Herbage Mass, Herbage Rejection, and Chemical Composition of Signalgrass under Different Stocking Rates and Distances from Dung Pads

Abstract

ABSTRACTNutrients from fecal return may improve herbage growth and chemical composition, but herbage rejection may occur around dung pads. Rejected herbage increases in maturity and might be rejected in future grazing cycles. The aim of this study was to determine the influence of dung pad on soil and herbage characteristics of signalgrass [Urochloa decumbens (Stapf) R. D. Webster (syn. Brachiaria decumbens Stapf.)] pastures managed under three stocking rates (1.9, 3.2, and 4.2 animal units (AUs) ha−1; 1 AU = 450 kg of cattle live weight). Herbage and soil responses were measured at different distances from the dung pad border (0 to 20, 20 to 40, and 40 to 60 cm). A rotational stocking was applied with 3 d of grazing and 32 or 67 d of resting for the dry and rainy seasons, respectively. Herbage mass increased near the dung pad by 40% compared to the surrounding areas but was not affected by stocking rate. Herbage rejection was greater near the dung pad and rejection was greater at lower stocking rate. Plants distant from the dung pad presented lower P concentration. Regardless of stocking rate, K, N, and P fecal and herbage concentrations were affected by the grazing cycle, and there was a higher nutrient concentration during the rainy season. Soil beneath dung pad had higher pH value (5.6 vs. 5.2), Mehlich‐I P (22.4 vs. 12.5 g m−3), and K concentration (9 vs. 5 mol m−3) compared to soil from the surrounding areas. Grazing management practices should improve fecal distribution in pastures to maximize nutrient return via this pathway.