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 acidification, and soybean yield. In our study, biogas slurry was derived from cow dung. Four treatments were applied: no fertilizer (CK), chemical fertilizer (N), biogas slurry (BS), and mixed fertilizer (BS + N). Our study revealed that fertilizer application showed a significant (P 0.05) impact on soil organic carbon (SOC) and total phosphorus (TP). The highest SOC (8.97 g/kg) and TN (1.30 g/kg) were observed under BS treatment. The soil pH was significantly (P 0.05) higher under BS (6.69) and BS+N (6.64) than under N (6.40), indicating a buffering effect. Microbial biomass carbon (MBC) and nitrogen (MBN) were significantly enhanced under BS and BS+N, while N alone reduced MBN ( P 0.05). BS significantly increased soil Cu (38.66mg/kg) and Cd (0.13mg/kg) concentrations, whereas Zn and Pb remained unchanged. Soybean yield was significantly affected by fertilization, with the highest yield observed under the BS+N treatment (1.65 Mg/ha), followed by chemical fertilizer (1.35 Mg/ha). Overall, biogas slurry improved soil fertility indicators and mitigated soil acidification under the experimental conditions, while mixed fertilizer provided the greatest yield benefits. However, these findings are based on short-term pot conditions, and long-term field studies are still required to confirm the potential environmental risks of biogas slurry application.
Bohoussou et al. (2026) studied this question.