EVALUATING SOIL HEALTH THROUGH NEMATODE ECOLOGY: A COMPARATIVE STUDY OF SOIL NEMATODE POPULATIONS IN CONVENTIONAL, ORGANIC, AND BIODYNAMIC VINEYARDS.

Soil nematodes occupy multiple trophic levels within the soil food web and are increasingly recognized as sensitive bioindicators of soil health and ecosystem function; however, their use in perennial systems such as viticulture remains underutilized. This study evaluated the effects of conventional, organic, and biodynamic vineyard management practices on nematode community structure, soil food web stability, and biological resilience across 17 vineyards in Massachusetts, New York, and Vermont. In total, 28,602 nematodes were manually extracted, identified, and assigned to 21 distinct families spanning bacterivores, fungivores, herbivores, omnivores, and predators. Soil food web indices, including the Maturity Index (MI) and Plant-Parasitic Index (PPI), were calculated to assess ecological conditions. Results showed that organic and biodynamic systems consistently supported higher MI values and more balanced PPI scores compared to conventional systems, indicating greater soil stability and reduced disturbance. Generalized Linear Models (GLMs) identified organic fungicide use as a positive predictor of MI, while synthetic insecticides and mowing practices were associated with reductions in PPI, suggesting management-driven shifts in nematode functional composition. Principal Component Analysis (PCA) further differentiated nematode community patterns based on management type and vineyard age, revealing a successional trajectory toward greater food web complexity in older sites that were organically and biodynamically managed. Methodological rigor was maintained through the reprocessing and cross-validation of 10% of samples, ensuring high taxonomic consistency and data reliability. The scale and depth of this work represent one of the most comprehensive nematode-based assessments of vineyard soil health in the northeastern United States. These findings highlight the critical role of ecological management in fostering soil biological diversity and resilience. Moreover, they demonstrate that nematode community analysis provides a cost-effective and ecologically meaningful tool for monitoring soil health and informing sustainable agricultural practices in vineyard systems.