PRODUCTIVITY AND NUTRITIVE VALUE OF TIFTON 85 IN SUMMER, WITH AND WITHOUT IRRIGATION UNDER DIFFERENT NITROGEN DOSES

Abstract

ABSTRACT The pasture irrigation has expanded, mostly in small areas in order to boost the production system, along with the use of soil improvement techniques and high-productivity grasses. Thus, this study, carried out on a small dairy farm property, aimed to evaluate the productivity, botanical composition and nutritive value of Tifton 85 with different nitrogen (N) doses, in the presence and absence of irrigation. The experimental design was a randomized block in a split-plot design with four replications, plots Non-irrigated and Irrigated. The subplots consisted of nitrogen doses: 25 kg ha−1 cycle−1 of N, 50 kg ha−1 cycle−1 of N, 75 kg ha−1 cycle−1 of N and 100 kg ha−1 cycle−1 of N. The irrigation increased the productivity in an average of 3,626.5 kg ha−1 cycle−1, with higher leaf stem ratio of 1.3, increasing the crude protein content of the pasture. The productivity responded quadratically to nitrogen fertilization with increases up to 84 kg N ha−1 cycle−1 with slight linear decrease of dead matter. There were linear increments of crude protein and digestibility “in vitro” of dry matter in function of applied nitrogen.