Aerobic rice

A fundamentally different approach to reduce water requirements from rice fields is to grow the crop like an upland crop, such as wheat or maize. Unlike lowland rice, upland crops are grown in non puddled, non saturated (i.e. ''aerobic'') soil without ponded water. The amount of irrigation water should match evaporation from the soil and transpiration by the crop (plus any application inefficiency losses). The potential water reductions at the field level when rice can be grown as an upland crop are large, especially on soils with high seepage and percolation rates. Besides seepage and percolation losses declining, evaporation decreases since there is no ponded water layer, and the large amount of water used for wet land preparation is eliminated altogether. Upland rice varieties are drought tolerant, but have a low yield potential and tend to lodge under high levels of external inputs such as fertilizer and supplemental irrigation. Alternatively, high yielding lowland rice varieties grown under aerobic soil conditions, but with supplemental irrigation, have been shown to save water, but at a severe yield penalty. Achieving high yields under irrigated but aerobic soil conditions requires new varieties of ''aerobic rice'' that combine the drought tolerant characteristics of upland varieties with the high yielding characteristics of lowland varieties.

Conservation agriculture

With aerobic rice, technologies of conservation agriculture, such as mulching and zero - or minimum tillage as practiced in upland crops, become available to rice farmers as well. Various methods of mulching (e.g., using dry soil, straw, and plastic sheets) are being experimented in non-flooded rice systems in China and have been shown to reduce evaporation as well as percolation losses while maintaining high yields.

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