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China's Yunnan Province was struck by drought in 2010, turning a normally verdant landscape into a dustbowl (AFP). - Controlling soil erosion is a key task if food security is to be assured. There are numerous techniques for controlling the problem that have been successfully applied on the local level, from planting trees, to rotating crops, to retiring farmland, to reducing tilling, and so on. Earth Policy Institute's Plan B calls for annual spending of $24 billion for the protection of vital topsoil.