Nutrient leaching evaluation in a dark-red latosol of cerrados II, magnitude and variability of the phenomena under irrigation

Abstract

Leaching of Ca, K and Mg in a LE soil (Dark-Red Latosol) was measured at three depths by using ceramic porous cups: 30, 75 and 105 cm during the growing cycle of irrigated corn (Zea mays L. cv. Cargill 111-X) in each of four plots that had received similar fertility, liming treatments and irrigation since 1977 and that hade been previously cropped to soybeans. For a total of 1920 mm of applied water, deep drainage (105 cm) varied from 637 to 1,555 mm. Nutrient leaching in the 0-75 cm depth took place mainly in the first 60 days after initial irrigation, the process being highly dynamic which can be attributed to macropore water movement. Ca, K and Mg concentrations in the 30 cm depth, in general oscilated from 38.8 e 12 ppm, respectively to 5.1 and 2 ppm as an average, respectively, 50 days after initial irrigation. Nutrient concentration peaks in the 0-75cm depth occurred almost simultaneously, with a slight shifting in time as depth increased. This shifting was more evident in the 105cm depth. Ca, K and Mg losses in the 105cm depth averaged 125.95, 20.28 and 49.71 kg/ha respectively. In spite of the considerable Ca leaching and the neutrality of solution pH, root development was restricted to the upper portion of the soil profille which suggests a different chemical or physical limiting factor.