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Key principles
DMCS MIRROR THE FUNCTION OF FOREST ECOSYSTEMS Featured
DMCs are designed to function like forest ecosystems, which are naturally stable, sustainable and based on high biological activity. This biological activity replaces mechanical tillage and enhances the soil structure, nutrient recycling and water management. These systems emulate the function of forests by promoting litter production and functioning in a closed circuit, without loss of material (chemical elements and soil) in deep horizons or on the surface, and with constant recycling between dead and live plant material. On a plot scale, DMCs are based on three key principles: The soil is never tilled and crops are sown by direct seeding.Plant cover (dead or live) provides permanent soil cover. Crop sequences or rotations are implemented in association with cover plants. The technical conditions for DMC implementation vary markedly depending on the prevailing socioeconomic and agroenvironmental settings. No standard ‘recipe’ can thus be proposed, which would be too simplistic.
PRINCIPLE 1: THE SOIL IS NEVER TILLED Featured
When a soil is not tilled for several successive years, the more or less transformed biomass (crop residue and cover) accumulates to form a mulch layer that protects the soil against erosion and climatic variations (buffer effect). In DMCs, traditional ploughing is replaced by ‘biological tillage’ via the root systems, which create an environment that is highly favourable for fauna, which in turn ‘biologically process the soil’ (worms, termites, etc.). In untilled soil, this creates a suitable habitat for the development of various organisms, ranging from insects to bacteria and microscopic fungi. These organisms process, incorporate and mix the mulch into the soil and decompose the product to form humus. Fungi and soil microfauna (worms, etc), or so-called ‘soil engineers’, feed on organic matter lignin, which is then further degraded by bacteria. This macrofauna is also involved in the formation of aggregates and galleries (macropores) in the soil. This activity distributes the organic matte ...
PRINCIPLE 3: CROP ROTATIONS Featured
In addition to their nutrient pump role, rotations of various plant species diversify the soil flora and fauna. Their roots secrete different organic substances that attract a diverse range of bacteria and fungi. These microorganisms subsequently play an important role with respect to nutrient availability for the crops. Crop rotations are especially important for integrated pest management since they upset the pathological cycles. Weeds are controlled through the effects of shade (competition for light) and/or allelopathic effects (competition between plants of different species via toxic substances excreted by the roots or leaves). Crop diversification also provides a range of different products (food for humans and livestock), thus enhancing economic stability.
PRINCIPLE 2: THE SOIL IS PERMANENTLY COVERED BY PLANTS Featured
Live or dead (straw) plant mulch provides permanent soil cover. Residue from the previous crop can be left on the soil or cover plants can be sown (row or relay intercropping). To avoid competition with the main crop, the cover is subsequently dried (mown, crushed or herbicide treated), kept alive or potentially controlled under the crop canopy by a low-dose herbicide treatment. Then the biomass is left on the surface, not buried. Finally, seeds are sown directly in the residual plant cover after opening a hole or furrow with an adapted seeder (manual cane planter or stick). Cover plants are selected according to their complementarity with the main crop, their possible uses (food for humans or livestock), but especially their soil fertility enhancement potential. They are carefully selected to emulate the function of forest ecosystems—they must provide quick biomass production and have a root system that can reach deep groundwater supplies. These plants act as ‘nutrient pumps’: Their powerful root ...
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