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Computational modeling of the impact of drainage design on crop yields and nutrient losses under climate change


Nitrate load in the Mississippi increased noticeably over much of the last halfcentury, rising from 300,000 tons per year in and 1960s to an average of approximately 1,000,000 tons per year during 1990s. More than 70% of the N and P delivered annually to the Mississippi river have been attributed to agricultural sources. A major producer of corn and soybean, the state of Illinois, has been a foremost nutrient flux contributor to the Mississippi river. Estimates show that Illinois alone contributes 17 % of the total annual flux of nitrogen and 13% of the total annual flux of phosphorus to the Gulf of Mexico. Most of these nutrients are transported to the river through subsurface flow. The agricultural yeld comes associated by applying fertilizers and pesticides. However, to be effective, certain precautions must be taken, since these inputs are not applied properly, groundwater contamination, due to leaching, can happen, especially under tropical soil conditions. Nutrients leaching varies according to soil physical properties, such as texture, structure, depth profile and especially porosity. To enable proper management of fertilizer application, the soil dynamic knowledge is necessary. The longterm goal of this collaboration is to develop expertise in modeling subsurface nutrient transport and crop yields from corn and sugarcane fields in Illinois and Brazil, respectively, under potential climate change conditions. We will establish research sites in both countries and model flow and transport with three models, DSSAT, DRAINMOD, and HYDRUS 3D. (AU)