7.3.1 Compost

Compost is a product derived from composting that is high in nutrients and rich in humic acids. Nutrients are usually bound organically and thus released at a moderate speed (Gobat et al. 2003). Mature compost contains a diverse community of microorganisms; addition of compost to soil modifies considerably its biological,

Decomposition of organic residues
and chelation with ash panicles

Release of soluble humic material
and aliphatic organic acids

Reduction in the quantity
of exchangeable Al

Fig. 7.1 A conceptual model of the major processes that lead to the detoxification of soil aluminum and an increase of phosphorous availability when wood ash compost is applied to acid soils

physical, and chemical properties in the short term as well as in the long term (Ryckeboer et al. 2003; Fuchs 2009). The use of compost in agriculture aids in replenishing and maintaining long-term soil fertility by providing optimal condi­tions for soil biological activity and a slow flow of nutrients adapted to the needs of the crop (Gobat et al. 2003).