Most cassava is produced by smallholder farmers living in marginal and fragile environments, and particularly on erosion-prone, acid and infertile soils. This ability to produce on poor soils, where most other crops would fail, has given cassava a reputation as a safeguard against food scarcity. However, there are serious environmental concerns about cassava production (FAO, 2001b). For the environmental impact of cassava processing, see the Cassava by-products datasheet.
Soil nutrient depletion
Cassava production can be detrimental to soil fertility through crop removal of nutrients. Due to the low value of cassava products, the application of manure and chemical fertilizers, which could easily correct nutrient depletion, may not be economically justified or affordable for smallholders. However, it should be noted that, at current yield levels, soil nutrient depletion by cassava is lower than depletion caused by other crops (FAO, 2001b).
Erosion
Cassava production can result in serious erosion when the crop is grown on slopes or on light soils. Good agronomic practices (adequate fertilizer, closer plant spacing, planting on contour ridges, intercropping, reduced tillage), used alone or in combination, can reduce erosion by 50-90%. Properly managed cassava production on slopes does not necessarily cause erosion (FAO, 2001b).
Water pollution
It is considered unlikely that cassava production results in water pollution, as it is grown mainly by poor farmers who apply no or very low rates of fertilizers, pesticides and herbicides. However, this may change in the future (FAO, 2001b).
Biodiversity
Cassava production does not seem to have had widespread effects on biodiversity, though some local situations may merit attention, such as deforestation in the north-east of Thailand or the competition with native cassava species in Latin America (FAO, 2001b).