Interactive Effect of Residue Quality and Agroecologies Modulate Soil C‐ and N‐Cycling Enzyme Activities, Microbial Gene Abundance, and Metabolic Quotient

Abstract

Understanding interactive effect of agroecology explained by rainfall, temperature, elevation, and biochemical composition of residues on soil microbial abundance and functions is crucial for unraveling soil ecological processes. This study aimed to investigate how agroecology and residue quality influence enzymatic activities, gene abundance, and metabolic quotient (qCO2). A field experiment was conducted using Leucaena leucocephala (LL) (high‐quality residue) and Acacia decurrens (AD) (low‐quality residue) in soils of highland and midland agroecologies. These residues differed in decomposability, characterized by a ratio of (lignin + polyphenol)/N of 5.0 for high‐quality residue versus 21.0 for low‐quality residue. Two experimental setups were employed: soil with litter mixture in polyvinyl chloride (PVC) tubes and residues buried in the surface soil using litterbags. Soil samples were collected after 30, 120, and 270 days of incubation and analyzed for biochemical properties, enzyme activities, and the abundance of nitrifying and total archaea and bacteria. Soil respiration was also measured at different intervals in the field. qCO2 was calculated using microbial biomass (MBC) and daily respiration (DCO2). Linear mixed model (P < 0.05) revealed that combined factors of agroecologies and residue qualities affected enzymatic activities, microbial abundance, soil properties, and qCO2. Agroecological differences exerted a greater influence than residue qualities. Positive and negative significant correlations (P < 0.05, r = 0.27 to 0.67) were found between different C and N pools as well as enzymatic activities. Positive correlations (P < 0.05) were observed between the abundance of total bacteria, total archaea, and ammonia‐oxidizing bacteria versus leucine‐aminopeptidases. qCO2 was influenced more by β‐xylosidase, leucine‐aminopeptidases, and thermolysin‐like neutral metalloproteases (TLP) than by β‐D‐glucosidase and β‐D‐cellobiohydrolase. Leucine‐aminopeptidases and TLP were identified as rate‐limiting factors for protein and peptide decomposition, while β‐xylosidase controlled hemicellulose degradation. In summary, this study provides insights into the intricate relationships between agroecology, residue quality, enzymatic activities, and microbial communities, shedding light on key processes governing soil ecological functions.