NO-TILLAGE IMPACTS ON SOIL ORGANIC CARBON IN A BLACK SOIL IN NORTHEAST CHINA

摘要

Many detailed studies found that no-tillage (NT) only stratified instead of increasing soil organic carbon (SOC) in the topsoil. To better understand the effect of short-term NT on SOC and selected soil physical properties relative to mouldboard plough tillage (MP) in corn-soybean rotation (C-S) and monoculture corn (C-C) systems, we conducted this study in Black soil in Northeast China in an 8-year field experiment. Relative to MP, NT produced significantly higher stratification ratio in SOC than MP, with significantly greater SOC in surface soil (0-5 cm) but lower SOC in subsurface soil (10-30 cm) in two crop rotation systems. No significant difference in SOC stock was found between NT and MP in two crop rotation systems when the contrast was based on the equivalent mass and soil depth, except that based on equivalent soil depth of 0-10 cm in C-S system. In two crop rotation systems, soil bulk density was close between NT and MP with depth; soil penetration resistance in NT soil was consistently higher than in MP soil; soil water content at 0-10 cm under NT was greater than under MP. No-tillage and C-C system resulted in relatively lower least limiting water range compared with MP and C-S system, respectively. It was concluded that NT has the potential to improve SOC sequestration in surface soil relative to MP. Least limiting water range, used as integrative measure, might help us predict whether or not the adoption of NT practice can increase SOC sequestration in Black soil in Northeast China.