引黄灌溉耕作对土壤团聚体有机碳的影响

为研究灌溉耕作影响下土壤团聚体及有机碳的特征情况,以宁夏引黄灌区为研究对象,选取对照土壤与耕作土壤,通过干、湿筛结合的方法,得到大团聚体(2mm)、中间团聚体(2~0.25mm)、微团聚体(0.25~0.053mm)和粉+黏团聚体(0.053mm),并测定团聚体有机碳含量,分析团聚体有机碳与总有机碳之间的关系。结果表明,灌溉耕作对团聚体分布具有极显著影响(P0.01),其中大团聚体和中间团聚体质量分数上升,微团聚体和粉+黏团聚体质量分数下降,灌溉土壤团聚体分布趋势为微团聚体粉+黏团聚体中间团聚体大团聚体。经灌溉耕作后土壤团聚体稳定性大于对照土壤,不同类型的灌溉土壤稳定性基本一致,对照土壤间差异明显。除0.053mm外,团聚体有机碳分布在经过灌溉耕作后有显著性差异(P0.05),团聚体有机碳分布随粒级大小基本呈"V"形分布。团聚体有机碳含量均表现出灌溉土壤高于对照土壤,其中灌溉土壤中灌淤土和潮土团聚体有机碳总量较高。未受人为灌溉耕作影响的自然土壤团聚体有机碳与总有机碳间具有显著的正相关性,土壤总有机碳增加主要依赖0.053mm团聚体有机碳增加。引黄灌溉耕作有利于增加大粒级团聚体的比例,提升团聚体稳定,显著增加有机碳含量。

Effect of Cultivation and Irrigation with Yellow River on Soil Organic Carbon in Soil Aggregates

In order to study the effects of cultivation and irrigation on soil aggregation and organic carbon, the study subjects were selected from the irrigation zone in Ningxia province, and selected the control and irrigated soil. Through the combination of dry and wet methods, we got the proportion of large macroaggregates (>2 mm), small macroaggregates (0.25~2 mm), microaggregates (0.25~0.053 mm) and silt + clay (<0.053 mm), and measured the content of organic carbon in each aggregate fraction and analyzed the relationship between organic carbon and total organic carbon. The results showed that aggregate distribution changed significantly (P<0.01) after irrigation, large macroaggregates and small macroaggregates proportion raised, microaggregates and silt + clay mass proportion decreased, the distribution trend was microaggregates>silt+clay>small macroaggregates>large macroaggregates. Irrigated soil aggregate stability was greater than that of the control soil, different types of irrigated soil had the same stability, and showed difference between control soils. In addition to <0.053 mm, the aggregate distribution of organic carbon after irrigation had significant difference (P<0.05), the organic carbon content had a "V" distribution with the size of the granule. Soil organic carbon in aggregate was higher in irrigated soil than that of the control soil, Irrigated-silted soil and Fluvo-aquic soil showed higher aggregate organic carbon content. There was a significant positive correlation between organic carbon in aggregate and total organic carbon in non-cultivated and non-irrigated natural soils, soil total organic carbon increase mainly depended on increment of >0.053 mm aggregate organic carbon. Cultivation and irrigation with sediment laden Yellow River water was significantly beneficial to increase the proportion of large scale aggregate, the stability of the aggregate, and the organic carbon content.