Responses of soil chemical and microbial indicators to conservational tillage versus traditional tillage in the North China Plain

This study compared the responses of soil chemical and microbial indicators to the conservational tillage (CT) versus traditional tillage (TT) in a Haplic Cambisol in the North China Plain (NCP). These indicators included soil organic C (SOC), soil total N (STN), soil available P (SAP), cation exchange capacity (CEC), exchangeable Ca2+ and Mg2+, microbial biomass C (MBC), microbial biomass N (MBN), alkaline phosphomonoesterase (AP), β-glucosidase, N-acetyl-β-glucosaminidase (NAG), nitrate reductase (NR), protease, urease and the geometric mean of the assayed enzymes (GMea). Our results showed that almost all investigated parameters, except the contents of CEC, Ca2+, Mg2+ and the ratios of GMea/MBN and C/N, were significantly higher under the CT (no-till, NT and reduced-till, RT) than those under the TT, whilst the crop yield was not significantly affected by tillage treatments. Principle component analysis (PCA) showed that the first and second component explained 67.2% and 16.6% of the total variation, respectively. The first component was significantly correlated with GMea, MBC, MBN and β-glucosidase, and effectively discriminated soils under the NT or RT from those under the TT. Our results indicated that the 6-year CT improved the quality of the Haplic Cambisol by enhancing its chemical and microbial properties, whilst GMea, MBC, MBN and β-glucosidase were among the most effective indicators for monitoring these improvements.