保護性耕作對東北黑土地區(qū)土壤團聚體和團聚體膠結物質的影響研究

李琪　張士秀　梁文舉

摘 要：耕作強烈地影響土壤團聚體的穩(wěn)定性，在一定空間尺度范圍內涉及到許多膠結物質的相互作用機理。為了更好地了解土壤膠結物質促進土壤團聚體團聚過程，在東北黑土地區(qū)開展了有關三種不同耕作方式（免耕、壟作、常規(guī)耕作）對土壤團聚體和土壤團聚體膠結物質（有機碳、微生物量、土壤球囊霉素相關蛋白）的影響試驗研究。研究結果表明，與常規(guī)耕作相比，壟作提高了所有粒級團聚體內有機碳含量，而免耕只提高了大團聚體內有機碳含量。在免耕和壟作條件下，全土和各個粒級土壤團聚體中的微生物生物量和土壤球囊霉素相關蛋白含量顯著高于常規(guī)耕作。在四個粒級土壤團聚體中，大團聚體和微團聚體內土壤有機碳、微生物生物量以及易提取球囊霉素相關蛋白含量較高，而土壤總球囊霉素相關蛋白則均勻地分布在各個粒級團聚體內。應用結構方程模型揭示土壤有機碳、微生物生物量及球囊霉素相關蛋白含量能夠解釋79%的土壤團聚過程。土壤有機碳是通過微生物量碳和微生物量氮而間接影響土壤團聚體穩(wěn)定性。在壟作和免耕系統(tǒng)中，土壤微生物生物量和球囊霉素相關蛋白是提高土壤團聚體穩(wěn)定性的重要驅動因子。該研究結果表明，在東北黑土地區(qū)實施保護性耕作（如壟作和免耕）措施有助于改善土壤結構，尤其是能顯著增強黑土團聚體團的穩(wěn)定性。

關鍵詞：保護性耕作 土壤團聚體 土壤有機碳 微生物生物量 土壤球囊霉素相關蛋白 結構方程模型

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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