Simulation of sediment and nitrate loss on a vertisol with conservation tillage practices.
1996
King K.W. | Richardson C.W. | Williams J.R.
Shrinking and swelling clay soils are dominant in the Blackland Prairie of Central Texas and comprise a vast majority of agricultural production land in the area. An agricultural field scale simulation model (EPIC) was applied on six small watersheds located in Riesel, Texas. A non-calibrated model performance evaluation of the runoff sediment yield, nutrient transport, and crop growth components was completed. Management practices included no-till and conventional till systems. Annual and monthly predicted parameter values were compared with measured data for a 5-year period. Annual comparisons indicate close agreement between means and standard deviations for runoff erosion, and nitrate-nitrogen. Significant correlation existed between monthly measured and simulated runoff and erosion. Significant correlation for nitrate-nitrogen was present in a majority of the cases studied. Prediction efficiency was significant for all elements except nitrate-nitrogen on two watersheds. The results of this study indicate EPIC's ability to simulate natural processes without calibration on shrinking and swelling clay soils with varying management practices.
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