Avaliação da qualidade física do solo em sistema integrado de produção agropecuária leiteiro

Abstract

The crop-livestock integrated system, when good conducted, generates benefits to the soil- animal-plant system, due to the synergism between its components. However, there is concern about soil compaction by animal trampling in intensive systems, which may compromise a soil structure. The last limiting water range (LLWR) is indicated as a tool to evaluate the physical quality of the soil, since it relates the physical factors directly related to the growth and development of the plants. In this context, it was sought evaluate different soil managements in a crop-livestock integrated system, with dairy cattle, by means the LLWR. Was given continuity to an experiment of one year in duration on a property in the municipality in São Pedro do Butiá - RS. The experiment was in blocks to chance with three treatments and four repetitions: T1: Area with grazing in winter (PAST); T2: Grazing area followed by scarification of soil (PAST + ESC); and T3: Area without grazing in winter (S.PAST). The soil characterized was as Oxisol. At the end of the grazing cycles it was evaluated the density and distribution of pores in layers 0-5, 5-10, 10-20 and 20-30 cm. For the LLWR creation of the were collected 120 samples with rings of the Uhland type and then made the modeling of each limit according variation of soil density and soil moisture. After the grazing cycle was implanted the soy culture and during its cycle soil performed moisture assessments soil and during the flowering and maturation, evaluations the roots distribution and grain production. They bovines increased the density and decreased the porosity of the soil in the most superficial layer (0-5 cm), as well as decreased an amplitude of the LLWR in the soil profile. The scarification was efficient to reduce the animal impact on the soil, to increase the LLWR up to 15 cm depth and the residence time of the soil moisture within the LLWR during the soybean cycle, but it was unnecessary because it did not influence the distribution of roots and crop productivity. The soy performance was not influenced by the treatments in a rainy year.