations as well as pathogen complexes that pose an enormous risk to crop yields and future food security. Crop simulation models have been validated as an important tool for the development of more resilient agricultural systems and improved decision making for growers. The Agricultural Production Systems Simulator (APSIM) is a software tool that enables sub-models to be incorporated for simulation of production in diverse agricultural systems. Modification of APSIM to incorporate epidemiological disease model for crop growth and yield under different disease intensities has few attempts in the UK or elsewhere. The overall aim of this project is to model disease impact on wheat for improved food security in two different agro-ecological zones. The incidence of wheat diseases between 2009 and 2014 in two different agro-ecological zones, UK and Oman were compared. Most of the fields surveyed in Oman and UK were found to have at least one disease. Leaf spot was the most prevalent foliar disease found in Omani fields while Septoria was the most common foliar disease in the UK. Fusarium followed by eyespot and ear blight represents the most common diseases of stem and ears in UK winter wheat between 2009 and 2014. However, in Omani wheat Fusarium causing stem base and loose smut of ears were the most common. Eyespot was not found in Omani winter wheat and this may relate to the high temperature during winter in Oman. This study discussed the first work on the occurrence of fungal diseases and their pathogens in Oman and the influence of agronomy factors. Large numbers of pathogenic fungi causing symptoms were found to be prevalent in wheat fields in Oman. Isolation from six symptomatic wheat varieties resulted in 36 different fungal species. Alternaria alternata was the most frequently isolated pathogen followed by Bipolaris sorokiniana, Setosphaeria rostrata, and Fusarium equiseti. Results also showed some agronomic practices influenced disease incidence. Mechanical sowing method and time of urea application were found to influence leaf spot disease. An investigation into the recovery of treatment cost for eyespot control through yield and the effect of fungicide treatment on risk showed that all fungicides apart from (epoxiconazole) Opus at 1 L ha-1 were found to be worth the costs, either under high disease pressure (inoculated sites) or naturally infected sites. For the risk averse manger fungicide treatment would be worth the cost as it would reduce the higher level of disease and consequently minimise associated yield losses. In this work, disease models were built to predict the disease development and yield loss in relation to crop phenology using results from previous literature on conditions favouring sporulation, infection and disease development and severity. Analysis of 461 data sets showed that climatic conditions and agronomic factors significantly influenced disease development either positively or negatively in all models. The application of a range of fungicides at GS31/32 reduced disease significantly at GS39 in comparison to epoxiconazole alone. Disease severity at GS39 decreased yield only slightly by 2.2% whilst only (prothioconazole) Proline 275 increased yield significantly with almost 30% yield increase. The performance of the APSIM wheat model to simulate phenology, leaf area index, biomass and grain yield of two winter wheat varieties (Okley and Cashel) was evaluated under UK conditions and the previously developed eyespot disease were linked with APSIM. Generally, APSIM poorly predicted the phenology, LAI, biomass and yield of winter wheat grown under UK conditions. The linked eyespot disease models with APSIM simulated an adequate level of disease predication at GS12/13 (9.6%), GS31/32 (1.3%) and GS39 (12%). Overall, the link between eyespot epidemiological disease models and crop growth model has successfully provided the basis for further development of the model and enhance crop growth simulation. Moreover identification of main diseases threatening wheat production in Oman can help to plan for future research, to assess the economic importance and to contrast environment models for yield loss.
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Burns, James Ian. "Agricultural Crop Monitoring with Computer Vision." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/52563.
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Precision agriculture allows farmers to efficiently use their resources with site-specific applications. The current work looks to computer vision for the data collection method necessary for such a smart field, including cameras sensitive to visual (430-650~nm), near infrared (NIR,750-900~nm), shortwave infrared (SWIR,950-1700~nm), and longwave infrared (LWIR,7500-16000~nm) light. Three areas are considered in the study: image segmentation, multispectral image registration, and the feature tracking of a stressed plant.
The accuracy of several image segmentation methods are compared. Basic thresholding on pixel intensities and vegetation indices result in accuracies below 75% . Neural networks (NNs) and support vector machines (SVMs) label correctly at 89% and 79%, respectively, when given only visual information, and final accuracies of 97% when the near infrared is added.
The point matching methods of Scale Invariant Feature Transform (SIFT) and Edge Orient Histogram (EOH) are compared for accuracy. EOH improves the matching accuracy, but ultimately not enough for the current work.
In order to track the image features of a stressed plant, a set of basil and catmint seedlings are grown and placed under drought and hypoxia conditions. Trends are shown in the average pixel values over the lives of the plants and with the vegetation indices, especially that of Marchant and NIR. Lastly, trends are seen in the image textures of the plants through use of textons.Master of Science
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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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Husaker, Douglas, and Dale Bucks. "Crop Yield Variability in Irrigated Wheat." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/200484.
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Optimum design and management of irrigated wheat production is limited by the scarcity of information available on yield variability. The purpose of this study was to evaluate the spatial variability in soil-water parameters and the effects compared to grain yield response under level-basin irrigation. Three levels of seasonal irrigation water and two border lengths were used. Grain yields were found to increase significantly with the amount of water applied and soil water depletion (estimate of crop evapotranspiration), although yield variability was greater with reduced or deficit irrigations. Variations in soil water content were responsible for about 22% of the variability in grain yield, indicating that other soil and crop- related factors had a significant influence on production. Spatial dependence was exhibited over a greater distance at the wetter compared with the drier irrigation regimes.