In intensive flooded rice systems that predominate in much of Asia, the management of crop residues can be a problem. With two or three crops grown each year, there is not enough time for the residues to break down and be incorporated into the soil. The Philippines produces approximately 15 million tons of rice per annum and this generates about 11 million tons of rice straw. In the past, farmers manually harvested rice and plowed the rice straw back into their fields. However, increased mechanization and, in particular, the use of combine harvestersleave more rice straw that is difficult to plow back into the soil.
The alternative of uprooting and collecting the straw is both labor intensive and increasingly expensive as labor in rural areas becomes scarcer. The easiest and cheapest method for farmers is to burn the straw in their fields. Farmers in the Philippines burn about 70% of the rice straw and this contributes to greenhouse gas emissions and air pollution, not to mention the loss of important nutrients from the soil. The problem that comes with the burning of straw, and its detrimental impact on the environment and human health, is not confined to the Philippines. The smog problems that affect Delhi in October and November have been linked to the burning of rice straw.
Almost two decades ago, the country enacted the Philippine Clean Air Act of 1999 to introduce stringent pollution standards and provide comprehensive policies to reduce, control, and prevent air pollution. The law not only covers the industrial and transportation sectors but also prohibits open-field burning, including that of rice straw. Although the legislative framework is important, it is seldom sufficient on its own to reduce the incidence of burning. There is also a need to provide incentives for farmers to reduce straw burning. Such incentives include the use of rice straw in ways that contribute to improved farmers’ livelihoods.