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16. Aerobic Rice System (STAR)

Full Title:

Developing a System of Temperate and Tropical Aerobic Rice (STAR) in Asia

Website:

http://www.knowledgebank.irri.org/theme1/PN16.htm

Download project proposal [PDF 2,455Kb]

Rice is the staple food in Asia and also the single biggest “user” of freshwater. It is mostly grown under submerged soil conditions and requires much water compared with other crops. The declining availability and increasing costs of water threaten the traditional way of irrigated rice production. Moreover, lack of rainfall is a major production constraint in rain-fed areas where many poor rice farmers live. An efficient use of water is critical to help reduce poverty and safeguard food security in water-scarce areas in Asia. Water requirements can be lowered by reducing water losses by seepage, percolation, and evaporation. Promising technologies include saturated soil culture, intermittent irrigation, and the system of rice intensification. However, these technologies still use prolonged periods of flooding, so that water losses remain high. A fundamentally different approach is to grow rice like an upland crop, such as wheat, on non-flooded aerobic soils, thereby eliminating continuous seepage and percolation and greatly reducing evaporation. Traditional upland rice has been bred in unfavorable uplands to give a stable though low yield under minimal external inputs.

Previous experiments of growing high-yielding lowland rice under aerobic conditions have shown great potential to save water, but with a severe yield penalty. A new type of rice is needed to achieve high yields under high-input aerobic conditions. Evidence of feasibility comes from northern China, where breeders have produced first-generation (temperate) aerobic rice varieties with a yield potential of 6 t/ha that use only 50 percent of the water used in lowland rice. However, initial high yields are difficult to sustain and yields may decline after 3–4 years of continuous cropping. There are no aerobic rice varieties for the tropics and crop-soil-water management recommendations are lacking. A shift from continuously flooded to aerobic conditions may have profound effects on the sustainability (e.g., soil-borne pests and weed dynamics) and environmental parameters (e.g., nitrate leaching and herbicide use). These need to be studied to develop sustainable and environmentally friendly production systems and crop rotations. We also need to deepen our understanding of the  potential target domains along with the biophysical and socioeconomic circumstances of the farmer beneficiaries.

Strategic research is proposed that allows us to develop sustainable aerobic rice systems for water-scarce irrigated and rain-fed environments in Asia. The objectives are to:
 
1. Identify and develop aerobic rice varieties with high yield potential.
2. Develop insights into key processes of water and nutrient dynamics that allow us to derive prototype management practices.
3. Identify key sustainability and environmental impact issues, and propose remedial measures, such as crop rotations.
4. Develop practical technologies for crop establishment and weed control.
5. Characterize and identify target domains and quantify the potential amounts of water savings and rice production.

The activities and methodology combine controlled field experiments (for variety selection, breeding, and study of crop-water-nutrient dynamics and of nematode ecology) with on-farm participatory research and development (R&D). Special attention is paid to practical technologies for crop establishment and weed control, to crop rotations and to socioeconomic implications of adoption.