Chemical fertillization of rice in the Northeast

Abstract

The authors present the results of 14 factorial experiments (NPK – 3x3x3) on rice fertilization carried out in alluvial soils of the coastal area of Brazilian Northeast. Excluding the experiment n. 39/59 located in an organic soil of Pium Valley, Rio Grande do Norte, where phosphorus shortage was detected, a 11 other pointed out lack of nitrogen alone and no reaction to both phosphorus and potash. Mitscherlich’s law, as applied to the point analysis of the 13 experiments, was the following: y = 2,4282 [1 – 10 - ^{0,8817 (x + 0,4 333)}].The estimation of the parameter c, which measures the efficiency of the fertilizer, was c = 0,88. The most profitable level of fertilization for nitrogen was established around 124 kg/ha, as shown in Fig. 1.