Leaching of cations in soil cultivated with sugarcane subjected to saline irrigation and leaching fractions

Abstract

ABSTRACT The objective of this study was to evaluate the concentration of cations in the leachate of soil cultivated with sugarcane irrigated with brackish water. An experiment was carried out in drainage lysimeters at the Federal Rural University of Pernambuco, at the Recife campus. The experimental design was completely randomized in a 5 x 2 factorial scheme, with four replicates, corresponding to five levels of electrical conductivity of the irrigation water (ECw) (0.5, 2.0, 3.5, 5.0 and 6.5 dS m-1) and two leaching fractions (LF1 = 0 and LF2 = 0.17) corresponding to water depths equivalent to 100 and 120% of crop evapotranspiration (ETc), by which the irrigations were managed. Electrical conductivity of the drained water was daily monitored and Na, K, Ca and Mg concentrations in the drainage water were determined at 129, 214, 286 and 324 days after planting (DAP). There were higher salt concentrations in the leachates when leaching fraction LF1 = 0 was used. The use of the 0.17 leaching fraction led to greater dissolution of the salts and may have caused a higher uptake of the essential cations by the crop. Sodium was the most quantitatively leached cation at all collection dates.