AAAS Day 2: Friday 16 Feb 2007
Another interesting session looked at the challenge of producing more food with less water by improving water use efficiencies in a variety of ways. While the focus of most of the presentations was US irrigation systems and technologies, the issues they raised are of relevance to rich and poor countries alike.
Because of an increase in population, urbanization and need for improved environmental services, the water demands drinking, sanitation, urban irrigation, industry and environmental uses are outbidding and reducing the water available for agriculture. Shrinkage of groundwater resources has aggravated the situation in many countries, and the greater frequency of more severe droughts predicted by some global climate change models are a cause for concern. In addition, the global warming appears to be increasing the water requirements of plants. Thus, the questions for the western United States and all semi-arid regions of the world are: How can irrigated agriculture sustain productivity and meet the growing need for food and fibre with reduced water available for irrigation? What research knowledge and technologies are needed to accomplish this sustainability? This symposium highlighted a range of actions and technologies to increase water use efficiency of crops, increase salinity management and reuse of waste water and reduce field losses of rain and irrigation water, among other things. Unfortunately, many of the technologies described by presenters are decidedly high-tech, requiring significantly levels of capital and training well beyond the means of most developing countries.
The only presentation from a developing country perspective came from John Bennett, Senior Molecular Biologist at the International Rice Research Institute, on “Can Genetics and Biotechnology Create More Crops for Less Water?” Bennett noted that in when considering investments in crop breeding and biotech to make rice systems more productive, one must distinguish between IWP – irrigated water productivity and PWP – precipitation water productivity. The former relates to irrigation and crop management and is open to genetic improvement for increasing irrigation efficiency, while the latter involves catchment management and genetic improvement for drought tolerance. IRRI is currently working to develop new varieties of rice with traits that for water-scarce environments that are more efficient in their use of water and more drought resistant, including those with traits to:
· Minimise non-transpirational uses of water
· Reduce transpiration without reduction production
· Increase production without increase transpiration, and
· Use cheap water (brackish, recycled, saline)
Bennett observed that no single trait is likely to work sufficiently and, therefore, in most cases a “package of traits” will be required. He argued that by investing in the R&D of global public goods such as new drought resistant, irrigation efficient rice varieties, the international community can bear the costs of improving the productivity of rice. If the emphasis is instead placed on improving management of the rice production system, it will be the farmers who have to pay (in terms of labour and other investments).
Interestingly, Bennett described advances in ‘Aerobic Rice Production” in upland systems in Brazil and China as a means of boosting productivity and saving water. When I pointed out that his description of this approach sounded strikingly similar to the System of Rice Intensification (SRI) that developed in Madagascar and spread to other parts of Africa and Asia, he said that SRI had been discredited and was not worth investigating further. However, he failed to draw a clear distinction between Aerobic Rice Production (and dry-direct-seeded rice production systems) and SRI.