Application of biofertilizer in degraded pasture modified C dynamics and improved forage yield in a short-term period at the tropical region

Recovery of degraded pastures improves the sustainability of meat and milk production systems. Humic acids (HA) and endophytic diazotrophic bacteria (EDB) are known to have bio-stimulating effects on several crops but have not been tested for the recovery of degraded pastures. The aim of the present study was to evaluate soil C and N dynamics, nutrient uptake and forage yield of Brachiaria decumbens following the foliar application of HA and EDB in a degraded pasture. A randomized block design with six replications was used. The four treatments were: HA, EDB, HA+EDB and Control. The subplots consisted of four evaluation times for soil characteristics: before treatment application (0) and 30, 60 and 120 days after treatment application (ATA). Soil total organic carbon (TOC), recalcitrant carbon (Crecal), labile carbon (Clabil), total nitrogen (TN) and C and N stocks were determined in the 0-5, 5-10, 10-20 and 20-40 cm of soil layers. Forage yield and leaf nutrient contents were evaluated at 30 days ATA. The application of the HA and EDB increased the TOC, Clabil, soil C stock (≈18%), forage dry matter yield (16 to 52%) and nutrient uptake (≈30%) after 30 days ATA. Our results showed that the application of HA combined with EDB may be a strategy for the recovery of degraded pastures in the tropical region.