Toward a Stable Low-Input Highland Agricultural System: Ley Farming in Imperata cylindrica Grasslands of Northern Thailand

Abstract

This paper considers popular misconceptions concerning Imperata cylindrica grassland areas and Imperata succession in Northern Thailand. It provides a description of a suggested ley farming system (alternation of pastures and crops). Only 2.5 percent of 2,500 km2 of Northern Thailand is covered by I. cylindrica, nearly all between 1,000-2,000 m and in the western part of the north. There is little evidence that watershed characteristics of I. cylindrica grassland are inferior to those of forested areas; it is readily grazed and is a poor competitor under grazing; it is also relatively easy to establish improved pasture; and grazing quickly results in sown legume dominance to the almost total exclusion of I. cylindrica. I. cylindrica is found mainly in maize/opium areas and is absent from the Karen integral swiddening areas. Establishment of I. cylindrica can be attributed to the removal of shade in the seed and seedling phase; this is a consequence of the intensive weeding practised in the maize/opium swidden systems. Preliminary experiments indicate the benefit of a previously fertilized sown legume pasture to a subsequent upland crop. I. cylindrica grassland should be oversown with Desmodium intortum cv. greenleaf pastures and grazed for 2-3 years, and then dibbled and cultivated with upland crops for two years. Management details are presented. Major constraints to the adoption of ley farming in the Northern Thailand highlands include entrenched traditional tribal attitudes, lack of expertise and interest by official personnel and organiza- tions, and the current high price for opium coupled with the ease of growing and selling it.