Abundance of earthworm species is influenced by the proximity to the tile drainage

English Abstract:

Earthworm burrowing affects water movement and nutrient transport in soil layers to a depth of more than 1 m, which is where subsurface tile drains are found. Subsurface tile drainage changes the soil moisture regime and is expected to alter the abundance as well as the composition of earthworm populations. The impact of tile drainage on earthworms will depend on soil properties, land use (cropping systems) and management. The objective of this study was to evaluate how earthworm abundance and composition was affected by the presence of subsurface tile drainage, and how the relationship was modulated by soil type and cropping systems at two farms in Southern Quebec. The spatial distribution of earthworms was considered in two 3m triangles located on top and between tile drain lines, which were the sampling points for earthworm collection by formalin extraction and hand sorting. We expect that earthworm species will respond differently to the presence of tile drain lines and anticipate an increase in earthworm populations above the tile drain lines, particularly of anecic species. The modulating effect of soil and land use on earthworm abundance and distribution gives us the opportunity to explain the spatial distribution pattern of earthworm species in this context. Knowledge about the number and distribution of earthworm species in relationship to tile drain lines permits us to draw conclusions about the potential contribution of earthworms to soil porosity and solute movement in tile-drained fields, which could be important to avoid nutrient loss from agroecosystems with tile drainage.