| Abstract: | Evaluation of nitrogen (N) dynamic in soil using regression equations is important for proper determination of N fertilization. A 3-year field experiment was conducted to (1) develop the best-fitted regression model relating corn grain and stover yield to soil residual ammonium (NH4)-N and nitrate (NO3)-N for corn yield prediction and (2) evaluate how such a model can be beneficial to the health of ecosystem by predicting the appropriate rates of N fertilization for corn production. Soil NH4-N and NO3-N were determined at corn harvest at the depths of 0–30 and 30–60 cm. Nitrogen fertilizer rates and soil mineral N accounted for a maximum of 93% variation in corn grain yield. Soil mineral N enhanced corn yield more than N fertilizer. Totals of 63.1 and 14.1 kg/ha of soil residual NO3-N and NH4-N were found in the 0- to 60-cm depth, indicating the importance of performing soil N tests. |
