Agriculture and Environment: Rice

Better Management Practices: Develop Innovative Production Systems

Rice can be cultivated without paddies and possibly still give yields that are superior to those obtained from paddy culture.

It can be irrigated with drip irrigation or over-head sprays in areas where adequate and timely rainfall is not reliable.

Rice can be grown in ways similar to vegetable crops and can even be mixed with vegetables and tubers in polyculture systems. New multicrop polyculture technologies could eliminate the need to convert broad areas of land for flooding, which can destroy habitat and local biodiversity in large regions, uses scarce water resources inefficiently, and can even fail.

This perspective is virtually absent from the major rice research institutions, though in fact this "technology" already exists. In Indonesia, Japan, China, and India these types of farming have existed in very old systems for centuries. They can provide insights as well as alternatives to high-input paddy rice cultivation that offer fewer negative environmental impacts.

For example, organic and low-input forms of conventional rice production in Japan and Thailand already demonstrate very high yields. Some produce yields of more than 10 metric tons per hectare per crop and show signs of increasing even more (Hawken et al. 1999). This indicates that environmentally sound practices can produce the improved yields of rice that will be required to feed expanding populations.

Other work suggests that additional improvements in rice production can be obtained by interplanting or sequence-planting rice with soybeans, field beans, or other legumes that improve soil fertility and soil biodiversity to improve plant vigour and resilience (Panfilo Tabora, personal communication). These polycultural cropping systems are also vital sources of protein for farmers, both from the plants produced and the wildlife attracted and harboured.

Rice systems contain some of the best-understood community relationships in the tropics. What is not well understood is the relationship of this biodiversity to ecological processes that either increase the viability of lower-input rice production systems or the provision of other marketable items or food for rice cultivators, such as the erodible frogs, snails, and fish that have now largely disappeared because of pesticide use.

In China, ecological farming (farming based on the principles of organics combined with modern science and technology to improve yields and quality as well as input use efficiency) is practiced on about 5% or less of rice land. Even so the results are interesting. When rice is combined with azolla (an aquatic fern that has symbiotic relationships with nitrogen-fixing cyanobacteria) cultivation, azolla inhibits weed growth and then can be cut as a green manure for the next rice crop. In combining rice cultivation with fish or duck production, 37-84% of weeds are consumed by either the fish or the ducks.

In addition, trials showed that there was a slight increase in soil organic matter with combined rice and fish production, plus increases of 16.4%, 50%, and 9.5% in the soil levels of phosphorous, potassium, and nitrogen respectively. Levels of dissolved oxygen also improved. Because of the nutrient-rich wastes produced by fish and other animals there are lower quantities of fertilizers and pesticides in the effluent because less of each is used (Chen et al. 1993).

Under some types of ecological farming, on 0.2 hectares of land some 1,800 kilograms of rice were produced as well as 130 kilograms of fish. Under traditional green revolution production systems only 1,668 kilograms of rice were produced under normal conditions (Chen et al. 1993).

Paddy rice production obliges in topographies that not only include clear-cutting but also changes in hydrology. Such changes are harmful to wildlife. In addition these changes are irreversible without considerable effort and investments when farmers decide to produce different crops. Investments are needed to develop or document technologies for rice production that are based on respecting the topographies and natural features of agricultural sites.