Rice paddies spew methane. A new variety makes them less gassy | Grist

Source: Rice paddies spew methane. A new variety makes them less gassy | Grist

The poor things can’t help it, but cows are really gassy, and that’s really bad for the planet: Microbes in their guts produce methane — a greenhouse gas up to 80 times more powerful than carbon dioxide — which comes out as burps. Consequently, livestock is responsible for 30 percent of humanity’s methane emissions. But it’s not just bovine belching that makes agriculture drive so much warming. Rice cultivation, surprisingly enough, accounts for another 12 percent of humanity’s global methane emissions.

As with cows, the problem is burps — lots and lots of tiny burps. Growing rice requires flooding fields, called paddies, with staggering quantities of water. Microbes known as archaea multiply in the wet, oxygen-poor conditions, releasing methane. One way to reduce those emissions is to inundate the fields less often, but that’s not always feasible given local irrigation infrastructure, and less water can lead to reduced yields. That’s a precarious situation, given that half the world’s population relies on rice, with current production at 500 million metric tons annually on average.

…With all that in mind, the researchers crossbred — without genetic modification — a high-yield rice variety and a low-methane variety, which produces less fumarate and more ethanol. (The less gassy kind is an old type that is no longer used commercially because it isn’t high-yielding.) The result is a new, non-GMO plant that generates 70 percent less methane while still generating plenty of grains: The global average yield of rice is 4.71 tons per hectare, while this new variety manages 8.96 tons.