Optimum Preplant Nitrogen Rates in Corn.

The overuse of nitrogen (N) fertilizer for maize production is prevalent. Optimum mid-season N rates are possible today using normalized difference vegetation index (NDVI) sensor based methods. This approach is necessary to prevent the overuse of fertilizers, save the farmer’s capital, and maintain competitive yields.

 Two trials were conducted where N as urea ammonium nitrate (UAN, 32-0-0, N-P-K) fertilizer was applied at rates of 0, 17, 34, 67, 101, 134, and 168 kg N/ha prior to planting. These preplant rates were replicated twice within each block. Fertilizer was applied within four days of planting at both sites. At the V-6 growth stage, an additional sidedress treatment was applied at 168 kg N/ha to plots receiving a range of pre plant N rates. The objective of this experiment was to determine the optimum amount of preplant N in corn with topdress N to maintain yield and improve nitrogen use efficiency (NUE).

This research should decipher the growth stage when maize plants will visibly show a deficiency. Furthermore, this work should determine the amount of preplant N and sidedress N required for maize, and that will optimize N from year to year.