Nitrogen rates and irrigation depths on corn yield cropped in on-season and off-season

Water and fertilizer management is vital for the development of crops, especially in sandy soils and less favorable seasons for cropping. Hence, this research was carried out at the State University of Maringá, in Cidade Gaúcha/PR county, Brazil, and aimed to evaluate the yield of a single hybrid (NK501-VIP3) in the spring/summer (on-season) and fall/winter (off-season) seasons under nitrogen top-dress rates and irrigation depths. The experiments were set up in strip-plot design with subdivided plots, four nitrogen top-dress rates (from 0 to 375 kg ha-1) in the plots, five irrigation depths (from 0 to 192% of the net irrigation depth) in the subplots, and three replications. The interactions between nitrogen and irrigation depths had statistical significance (p ≤ 0.05), and second-order polynomial equations with two variables quantify the corn yield at a level of 69.78% (on-season) and 85.50% (off-season). A combination of 335.8 kg ha-1 of nitrogen with an irrigation depth of 164.4% resulted in the maximum corn yield (12,259.9 kg ha-1) on-season, whereas over the off-season maximum yield (9,122.6 kg ha-1) was achieved with 278.7 kg ha-1 of nitrogen and 162.2% of the net irrigation depth. Regarding rainfed crop systems with the tested nitrogen rates, the investment in crop irrigation systems can provide corn-cropped on-season potential yield gains of 23.9 to 29.5%, on the other hand for off-season these gains reach 82.3 to 136.7%.