Rice Fields Contribute Greatly to Global Warming

Methane is the second leading gas responsible for the greenhouse effect and it accounts for 20 percent of global warming. Paddy fields of rice are among the leading producers of methane, contributing about 10 percent of all global emissions. Rice absorbs carbon from the atmosphere, but if the plant cannot utilize it efficiently, the carbon is dispersed into the soil, where it converts to methane

Scientists have found a way to get rice to produce higher yields and make less of the potent greenhouse gas methane. The researchers wrote in the journal The Proceedings of the National Academy of Sciences, that their discovery “provides opportunities to mitigate methane emissions by optimizing rice productivity”.

Methane is produced from carbon and hydrogen by bacteria in the soil. Some carbon enters the soil from the roots of rice plants which have taken it from the atmosphere via photosynthesis. Scientists from Wageningen University in Netherlands, Fraunhofer Institute in Germany and International Rice Research Institute in the Philippines discovered when plants channel carbon into producing flowers and grain, less carbon finds it way into the soil.

The crucial factor in lessening carbon deposits is the number of spikelets that a plant produces. Spikelets hold the flowers and later the grain, so researchers are producing new strains of rice which produce more spikelets, and therefore more grain.

As the researchers work to develop new strains, global warming is taking its toll on rice production, since warmer weather causes plants to produce fewer spikelets. Rice, the staple crop of half of the world’s population, has varying yields from field to field. One field may produce eight tons per hectare while another produces only three.

Ronald Sass, of Rice University in Houston and Ralph Cicerone, of the University of California wrote in the same journal that the research was “timely and a call to action”. Understanding the link between temperature and spikelet formation could help researchers develop new strains which channel more atmospheric carbon into rice and less into methane production in the soil, Sass and Cicerone noted.

Robin Matthews, of Cranfield University in the UK, thinks the link between spikelets and methane is more complex, especially when studied outside of greenhouse experiments. “It’s a complex situation, and there may be other factors which come into play when you grow rice in open fields,” he told BBC News.

Source: Wageningen University Fraunhofer Institute and the International Rice Research Institute