Dynamic changes of soil nematodes between bulk and rhizosphere soils in the maize (Zea mays L.)/alfalfa (Medicago sativa L.) intercropping system

Abstract

The importance of habitat spatial variability as a key driver of soil biota patterning (e.g., soil nematodes) has lately gained a lot of attention. It is generally accepted that rhizosphere soil has a distinct faunal assemblage than bulk soil, but less is known about the patterning of soil nematodes and the causes of these changes in maize-alfalfa agroecosystems. As a result, the purpose of this study was to assess the dynamic changes in soil nematodes across bulk and rhizosphere soils when maize and alfalfa were grown separately and in a combination at varying levels of nitrogen fertilizer. The results of a field experiment in a 2 × 3 factorial completely randomized block design revealed that total nematode and omnivore-predator abundance, as well as nematode generic diversity and richness, maturity, and structure indices, were significantly increased in the rhizosphere of monoculture alfalfa and alfalfa grown in a mixture with maize when compared to the bulk soil. Furthermore, we discovered elevated levels of total sugars and organic acids in rhizosphere soils. Plant- and fungal-feeding nematodes increased in both bulk and rhizosphere soils, whereas omnivores and predators decreased in soils treated with monoculture and nitrogen fertilizer. Furthermore, we discovered a significant positive relationship between total nematode and omnivore-predator abundance and soil organic carbon and total nitrogen, soil moisture content, and microbial biomass C and N, implying that changes in these soil properties and rhizodeposition may shape the nematode community assemblage between the bulk and rhizosphere soils. Our findings suggest that crop mixes containing alfalfa would improve soil characteristics and rhizodeposition, resulting in increased nematode number and variety and contributing to sustainable agriculture.