Rethinking erosion on Java: a reaction

In a recent article (Diemont et al., 1991) about erosion on Java, it has been postulated that low inputs, not surface erosion, is the main cause of low productivity of upland food crops on this island. In this article it is argued that this hypothesis is too simple. An analysis of empirical field data about the effect of erosion on crop productivity indicates that the effects of erosion and agronomic inputs are confounded. Erosion causes farmers to apply low inputs because only limited returns can be expected on eroded lands. The relations between erosion and crop productivity are site specific; the extent and quality of conservation measures and intensity of agronomic inputs varies per soil type.