Corn agronomic traits and recovery of nitrogen from fertilizer during crop season and off-season

Abstract

The objective of this work was to evaluate corn agronomic traits in a cultivation subjected to different N rates, during the fall–winter (off-season) and spring–summer crop seasons, and N recovery from fertilizer. The experiment was set up in a randomized complete block design with four replicates, in a 5x2 factorial arrangement, with the following treatments: five N topdressing rates – 0, 30, 60, 90, and 120 kg ha^-1 –, using urea as source; and two crop seasons, fall–winter and spring–summer. The following variables were determined: plant height, height of the first ear insertion, number of grains per ear, diameter and length of ear, 1,000-grain weight, N concentration in the leaves and grains, grain-protein concentration, grain yield, N recovery from fertilizer, and soil-N supply. Nitrogen rates in the fertilizer in the fall–winter season had no effect on grain yield, although corn agronomic traits showed a greater reliance on fertilizer-N rates in that season than in the spring–summer, which is a season associated to a greater capacity of soil-N supply to plants. The quantification of soil-N supply enabled knowing the nutrient dynamics during the fall–winter and the spring–summer seasons, which may be useful to guide N fertilization of corn.