Grazing combined with white clover reseeding enhances grassland productivity by improving soil nitrogen and...

The implementation of grazing practices and the introduction of leguminous species in grasslands are recognized as effective strategies for improving soil health and forage production. However, it is still uncertain if these benefits can be further improved by integrating appropriate sowing rates of legume species in grassland alongside with grazing. Therefore, a two-year field experiment was conducted in Southwest China to investigate the effects of grazing (0 and 3 cattle months ha^-1) and reseeding rates of white clover (0, 20, 40, and 60 kg ha^-1) on forage yield, soil nutrients and microbial activity). The results indicated that compared to the control, both enclosure and grazing significantly increased the above- and below-ground biomass as white clover reseeding rates increased, with no significant difference observed between the 40 kg ha^-1 and 60 kg ha^-1 reseeding rates. Under enclosure and grazing management, the two-year average above-ground biomass (AGB) increased by 17.3 % and 28.2 % (40 kg ha^-1), 17.5 % and 35.9 % (60 kg ha^-1) compared to the control (0 kg ha^-1), respectively. In addition, the belowground biomass increased by 24.8 % under enclosure and 30.0 % under grazing at a white clover reseeding rate of 40 kg ha^-1. Compared to the enclosed grassland, grazing significantly increased soil total nitrogen (STN), total phosphorus (STP), available nitrogen (SAN), and available phosphorus (SAP) contents but reduced the carbon-to- nitrogen ratio (C:N) and carbon-to-phosphorus ratio (C:P). The Shannon and Pielou_e indices of soil bacteria exhibited a significant increase following white clover reseeding, while soil bacterial diversity was reduced under grazing compared to the enclosure. The white clover reseeding had no significant effect on soil fungal diversity. Soil bacteria diversity in the 0-10 cm layer was significantly correlated with pH, STN, STP, SAN, C:N, and C:P, while the fungi diversity was significantly correlated with AGB, STN, STP, C:N, and SAP. Overall, the findings indicate that integration of grazing with an appropriate reseeding rate of leguminous specie enhances soil nutrient content, microbial activity, and forage productivity, providing valuable insights for the sustainable development of warm-season grasslands in southern China.