Intensification of Shifting Cultivation by the Use of Viny Legumes in Northern Thailand

Abstract

The present study describes a complex multiple cropping system of six crops which has evolved in a Lisu village in Chiang Mai during the last 17 years. The system involves relay planting of three viny legumes [cowpea (Vigna unguiculata), rice bean (Vigna umbellata) and lablab bean (Lablab purpureus)] after inter-cropping of maize and wax gourd (Benincasa hispida) or pumpkin (Cucurbita moschata). The relay-cropping of the three viny legumes could be considered as a locally evolved type of accelerated seasonal fallow management aimed at soil fertility replenishment and income generation in an intensified shifting cultivation system. The Lisu farmers adopted this system because of their prior experiences on market economy and their knowledge of multiple cropping technology through previous maize-opium based farming, as well as because of the availability of a large area of fertile land to sustain intensive cultivation without external inputs. The ability of the multiple cropping system to generate acceptable income and the availability of transportation for the products were also positive factors favoring its adoption. On the other hand, its lower profitability than competitive cropping systems, such as vegetable seed production, and its requirement for good transportation, large farm size and fertile soils constrained its expansion. The present study also revealed that external factors of economy and technology development are crucial in determining if environmentally beneficial cropping systems will continue in use in the long-term or be replaced with less environmentally friendly agricultural practices.