Efeito da presença de árvores e de adubação nitrogenada sobre os teores de N-mineral em um solo arenoso em ponto de deposição de urina bovina

Abstract

In integrated agricultural production systems, the nitrogen ingested by animals through grazing, returns to the soil via urination and is absorbed again by plant species, favoring the cycling of nutrients in the system. The objective of the present experiment was to evaluate the behavior of mineral-N in the soil in animal urine points on the effect of two doses of nitrogen fertilization (90 and 180 kg ha-1) in intercropped pasture of Lolium multiflorum + Avena strigosa in two different models of integrated systems, livestock farming (ILP) and forest livestock farming (ILPF). For this purpose, a randomized block design and a 2x2x3x4x4 factorial scheme was adopted. The first factor was composed of two nitrogen fertilization treatments (N90 -90 kg N ha-1 and N180 - 180 kg N ha-1). The second factor consisted of the use of two models of integrated systems (CL – crop-livestock and CLT – crop-livestock-forest). The third factor was composed of days after urination (DAM), namely: day zero (immediately after urination), 6 and 7 days after urination (DAM0, DAM6, DAM12). The fourth factor was obtained by the distance from the central point (PC) of urination– zero (at the center of the urination site), 25, 50 and 75 cm (PC0, PC25, PC50 and PC75). Finally, the fifth factor refers to the different depths of the soil profile (0-5, 5-10, 10-20, 20-40 cm). It was concluded that the dose of nitrogen fertilization in ryegrass and oat pasture directly affects the N-mineral content in bovine urine and that the higher the dose of nitrogen in the ryegrass and oat pasture, the higher the mineral N content. in bovine urine. In addition, the mineral-N content in the soil decreases considerably up to 6 days after urination, but stabilizes after this period, while the content of this substance decreases with increasing soil depth and distance from the central point of urination.