连续种植超级稻对土壤有机碳及团聚体稳定性的影响

Effects of Continuous Super Rice Planting on Organic Carbon and Aggregates Stability

分别在长江中下游地区3处超级稻育种试验基地,选择多年连续种植超级稻和未种植超级稻的稻田,于水稻收获后采集表土未破坏土壤样品,采用低能量超声波分散法分离得到不同粒径的团聚体颗粒组,研究超级稻连续种植后有机碳含量变化及其有机碳在团聚体颗粒组中的分配,探讨连续种植超级稻对土壤有机碳和团聚体稳定性的影响。结果表明:连续种植超级稻后,水稻土表土有机碳含量均下降,降幅介于3%～14%;团聚体颗粒组组成以2000～200μm和200～20μm粒径为主,有机碳在2000～200μm和<2μm两个粒级中最高;连续种植超级稻后2000～200μm大团聚体颗粒组质量分数提高,土壤团聚体稳定性增强。连续种植超级稻后有机碳含量下降可能是土壤短期的一种响应机制,长期来看并不改变水稻土的固碳潜力。

In this study, Soil organic carbon（SOC ）, soil aggregates and SOC distribution in aggregates were investigated using cross-site study, the top-soil samples were from three sites of continuous super-rice planting experiments in the mid-lower Yangtze River. Undisturbed top-soil samples were separated to different size aggregates by low-energy ultra-sonic dispersion procedure. Soil aggregares, variation of SOC and SOC distribution in aggregates were analyzed to illuminate the effects on aggregates stability and SOC reserves after continuous super-rice planting. The content of SOC decreased in three sampling sites after continuous super-rice planting, deceasing from 3% to 14%; SOC content was higher in aggregare of 2 000-200μm and〈2 μm than in the others, and the content of SOC decreased after continuous super-rice planting in these aggregates. The distribution of aggregates was dominated by 2 000-200μm and 200-20 μm fractions, and the content of 2 000-200 μm macro-aggregates and soil aggregate stability increased after continuous super-rice planting. Decreasing SOC was a soil dynamics after continuous super-rice planting in short time, but did not change the carbon storage potential in long time.