The use of phosphate and potassium fertilizers in soybean culture in the State of Paraná, Brazil

Abstract

Several fertilization experiments were carried out during the 1974-1977 soybean (Glycine max (L.) Merrill) growing season in the State of Paraná, Brazil, in order to determine the effects of phosphate and potassium fertilization levels on soybean performance and to determine response classes as a function of phosphorus and potassium levels in the furrow. The results indicated that: a) the phophate fertilization provided bettter results in newly cultivated soils with wheat and soybean than in old ones, indicating a greater absorption capacity of residual phosphorus by this plant; b) the potassium fertilization did not result significant increases in soybean yield. For the low residual-P soils, nutrient availability classes were established by the Mehlich determination method: very low (Below 1,5 ppm), low (1,5 - 3,0 ppm). medium (3,0 - 6,5 ppm) and high (greater than 6,5 ppm), The Mehlich determination method was not efficient for the evaluation of available residual phosphorus.