Cover crops were almost as effective as restored prairie at reducing nitrate concentrations in tile-drained water, according to recent research at Iowa State University.This was one of the key findings from a study led by Marshall McDaniel, associate professor of agronomy at Iowa State. The project was designed to better understand how the quantity and quality of tile drainage water impacts in-stream potential for nutrient enrichment, leading to growth of algae and depletion of vital oxygen in aquatic ecosystems.