Spirits in the swamps: methane and rice

Swamps are not nice places to be sometimes. Even when they are called wetlands. Rice paddies are really just small little swamps that only last a few months. So they don’t accumulate all the evil that swamps do, but they get close.

Probably one of the most evil things that swamps produce is a deadly odorless gas called methane. You might have methane in pipes going into your house. It’s called natural gas today because the industry has good public relations people. The producers of natural gas have to mix it with really smelly stuff so you notice and get out when there is a leak. Or you would die. Swamps and rice fields produce methane in abundance.

Those of us who live close to swamp areas, have lots of stories about methane–also called swamp gas. Occasionally it is ignited and appears to be a lantern or a face running through the woods (“will-o’-the-wisp”). European folkfore has numerous stories about strange, bright apparitions leading lonely travelers astray–all inspired by methane somehow ignited in the woods. Watch the following video to see how much methane swamps produce.

in modern times, methane has become even scarier since it is one of the greenhouse gases leading to climate change. Methane is way more potent the carbon dioxide. Over 20 years methane traps 84 times as much heat as carbon dioxide. In 100 years it degrades, but still traps 28 times as much. Methane emissions from swamps are the largest natural source of methane in the world, contributing roughly one third of all methane released from nature and by man combined.

Methane is produced by bacteria decomposing organic matter under water. When rice is flooded, man is creating a little swamp with perfect conditions for methane producton.

Rice doesn’t produce nearly as much methane as swamps (about 2 per cent of the methane released by human activity). So rice fields are a small, but definite contributor to our GHG problem. And its a problem which can be solved. We just have to figure out ways of growing rice with less flooding. Researchers are figuring out ways to do that and rice farmers are implementing them resulting in lower costs for water and lower methane production.

It seems like a great achievement. Except in some places, like California, all the natural lakes have been destroyed and there is no habitat for migrating waterfowl except flooded rice fields. So in the short run, we have to keep flooding California rice fields.

As soon as possible, however, we need to get farmland in California converted back to natural lakes. Natural lakes in a dry climate like California’s rice growing area do not accumulate the high levels of organic matter under water which leads to methane production. Reestablishing that system should be our goal, not flooding rice fields and watching the methane bubble up.

In Arkansas, with 50+ inches of rain a year, we have plenty of habitat for migrating waterfowl without flooding rice fields and are trying everything we can to reduce the period of flooding on rice fields.    

Wetlands and rice fields do produce methane. We can’t just sweep that fact under the rug because we need flooded rice fields for waterfowl migration. Instead, let’s recreate the lakes destroyed in the Pacific flyway. We don’t have to settle for methane production from rice fields.

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