Nematode community structure and its relationship to soil health in vegetable cropping systems

Abstract:

Much like a physician reads a blood panel to gauge a patient’s internal condition, soil ecologists can read the nematode community to assess what is happening beneath the crop canopy long before visible symptoms emerge. This research characterised nematode assemblages under three vegetable management systems—continuous monoculture, two-year rotation, and rotation with a fallow phase—at 24 field sites near Hawassa, Ethiopia, between April 2022 and October 2023. From 192 composite soil samples collected over eight sampling rounds, a total of 41,260 nematodes were extracted, identified to genus, and assigned to trophic groups. Bacterivores made up 39-48% of total abundance across systems, while plant-parasitic nematodes peaked at 29.4% under monoculture and dropped to 11.8% under fallow rotation. The Maturity Index was 2.14 in monoculture versus 3.91 in fallow rotation. Structure Index followed the same gradient (28.7 vs 74.8). Soil organic carbon correlated most strongly with the Maturity Index (r = 0.84, p<0.01). These results validate nematode-based profiling as a practical biological indicator of soil condition in Ethiopian vegetable production.