长期不同施肥黑土团聚体有机碳分布特征

SOC Distribution Characteristics of Mollisols Aggregates in Different Long-term Fertilization Systems

土壤有机质是土壤的重要组分部分,在土壤肥力、环境保护及农业可持续发展等方面都具有重要作用。团聚体是土壤结构的重要组成部分,是形成土壤良好结构的物质基础,能够综合地反映土壤整体的肥力状况,其大小和含量成为土壤质量高低、抗侵蚀能力强弱的指标。近年来土壤有机质和团聚体的相互关系及其影响因素的研究越来越受到重视。本研究利用黑土长期定位试验4个典型施肥处理:有机肥马粪与无机肥氮磷钾混合施用(MNPK)、施用化肥氮磷钾(NPK)、施用有机肥马粪(M)和不施肥处理(CK),分析土壤团聚体粒级组成,以及不同粒级团聚体中有机碳含量分布特征,并分析不同粒级团聚体对土壤有机碳的贡献率。结果表明:长期定位施肥的黑土(0~20 cm)进行团聚体颗粒分级后,土壤2 mm^0.25 mm和0.25 mm^0.053 mm团聚体为优势粒级,二者占土壤团聚体总量的46.5%和39.6%。各处理团聚体中有机碳含量因粒级而异,0.25 mm^0.053 mm粒级团聚体有机碳含量最高,<0.053 mm粒级团聚体中有机碳含量最低。有机无机肥配施(MNPK)处理各粒级有机碳含量较对照都有不同程度增加,MNPK、M、和CK处理在2 mm^0.25 mm对土壤有机碳的贡献率最大,分别为53.0%、45.7%和51.1%,单施化肥处理(NPK)在0.25 mm^0.053 mm对土壤有机碳的贡献率最大为47.9%。以上结果与各粒级团聚体在长期施肥土壤中所占比例相一致。

Soil organic matter is an important component in soil and plays an important role in soil fertility, environmental conserva- tion, and sustainable agricultural development. Aggregate is an essential part of soil structure and the key material basis for good soil structure, which comprehensively reflects the status of soil fertility. The size and content of soil aggregate have become indicators for e- valuating soil quality level and anti-erosion ability. Recently, the research on the relationship between soil organic matter and aggregate as well as its influencing factors has attracted more attention. Based on four typical fertilization treatments （ MNPK - mixed application of organic and chemical fertilizers, NPK - application of chemical fertilizers only, M - application of organic fertilizer only, CK - non -fertilization） under long-term fertilization experiment in Mollisols, we analyzed the size composition of soil aggregates and their soil organic carbon （SOC） contribution rates to total SOC. The results showed that Mollisols, under different long-term fertilization sys- tems, the sizes of 2 mm - 0. 25 mm and 0. 25 mm -0. 053 mm aggregates, at 0 - 20 cm soil depth were the main components, ac- counting for 46. 5% and 39. 6% in total soil aggregate, respectively. The SOC content varied among different size soil aggregates. The highest was found in O. 25 mm - 0. 053 mm aggregate but the lowest in 〈 0. 053 mm aggregate. Compared with CK, the combined ap- plication of organic and inorganic fertilizer （MNPK） increased SOC content in different size aggregates to some extent. The contribution rate of 2 mm-0.25 mm aggregate in total SOC was 53.0%, 45.7% and 51.1% in MNPK, M, and CK, respectively, while the contribution rate of 0. 25 mm - 0. 053 mm aggregate was 47.9%, with the highest contribution rate in total SOC in chemical fertilizer treatment （NPK） . The above mentioned was consistent with the aggregate size proportion in long-term fertilization systems.