Decomposition and stabilization of the organic matter in integrated livestock production systems

Abstract

Integrating agricultural production with livestock systems can restore soil quality from poorly managed pastures, reduce greenhouse gas emissions, and increase carbon sequestration. We evaluated soil fertility, litter decomposition, and stabilization in extensive continuous grazing without management, intensified rotation grazing, integrated crop-livestock, livestock-forestry, crop-livestock-forestry systems, and a forest for comparison. Intensified systems showed the highest cation concentrations due to tree nutrient use while extensive systems had lowest nitrogen and carbon:nitrogen values. Forest sites had lower phosphorus and carbon:nitrogen ratios than pastures but higher organic matter, nitrogen, and nitrogen:phosphorus ratios. Higher decomposition rates and lower stabilization factors were found in open pastures compared to areas with trees and the forest. A structural equations model indicated direct negative effects of shading by trees on decomposition rates, possibly correlated with lower temperatures or different decomposer composition due to differential litter composition in systems with trees. Increased radiation had adverse effects on the stabilization factor and positive effects mediated by soil base saturation, which was higher in more open pastures. Integrated systems including forestry presented similar decomposition rates and stabilization factors to forest sites, although the responsible mechanisms may differ, with higher nutrient limitation for decomposers in forest sites due to higher nitrogen:phosphorus ratios. Therefore, our results indicate that better management practices can improve nutrient cycling in intensified and integrated livestock production systems and contribute to stabilizing the soil organic matter.