Resistência do solo à penetração em pasto de capim-tifton 85 sob irrigação e adubação nitrogenada

Abstract

The organic fertilizers use, associated with irrigation of pastures with vigorous grasses, can provide favorable conditions for the plants development, reflecting on the the soil structural quality improvement. The aim of this work was to evaluate the penetration resistence of a clayey dystrophic Latosol, cultivated with Tifton 85 and fertilized with different nitrogen sources, under irrigated and rainfed systems, in order to determine if there is maintenance of soil physical quality. The treatments corresponded to different forms of N supply: 400 kg/ha of N, in the form of urea (T1); 400 kg/ha of N, in organic form via bovine manure (T2); 400 kg/ha of N, 50% in mineral form and 50% in organic form, using the same sources (T3) and the control, without nitrogen fertilization (T4). The soil penetration resistence (PR) was evaluated up to 50 cm depth. Soil moisture was determined in the 0-20, 20-40 and 40-50 cm layers. Pearson correlation analyzes were performed between soil organic matter content (SOM) and PR at layers 0-5 and 5-10 cm. There was no significant difference between the treatments (p <0.05), and there was no significant correlation between PR and SOM. However, the use of irrigation favored soil compaction. The N source for fertilization of Tifton 85 indicates to be little relevant to induce modifications in PR, but the water regime was a significant factor, even with the soil biological decompaction capacity of the used specie.