Abstract:

Abstract : A seven years’location experiment of wheat-corn rotation in Guanzhong plain was conducted for studying the effects of sub-soiling, rotary tillage and no-tillage on the oxidation stability of soil organic carbon in soil aggregates. The results showed that compared with conventional tillage, sub-soiling, rotary tillage, no-tillage and conventional tillage with straw incorporated all increased the content of total organic carbon and readily oxidizable organic carbon in soil aggregates. The effects of sub-soiling and rotary tillage were significant, but no-tillage have a little effect, Effects of sub-soiling, rotary tillage and no-tillage on the content of difficultly oxidizable organic in soil aggregates were insignificant. It implied that the increase of total organic carbon in soil aggregates by conservational tillage measures was mainly by enhancing the content of readily oxidizable organic carbon. The oxidation stablility coefficient (Kos) of organic carbon in soil aggregates was decreased by conservational tillage measures, but the effects was insignificant. The content of total organic carbon, readily oxidizable organic carbon and difficultly oxidizable organic carbon in smaller sizes (0.5～0.25mm and<0.25mm )of soil aggregates were higer than that in lager sizes (>0.5mm ) of soil aggregates. But the oxidation stablility coefficient (Kos) of organic carbon in smaller sizes of soil aggregates were lower than that in lager sizes of soil aggregates. The correlation analysis demonstrated that except for 5～2mm soil aggregates, correlation between soil organic carbon in different size of soil aggregates all were very significant, as well as the readily oxidizable organic carbon between different sizes of soil aggregates. The correlations between readily oxidizable organic carbon and total organic carbon in different sizes aggregates were very significant. the correlations coefficients of total organic carbon, readily oxidizable organic carbon between <0.25mm aggregates and the other sizes of soil aggregates were higher.