Soil compaction in a crop-livestock system with maize (Zea mays L.) cultivation in the northeastern region of Brazil

The intensification use of the soil in agricultural areas has become a worrying factor, where the presence of animals and machines in an intense form has caused the increase in the soil density. The crop-livestock integration (CLI) is a system that use of these agricultural areas with the aim of alternating crops and animals in the same area, increasing the sustainability of production systems and improving profitability through the introduction of annual pasture cultivation. The objective of this work is to evaluate soil compaction in the crop-livestock integration system through as a function of water content and structural void ratio at soil depths of 0 to 5, 5 to 10 and 10 to 20 cm. Structural void index, compression index and pre-compression pressure of the soil were analyzed with treatments arranged in a 2x4x3 factorial scheme with 3 replications. The factors correspond to two collection periods (1) before sowing and (2) after harvest; four blocks of 0.25 ha (50 meters long by 50 meters wide) each and three depths (0 - 5; 5 - 10 and 10 - 20) cm; with three repetitions. The soil was more susceptible to compaction, revealed by the soil compression index when it had a lower structural void ratio and a water ratio greater than 0.20 cm3 cm-3. The precompression stress of the soil revealed a moderate negative correlation with the structural void ratio in the surface layer of the soil.