TWO STUDIES EVALUATING INPUT USE IN SOYBEAN AND COTTON PRODUCTION

Farmers are price takers for both inputs and outputs. Therefore, when the prices of inputs rise, as they have with many inputs used in agricultural production, optimal production practices may change. Two separate studies of the impacts of agricultural technology on input use in crop production were undertaken in this thesis. The first study evaluated economically optimal plant population considering seeding rate, maturity group, row spacing, and input-output prices in soybean production in the rolling uplands region of the upper Midsouthern United States. Data from field experiments at the University of Tennessee Research and Education Center at Milan, Tennessee during 2005, 2006, and 2007 were used to model yield response to plant population density (PPD). Given that farmers must make their planting decisions based on expected weather, original models were weighted by year based on the Ångström weather index. Evaluation of weighted average response functions found that maturity group IV soybean cultivars planted in 38 cm rows at seeding rates necessary to achieve final PPD of 115,000 plants ha⁻¹ would maximize farmers returns to soybean production. The second study evaluated factors influencing cotton farmers’ decisions to adopt information technologies for variable-rate input application and subsequent perceptions of directional changes in the overall use of fertilizer in cotton. Data from the Cotton Incorporated 2009 Southern Precision Farming Survey were evaluated using probit models with sample selection given the sequential nature the adoption decision and farmer perceptions of directional changes in fertilizer use. Results suggest that cotton farmers in the sample who rented more of their cotton area and used picker harvest technology were more likely to perceive that overall fertilizer use declined with the use of the selected information technologies and VRT. This and other key findings of this research have implications for a wide range of audiences ranging from University Extension to policy makers given the economic and environmental impacts.