Slurry reflux is a low-cost slurry reduction technology, which can solve the problem that a large amount of slurry cannot be completely consumed in a biogas plant. Anaerobic digestion (AD) of corn stalks with slurry reflux and non-reflux was compared and evaluated in continuous anaerobic digestion to clarify the effects of slurry reflux on AD with organic loading rate (OLR) variation. It was found that slurry reflux increased cumulative methane production and improved system stability. The average methane yield of the slurry reflux group was 224.19 mL/gVS, which was 41.35% higher than that of the non-reflux group. High-throughput sequencing results showed that slurry reflux increased the microbial community richness. The dominant microorganisms in the reflux group were in phylum Bacteroidetes, which have the capacity to degrade polymers, and Methanothrix, which is an aceticlastic methanogen. The relative abundances of Bacteroidetes and Methanothrix were 32.41% and 41.75%, respectively. Clostridium III and Saccharofermentans, which are related to syntrophic acetate oxidation and hydrolysis, were increased in relative abundance in the slurry reflux system. The increase of the OLR altered the main methane-producing pathway from the acetoclastic methanogenic pathway to the hydrogenotrophic methanogenic pathway in the AD system, and the slurry reflux can delay this trend. This study provided an effective way for the reduction and utilization of slurry in a biogas plant.

This study investigated whether legume cover crops, particularly Vicia sativa L., improve soil fertility and fruit quality via microbial community remodeling, and whether this practice outperforms natural grass management in pear orchards. Five treatments were established: clean tillage (CK), natural grass (T1), Vicia sativa L. (T2), Vicia villosa Roth (T3), and a mixture of V. sativa and V. villosa (T4). High-throughput sequencing, soil biochemical assays, microbial co-occurrence network analysis, and PLS-PM were integrated to explore underlying mechanisms. Results showed that V. sativa significantly altered bacterial and fungal communities versus CK and T1, enriching beneficial taxa (Bradyrhizobium, Nitrospira, Mortierella, Tausonia) while suppressing pathogens (Alternaria, Fusarium, Curvularia). The V. sativa treatment also enhanced soil enzyme activities and nutrient availability, leading to increased fruit weight, soluble sugars, and ascorbic acid. PLS-PM revealed that legume treatments increased bacterial but decreased fungal abundance; bacterial communities positively correlated with soil nutrients and enzymes, whereas fungal communities showed negative correlations. Soil nutrients emerged as the primary factors associated with fruit quality improvement, with bacterial and fungal contrasting effects suggesting a potential microbial pathway. Collectively, V. sativa green manure optimized microbial structure by enriching beneficial microbes and suppressing pathogens, thereby improving soil health and pear fruit quality synergistically.

Anaerobic digestion (AD) of corn stalks with slurry reflux and non-reflux was compared and evaluated，to clarify the effects of slurry reflux on AD. It was found that slurry reflux increased cumulative methane production by 45.80% and improved system stability. With the increase of organic loading rate (OLR), pH value and oxidation-reduction potential (ORP) of reflux group remained 7.16±0.23 and -338.71±9.22. High-throughput sequencing results showed that slurry reflux slowed down the decrease of microbial community diversity, and the richness of bacterial community increased by 9.16%. The dominant microorganisms were Bacteroidetes and Methanothrix in reflux group, the relative abundances were 32.41% and 41.75%, respectively. The increase of organic loading rate (OLR) altered the main methane-producing pathway of the AD system, and slurry reflux can delay this trend.