Long‐term no‐tillage and rye cover crops affect soil biological indicators on Andosols in a humid, subtropical climate

Abstract

AbstractThe effects of tillage and cover crop management on the physical and chemical properties of soil are well‐documented. However, the responses of soil microbes to long‐term tillage and crop rotation schemes still need clarification. The objective of this study was to determine the effects of different tillage and cover crop systems on soil biological indicators and their interactions in Andosols in a humid subtropical climate in Japan. This study was conducted during a field trial established in 2002. The main factors were tillage systems (no‐tillage [NT] and mouldboard ploughing [MP]); the subplot was winter cover crop treatments (bare fallow [FA] and rye [RY]) succeeding summer soya bean. Soil microbial biomass, community and structure, and soil organic carbon (SOC) stock were assessed, as well as soil respiration in the past 2.5 years. Overall, the NT and RY systems increased the soil respiration and SOC stocks relative to those detected in the MP and FA systems. After being differentiated for 18 years, the tillage systems showed a greater influence on the soil microbial community and biomass than cover crop treatments. These tillage systems significantly altered the bacterial alpha diversity (NT > MP) and soil microbial biomasses (NT > MP) based on soil Adenosine 5′‐triphosphate content, substrate‐induced respiration and ergosterol content. The NT and RY treatments stimulated soil respiration by positively affecting plant residue retention, SOC stocks, bacterial alpha diversity, soil microbial biomass in summer, and the relative abundance of organic matter decomposers, such as Bacteroidetes‐, Basidiomycota‐ and Ascomycota‐related species. These results suggest that the NT and RY systems helped improve the soil microbial properties of Andosols in a humid subtropical climate in Japan. However, their potential vulnerability to SOC sequestration due to elevated soil respiration needs further clarification, especially in the context of global warming.Highlights Soil microbe responses to agricultural measures on Andosols were studied. No‐tillage and rye cover crops stimulated soil respiration. No‐tillage shifted the soil microbial community more than cover crops. No‐tillage improved the soil organic carbon stock and bacterial alpha diversity.