Diversity, Abundance, and Distribution of Soil Nematode Communities in Wheat Agroecosystems

Soil nematodes are a part of soil food webs and are sensitive indicators of soil ecological conditions. In this study, the diversity, abundance, trophic structure and temporal distribution of soil nematode communities in a wheat (Triticum aestivum L.) agroecosystem were evaluated over a period of one year. We collected soil samples on 8 occasions from June 2008 to April 2009, with cover ranging from different crop growth stages, including fallow periods, in a conventionally cultivated wheat field, Aligarh district, India. Nematodes were obtained by modified Cobb’s sieving and decantation followed by Baermann funnel technique and identified to the generic level. A total of 50 nematode genera with 10 orders and 30 families were identified. Number of genera per sample varied from 13 to 23, with total nematode abundance being between 105 to 1178 individuals. The most abundant order was Rhabditida, and Dorylaimida had the highest level of generic diversity. Within trophic groups, bacteriovores were the most common organisms (58%) and were followed by fungivores (21%), herbivores (13%), omnivores (5%), and predators (3%). The most common genus throughout the course of the study was Acrobeloides. The measured trophic diversity index was from 1.03 to 1.25, suggesting moderate trophic complexity. Seasonal dynamics were well recorded with high levels of bacteriovorous nematodes in post-harvest periods, probably as a consequence of the higher organic matter content generated due to crop residues. The evidence indicates that soil nematode community structure is highly determined by crop phenology, organic amendments and the season. Soil nematode faunal analysis was used in this study and is effective for assessing soil health and ecosystem functioning in wheat-based agroecosystems.