The government plans to prohibit rice planting in fields where the concentration of radioactive cesium exceeds 5,000 becquerels per kilogram of soil.
The government plans to prohibit rice planting in fields where the concentration of radioactive cesium exceeds 5,000 becquerels per kilogram of soil.
Chief Cabinet Secretary Yukio Edano said Friday that the new bans would apply to areas beyond the current 30 kilometer exclusion zone around the stricken Fukushima No. 1 nuclear power plant. Rice production within the 30-km zone is already effectively banned.
An analysis by the Ministry of Agriculture, Forestry and Fisheries found that 10 percent of cesium in soil is absorbed into rice by the time of harvest.
The safety standard for cesium in rice is a maximum of 500 becquerels per kg of rice, so the ministry decided that the corresponding standard for soil should be 5,000 becquerels per kg of soil.
Prime Minister Naoto Kan will issue the prohibition to farmers in designated areas using special powers conferred by a nuclear disaster management law. It will be the first time such prohibitions have been imposed.
Tokyo Electric Power Co. (TEPCO) and the government will compensate farmers for financial damage suffered as a result.
On Wednesday, the Fukushima prefectural government announced the results of soil surveys at 70 places on farmland, including rice fields, in the prefecture.
The concentration of radioactive cesium exceeded 5,000 becquerels in only two of the rice fields, both located in Iitate village.
The prefectural government plans to announce the results of additional surveys on Tuesday.
Eight other prefectural governments also announced the results of similar surveys on Friday night. There were no reports of radioactivity exceeding 5,000 becquerels in any of the farmland inspected.
The eight prefectures were Miyagi, Yamagata, Ibaraki, Tochigi, Gunma, Saitama, Chiba and Kanagawa.
The Ministry of Agriculture, Forestry and Fisheries will use the survey results as a basis for discussions with prefectural governments about the planting prohibitions, and then select the areas to be banned.
Soil surveys have not been conducted within 30 km of the nuclear power plant because those areas are currently off-limits.
"Rice cultivation itself is impossible in those areas," a ministry official said.
The agriculture ministry is considering whether to impose a uniform ban on rice cultivation on the entire 30-km zone.
With the nuclear crisis at the Fukushima plant still unresolved, there is a continuing risk of radioactive substances falling on agricultural land and products. Soil surveys will continue to be conducted on rice fields not covered by bans.
Rice will also be inspected at the time of harvest. If cesium figures exceed safety standards, farmers will be instructed not to ship their rice.
The half-life of cesium is 30 years, so the problem is likely to persist. The agriculture ministry will look at whether replacing soil in banned farmland is a feasible option or whether alternative crops that absorb fewer radioactive substances than rice might be allowed.