东北黑土水稳性团聚体及其结合碳分布特征

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

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0～30cm水稳性大团聚体(>0.25mm)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(<0.25mm)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>1mm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>1mm大团聚体;耕作土壤>1mm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.

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.