.:: Lao Knowledge Base on Conservation Agriculture ::.
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 matter in different soil layers and mixes it with mineral matter derived from rock decomposition. Finally, the soil structure is improved and stabilised. Water infiltration is also facilitated, thus reducing runoff and risks of flooding during rain storms.
