Doses de fósforo e potássio no cultivo de soja sob sistema plantio direto em sucessão à Urochloa brizhanta cv. Marandu

Abstract

Phosphorus (P) and potassium (K) are nutrients highly required by soybeans, it is of great importance that their availability comes from the previous crop, or supplied in the form of fertilizer. Therefore, it is essential to evaluate the effects of the no-tillage system in succession, as it increases the availability of these nutrients, reducing the need for chemical fertilizers in successive plantings. This study evaluated increasing rates of P2O5 and K2O at different levels of phosphorus and potassium that provide desirable quality to the physical and chemical attributes of the soil, and to the agronomic characteristics of soybeans in succession to Urochloa brizhanta cv. Marandu. The experimental design was in randomized blocks, with four levels of potassium and four levels of phosphorus, totaling 16 treatments, with three replications, distributed in 48 plots, plus one additional treatment. Fertilization was with 240 kg of NPK in the 5 - 25 - 25 formula, and in the additional treatment 400 kg ha-1 on the different doses of P an K from the previous planting. The doses of N - P - K on different combinations of potassium (K2O) and phosphorus (P2O5) levels did not differ significantly in the agronomic variables of soybean and soil fertility.