Synonym(s) : Living mulch; no tillage; zero tillage; strip tillage; stubble tillage; conservation tillage
Set of various techniques to prepare the soil at varying depths but without turning over the soil. This evolution of tillage was brought about by wind and water erosion issues in the United States of America and Brazil in the last century. The spread of these practices has been relatively slow in France. Today, this set of techniques is well developed on oilseeds and cereals.
- Pseudo-ploughing consists of mixing the residues at the surface and loosening the first 15 to 30 centimetres without turnover. Several passages can result in less than 30% of soil covered by residues, which no longer meets the criteria of conservation agriculture.
- Shallow tillage mixes crop residues and sometimes leaves a portion at the surface to limit erosion, but there is no turnover. It is equivalent to a pseudo-ploughing for a depth of less than 15 centimetres.
- Strip-till is based on the establishment of crops in a strip of land worked to a depth of 15 to 23 centimetres. The intact inter-row is covered by plant residues or a living mulch.
Using these techniques, it is possible to limit erosion but not cancel it, and limit soil compaction. These techniques have a positive impact on soil life but require greater technical control than ploughing does in order to ensure good planting (enough fine soil) without promoting the creation of a slaking crust. The preservation of a good soil life is part of the preservation of biodiversity and the conservation of soil fertility, which are principles of agroecology.
The management of weeds and certain pests is more difficult in simplified tillage because of the absence of soil turnover. In addition, the mineralization of humus is slow in spring and soil temperature is reduced (pH as well under certain circumstances). It is therefore necessary to combine other levers such as the diversification of crop rotations (the second tenet of conservation agriculture) or the anticipated intake of nitrogen fertilizers.