The most farmer-requested performance measure is the Cornstalk Nitrate Test (CNT). The CNT is a direct performance evaluation of nitrogen and/or manure N management measured by the Nitrate-N concentration in the lower cornstalk. The sample consisting of 15 random 8” cornstalk sections will indicate nitrogen available during grain filling. Inadequate nitrogen is associated with reduced yields. More nitrogen than needed for maximum yields is indicated by nitrate accumulation in the lower cornstalks at the end of the season. Multiple year testing to account for seasonal variability will increase confidence in refining nitrogen management.
Farmers are reluctant to take time during harvest season to collect the samples, so in each watershed a third-party has been hired to collect the samples and ship them to the lab for analysis. The incentive program provides funding for sample collection and then offers additional incentives based on farm-average sample results. As seen below, some watershed councils also offer incentives for late spring soil nitrate sampling.
Variations of the following “per-farm” NITROGEN MANAGEMENT PERFORMANCE incentives have been used in four watersheds.
- $400 payment if the farm weighted average analyses does not exceed 1,700ppm
- $200 bonus if the weighted average (Max. 50 acres/field) is less than 1,300ppm
- $100 for the first two cornstalk N samples analyzed and $40.00 for each additional sample (up to 4 samples total)
- $50 per sample (or up to four) late spring soil N samples analyzed