Thousands of rice farmers in China have doubled their yields of rice - their most valuable crop - and nearly eliminated its most devastating disease "without using chemical treatments or spending a single extra penny," according to a report published last week by The New York Times. The paper called the new evidence "stunning new results from what has become one of the largest agricultural experiments ever."The unusual experiment, entitled by some reports "Don't Fool With Mother Nature and Double Your Yields," and described in detail by some professional and trade journals, notably in Nature Magazine, surveys a two-year experiment led by an international team of scientists, in which five townships in 1998 and ten townships in 1999 in Yunnan Province implemented a simple change in their cultivation practice.Instead of planting a single type of rice, as they have done in the past, the farmers planted a mixture of varieties of rice. With this simple, one change, farmers were able to "radically restrict the incidence of rice blast," the most devastating disease of the most valuable food crop in China, and the staple crop of most people worldwide. Within two years, farmers stopped using the chemical fungicides previously used extensively to combat the disease. Rice blast fungus destroys millions of tonnes of rice and costs farmers several billion dollars in losses each year.Scientists said there was no reason why planting diverse varieties could not decrease disease spread in other crops as well. The New York Times quotes Dr Christopher Mundt, Population Biologist at Oregon State University and the one American-based author of the study, as published in Nature: "there's already a lot of work with barley in Europe and coffee in Colombia, and I've seen beautiful disease reduction in mixtures of willows grown in England."The report noted that the Chinese experiment is of particular interest for organic farming as it involves cultivation without the need to apply chemicals.