Effect of Biogas Slurry on the Soil Properties and Microbial Composition in an Annual Ryegrass-Silage Maize Rotation System over a Five-Year Period

Abstract

Soil health is seriously threatened by the overuse of chemical fertilizers in agricultural management. Biogas slurry is often seen as an organic fertilizer resource that is rich in nutrients, and its use has the goal of lowering the amount of chemical fertilizers used while preserving crop yields and soil health. However, the application of continuous biogas slurry has not yet been studied for its long-term impact on soil nutrients and microbial communities in a rotation system of annual ryegrass-silage maize (Zea mays). This study aimed to investigate the impacts on the chemical properties and microbial community of farmland soils to which chemical fertilizer (NPK) (225 kg ha−1), biogas slurry (150 t ha−1), and a combination (49.5 t ha−1 biogas slurry + 150 kg ha−1 chemical fertilizer) were applied for five years. The results indicated that compared to the control group, the long-term application of biogas slurry significantly increased the SOC, TN, AP, and AK values by 45.93%, 39.52%, 174.73%, and 161.54%, respectively; it neutralized acidic soil and increased the soil pH. TN, SOC, pH, and AP are all important environmental factors that influence the structural composition of the soil’s bacterial and fungal communities. Chemical fertilizer application significantly increased the diversity of the bacterial community. Variation was observed in the composition of soil bacterial and fungal communities among the different treatments. The structure and diversity of soil microbes are affected by different methods of fertilization; the application of biogas slurry not only increases the contents of soil nutrients but also regulates the soil’s bacterial and fungal community structures. Therefore, biogas slurry can serve as a sustainable management measure and offers an alternative to the application of chemical fertilizers for sustainable intensification.

Soil Microbial Community Characteristics and Their Effect on Tea Quality under Different Fertilization Treatments in Two Tea Plantations

“…During rice practice, biogas slurry coupled with chemical fertilizer (BCF) improved the rhizosphere microbial diversity and abundance compared with the application of solely chemical fertilizer [18]. Another work suggested that the application of biogas slurry not only improved the contents of available nutrients but also regulated the microbial community structures [19]. Through 16S rDNA amplicon analysis, it was found that the abundance of microbial functional groups related to the metabolism and circulation of carbon (C), nitrogen (N), and phosphorus (P) and antibiotic biosynthesis significantly increased under long-term organic fertilizer treatment [20].…”

“…Another finding showed that microbial biomass and oxidoreductase enzyme activities are tightly correlated with the supplementation of organic municipal solid waste [21]. It has been proved that organic fertilizer can improve the physical and chemical properties of the soil, with higher SOC and available N and P contents than chemical fertilizer, and promote microbial growth and enzyme activity [19,22,23]. Furthermore, the bacterial richness and diversity of microorganisms potentially contributed to the production of high-quality crops [24].…”