Study: Not fooling with Mother Nature brings better rice crop

(AP) -- Chinese farmers who abandoned the modern practice of planting a single type of rice in their paddies and adopted the more natural course of mixing varieties were rewarded with bigger harvests, and they no longer had to spray expensive fungicides.

While the benefits of genetic diversity were known to Darwin, the study serves as an important reminder at a time when agriculture is increasingly looking to high-tech solutions, said Martin S. Wolfe of Wakelyns Agroforestry in Pressingfield, England.

"This deceptively simple experiment deserves wide attention, partly because of the principle that it illustrates, and partly because it may never be repeated on such a scale," Wolfe wrote in a commentary on the study, published in Thursday's issue of the journal Nature.

Oregon State University plant pathologist Christ Mundt and colleagues organized farmers in five townships in China's Yunnan Province in 1998 to switch from planting a single variety of sticky rice -- a practice known as monoculture -- to alternating rows of sticky rice with hybrid varieties.

Seeing their neighbors getting bigger harvests and saving money on fungicide, farmers in 10 townships joined the experiment in 1999, bringing the total area of farms switching to diverse planting to 8,255 acres.

Though the sticky rice brings a higher price, it is susceptible to a fungus known as rice blast, which reduces yields and is generally controlled by spraying with expensive chemicals.

Planting different varieties of rice in the same field cut the incidence of rice blast in the sticky rice by 94 percent and increased yields by 89 percent.

Though more research is needed to pinpoint why, it appears that the alternating rows of different varieties thwarted the spread of rice blast, Mundt said.

"One way of thinking about this monoculture would be kind of like a field of dry grass: Drop a match in it. There is nothing to stop the fire from moving through it," Mundt said.

"A mixed population is like a field of dry grass and wet grass. Drop a match one there and it is going to be slowed down. It will burn up a dry grass patch, then hit a wet one."

Oregon wheat farmers already plant a mix of varieties in their fields, but rice farmers tend toward monoculture, because planting, harvesting and selling the crop are easier with one variety.

"I think our goal should be to fool with Mother Nature as little as possible," Mundt said. "Sometimes there is a simple fundamental fix that makes a whole lot more sense than going for a real high-tech system."

Copyright 2000 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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