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Determining Optimal Levels of Nitrogen Fertilizer Using Random Parameter Models AgEcon
Tumusiime, Emmanuel; Brorsen, B. Wade; Mosali, Jagadeesh; Johnson, Jim; Locke, James; Biermacher, Jon T..
The parameters of yield response functions can vary by year. Past studies usually assume yield functions are nstochastic ‘‘limited’’ stochastic. In this study, we estimate rye– ryegrass yield functions in which all parameters are random. The three functional forms considered are the linear response plateau, the quadratic, and the Spillman-Mitscherlich. Nonstochastic yield models are rejected in favor of stochastic parameter models. Quadratic functional forms fit the data poorly. Optimal nitrogen application recommendations are calculated for the linear response plateau and Spillman-Mitscherlich. The stochastic models lead to smaller recommended levels of nitrogen, but the economic benefits of using fully stochastic crop yield functions are small because...
Tipo: Journal Article Palavras-chave: Cereal rye–ryegrass; Monte Carlo; Nitrogen; Random parameters; Stochastic plateau; Production Economics; Q10; C12; D24.
Ano: 2011 URL: http://purl.umn.edu/117949
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Determining Optimal Levels of Nitrogen Fertilizer Using Random Parameter Models AgEcon
Tumusiime, Emmanuel; Brorsen, B. Wade; Biermacher, Jon T.; Mosali, Jagadeesh; Johnson, Jim; Locke, James.
The parameters of yield response functions can vary by year. Past studies usually assume yield functions are nonstochastic or ‘limited’ stochastic. In this study, we estimate rye-ryegrass yield functions where all parameters are random. Optimal nitrogen rates are calculated for two yield response functions: linear response plateau and quadratic. Nonstochastic models are rejected in favor of stochastic parameter models. However, the economic benefits of using fully stochastic models are small since optimal nitrogen rates do not differ greatly between stochastic and nonstochastic models.
Tipo: Conference Paper or Presentation Palavras-chave: Linear response plateau; Monte Carlo; Nitrogen; Random parameters; Agricultural and Food Policy; Crop Production/Industries; Farm Management; Production Economics.
Ano: 2010 URL: http://purl.umn.edu/56514
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Effect of Nitrogen Fertilization and Liming on Rye-Ryegrass Yield and Soil pH Dynamics AgEcon
Tumusiime, Emmanuel; Brorsen, B. Wade; Biermacher, Jon T.; Mosali, Jagadeesh.
Using ammonium based nitrogen fertilizers in crop production has been shown to acidify soils. Lime used to correct soil pH is an important cost to producers. Recommendations of the optimal level of nitrogen to apply typically ignore the cost of lime created by nitrogen fertilization. This study was aimed to estimate soil pH change in response to nitrogen and lime application, and determine the effect of considering the cost of lime on recommendations about the optimal level of nitrogen. Yield response and pH functions were estimated and used to determine optimal levels of inputs. The effect of the cost of lime on recommendations about the optimal level of nitrogen was found to be marginal. Nitrogen acidification was found to be more severe with nitrogen...
Tipo: Conference Paper or Presentation Palavras-chave: Lime; Nitrogen; Soil pH; Rye-ryegrass; Crop Production/Industries; Production Economics.
Ano: 2010 URL: http://purl.umn.edu/61295
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The Cost of Coexistence between Bt Maize and Open Pollinated Maize Varieties in Lowland Coastal Kenya AgEcon
Tumusiime, Emmanuel; De Groote, Hugo; Vitale, Jeffrey D.; Adam, Brian D..
Kenya is currently in the process of introducing genetically modified maize (Bt maize). A major concern is that the Bt gene might cross into local varieties through cross pollination. Current regulatory strategies to ensure coexistence of the two cropping systems at the farm level rely on spatial isolation measures-separation distances and/or buffer zones. However, the interaction of practical measures and costs of spatial isolation with the farmer’s economic incentive to plant a Bt maize crop have not been studied in Kenya. The purpose of this study was to analyze the technical and economic feasibility of the implementation of spatial coexistence measures. Using spatial geo-referenced data from the actual agricultural landscape in lowland coastal Kenya,...
Tipo: Conference Paper or Presentation Palavras-chave: Coexistence; Regulatory; Spatial; Agro-ecological zone; GM crops; Resource /Energy Economics and Policy.
Ano: 2009 URL: http://purl.umn.edu/46726
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The Law of the Minimum and Sources of Nonzero Skewness for Crop Yield Distributions AgEcon
Tumusiime, Emmanuel; Brorsen, B. Wade; Boyer, Christopher N..
Crop yields are not commonly found to be normally distributed, but the cause of the non-normal distribution is unclear. The non-normality might be due to weather variables and/or an underlying von Liebig law of the minimum (LoM) production function. Our objective is to determine the degree to which an underlying linear response stochastic plateau production function can explain the skewness of Oklahoma wheat yields at varied nitrogen rates. We use farm-level wheat data from a long-term experiment in Oklahoma, which is a unique data set to the literature. The Tembo et al. (2008) production function provides negative skewness at all levels of nitrogen with skewness near zero for both very high and very low levels of nitrogen. Observed skewness for wheat...
Tipo: Conference Paper or Presentation Palavras-chave: Linear plateau model; Non-normal distributions; Skewness; Wheat; Yield distribution; Production Economics; Risk and Uncertainty; Q10.
Ano: 2011 URL: http://purl.umn.edu/98820
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