Investigation of Benefits from Organic Management Alternatives Using DNDC Model Simulations for Developing Sustainable Practices in Texas Rice Production.

Evaluation of both greenhouse gas (GHG) emission and carbon sequestration potential of soil, after implementing organic rice production systems over conventional techniques in Texas is limited. Previous studies have conducted comparisons between isolated management alternatives, but a holistic set of ideal organic practices have not been defined. Studies using the Denitrification and Decomposition (DNDC) model have accurately simulated rice ecosystem emissions, and predicted long-term benefits from management alterations. Therefore, our overall objective is to use DNDC to assess the benefits of organic over conventional systems and to develop a standardized system of organic rice production in Beaumont, Texas. This is the first step towards our long-term goal, which is to determine the components needed to assess ecosystem services gained by farmers from adopting sustainable alternatives. The Most Sensitive Factor (MSF) method is used to establish confidence intervals that include the ‘true’ values of spatially variant soil properties to improve accuracy. Data from the DNDC model and the greenhouse trial are compared. The DNDC calibration using the Shuffled Complex Evolution Approach (SCEA) and the Root Mean Square Error (RMSE) are discussed. The optimized model is then used to simulate systems with different rates of organic and conventional nitrogen inputs. Through this analysis, we aim to identify an ideal production system that includes management for minimum GHG emission rates, overall mitigation of GHG effect, crop residue with optimum C:N to maintain soil nutrient and water quality, improving carbon sequestration in soil and increasing benefits from ecosystem services, for rice farmers in Texas.