WHY THIS MATTERS Chemical fertilizers account for up to 45 percent of input costs for some crops. Engineered biofertilizers may reduce these costs and increase crop yields. KEY TAKEAWAYS » Engineered biofertilizers are made of microbes and other organic materials that improve nutrient supply in soil. » The lack of a clear definition for biofertilizers leads to uncertainty about whether existing regulations apply. » Current regulations may also not be equipped for genetically engineered microbes, which may hamper U.S. competitiveness.