Soil faunal community transfers nutrient cycling functionality and plant-parasitic nematode suppression from different depths of a natural soil to an agricultural soil

Soil biota play a pivotal role in shaping various ecosystem functions, ultimately contributing to soil health and human well-being. In this study, soil samples from four depths were collected from a remnant vegetation site and used as donor soil to assess whether soil fauna could transfer ecosystem functions, such as nitrogen (N) and phosphorus (P) cycling and nematode pest suppression, to a homogenised agricultural soil (receptive soil) in three incubation experiments. Ammonium, nitrate and plant-available phosphorus concentrations were measured as proxies for nutrient cycling, while the abundance of the two key plant-parasitic nematodes, Pratylenchus neglectus and Merlinius brevidens, served as proxies for plant-parasitic nematode suppression. Results revealed that soil fauna facilitated the transfer of up to 26 % more nitrogen from donor to receptive soil, but phosphorus levels remained unaffected. Nematode suppression effects were depth-specific and species-specific. The organic layer showed the highest nematode suppression, but depth 0-10 cm yielded the highest plant growth, suggesting physicochemical constraints in the organic layer. Nematode-based indices shifted towards a more mature and structured soil food web in the receptive soil. This study demonstrates the significant role of soil fauna in performing ecosystem functions particularly N cycling and plant-parasitic nematode suppression. These findings highlight the potential for using targeted soil amendments to enhance soil health, ultimately contributing to sustainable plant growth.