A Minnesota mandate that most diesel fuel sold in warm-weather months be a blend containing 10 percent biodiesel faces an uncertain future. Minnesota currently requires a year-round 5%blend known as B5 for most diesel sales. The B10 mandate is to begin in July, and then rise to 20% by next year. But there have been delays to ensure adequate supplies and set up regulatory protocols. Those delays might continue. Nicollet County State Representative Clark Johnson has proposed a bill pushing the 20% requirement back another three years. He says the state again needs more time to prepare. Biodiesel is mostly made from soybean oil. The state’s soybean farmers association says it supports Johnson’s bill.