Earthworms are well known for their casting and burrowing activities which improve soil structure and soil fertility. However, earthworm populations in temperate regions exhibit patchy distribution in space and time. This makes it difficult to predict how earthworm activities may influence paedogenesis and nutrient cycling processes at the ecosystem level. The main objective of this study was to determine the spatiotemporal dynamic of surface cast production of two earthworm species, Aporrectodea turgida and Lumbricus terrestris, on the row-interrow scale in a temperate soybean agroecosystem. Our observations demonstrated that casting activity was synchronous with plant growth. More casts were also found in the row intercepts compared to the interrow ones. Both the spatial and temporal variations are thought to be caused by the microclimate found under the plant canopy, verifying results from controlled laboratory studies that show casting activity to be controlled by soil temperature and moisture. These results suggest a possible mutualism between earthworm and plants in cultivated temperate soybean agroecosystems, but this remained to be confirmed.

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