典型农耕区棕壤水稳性团聚体及其有机碳特征

Characterization of Water Stable Aggregates and Organic Carbon in Typical Brown Arable Soil

对山东半岛棕壤区耕地和荒地土壤水稳性团聚体及其有机碳进行解析。结果表明:各级土壤团聚体质量比总体呈"两头低中间高"的不规则"W"形分布,耕地和荒地土壤微团聚体(<250μm)平均含量分别为51.74%和51.61%,耕种的扰动增加了土壤颗粒分散度,水流对大团聚体的破坏作用更大。有机碳分布受团聚体分配的制约,其含量随团聚体粒径减小而增加。耕地和荒地有机碳在大团聚体中平均含量分别为5.98,3.48g/kg,而在微团聚体中含量分别为8.05,9.11g/kg,有机碳含量比例分别高达55.36%和68.58%,其中<20μm粉黏团聚体中有机碳含量最高(耕地为10.97g/kg;荒地为11.63g/kg),可作为研究区土壤固碳潜力评价指标。傅立叶变换红外光谱(FTIR)解析发现,棕壤微团聚体有机碳以芳香碳和多糖碳为主。

This paper was aimed at the distribution and composition of water stable aggregates together with organic carbons in brown soil in Shandong peninsula. The results showed that： The size distribution of water stable aggregates was as irregular ＂W＂ with two lower ＂shoulders＂. The microaggregates （%250μm） accounted for 51.74% in arable soil and 51.61% in uncultivated soil, respectively. The dispersion degree of soil particles was increased due to the cultivation disturbance and the smaller aggregates resisted the water erosion. The distribution of soil organic carbon（SOC） in soil predominately was constrained by the allocation of aggregates, which was increased with the decreasing of particle sizes. The average content of SOC in macroaggregates was 5.98 g/kg in arable soil and 3.48 g/kg in uncultivated soil, respectively. The content was 8.05 g/kg for arable soil and 9.11 g/kg for uncultivated soil in microaggregates, accounting for 55.36% and 68.58% of the total organic carbon content in soil, respectively. It was notable that the content of SOC in silt-clay microaggregates（〈20μm） was the highest（10.97 g/kg and 11.63 g/kg in arable and uncultivated soil, respectively）, which could be regarded as the indicator for potential of SOC sequestration of brown soil in study areas. Fourier transform infrared spectroscopy （FTIR） resolve showed that organic carbon in microaggregates predominately consisted of stable aromatic and carbohydrate carbon.