Abstract:ObjectiveThe aggregate distribution, the composition of the fungal community, and the production of biological binding agents can be significantly changed by different nitrogen (N) application rates. However, whether there is a correlation between these properties remains unclear.MethodA 16-year field experiment located in Fengqiu Agro-ecological National Experimental Station was used as the research platform, and this included five levels of N application rates, i.e. (1) F0: 0, (2) F1: 150 kg·hm-2, (3) F2: 190 kg·hm-2, (4) F3: 230 kg·hm-2, and (5) F4: 270 kg·hm-2. The effects of different N application rates on water-stable aggregate distribution (> 2 000 μm, 2 000-250 μm, 250-53 μm and < 53 μm) were explored, and the correlation between aggregate distribution and the major biological binding agents(glomalin-related soil proteins(GRSP) and microbial biomass carbon (MBC)) and soil fungal community was studied.ResultThe soil aggregate distribution and fungal community composition were divided into three significantly different groups: F0, F1 and F2, F3 and F4, respectively. The results showed that: (1) F1 and F2 treatments had the highest mean weight diameter of soil aggregates and significantly increased the proportion of > 2 000 μm aggregates and this was mainly related to the enrichment of Pyrenochaetopsis; (2) F1 and F2, F3 and F4 treatments all increased the proportion of 2 000-250 μm aggregates, while they significantly decreased the proportion of < 53 μm aggregates. The increase of the proportion of 2 000-250 μm aggregates was significantly positively correlated with the ratio of easily extractable glomalin-related soil proteins to total glomalin-related soil proteins (EE-GRSP/T-GRSP) and easily extractable glomalin-related soil proteins (EE-GRSP). However, it was significantly negatively correlated with the relative abundance of Didymella and Mortierella. The decrease of the proportion of < 53 μm aggregates was significantly positively correlated with the relative abundance of Mortierella, Phlebia, Melanospora, Fusicolla, Podospora and Didymella, but significantly negatively correlated with EE-GRSP and/or the relative abundance of Acremonium, Scytalidium and Exophiala, EE-GRSP/T-GRSP and MBC.ConclusionThe variation of soil aggregate stability was affected by the level of N application. Also, the stability of soil aggregates under N application rates of 150 kg·hm-2 and 190 kg·hm-2 was higher than that under N application rates of 230 kg·hm-2 and 270 kg·hm-2, which was significantly correlated with the changes in fungal community composition and biological binding agents under different N application rates.