Effect of potassium fertilization on the cation equilibrium of a Dystrophic Dusky Red Latosol, under "cerrado" vegetation

Abstract

The need for increasing KCl fertilizar efficiency led to the present study carried-out field conditions on a Dystrophic Dusky Red Latosol, "cerrado" phase. The soil was limed with 2.5 t/ha limestone to correct soil acidity. Also, "build up" phosphate fertilization was carried out with 240 kg/ha of P₂O₅as simple superphosphate. The experimental design was in randomized blocks with three replications, using a split-split-plots band system. Rates of K₂O correspond to plots, methods of application to sub-plots, and depths of soil sampling to sub-sub-plots. The treatments consisted of four different rates: 60, 120, 240 and 480 kg/ha of K₂O and two depths (0 cm to 40 cm, and 40 cm to 120 cm) were used for soil sampling. An increase of available K and exchangeable Ca, and a decrease of exchangeable Al with the increase of K₂O was observed. Higher rates of applied K (240 and 480 kg/ha) gave higher K movement to the 40 cm to 120 cm layer. It was suggested that the use of KCl at very high rates favored losses of K due to leaching and soil cation unbalance. A higher efficiency of fertilizer was obtained with application of intermediary rates.