Quantifying the Economic and Environmental Benefits of Paraquat

Much has been written about the benefits of paraquat, currently the world's second largest herbicide in sales terms. It was introduced in 1962 by ICI and is now used in almost 100 countries and by an estimated 25 million, mainly small, farmers. However, previous examinations have tended to focus on the environmental benefits, such as reduced soil erosion in no-till situations, and been qualitative in nature. This paper looks at the economic and environmental benefits, quantifying them as far as possible in monetary terms and scaling them up to reach an approximate global estimate of the economic benefits. It pulls all available economic benefits information on paraquat together, but builds particularly on two recent case studies from Vietnam and the Philippines and also considers some new and increasingly topical aspects not addressed before such as soil microbial activity. All the studies presented provide strong evidence that the use of paraquat contributes to significant increases in farmer income, commonly in the range $20–400/ha. These increases can derive in roughly equal measure from the increased yields obtained, and the cost savings from reduced labour requirements for land preparation and weed control. The increased yields can derive from a combination of factors, some of which stem from paraquat's unique properties. In future it is likely paraquat's benefits will become even more important: Global warming will increase precipitation and extreme events such as floods, which will exacerbate the problems of soil erosion; Continued high and increasing levels of glyphosate use, especially with the increasing adoption of glyphosate-tolerant GM crops, will provide the basis for the continued spread of glyphosate tolerant weeds. With its unique mode of action paraquat will be an important tool in the armoury for combating weed resistance, especially in no-till situations. No new herbicide mode of action has been introduced since 1991, so it is vital to maintain access to those which already exist in order to address weed resistance to herbicides; As the process of migration from the countryside to the cities continues, GDP per capita in emerging markets grows and rural labour becomes more scarce, labour costs and with them the cost of land preparation and hand weeding will increase, further improving the cost-benefit of paraquat use.