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
通过对松嫩平原玉米田土壤CO2排放的连续观测,研究连作玉米田土壤CO2排放规律及与土壤温度、土壤水分的关系,并计算玉米田土壤碳平衡特征。结果表明,玉米田土壤CO2排放通量呈现明显季节性,6~8月土壤CO2排放量较大,而在4和11月维持较低...通过对松嫩平原玉米田土壤CO2排放的连续观测,研究连作玉米田土壤CO2排放规律及与土壤温度、土壤水分的关系,并计算玉米田土壤碳平衡特征。结果表明,玉米田土壤CO2排放通量呈现明显季节性,6~8月土壤CO2排放量较大,而在4和11月维持较低水平。秸秆还田处理（MTS）土壤CO2排放通量、最大通量和平均通量高于翻耕处理（CT）。土壤CO2排放通量与地温呈显著正相关,指数方程表征二者关系效果最佳,线性方程效果最低,除个别情况,深层土壤拟合效果高于浅层土壤;MTS处理的土壤CO2排放通量与土壤温度相关性高于CT处理。土壤CO2排放通量与12 cm深度土壤水分相关性不显著。通过对秸秆、根茬还田碳与土壤CO2排放碳的测算,MTS处理秸秆还田碳量较CO2排放碳量平均每年多2 744.6 kg C·hm-2,呈碳汇效应;CT处理秸秆还田碳量较CO2排放碳量平均每年少810.4 kg C·hm-2,呈碳源效应。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.
文摘通过对松嫩平原玉米田土壤CO2排放的连续观测,研究连作玉米田土壤CO2排放规律及与土壤温度、土壤水分的关系,并计算玉米田土壤碳平衡特征。结果表明,玉米田土壤CO2排放通量呈现明显季节性,6~8月土壤CO2排放量较大,而在4和11月维持较低水平。秸秆还田处理（MTS）土壤CO2排放通量、最大通量和平均通量高于翻耕处理（CT）。土壤CO2排放通量与地温呈显著正相关,指数方程表征二者关系效果最佳,线性方程效果最低,除个别情况,深层土壤拟合效果高于浅层土壤;MTS处理的土壤CO2排放通量与土壤温度相关性高于CT处理。土壤CO2排放通量与12 cm深度土壤水分相关性不显著。通过对秸秆、根茬还田碳与土壤CO2排放碳的测算,MTS处理秸秆还田碳量较CO2排放碳量平均每年多2 744.6 kg C·hm-2,呈碳汇效应;CT处理秸秆还田碳量较CO2排放碳量平均每年少810.4 kg C·hm-2,呈碳源效应。
