东北黑土水稳性团聚体及其结合碳分布特征

以东北黑土区32对自然和耕作黑土为研究对象，对比研究了两种土壤水稳性团聚体及其结合碳的分布特征.结果表明：自然土壤0～30 cm水稳性大团聚体（>0.25 mm）质量分数及其结合碳均高于微团聚体；随着土层深度的增加，大团聚体及其结合碳逐渐降低，而微团聚体（<0.25 mm）及其结合碳显著增加（P<0.01）.耕作土壤团聚体分布特征与自然土壤相反，与自然土壤相比，耕作土壤大团聚体数量及其结合碳急剧降低，且>1 mm的大团聚体降低幅度远大于其他粒级团聚体.自然土壤大团聚体质量分数与土壤有机碳（SOC）存在明显的正相关关系（P<0.01），尤其是>1 mm大团聚体；耕作土壤>1 mm大团聚体质量分数与土壤总SOC相关不显著；自然与耕作土壤总SOC与各级团聚体结合碳呈极显著正相关（P<0.01）.与自然土壤相比,耕作土壤大团聚体结合碳明显降低，而微团聚体结合碳增加了37.1%，总SOC含量下降了29.5%，表明大团聚体在总SOC变化中起主要作用.水稳性大团聚体对管理措施响应迅速，可以作为评价农业管理措施转变对土壤肥力和土壤质量影响的指标.

Distribution of water-stable aggregates and aggregate-associated C in black soil in Northeast China.

The study on the distribution characters of water-stable aggregates and aggregate-associated C in 32 pairs of virgin and cultivated black soils in Northeast China showed that in virgin soils, the amount of water-stable macroaggregates (>0.25 mm) and their associated C in 0-30 cm layer were higher than those of microaggreagtes (< 0.25 mm). With the increase of soil depth, the amount of macroaggregates and their associated C showed a decreasing trend, while those of microaggregates increased significantly (P < 0.01). The distribution characters of aggregates in cultivated soils were in adverse to virgin soils. Compared with those in virgin soils, the amount of macroaggregates and their associated C in 0-30 cm layer in cultivated soils declined drastically, particularly for >1 mm aggregates. In virgin soils, the proportions of soil macroaggregates, especially for >1 mm aggregates, were positively correlated to soil organic carbon; but in cultivated soils, no obvious relationship was observed between them. The associated C of soil aggregates was positively correlated to soil total organic carbon in both virgin and cultivated soils (P <0.01). In cultivated soils, less C was associated with macroaggregates but 37% more C was associated with microaggreagtes, and the total soil organic carbon was decreased by 29.5%, in comparison with those in virgin soils, which suggested that soil macroaggregates played an important role in the dynamics changes of soil total organic carbon. It was indicated that soil water-stable macroaggregates were sensitive to soil management, and could be an indicator in evaluating the impacts of agronomic managements on soil fertility and soil quality.