27 Février 2012
February 27, 2012
TSUKUBA, Ibaraki -- Fertilizer mixed with potassium can greatly reduce the amount of radioactive cesium absorbed by brown rice from contaminated rice paddies, researchers at the National Agricultural Research Center have found.
Officials at the research center based in Tsukuba, Ibaraki Prefecture, said they succeeded in cutting down the amount of cesium absorbed by brown rice by up to 50 percent after they used potassium-laced fertilizer in contaminated paddies in four prefectures, though the results differed depending on soil characteristics. Potassium is known to be easily absorbed by plants.
The experiment covered a total of five paddies in Fukushima, Ibaraki, Tochigi and Gunma prefectures, which were contaminated with radioactive materials emitted from the disaster-crippled Fukushima No. 1 Nuclear Power Plant. Researchers used fertilizer under different conditions to study cesium absorption by brown rice.
As a result, the levels of cesium absorbed by brown rice were reduced by 6 to 46 percent in rice fields where potassium compounds three times the normal amount were applied. Researchers presume that the similarity in chemical characteristics between cesium and potassium helped brown rice to absorb more potassium.
Researchers have also found that the optimal amount of potassium compounds is 25 milligrams per 100 grams of soil and that any amount beyond that would bring about no remarkable results. Currently, the target amount of potassium compounds in rice paddies is set at 15 to 30 milligrams per 100 grams of soil.
"I hope the results will be reflected in this year's rice planting," said Naoto Kato, a senior scientist at the center.