Burn or bury? A comparative cost-benefit analysis of crop residue management practices among smallholder rice farmers in northern Vietnam

摘要

In Vietnam, approximately 39 million tons of rice (Oryza sativa) residues are produced every year. While a substantial quantity of these residues are used for animal feed, soil mulching, or fuel purposes, a large portion is burned on-farm. The burning of crop residues not only causes environmental pollution through greenhouse gas emissions adding to global warming but also results in the depletion of valuable nutrients such as nitrogen, phosphorus, and potassium. With current increasing trends in cropping intensities, the amounts of residues that are burned on the field are expected to increase dramatically, unless crop residues are managed more sustainably. In this study, we examine the present cropping systems and the patterns of crop residue management prevalent in three different ecological zones of Northern Vietnam. We compare the farmers' practices of either burning or incorporating the residues of their rice crops, and furthermore, calculate involved costs and benefits. Our data demonstrate that the burning of crop residues might be an erroneous trend from an ecological perspective, but is rational from an economic point of view. Based on this finding, we argue that a change of the prevalent burning practice cannot be achieved without the farmers getting their extra expenses refunded.