Addition of hydrothermal biochar significantly alters growth of forage oats and rhizosphere microbiota.

There are few reports on the application of biochar in forage oat cultivation. Therefore, we compared the effects of adding different amounts of hydrothermal biochar on the growth of forage oats and the properties of rhizosphere soil. Results indicated that biochar significantly enhanced forage oats biomass, crude protein (CP) content, and chlorophyll content, with optimal effects at a 10 t/ha application rate. The C and N content and the C/N ratio in rhizosphere soil increased with biochar addition. Excessive addition of biochar reduced the diversity of rhizosphere bacteria. The addition of biochar increased the abundance of Patescibacteria and Ascomycota and decreased the complexity and stability of bacterial communities, while the fungal communities showed the opposite trend. Moderate addition of biochar can promote microbial processes such as the degradation of aromatic compounds and nitrogen cycling. This study provides a scientific basis for the application of hydrothermal biochar in forage oat cultivation.