Cassava is mostly cultivated by smallholder farmers living in marginal and fragile environments, 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 somehow undeserved reputation. 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 the low value of cassava products, the application of manures and chemical fertilizers, which could easily correct nutrient depletion, may not be economically justified or not affordable for smallholders. However, it should be noted that, at current yield levels, soil nutrient depletion by cassava is lower than by that of other crops (FAO, 2001b).
Erosion
Cassava production can cause serious erosion when the crop is grown on slopes 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 serious 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 broad effects on biodiversity, though some local situations, such as deforestation in the northeast of Thailand or the competition with native cassava species in Latin America, may merit attention (FAO, 2001b).