保护性耕作对东北黑土地区土壤团聚体和团聚体胶结物质的影响研究

李琪　张士秀　梁文举

摘 要：耕作强烈地影响土壤团聚体的稳定性，在一定空间尺度范围内涉及到许多胶结物质的相互作用机理。为了更好地了解土壤胶结物质促进土壤团聚体团聚过程，在东北黑土地区开展了有关三种不同耕作方式（免耕、垄作、常规耕作）对土壤团聚体和土壤团聚体胶结物质（有机碳、微生物量、土壤球囊霉素相關蛋白）的影响试验研究。研究结果表明，与常规耕作相比，垄作提高了所有粒级团聚体内有机碳含量，而免耕只提高了大团聚体内有机碳含量。在免耕和垄作条件下，全土和各个粒级土壤团聚体中的微生物生物量和土壤球囊霉素相关蛋白含量显著高于常规耕作。在四个粒级土壤团聚体中，大团聚体和微团聚体内土壤有机碳、微生物生物量以及易提取球囊霉素相关蛋白含量较高，而土壤总球囊霉素相关蛋白则均匀地分布在各个粒级团聚体内。应用结构方程模型揭示土壤有机碳、微生物生物量及球囊霉素相关蛋白含量能够解释79%的土壤团聚过程。土壤有机碳是通过微生物量碳和微生物量氮而间接影响土壤团聚体稳定性。在垄作和免耕系统中，土壤微生物生物量和球囊霉素相关蛋白是提高土壤团聚体稳定性的重要驱动因子。该研究结果表明，在东北黑土地区实施保护性耕作（如垄作和免耕）措施有助于改善土壤结构，尤其是能显著增强黑土团聚体团的稳定性。

关键词：保护性耕作 土壤团聚体 土壤有机碳 微生物生物量 土壤球囊霉素相关蛋白 结构方程模型

Abstract：Tillage strongly affects the process of soil aggregate stabilization， which involves a variety of binding mechanisms interacting at a range of spatial scales. To understand how binding mechanisms interact to promote soil aggregation， the impacts of three tillage systems （no tillage （NT）， ridge tillage （RT） and conventional tillage （CT）） on soil aggregate binding agents （i.e.， organic carbon （SOC）， microbial biomass and glomalin-related soil proteins （GRSPs）） and aggregation were studied in the black soil of Northeast China. Compared with CT， RT increased all the aggregate-associated SOC， and NT only increased the SOC in the microaggregates. However， the contents of microbial biomass and GRSPs within bulk soil and different aggregate fractions were higher in NT and RT than in CT. Among the four aggregate fractions， greater values of SOC， microbial biomass and easily extractable GRSP （EEGRSP） were found in microaggregates and macroaggregates， respectively； while the total GRSP （TGRSP） was distributed equally among aggregate fractions. Structural equation modelling revealed that SOC， microbial biomass， and GRSPs accounted for 79% of the variation in soil aggregation. Soil organic carbon influenced aggregate stability indirectly through the effects on MBC and MBN. Microbial biomass and glomalin were more important driving factors for aggregate stability in the RT and NT systems. Our results suggest that conservation tillage （RT and NT） is beneficial for soil structure due to its positive effects on aggregation processes in black soil region of Northeast China.

Key Words：Conservation tillage；Soil aggregation；Soil organic carbon；Microbial biomass；Glomalin-related soil protein；Structural equation modelling

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