Soil structure and earthworm activity under different tillage systems in organic farming

Summary

Organic farmers are encouraged to adopt conservation tillage to preserve soil quality and fertility and prevent erosion. However, many studies in different soil and climate conditions have demonstrated that the compaction of the untilled layer is higher in conservation tillage than in conventional tillage. As earthworm activity may help alleviate soil compaction in organic farming, the impact on the soil structure and earthworm population and activity was studied for 4 different tillage managements (1) mouldboard ploughing (MP), (2) shallow ploughing (SP), (3) reduced tillage (RT) and (4) no-tillage (NT), in 3 french areas. The first results are: (1) MP soil structure is better than SP, RT and NT, (2) water infiltration is higher at soil surface in SP, RT and NT, lower at 17 cm depth, (3) more earthworms, especially anecic species, are found in NT, (4) but more opening channels are found in MP. Then, during the first years of transition from MP to NT, soil structure is better in MP, and whereas earthworm numbers is reduced, it favours earthworm activity.