N-Mineral em sítios de micção no sistema integração lavoura-pecuária

Abstract

In Crop-Livestock Integration, when one opts to adopt the method of fertilizing systems, which values the anticipation of nitrogen fertilization in the pasture and is based on the cycling of nutrients between the phases of the system, a residual effect of nitrogen in the soil, which ma even nourish the subsequent crop. This phenomenon is further intensified through the cycling of nutrients promoted by the excreta of feces and urine from cattle, allowing nitrogen to remain in the system for a longer time, cycling between the soil, plant and animal components. The objective of this work is to evaluate the effect of nitrogen fertilization and grazing pressure on the behavior of N−N O−3 and N−N H+4 in urine deposition sites. The experimental design was randomized blocks in a factorial scheme (2x2x4x4x4), with three replications. The pasture was used ryegrass, which was managed with two different pasture heights (10 and 25 centimeters) and two different times of nitrogen fertilization with urea, anticipated in the pasture phase or during grain cultivation. The third factor studied waws the days of soil collection after urination, which were performed on day zero (just after urination), three, six and 12th days after the beginning of the evaluation. The fourth factor was composed of different depths of collected soil (0-5, 5-10, 10-20 and 20-40 centimeters). The fifth factor was composed of different horizontal distances from the central point of urination, which are 0 cm (exactly at the central point of urination 0, 25 cm, 50 cm, and 75 cm. It was concluded that nitrogen fertilization in the pasture provided higher levels of ammonium and nitrate in the soil. When ryegrass pasture was managed at high grazing height, the N content in the soil was heigher, providing a greater amount of residual N in the soil. There was no nitrate leaching in the soil in any treatment. The presence of cattle increased nitrogen cycling in the system.