Conservation agriculture in organic farming: Experiences, challenges and opportunities in Europe

Abstract

Conservation tillage includes a range of tillage practices, mostly noninversion, which aim to reduce soil erosion by leaving the soil surface covered by crop residues. Despite conservation tillage having been promoted in organic farming (OF) to improve inherent soil quality, several factors hinder its development such as weed control and soil compaction. Consequently, to enhance the adoption of conservation tillage in OF, long-term experiments were established several years ago in Europe. Different tillage techniques have been assessed from mouldboard ploughing to direct drilling under cover crops. In all cases, the effects of conservation vs. conventional tillage on soil fertility and weed and crop development were compared. Preliminary results show that the effects of conservation tillage are closely related to soil and climatic conditions, practices conducted in the field, and initial experimental conditions (level of weeds, previous crop, soil structure, etc.). Direct seeding under a cover crop or mulch remains a major challenge in OF, since weeds are not mechanically controlled, which thus affect crop performance. However, with other reduced tillage techniques, such as using a layer cultivator, weed development has had minimal effects with no impact on yields. In addition, to improved soil fertility, reduced tillage can increase crop yields. Most of the results of conservation tillage effects were obtained from experiments conducted for less than 10 years under OF management. Assessment over longer periods is needed and then shared with organic farmers to design new cropping systems. Introduction of new equipment and knowledge exchanges between conventional farmers practising conservation tillage and organic farmers could improve the adoption of conservation tillage in OF.