Building research on farmers' innovations: soil conservation using low-cost natural vegetative strips and soil fertility management

Contout hedgerows using nitrogen-fixing trees have widely promoted in Southeast Asia to minimize soil erosion and improve crop yield, but few farmers have taken them up. This is party because establishing and managing such hedgerows is very labor-intensive. The spontaneous use of narrow buffer strips consisting of natural vegetation, so-called Natural Vegetative Strips (NVS), by farmers in the philippine uplands has been viewed as a low-cost, yet effective alternative to the establishment of tree hedgerows. Formal research on this farmer technology proved that NVS are at least as effective in controlling soil erosion as tree hedgerows, while causing minimal competition effects on the associated field crop and requiring only a fraction of the labor needed to establish and maintain pruned tree hedgerows. As in convetional hedgerows system, however, natural, terrace formation resulting from the redistribution of sediment from upper to lower terrace zones, a process called 'scouring', leads to the development of a soil fertility gradient. The result is a significantly lower crop yield on the degraded upper terrace concluded that practices, which increase soil organic matter levels and raise the soil pH, may be needed to sustain yield in NVS systems in the long run. Future research by the International Centre for technology, along with improved soil fertillity management practices anf fruit and timber trees planted on the strips, under the contrasting conditions of the shallow, marine limestone-derived soils typical of the central Philippines. This is another major soil enviroment, common in several countries in Southeast Asia. The active participation of local land users in the research process, and the strengthening of the efficient development and dissemination of appropriate soil conservation technologies.