Recycling Organic Waste Products in a Tropical Context

Organic waste products are defined as all residues of an organic nature and of agricultural, urban or agricultural‐industrial origin emphasized in agriculture. Composting is an aerobic process of transforming organic matter. Anaerobic digestion (or methanation) is also a biological process of degradation of organic matter, but which takes place in the absence of oxygen. Changes in the biological characteristics of soils, after the input of organic waste products, are revealed on macrofauna (hymenoptera, etc.), microorganisms (bacteria, fungi, algae, etc.) and their activities. Beyond affecting the actual fertilizer value of organic waste products, nitrogen losses through ammonia volatilization contribute to the eutrophication of ecosystems and the genesis of acid rain. The inexorable decline in the organic matter content of tropical soils is mainly linked to their rapid mineralization due to high temperature and humidity variations as well as soil types. Sandy soils, ferrasols, with low nutrient retention and organic matter accumulation capacities, are particularly vulnerable.