Soil carbon change and yield increase mechanism of conservation tillage on sloping drylands in semi-humid arid area

Abstract

A long-term field experiment was conducted in the semi-humid areas of western Henan Province to study the changes of soil organic carbon (SOC), soil microbial biomass carbon (SMBC) and yield increase mechanism of wheat. The results show that SOC increases significantly under sub-soiling tillage and no-tillage, especially in cultivated soil layers. SOC (6.79 g·kg-1) is highest under sub-soiling, which is 13.8% higher than that under conventional tillage. SOC under no-tillage is 11.6% higher than conventional tillage, which also drops by 1.4% under reduced tillage. The deeper the soil layer, the lower SOC content is. SMBC content occurs in the following order: no-tillagesub-soilingconventional tillagereduced tillage; while SMBC contents under no-tillage, sub-soiling tillage and reduced tillage are 79.3%, 19.9% and-2.5% higher than that of conventional tillage. Ratio of SMBC to SOC under no-tillage and sub-soiling are 3.11% and 2.04%. Through out the field trial experiments, sub-soiling yields the highest. No-tillage increases wheat yield, except in very rainy years. No-tillage and sub-soiling tillage store more water in the soil and improve accumulation of dry matter during the later growing stage of winter wheat, postpone plant co-senescence in wheat.