The combination of fragile, often steeply sloped terrain, low fertility, crops unsuited to the terrain, lack of external inputs, and “slash-and-burn” farming techniques results in serious and rapid soil exhaustion, erosion and sedimentation 3 [see Annex 1]. In these cases, cleared land has to be abandoned after only a few cropping seasons, triggering a need for further forest land conversion farther out on the agricultural frontier. The impacts of such “informal agricultural expansion” on downstream infrastructure, including roads, irrigation, water supply, and hydroelectric facilities often far exceed the value of the crops produced. The uncontrolled expansion of agriculture on marginal land is also a major cause of.
