Decomposition kinetics and nutrient release in winter pastures under grazing with legume intercropping and supplementation

Abstract

The objective of this work was to evaluate feces decomposition and residual biomass, as well as nutrient release dynamics, in grazed winter pastures under legume intercropping and animal supplementation. The experiment was carried out in a randomized complete block design with three treatments: black oat + ryegrass + supplementation, black oat + ryegrass + vetch, and black oat + ryegrass + vetch + supplementation. Supplementation increased the labile fraction of fecal dry matter and nitrogen, accelerating their decomposition and favoring a faster nutrient turnover. The inclusion of vetch enhanced nitrogen release from feces and biomass, although its contribution was partially reduced when combined with supplementation likely due to changes in grazing dynamics. Potassium release from feces and biomass was rapid and little affected by the treatments, indicating that most of this nutrient returns to the soil via urine deposition. Supplementation and legume intercropping are complementary strategies: supplementation accelerates fecal decomposition, while legumes improve nitrogen cycling from residual biomass. This integration enhances nutrient recycling efficiency and reduces the need for external fertilization.