Paludalfs under different crop rotation systems in North Huai region,China were sampled and soil aggregates were separated by ultra sonic dispersion followed by sedimentation and centrifuging.The particle size distrib...Paludalfs under different crop rotation systems in North Huai region,China were sampled and soil aggregates were separated by ultra sonic dispersion followed by sedimentation and centrifuging.The particle size distribution,SOC (Soil organic matter) contents and the natural abundance of 13 C in these aggregates were studied.Significant difference in size of the aggregates and organic carbon storage in the studied soils were found after 5 years of the crop rotation on the soil.SOC was mainly found in 0.02～0.25mm fraction of aggregates in the soils.The aggregates in layers deeper than 35cm became coarse and richer in SOC under corn peanut sweet potato rotation.Young carbon derived from corn tended to be accumulated in the coarse fractions as revealed by heavier stable carbon composition in those aggregates from deep layer under the rotation system containing corn crop.Compared to the soil under think pine forest,All soils under crop rotation system showed rapid increase of SOC at rates ranging from 0.14C g·kg -1 ·a -1 to 0 22C g·kg -1 ·a -1 ,with the highest under corn peanut sweet potato system.Thus,the significance was indicated for increasing SOC storage by crop rotation in paludalfs and for reinforcing terrestrial carbon retention of atmospheric CO 2.展开更多
文摘Paludalfs under different crop rotation systems in North Huai region,China were sampled and soil aggregates were separated by ultra sonic dispersion followed by sedimentation and centrifuging.The particle size distribution,SOC (Soil organic matter) contents and the natural abundance of 13 C in these aggregates were studied.Significant difference in size of the aggregates and organic carbon storage in the studied soils were found after 5 years of the crop rotation on the soil.SOC was mainly found in 0.02～0.25mm fraction of aggregates in the soils.The aggregates in layers deeper than 35cm became coarse and richer in SOC under corn peanut sweet potato rotation.Young carbon derived from corn tended to be accumulated in the coarse fractions as revealed by heavier stable carbon composition in those aggregates from deep layer under the rotation system containing corn crop.Compared to the soil under think pine forest,All soils under crop rotation system showed rapid increase of SOC at rates ranging from 0.14C g·kg -1 ·a -1 to 0 22C g·kg -1 ·a -1 ,with the highest under corn peanut sweet potato system.Thus,the significance was indicated for increasing SOC storage by crop rotation in paludalfs and for reinforcing terrestrial carbon retention of atmospheric CO 2.
