49-24 Optimum Preplant Nitrogen Rates in Corn.
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.