Eficiência de fertilizantes fosfatados aplicados em pastagem de Megathyrsus maximus cv. Mombaça solteira e consorciada com leguminosas

Abstract

The objective of this study was to evaluate the response of Megathyrsus maximus cv. Mombasa, cultivated in a consortium with legumes, to phosphate fertilization with fertilizers of different solubilities. The experiment was set up in February 2015 and was conducted for a period of three years (2015 to 2017), at the Experimental Farm of Universidade do Oeste Paulista - UNOESTE, in Presidente Bernardes-SP. The experimental design was in randomized blocks, in a 4x3 factorial scheme in subdivided plot, with four replications. The plots consisted of four forage systems (SF): single mombaça (Megathyrsus maximus cv. Mombaça) with absence of nitrogenous cover fertilization; single mombaça with nitrogen fertilization coverage (250 kg ha-1 of N per year); mombaça intercropped with Macrotyloma axillare cv. Java and Mombasa consorted with dwarf pigeon bean (Cajanus cajan). The subplots were composed of absence of phosphate fertilization; application of phosphate fertilization with soluble source (triple superphosphate); application of phosphate fertilization with natural reactive source (Bayóvar natural phosphate). The data were submitted to analysis of variance and the mean values were compared using the Tukey test (p <0.05). The bayóvar and the SFT in SF M + N provided the highest forage yields in relation to the other SF. The bayóvar fertilizer ended up producing more than the SFT even though it did not present a significant difference in SF, a fact that can be explained by the gradual release of the natural source. In the accumulated of the first year the SF M + N when fertilized with bayóvar and SFT and M + G independent of the source of P used presented significant difference among the other treatments. These SFs extracted approximately 700 kg ha-1 of N per year, thus showing that intensive production systems require a high amount of nitrogen fertilization, since these plants extract a large amount of nutrients to convert to MMS. The crude protein content was higher at all times of the year in the grass and legume consortia, providing a better quality of this forage system. Based on the results of the present experiment it was possible to conclude that phosphate fertilization independent of the source of phosphorus is indispensable for the production of pasture and the mineral nitrogen fertilization is superior when combined with phosphate fertilization. The mombaça intercropped with Macrotyloma axillare cv. Java and mombaça with dwarf pigeon peas (Cajanus cajan) provided better bromatological quality.