Abstract:

【Objective】 In order to get a good indicator to evaluate the impacts of no tillage (NT) on soil structure and soil quality, the dynamics of total soil organic carbon (SOC) and SOC associated with aggregates, and the relationships between total SOC and aggregate-associated SOC in the plow layer (30 cm) in black soil in Northeast China under NT practice were sludied. 【Method】 The tillage experiment was established in Dehui County, Jilin Province in 2001. The total SOC and aggregate-associated SOC in 5-year tillage treatments were measured. 【Result】 NT practices did not lead to increase of average SOC content at 0-30 cm depth, but it did significantly increase SOC at the top soil (0-5 cm). In NT plot, the change trend of SOC in ＞1 000 μm aggregate was the same with that of total SOC, but the effect of NT on SOC in ＞1 000 μm aggregate was greater than the effect on total SOC, suggesting that ＞1 000 μm aggregate had more sensitive response to the impact of tillage practices. Significant positive correlation occurred between total SOC and SOC in ＞1 000 μm aggregate in black soil. 【Conclusion】 In the short term soil macroaggregate ＞1 000 μm could be used as an indicator to evaluate the impacts of tillage practices on soil structure and soil fertility in black soil in Northeast China.

Key words: no tillage, soil organic carbon, water-stable aggregate, black soil