Upland Farming Systems Coping with Uncertain Rainfall in the Central Dry Zone of Myanmar: How Stable is Indigenous Multiple Cropping Under Semi-Arid Conditions?

摘要

A semi-arid climate that has relatively low and uncertain rainfall, 500 to 1,000 mm per year with a coefficient of variation greater than 0.2, is a harsh ecological condition for rural people engaging in rain-fed farming in the tropics. Unstable production of rain-fed farming in African and Asian dry regions has been widely reported, for example, maize and sorghum in Zimbabwe, Malawi, and Zambia at the national and village levels (Scoones et al. 1996; Takane 2006; Kajoba 2008; Lekprichakul 2008), and rain-fed paddy farming in Northeast Thailand on the village level (Kaida et al. 1985; Miyagawa and Kuroda 1988). Rural people in such dry regions in developing countries have generally diversified income sources to mitigate ecological and market risks by integrating crop production, animal husbandry, and non-farm activities (Scoones 1995; Ellis 2000; Uphoff 2002). Additionally, social networks such as mutual aid within kinship groups as well as among wider social groups contribute to stabilizing livelihoods under uncertain conditions (Berry 1989; Shimada 1999). In addition, farmers often combine a variety of crops to cope with fluctuations in climatic and economic conditions (Devendra and Thomas 2002). Such multiple crop farming could limit the negative impact of an ecological risk on farm households, but crop diversity does not prevent outbreaks of crop disease or pests (Goldman 1995). Using data from farm experiments or analyses of farmers’ perceptions, a number of previous studies have suggested that intercropping and mixed cropping can achieve higher stability of total outputs and income than monoculture (Francis and Sanders 1978; Sugimura 1987; Francis 1989; Kajoba 2009). However, few studies have examined in depth how and to what extent multiple cropping systems reduce ecological risk and increase the stability of production in rural villages and farm households.