Effects of Nitrogen Fertilization on Organic Rice Production
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The increased demand for organic rice has led to a quick expansion of the industry; however, there has been little research conducted on organic rice systems that are relevant to the unique flooded paddy system that is used to produce organic rice. A critical issue for organic rice production is nitrogen management. A laboratory trial was conducted to better understand the N mineralization rates and dynamics. The specific objectives were to examine the role of cover crop and soil amendment on nitrogen mineralization under aerobic and anaerobic conditions, as well as determine which combination of cover crop and organic amendment is optimum for a maximum N mineralization. Total mineralized nitrogen over time under aerobic and anaerobic incubations of soil – amended with Durana clover and Nature Safe (13-0-0) – seemed to be dictated by the amount of available nitrate and nitrite, since a linear increase with time was observed for the ammonium content. Of the two factors analyzed – amount of biomass and nitrogen rate added – enough statistical evidence was found to determine that the amount of N added via organic soil amendment has the greatest impact on the total amount of mineralized N. Finally, the combination of 100% cover crop plus 200 kg N/ha was determined as the optimum combination of cover crop and organic amendment because it mineralized the most N during the incubation period and presented only positive mineralization rates. Complementary to the previous experiment, a greenhouse trial in Beaumont, TX, was conducted from May to August 2015 to study the effects that organic soil amendment (Nature Safe 13-0-0) with different rates of application (0, 50, 100, 150, 200, and 250 kg N/ha) had on the yield components in comparison with conventional rice production (urea fertilizer 46-0-0). For the organic treatment, the highest yield and nitrogen use efficiency (NUE) was reached at 200 kg N ha^-1 and not 250 kg N ^ha-1, which stated a quadratic function of added N and yield. Similar results were found for the conventional treatment, however, the NUE and highest yield were achieved at 150 kg N ha^-1 and 250 kg N ha^-1, respectively.
Valdez Velarca, Mariana (2016). Effects of Nitrogen Fertilization on Organic Rice Production. Master's thesis, Texas A & M University. Available electronically from