Mixed tree-vegetative barrier designs: experiences from project works in northern Vietnam

There has been an increased interest in the use of vegetative barriers in acid-infertile upland management systems in Southeast Asia. This paper analyses the experimental designs and policies in early-1990s of using vetiver grass barriers (Vetiveria zizanioides L.) in microwatersheds with short-rotation tree plantations in Vinh Phu Province, Vietnam. Four different mixed tree-vetiver models on degraded Ferric-Plinthic Acrisols are discussed. It is concluded that the institutional approach of demonstrating vetiver barriers as a model had a poor cost-wise performance, and that the model itself did not address the underlying issues of land degradation due to uncontrolled harvest of organic matter from the forest floors. The institutional approach was tainted with price distortions and ‘disbursement-oriented’ actions. Alternative and more flexible on-farm approaches, using V. zizanioides or the indigenous leguminous shrub Tephrosia candida (Roxb.) DC as vegetative barriers, were found to be more cost-effective and likely to have a higher rate of adoption among farmers. The institutional changes in land allocation policies (securing long-term usufruct users and transfer rights of agricultural and forest land) that took place in Vietnam in the early 1990s, in combination with a reorientation of programme policies to support needs of individuals and farmers' households, are hypothesized to have contributed more to the ‘regreening’ of the hills, than any single approaches of technical barrier designs by the Swedish-Vietnamese Forestry Co-operation Programme (FCP) in northern Vietnam.