Free-living nematode community structure and distribution within vineyard soil aggregates under conventional and organic management practices

Abstract

Soil biota play a crucial role in soil ecosystem stability, promoting decomposition of organic matter and nutrient cycling. The influence of organic farming versus conventional farming is known to improve soil properties such as aggregation. Despite the importance of soil microbial communities in soil biogeochemical processes, our knowledge of their community dynamics is rudimentary especially under different agricultural managements. Here we studied the effect of two types of vineyard managements (conventional, and organic), and three soil aggregate sizes (macro – LMA, 8,000-9,800 μm; meso – SMA, 500-2000 μm and micro – MA, <500 μm) on free-living soil nematodes. The abundance, diversity, and indices of free-living soil nematodes were determined. We found that the abundance of free-living soil nematodes increased with organic treatment, and that the nematode community guild structure altered toward changes in the Wasilewska index, where plant parasites were found to increase macro-aggregates in the agricultural practices that may be attributed to weed management (no-tillage and no herbicides) in the organic treatment. The network connectivity increased in complexity with increasing aggregate sizes, highlighting the importance of the interplay between nematodes and soil inter-aggregate pore size and connectivity.