Eficiência de adubos fosfatados associados a enxofre elementar na cultura do milho

Abstract

With the objective of comparing the efficiency of the natural reactive phosphate (NRP) and the triple super-phosphate (TSP) associated with the elementary sulfur in the ridge of the maize plantation and also evaluate the influence of the elementary sulfur in the solubility of the NRP it was installed a field experiment in Toledo-PR in a eutroferric Red Latosol (Oxisol). In the experiment used a totally randomized design, with two sources of phosphorus in four levels of phosphate-fertilizers (0, 100, 200, e 300 kg ha-1 of elementary sulfur) applied in the plantation ridge, in four repetitions. In the beginning of the culture blossom it was carried out collects of vegetable tissue to determine the content of phosphorus and sulfur in the foliar tissue. In the end of the plantation it was evaluated the insertion height and the spike size, the mass of grains in each spike is of 1000 grains, the number of lines and the grains in each spike and also the productivity of each allotment. It was collected some soil samples from 0-10 cm and 10-20 cm of depth to determine the contents of phosphorus, sulfur, potassium and pH. It was evaluated the index of agronomical efficiency (IAE), the equivalent in triple super-phosphate (EqTSP), the utilization factor of P and the efficiency of the fertilizer´s utilization (EFU). The triple super-phosphate provided greater income of grains in comparison to the Gafsa phosphate in the first year of plantation. The agronomical efficiency of NRP was of 43% with the elementary sulfur addition and of 33% in the absence of sulfur. The phosphorus content in the foliar tissue was inferior with the utilization of the Gafsa phosphate related to the smaller availability of phosphorus in the soil with NRP application. The dose of 30kg ha-1 of elementary sulfur did not interfere in the soil´s pH, but the efficiency of the utilization of the phosphate-fertilizers was greater with the application of sulfur.