Anaerobic digestion (AD) is a mature industrial fermentation technology for converting organic matter into renewable bioenergy, and chicken manure (CM) is a promising feedstock due to its high organic content. However, the industrial-scale AD of CM is often hindered by ammonium inhibition, particularly under high organic loading rates (OLRs). Biochar has emerged as a sustainable additive that can enhance microbial activity, buffer pH, and improve system stability. In this study, the effects of biochar on the methane production and fermentation performance of CM in terms of AD were evaluated under both batch and continuous conditions, where batch experiments were conducted at different biochar-to-CM ratios. Ammonium nitrogen and methane production were monitored to determine the optimal biochar addition ratio. Continuous stirred-tank reactors (CSTRs) were then operated with the optimal biochar addition ratio under stepwise-increasing OLR conditions to assess methane production, fermentation parameters, and methanogen community composition. The results showed that an optimal biochar addition of 9% reduced total ammonium nitrogen (TAN) by 31.75% and increased cumulative methane production by 25.93% compared with the control. In continuous operation, biochar addition mitigated ammonium inhibition, stabilized pH, enhanced system stability and organic loading capacity, and improved methane production by 21.15%, 27.78%, and 83.33% at OLRs of 2.37, 4.74, and 7.11 g volatile solids (VS)/(L·d), respectively, compared to the control. Biochar also inhibited the growth of methylotrophic methanogen of RumEn_M2. These findings provide scientific and technical support for applying biochar as a process enhancer during the AD of CM.

In this study, we examined the impact of various physical and chemical properties of growth media on strawberry growth, yield, quality, and economic returns. Six treatments were established: T1 (biogas residue/peat/perlite/vinegar residue = 1:5:1:4), T2 (biogas residue/peat/perlite/vinegar residue = 2:3:1:5), T3 (biogas residue/peat/perlite/vinegar residue = 2:3:1:4), T4 (biogas residue/peat/perlite/vinegar residue = 2:4:1:3), T5 (biogas residue/peat/perlite/vinegar residue = 3:4:1:5), and CK (peat/perlite = 4:1). The results showed that compared with CK treatment, the total nitrogen level increased by 3.26- to 3.95-fold and the organic matter content increased by 14.13–25.70%. In particular, T3 (biogas residue/peat/perlite/vinegar residue = 2:3:1:4) exhibited significant growth advantages, with stem diameter, root volume, and fresh weight increasing by 18.89%, 36.41%, and 35.26%, respectively, compared to CK. The yield per plant saw a 14.54% increase, soluble solids rose by 29.34%, and the solid acid ratio was 1.68 times higher than that of CK. Furthermore, the net income was 2.37 times greater than that of CK. A comprehensive assessment revealed that the T3 treatment demonstrated superior performance in both growth parameters and economic returns, suggesting its suitability as an optimal formulation for further experimentation.

To investigate the adaptability and efficacy of biogas residue soil conditioner in conjunction with other commercially available soil conditioners in arid conditions, a study was conducted using dryland maize as the experimental crop. Five treatments were implemented based on the “dry sowing and wet emergence” method for Xinjiang cotton: T1 with traditional fertilization, T2 with biogas residue soil conditioner, T3 with biogas residue soil conditioner and endophytic arbuscular mycorrhizal bacteria, T4 with commercial Fuli Bang soil conditioner, and T5 with commercial Tianji soil conditioner. Results indicated that the combined use of biogas residue particulate soil conditioner and arbuscular mycorrhizal fungi (T3) had the most positive effects. T3 treatment reduced soil bulk density, increased soil organic matter content, and enhanced rhizosphere microbial diversity. Compared to T1, T3 led to a decrease in soil bulk density by 8.89%, higher microbial diversity indices, and significant increases in plant height, stem diameter, and yield by 6.25%, 15.48%, and 37.43%, respectively. Moreover, T3 showed elevated antioxidant enzyme activities (SOD and POD) and lower malondialdehyde content, indicating enhanced stress resilience and root activity. T3 showed ideal balance in yield, aboveground growth, and root stress resilience. It also improved soil organic matter levels and structure, highlighting the significant potential of combining biogas residue soil conditioner and endophytic arbuscular mycorrhizal fungi to alleviate spring drought stress.