Atributos físicos do solo em sistema de integração lavoura-pecuária em onze anos de protocolo experimental

Abstract

In recent years there has been an increase in the number of agricultural areas that have adopted the integrated crop-livestock system due to its numerous benefits. However, there is still a need for research on the effect of this system on soil physical quality, especially those that compromise productivity, such as soil compaction. The objective of this work was to evaluate soil physical attributes after 11years of experimental protocol. The design was of randomized blocks with subdivided plots with 3 replicates. The winter plots were composed of nitrogen, 0, 75, 150 and 225 kg ha-1, in ryegrass, oats and rye pastures. In the summer, by bean and corn cultivation. The subplots were with and without grazing. The grazing with sheep was in a continuous stocking system with variable load. In the years 2006, 2007, 2009, 2010, 2017 and 2018, after the grain crops were collected and the grazing of the animals, undisturbed samples were taken from the 0-5, 5-10 and 10-15 cm layers for the assessment of soil physical attributes. The analysis used two replicates for grazing areas (CP) e one replicate for areas without grazing (SP). Soil density was determined by the volumetric ring method; total porosity (Pt), macroporosity (Ma) and microporosity (Mi) were determined by the voltage table methods. The determination of soil penetration resistance was carried out together with the evaluation of the soil physical attributes, with the aid of the penetrometer, to the depth of 60 cm. As a complementary analysis, the multivariate technique was performed through principal component analysis (PCA). No limiting values were observed for the development of the cultures. There was no significant difference in the physical attributes of the soil evaluated after grazing, between CP and SP, regardless of the dose of N used. Summer crops had a positive effect on the mechanical resistance to penetration and soil physical attributes, favoring the lowest Surface RP. The crop-livestock integration system, after eleven years of experiment, increased soil macroporosity in all strata evaluated.