Direct Seeding of Rice Crop in Flooded Paddy Fields Using Iron-coated Seeds

Labor costs in rice production can be reduced by changing planting methods from transplanting to direct seeding. However, the adoption of direct seeding in fields is limited, since seedlings tend to float in standing water. We report on a new approach to solve this problem through the use of iron-coated seeds. Soaked or pregerminated rice seeds are covered with reduced iron powder mixed with calcined gypsum using a water spray. The iron powder on the seed surface is oxidized, producing rust which works as a binder constituting a firm coating layer. The iron-coated seeds can be prepared manually or through mechanization in large quantities and safely stored for one to two years. They are sown directly onto the soil surface in the same way as water seeding common in US or wet seeding in tropical Asia. The iron-coated seeds are less vulnerable to sparrow attack and are more resistant to seed-borne diseases and insect damage. This technology is adopted in the farmers’ fields in some private sectors. The main issues which must be overcome to further adoption of this method are the protection of seeds from the heat generated by the iron oxidation, the acceleration of initial seedling growth, the improvement of water control, and the increase in grain yield.