Forage legume establishment in rice slash-and-burn systems.

Abstract

Increasing population pressures combined with government policies exert considerable pressure on traditional slash-and-burn farmers in northern Laos to change to other production systems. Replacing the natural fallow vegetation with fodder legumes could increase fodder availability, suppress weeds, and accelerate nutrient cycling. Establishment methods for potential forage species were evaluated at the Houay Khot station during 1992 and 1993. When broadcast into upland rice immediately after weeding in July, good or excellent establishment was observed for Stylosanthes guianensis, S. hamata, Macroptlium atropurpureum, Pueraria javanica. P. phaseoloides, Calopogonium mucunoides, C. caeruleurn, Leucaena leucocephala, Centrosema pubescens, and C. plumieri. Poor establishment was observed for Arachis pinto!, Flemingia congesta, Crowaria anagyroides, C. juncea, pigeon pea (Cajanus cajan), Tephrosia vogelil, and Lablab purpureus. July and August sowings resulted in better plant densities thaui June or September sowings. However,, early sowing of &ylosarzthes species reduced rice yield by 20-30% in 1993. Dibbling rice mixed (same hill) with leucaena resulted in good establishment without detrimental effect on rice yield, while dibbling race mixed with pigeon pea reduced rice yield by 55-65%.