A Case Study for Salt Injury on Paddy Rice due to Ground Liquefaction Caused by the 2011 off the Pacific Coast of Tohoku Earthquake in Japan
Abstract
About 24000 ha of farmlands were heavily damaged by the 2011 off the Pacific Coast of Tohoku Earthquake in the following two patterns; (i) an invasion of the sea water caused by tsunami in the coastal agricultural areas, (ii) a ground liquefaction around inland rivers. In the past case, ground liquefaction caused damage, for example, cracks or mixing sand boil into topsoil. This is the first report on a case of salt injury to paddy rice due to ground liquefaction. Rice paddies along the downstream of the Tone River were suffered from a large amount of sand boils due to the ground liquefaction. At one paddy fields at 50 km from mouth of the Tone River, farmers temporarily repaired their paddy fields and planted rice in may, 2011. The surface of the rice paddy field was speckled with sand boils. A week after planting, the authors incidentally found salt injury on the growth of rice plant at the paddy fields. Sand boil contained much more chlorine ion, sodium, sulfide ion than preexisting top soil. This data suggested that sand boil contained salt moved from underground to the surface of paddy fields. During May and September in 2011, the salt injury paddy fields was supplied irrigation water pumping from drainage canal, because irrigation facilities was destroyed by ground liquefaction. The electrical conductivity (EC) of water in the drainage canal ranged from 2 to 8, much higher than the salt-tolerant limit for rice. Consequently, the yield of the rice in the salt injury rice field due to ground liquefaction ranged from 55 to 107 kg/10a, much lower than the usual (about 450 kg/10a). The result of the yield was 55 kg/10a got around sand boil, on the other hand, the yield was 107 kg/10a got preexisting top soil area using drainage water contained salt. The yield of the whole paddy fields which size was 50 a was bad, but the yield around sand boil area was much worse. This case reported that chemical components in the boiled materials should be paid more attention if rice paddies will damaged by grond liquefaction.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.V11D2790Z
- Keywords:
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- 9320 GEOGRAPHIC LOCATION / Asia