Nitrogen management in corn under no-tillage with different cover crops in a Rhodic Hapludox soil

Abstract

The objective of this work was to evaluate the best rate and time for N application, and N utilization using urea-¹⁵N, by corn crop grown under no-tillage system, in succession to sun hemp (Crotalaria juncea L.), millet (Pennisetum americanum) and to the spontaneous vegetation (fallow ground), in a Rhodic Hapludox soil in Cerrrado. The experimental design was randomized complete blocks, with 24 treatments and four replications, in an incomplete factorial 3x3x2 + 6: three N rates (80, 130 and 180 kg ha^-1 N); three preceding cover crops (sun hemp, millet and fallow ground); two N application time (four leaves or eight leaves stage); and six additional treatments (three without N application and three that received 30 kg ha^-1 N at seeding). The corn grown in succession to sun hemp provided higher amount of N derived from fertilizer, N utilization efficiency and grain yield. Application of N to corn four leaves stage provides higher grain yield, compared to the application to eight leaves stage, in succession to millet.