Exchange traded funds tracking farm commodities and Greece outpaced all nonleveraged ETFs Tuesday as global markets rallied across the board, the dollar weakened and Fed officials began a two-day policy meeting. IPath Pure Beta Agriculture (DIRT) vaulted 7.26% as corn, soybeans, coffee and wheat climbed amid hot, dry weather in the Midwest, which threatened harvests. The U.S. Department of Agriculture reported a larger-than-expected drop in weekly