The effect of a medic-wheat rotational system and contrasting degrees of soil disturbance on nematode functional groups and soil microbial communities

During a four-year cropping cycle, the effects of cropping sequence (wheat-medic rotation and wheat monocropping) and contrasting degrees of soil disturbance (conventional tillage and zero tillage) on nematode functional guilds and soil microbial diversity indices and enzymatic activities were quantified. Extracted and identified nematode taxa were sorted into functional guilds and assigned to a colonizer-persister (cp) scale. Soil microbial species richness and abundance were measured using the Shannon-Weaver and Evenness diversity indices, respectively, while microbial enzymatic activities (ß-glucosidase, phosphatase, urease) were assayed to evaluate ecosystem functioning over time. Crop rotation and zero tillage practices increased nematode trophic linkages, whereas plant-feeding nematodes declined over time in soils subjected to conventional tillage practices. Zero tillage practices and crop rotation over time were found to increase soil microbial richness and evenness. Carbon, phosphorous and nitrogen mineralization rates were independently influenced based on cropping sequence, but were found to have increased (p < 0.05) over time under zero tillage practices. Quantitative analyses of integrated biological indicators under various agricultural management practices will assist in our understanding of possible practices to ensure healthier soils with the ability to support sustainable crop production.