Abstract

The aim of this study was to determine the effects of increasing irrigation levels on the movement of nitrate and potassium in clay soil and on crop yields for the common bean irrigated by central pivot under Brazilian Cerrado conditions. The experiment was conducted in Urutaí, Goiás, Brazil, in Dystrophic Oxisol clayey soil in 2014. Four irrigation regimes were tested, which were equivalent to 50, 100, 150 and 200% of crop evapotranspiration (ETc), estimated using the Class A tank method. The plots were arranged in a randomized complete block design with four replications; the soil solution was evaluated seven times during the cycle. Potassium chloride with 58% K₂O was used as the potassium source, and calcium nitrate with 15.5% total nitrogen (N) as the nitrogen source. To collect the soil solutions, extractors were installed at depths of 0.20, 0.40, 0.60, 0.80 and 1.00 m. The concentrations of nitrate (NO₃^-) and potassium (K⁺) were determined without filtering or digestion. At harvesting, the production components and yield were evaluated. The NO₃^- and K⁺ levels within the soil profile varied between treatments, showing nutrient leaching below the root system for the higher irrigation treatments. Therefore, the application of appropriate irrigation techniques should reduce the leaching of NO₃^- and K⁺ and lead to higher yields for the common bean.

Key words: Bean, aspersion, water management, loss of NO₃^- and K⁺.