Ion concentrations in the solution of an Oxisol under different management systems

The objective of this work was to evaluate ion concentrations in an Oxisol solution, in plots subjected to different management systems. Continuous crop and pasture, and the integrated crop-livestock management system were evaluated. The experiment started in 1991, and the soil solutions were collected in 2005 and 2006. Ceramic cups were installed at 20 and 150 cm soil depths, and the solutions were extracted six times each year. The concentrations of Cl(-), SO(4)(2-), NO(3)(-), H(2)PO(4)(-), K(+), Mg(2+), and Ca(2+) were determined. Irrespective of the depths and cropping systems considered, the concentrations of ions into the soil solutions, in decreasing order, were: NO(3)(-)>Cl(-)>SO(4)(2-)>H(2)PO(4)(-) and Ca(2)(+) >K(+) >Mg(2+). Among the cropping systems, the ion concentrations in the soil solution was higher in the continuous crop under conventional tillage, followed by the continuous crop under no-tillage, and finally by the integrated crop-livestock system and the continuous pasture. At 150 cm depth, the ion concentrations in soil solutions under continuous pasture and integrated crop-livestock system were always low, which indicates a low leaching risk.