Mainland grain and flour imports fell almost 77 per cent last year as a bumper harvest filled granaries and boosted exports. The booming harvests may keep pressure on prices of commodities such as rice and corn as mainland farmers increasingly compete with growers from the US, Canada, and Australia. The mainland imported 460,000 tonnes of cereal and flour in December, bringing the full-year tally to 4.17 million tonnes, the China Securities newspaper reported, citing Customs data. Wheat imports reached 1.86 million tonnes, down 77.4 per cent from their level in the previous year.