Scientific Research Funds Project of Education Department of Liaoning Province (No. LSNQN202001)， Science and Technology Plan Project of Liaoning Province（No. 2020JH2/10200034）, Postgraduate Innovation Cultivation Project in 2022(No.2022YCXS39)
【Objective】 The aggregation of soil colloids is closely related to the formation of soil aggregates. Fertilization can change the environment of soil solution, and affect the formation of soil aggregates, soil structure and soil mineral composition. It is necessary to explore the relationship between the long-term effects of different fertilization on the microscopic properties and interactions of soil colloids and thus the macroscopic phenomena of soils. 【Method】 Based on a 35-year long-term fertilization monitoring experiment in the experimental station of brown earth, soils treated with no fertilization(CK), nitrogen fertilizer(N), organic fertilizer(M) and the combination of nitrogen fertilizer and organic fertilizer(N+M) were selected as the research objects in this study. Dynamic light scattering technology was used to monitor the dynamic aggregation process of soil colloids with different fertilization treatments. The effects of fertilization treatments on colloid aggregation were comparatively analyzed through the organic matter content, soil mineral composition and surface chemical properties. 【Result】 The soil colloids of the four treatments showed the characteristics of slow aggregation(RLCA) at low electrolyte concentration and fast aggregation(DLCA) at high electrolyte concentration. The order of critical coagulation concentration of four different fertilization treatments was M > N+M > CK > N. Also the long-term application of organic fertilizer increased soil organic matter, thereby increasing the electric field strength near the surface of colloidal particles and the electrostatic repulsion between colloidal particles. Furthermore, the steric hindrance effects of humus weakened the phenomenon of colloid aggregation; On the other hand, long-term fertilization did not change the soil clay mineral composition type, but had an impact on its relative content. The application of organic fertilizer increased the relative content of 2:1 type illite and decreased the relative content of 1:1 type kaolinite. The application of nitrogen fertilizer reduced the relative content of illite and increased the relative content of kaolinite. 【Conclusion】 Different fertilization treatments for a long time changed the basic physicochemical properties and mineral composition ratio of brown earth colloids, which in turn affected the aggregation kinetics of brown earth colloids.
REN Kailu, ZUO Yan, KOU Qi, ZHANG Guangcai, ZHANG Yun, WANG Jingkuan, GAO Xiaodan. Comparative Study on Colloidal Aggregation Kinetics of Brown Earth under Long-term Fertilization[J]. Acta Pedologica Sinica,2024,61(2):484-494.Copy