Peanut ( Arachis hypogaea L.) yield and quality are seriously compromised by consecutive monoculturing in southeastern China. This work investigated the population size and community structure of soil nematodes in 3-, 6-, and 20-yr-old peanut monoculturing systems. A grass pasture was used as the control. The results showed that continuous peanut monocropping had detrimental effects on the soil nematode abundance and functional composition compared with the control. The reductions in the abundance of total and microbivorous nematodes with increasing years of monocropping are likely to reduce bioturbation and nutrient mineralization, and an elevated abundance of plant parasitic nematodes may result in serious damage to peanut roots, thus aggravating root rot. Furthermore, the significant variations in soil nematode functional indices across the three monocropped peanut fields may produce negative effects on sustainable agroecosystems. Our study also contributes to the identification of locally applicable indicator species of soil nematodes, i.e., Tylenchus, Doryllium, and Mesorhabditis, which can be applied in the assessment of soil status within monocropped peanut fields. Our results suggest that the soil nematode community exhibits evident responses to peanut monocropping.
