Cover crops significantly re­­duced nutrient runoff in crop fields in 2018, according to tile drainage water monitoring by the Iowa Soybean Association (ISA). Statewide, average drainage water nitrate concentrations were 23 percent lower in fields with cover crops than those without them, according to the ISA’s 2018 research annual report.

“We’re seeing significantly less nitrate concentration and less loading in cover crop fields,” ISA Environmental...