Aerobic rice: responding to water scarcity

Food and water are two of the most important necessities for survival, but, with an increasing demand for food and a looming water crisis, a shortage of both may be on the horizon unless innovative technologies are developed. Water, especially, is fast becoming a precious commodity, as more and more people continue using water for the household, industry, and agriculture. Scientists are now taking on the challenging task of developing rice production systems that can cope with water scarcity.

One technology that enables rice to be grown in dry land without flooding, and help farmers cope with water scarcity is the aerobic rice system.

Less is more

Aerobic rice is a new way of growing rice that needs less water than lowland rice. It is grown like an upland crop such as wheat, in soil that is not puddled, flooded, or saturated. The soil is therefore “aerobic” or with oxygen throughout the growing season, as compared to traditional flooded fields, which are “anaerobic.”

The difference, however, between aerobic rice and upland rice is that aerobic rice produces higher yields, 4–6 tons per hectare and perhaps beyond. This is possible because the crop is grown in aerobic soil but cared for with external inputs such as supplementary irrigation (if rainfall is insufficient) and fertilizers. This new way of growing rice started as early as the mid-1980s in China. To differentiate it from traditional upland rice, the International Rice Research Institute (IRRI) coined the term “aerobic rice.”

Aerobic rice can be considered a mature technology in temperate countries such as northern China and Brazil, where aerobic rice area is estimated at 80,000 and 250,000 hectares, respectively. In both countries, breeding programs since the 1980s have resulted in the release of several high-yielding aerobic rice varieties by crossing high-yielding lowland rice varieties with traditional upland types. In northern China, new high-yielding aerobic varieties such as Han Dao 277, Han Dao 297, and Han Dao 502 were released in the late 1990s with yield potential of up to 6.5 tons per hectare. After a 20-year breeding program in Brazil, aerobic rice varieties have yielded 5–7 tons per hectare under sprinkler irrigation in farmers’ fields.

In the tropics, aerobic rice systems are still very much in the research and development phase. IRRI started to develop varieties for the Asian tropics in 2001. The first generation of tropical aerobic rice varieties consists of IR55423-01 (Apo) and UPLRI-5 from the Philippines, B6144-MR-6-0-0 from Indonesia, and CT6510-24-1-2 from Colombia. These varieties were mostly derived from crosses between indica and tropical japonica parents.

Current research focuses on the development of improved management systems and on breeding further improved varieties.

Managing aerobic rice

The usual way of planting aerobic rice is the same as how you would plant wheat or maize—by dry direct seeding. And, like these cereal crops, aerobic rice can be rainfed, supplementary irrigated, or fully irrigated.

However, compared with flooded rice, weeds pose a bigger threat in aerobic soils. To control weeds, the use of pre- or post-emergence herbicides is recommended when weed pressure is high, plus additional manual or mechanical weeding in the early phases of crop growth. Yield decline has also been experienced after growing aerobic rice continuously
each year on the same piece of land. Possible reasons for declining yields or even failures to grow crops for the first time in an area could be soil-borne pests and diseases such as fungi, nematodes, and root aphids, particularly in the tropics.

Current research focuses on determining the causes of yield decline under continuous cropping, and on developing resistant varieties, suitable management options such as crop rotation, and integrated weed management practices.

Latest research

In the Philippines, participatory testing of aerobic rice by farmers is being done in the provinces of Tarlac, Nueva Ecija, Bulacan, and Bohol. The 2003-05 experiments produced yields of up to 6.4 tons per hectare. Farmers in India are also trying out aerobic rice in their fields, and they have identified well-performing varieties. Water savings were also achieved at 30–40% for production levels of 4 tons per hectare. (Learn more about India’s progress in Saving water for food security in India).

Farmers experiment with hand dibbling of tropical aerobic rice (Apo Variety) in Central Luzon, Philippines. (Photo by R. Lampayan)

Varieties are being tested in Lao PDR, while activities in northeast Thailand are set to evaluate genotypes
and start on-farm tests to overcome problems of labor shortage and weeds. Experiments are actively ongoing in China, and the Chinese experience of developing aerobic rice will be highlighted at the International
Workshop on Aerobic Rice set for 22-25 October.

Airing out aerobic rice

Various activities are being done to extend aerobic rice to farmers. Demonstrations are being held for farmers, researchers, and other stakeholders at most experimental sites in China, the Philippines, India, and Thailand. In the Philippines, the technology is included in a number of training packages on water-saving technologies in rice production. Training courses for farmers and irrigation engineers have been organized at the Philippine Rice Research Institute and in several provinces in the Philippines.

In China, aerobic rice concepts are circulated through two national extension networks. Seminars have been organized at all sites for the targeted farming communities. The China Central Television network, a major TV network in the country, is coordinating with the China Agricultural University to produce a video on aerobic rice to be shown nationwide.

Internationally, information on aerobic rice is shared through the IRRC and the CGIAR-Challenge Program on Water and Food (through the STAR project). Lectures have been given in the Philippines and in Vietnam. Posters and oral presentations were given at conventions and at various Chinese national conferences and workshops.

With predictions suggesting that many Asian countries will have severe water problems by 2025, aerobic rice gives hope to farmers who do not have access
to enough water to grow flooded lowland rice. The Water-Saving Work Group of the IRRC is committed to further developing this new technology and making it available to farmers in Asia.

Trina Mendoza (t.mendoza@cgiar.org), Ruben Lampayan (r.lampayan@cgiar.org), and Bas Bouman (b.bouman@cgiar.org)

Research streams archive