Where aerobic rice?
Aerobic rice can be found, or can be a suitable technology, in the following major rice-growing environments:
- So-called “favorable uplands” (see FAQ: Why aerobic rice?): areas where the land is flat (or terraced), where rainfall with or without supplemental irrigation is sufficient to frequently bring the soil water content close to field capacity, where no serious soil-chemical limitations such as aluminium toxicity or salinity occur, and where farmers have access to external inputs such as fertilizers. A typical example is in the Cerrado region of Brazil, where farmers grow aerobic rice in rotation with crops such as soybean and fodder on large commercial farms with supplemental sprinkler irrigation on an estimated 250,000 ha of flat lands, realizing yields of 3-4 t ha-1. Another example is rainfed aerobic rice grown in newly-formed terraces in the hills of Yunnan, China, where yields are also typically 3-4 t ha-1.
- Fields on upper toposequence locations in undulating so-called “rainfed lowlands”. Quite often, the soils of such upper fields or terraces are relatively coarse-textured and well-drained, so that ponding of water only occurs for a limited (or no) part of the growing season. No widespread examples of aerobic rice in rainfed lowlands are known, but these upper fields have been proposed as target domain for aerobic rice.
- Water-short irrigated lowlands (see FAQ: Why aerobic rice?): areas where farmers do not have access to water to keep rice fields flooded for a substantial period of time anymore. Water shortage can be encountered in tail-end parts of large-scale surface irrigation systems, in areas where the groundwater has been drawn down so that pumping costs have become very high, in irrigation systems that receive less and less water because of redirected use (cities, industry) or because of reduced stream flow in rivers. A good example is the North China Plain where aerobic rice is grown on about 80,000 ha with supplemental irrigation.
Beside these typical rice-growing environments, aerobic rice can also be found in traditionally non-rice growing areas. Again in the North China Plain, farmers are experimenting with aerobic rice as a means of crop diversification in areas where traditionally maize is the dominant crop.
Aerobic rice can be found in tropical and in temperate climates. Most advances in developing aerobic rice systems, and in adoption by farmers, have been made so far in China and Brazil.