A farmer uses agricultural machinery while preparing a rice paddy field in Kim Boi village, about 60 km (37 miles) south of Hanoi February 27, 2013. Vietnam's rice companies have begun buying winter-spring paddy under a government-backed plan to stockpile 2 million tonnes of the grain, equivalent to 1 million tonnes of husked rice or about a fifth of the crop output to prevent price falls. REUTERS/Kham (VIETNAM - Tags: AGRICULTURE FOOD BUSINESS)