The impact of irrigation on nutrient export from agricultural fields

The role that irrigation plays in runoff and nutrient export from agricultural areas in Alabama was examined using an industry standard crop model (DSSAT) together with a water and nitrogen export routine using the kinematic wave approximation. The goal was to estimate a percentage of the nitrate left by the DSSAT model at each time step that might be exported. The results show that irrigated crops do uptake significantly more nitrogen than do rain fed crops. The results of this study suggest that irrigation is an effective management practice to decrease the amount of nitrate in the surface layer, thus decreasing the amount of surface export. The study also concludes that irrigation decreases the residual (fall/post season) nitrate in the soil column. Irrigation provides the vertical movement and aerobic conditions for nitrogen to be consumed by the plant as compared to rain-fed fields.