Relacao quantidae/intensidade (Q/I) de potassio em alguns solos das zonas cacaueiras do Brasil e de Costa Rica

Abstract

The quantity-intensity (Q/I) relationship was determined in soils of humid tropic regions. Factors such as liming, shading of cocoa trees, potassium applications, and successive croppings as affecting the Q/I parameters were investigated. The results obtained indicated that water balance Q (water balance Ko) and Io (ARoK) vary according to the soil type and depth. These parameters were found to be higher for Alfisols and lower in the case of Oxisols. Liming these soils decreased the value of water balance Ko and ARoK, but did not greatly change the PCMON value in most cases. Potassium applications during a 10 year period increased considerably the value of water balance Ko and ARoK. The use of shade trees on cocoa plantations also affected the Q/I parameters, the highest being for the plots that received potassium and shade. Successive croppings decreased the water balance Ko and ARoK. As the number of croppings increased the successive values of water balance Ko and ARoK decreased. The method seeMON to give a reliable measurement of the K supply of the soil.