Reconstruction support of the disaster-stricken areas in the city of Soma, Fukushima Prefecture, was started in May 2011. Sediment transported from the sea by the tsunami was from 5 to 10 cm thick on surface of the paddy fi elds. The tsunami sediment was mixed with the original soil of the paddy fi elds, and mole drains were formed to improve water drainage toward the lower layer. Subsequently, rainwater alone was used for salt removal. However, the pyrite in the soil had gradually oxidized

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... l the pH dropped to 3.8, so converter slag was applied to neutralize the sulfuric acid. In May 2012, rice was transplanted into paddies from which the salt had been removed. On September, 10.7 t brown rice was harvested. The yield of brown rice harvested per hectare was 6.3 t, about 20 % higher than the amount before the disasters.