Impact of biogas slurry on soil health, organic carbon, soil acidification, and soybean yield in Northeast China’s black soils

Black soils in Northeast China are among the most fertile globally, but have experienced significant degradation due to long-term intensive use of chemical fertilizers. Although organic amendments such as biogas slurry are considered promising alternatives, their effects on black soils in this region remain underexplored. In this study, a controlled pot experiment was conducted to evaluate the effect of biogas slurry on soil health, soil organic carbon (SOC), total nitrogen (TN), soil acidificat