Impact of Drought and High Nitrate Groundwater On Residual Soil Nitrogen

Groundwater nitrate contamination is a major water quality concern in the Texas Rolling Plains. We have demonstrated that NO3-N in irrigation water is a plant-available source that can be credited towards crop nitrogen (N) requirements.  During 2011 and 2012, irrigation rates were above average with below average yields.  As a result, more than 100% of crop N needs were applied through irrigation water alone.  As a result, residual N levels in the soil were sufficient to meet 2012 crop N needs.  For scenarios involving drought and use of high nitrate groundwater, producers should soil and water test to account for residual soil N for the subsequent crop season.