Changes in soil enzyme activity, fertility, aggregation and C sequestration mediated by conservation tillage practices and water regime in a maize field

We examined the medium-term (3 year) effects of no-tillage, reduced tillage (subsoil-bedding and shred-bedding) and water regime on the soil profile distribution of organic matter and physical and microbiological soil quality indicators in a maize field under subtropical conditions. Soil carbon sequestration was evaluated as well. Residue on the soil surface was about 17-21-fold increased in the no-tillage plots over the mouldboard plough plots, with intermediate increases in the reduced tillage plots. In the surface 0-5 cm, organic matter decreased with increasing tillage and was increased by irrigation. The no-tilled soil had increased values of water-soluble C, dehydrogenase, urease and acid phosphatase activities, aggregate stability and glomalin compared to tilled soils, especially in the shallowest (0-5 cm) layer. The water regime had no effect on soil structural stability or total microbial activity.