The performance number “driving all of this good volunteer work,”is the NRCS soil-conditioning index, says John Rodecap, retired northeast Iowa Extension water quality specialist, who coordinated the efforts. A composite of soil loss, slope, rotation, tillage and other practices affecting N and P loss, “it was a tremendous yardstick for grower-volunteers. Once you let farmers know their performance numbers by field (anonymously), they worked hard to improve their scores.”

The fall cornstalk nutrient nitrate test (CNT) was also useful in measuring how much of a crop’s nitrates remained unused in the plant at the end of the growing season. Over four years, 43 Coldwater Creek growers reduced their CNT levels by 75%.

Growers set their own goals and adjusted incentives based on scientific guidance, results feedback and grower response. For example, watershed growers used annual performance reports to target grassed waterways, vegetative filters and tillage management; reducing annual sediment and P delivery by 1,294 tons and 1,681 lbs., respectively.

“This type of environmental-performance rewards have been cost-effective in reducing water quality problems in a changing agriculture with increasing land-rental arrangements by rewarding farm operators to do applied research cooperatively with their watershed neighbors,” Rodecap says. “The four northeast Iowa watersheds where they’ve been demonstrated include karst and prairie soils; also conventional and large livestock operations. This multi-year, multi-watershed demonstration is an alternative to direct payments in recent farm bills that are increasingly unpopular with taxpayers.”

Each grower figures out the best plan for his individual operation. Biofilters, for example, need to be site-specific based on available space and water flow. Similarly, cover-crop mixes are highly climate-specific. That might be the best argument of all for locally based nutrient-management efforts.