Maryland paid up to $90 an acre for cover crops, tiered by pollution cut

Cover crops hold soil and keep nutrients out of streams, but satellite images analyzed by the Environmental Working Group showed farmers in Iowa and Illinois had planted them on under 3% of corn and soybean fields, and Indiana about 7%. Iowa's planners want at least 60%.

Maryland did something different on the Eastern Shore, along the Chesapeake Bay. The state pays farmers for a range of practices that cut nitrogen and phosphorus runoff, and the more effective the practice, the more money. The top payment, up to $90 an acre, goes to planting rye on corn fields early in fall and holding off manure until spring.

University of Maryland scientist Ken Staver says arguments that cover crops pay for themselves did not move farmers, and an earlier offer of about $20 an acre signed up some but not enough. It took more generous payments to win the majority.

Skip persuasion: pay per acre, with the biggest checks for the practices that cut the most nitrogen and phosphorus.

Cover crops mean extra work at busy fall and spring times.

Appeals to long-term soil benefits had failed for about 20 years.

Paying more for more effective practices steers farmers toward the biggest pollution cuts.

Fall manure is convenient but washes away in winter, so the top payment requires waiting until spring.

When a public good costs private effort, price the effort, and scale the payment to the benefit so it buys the best outcomes.

Staver told NPR in 2017 that farmers now plant cover crops on well over 50% of Eastern Shore corn fields. He concedes it is easier in Maryland than Iowa because Maryland has far less cropland relative to its budget. An EWG researcher notes Iowa farmers got about $10 million a year in cover-crop incentives against over $1 billion in federal subsidies in 2015.