华北平原农业土地利用方式对土壤水稳性团聚体分布特征及其有机碳含量的影响

Effects of Agricultural Land Uses on Water-Stable Aggregate Distribution and Organic Carbon in Farmland Soil in the Northern China Plain

以在华北平原具有典型代表的禹城市为研究区域，通过对该地区主要农业土地利用类型的土壤进行采样和分析，系统研究和比较了不同农业土地利用方式下土壤团聚体分布特征及其有机碳的含量。研究结果表明，不同农业土地利用方式对土壤水稳性团聚体分布和组成有着显著（p〈0．05）影响。与传统粮田比较，果园和苜蓿地土地利用方式明显提高了土壤中〉2mm和〉0.25mm水稳性团聚体的比例，同时也降低了0．5～1mm和0.25～0．5mm粒级的水稳性团聚体比例。果园土壤平均重量直径（MWD）和几何平均直径（GMD）较传统粮田分别提高了70．5％和108．4％。设施农业用地降低了土壤较大粒级水稳性团聚体的比例和团聚体的稳定性。果园表层土壤总有机碳（TOC）、轻组分有机碳（LFOC）和颗粒有机碳（POC）较传统粮田分别提高了54.8％、136.4％和124．6％。设施农业用地则显著（p〈0．05）降低了土壤TOC、LFOC和POC的含量。不同粒级团聚体中土壤有机碳含量皆以果园为最高，苜蓿地次之，设施农业用地土壤不同粒级团聚体中有机碳平均含量为最小，这种差异在〉2mm和0．5～1mm的团聚体中表现最为明显。相关和回归分析表明，〉0.25mm团聚体含量、MWD和GMD与土壤TOC、LFOC和POC皆呈现显著正相关性，其中与POC之间的相关关系达到极显著水平（p〈0．01），其相关系数，分别为0.923^＊＊、0,912^＊＊和0．897^＊＊。

As a crucial indicator of soil quality, soil aggregate and its stability play key roles in a number of soil chemical, physical, and biological properties and processes. To study systematically and compare effects of different types of land use on distribution characteristics of soil water-stable aggregates （WSA） and content of soil organic carbon （SOC）, soil samples were collected from farmlands under different major types of landuse in Yucheng, typical of the Northern China Plain. Results revealed that significant （p〈0.05） differences in WSA distribution were detected between these types of land use. Orchard and clover cultivation markedly increased 〉 2 mm and 〉 0.25 mm WSA, but decreased 0.5 - 1 mm and 0.25 0.5 mm WSA as compared with CK, conventional crop field. Orchard increased mean weight diameter （MWD） and geometric mean diameter （GMD） of the soil by 70.5% and 108.4%, respectively, whereas greenhouse vegetable cultivation decreased soil WSA stability. Orchard soil showed 54.8%, 136.4% and 124.6% higher in content of total organic C （TOC）, light fraction organic C （LFOC）, and particulate organic C （POC）, respectively than the conventional crop field. Orchard soil was the highest in SOC content of WSA, followed by clover field. The greatest differences in SOC content between different types of land use were found in the size fractions of WSA, 〉 2 mm and 0.5 - 1 mm. Correlation and regressive analysis showed that 〉0.25 mm WAS, MWD and GMD were significantly （p〈0.01 or p〈0.05） related to TOC. LFOC, and POC. More significant correlations between POC and 〉0.25 mm WAS, MWD and GMD were founded with coefficients （r） being 0.923, 0.912 and 0.897（p〈0.01）, suggesting that soil particulate organic C plays a more important role in maintaining soil aggregate stability.