Abstract: Nematodes are a class of active organisms in soils, with important ecological functions in maintaining the stability of soil ecosystems and promoting material cycling and energy flow. At present, the response of nematode communities in soil aggregates in fluvo-aquic soils of the North China Plain under different tillage methods is not clear. In this study, we investigated the effects of tillage methods on nematode community in soil aggregates in a fluvo-aquic soil in Qihe County, Shandong Province. There were four treatments, including rotary tillage + straw return (RT), deep plowing + straw return (DP), deep loosening + straw return (SS) and no-tillage + straw return (NT). The results showed that deep loosening and no-tillage treatments increased the percentage of bacterial-feeding nematodes in small mega-aggregates (2-5 mm), and decreased that of plant-parasitic nematodes. Moreover, deep loosening and no-tillage treatments increased the Wasilewska index (WI), which was favorable for bacterial-feeding nematodes to participate in organic matter and nutrient cycling. Deep loosening and no-tillage treatments increased the soil nematode pathway index (NCR), and increased soil organic matter index in large mega-aggregates (> 5 mm), within which the decomposition pathway of soil organic matter was dominated by bacteria. Soil organic carbon, total nitrogen content, and soil pH were the main environmental factors affecting the total number of soil nematodes and the number of each trophic group. Overall, deep loosening and no-tillage conditions favored the formation of stable nematode community structure in soil aggregates, which provides a theoretical basis for the selection of farming practices in the fluvo-aquic  soils of the North China Plain.

Key words: soil nematode, farming method, fluvo-aquic soil, North China Plain, soil aggregate