Soil fauna and soil fertility

Research to seek low input sustainable agricultural systems in the tropics during past decades has suggested a need to maintain the activity of soil fauna. In this chapter, we synthesize/review the role of earthworms (Hyperiodrilus africanus and Eudrilus eugeniae)(macrofauna) and soil microarthropods (mesofauna) in maintaining and improving soil fertility in West Africa. Earthworms contribute to the breakdown of organic materials and improve soil structure. As a result of mutualistic relationships with microflora inside their gut, earthworms digest some organic compounds and increase nutrient mineralization. Soil organic matter can be protected within casts. Research has confirmed the positive effect of earthworms on plant growth and crop yield, although mechanisms governing such processes are not fully understood. The exclusion of soil microarthropods has reduced litter decomposition rates. Evidence has been found that role of soil microarthropods in litter decomposition becomes more important under environmentally stressed conditions. The restoration of populations of earthworms and soil microarthropods lost with the conversion to agricultural systems in West Africa is discussed in the context of natural and planted fallow, cover cropping, and plant residue mulch that could potentially increase ground cover and organic input, and reduce soil disturbance.