Assessment of soil food webs across time and place: How do nematode communities infer shifts in soil function over 30 years under systems of varying management intensity?

Background/Question/Methods

Agriculture intensity decreases soil biodiversity and soil health, which can be assessed using free-living nematodes. Specifically, nematodes can indicate soil food web structure and function because they span the trophic food web and are sensitive to management perturbations within the soil environment. Currently, little is known regarding how free-living nematode communities can infer soil biological health within row-crop agriculture systems. The objectives of this study were to 1) Assess how contrasting agricultural management impacts soil food web structure and function after 32 years 2) Evaluate how nematode communities can infer soil biological health. Soil samples were collected in 2021 from treatments that ranged in management intensity at the W.K Kellogg Biological Station (KBS) Long-Term Ecological Research site (LTER). Samples were collected during the soy year from the following treatments: conventional corn-soy-wheat, no-till corn-soy-wheat, reduced input corn-soy-wheat, biologically based corn-soy-wheat. Additionally, samples were collected from two perennial systems, poplar and perennial switchgrass, and two unmanaged system, an early successional community and mown grassland. Free-living nematodes were extracted from each sample and identified to genus. Additionally, we used the National Science Foundation funded KBS LTER dataset to compare nematode community shifts from year one to year 32 of the KBS LTER study.

Results/Conclusions

Results indicated that treatments with reduced management intensity and increased perenniality had a more structured nematode community and a greater abundance of nematodes that are sensitive to management perturbation. Specifically, perennial systems were found to enhance nematode community structure (p< 0.05). When comparing nematode communities between 1989 and 2021, treatment effect appeared to be more significant in 2021. These results indicate that long-term management does have a significant effect on soil biological health. In conclusion, this study indicates that soil biodiversity and soil health can be enhanced through management practices that incorporate perennial species and are reduced in disturbance.