Environmental Performance Measures
Environmental performance measures are used to monitor improvements or anticipated improvements in water quality due to changes made on the landscape. Farmer-useable, science-based performance measurements such as the late-season Cornstalk Nitrate Test, the Soil Conditioning Index, the Iowa Phosphorus Index, and residue measurement will be used in watersheds to assess environmental performance and monitor improvements in water and soil quality over time. Reductions of phosphorous and nitrogen delivery to surface waters, improvement in soil condition, and reduced erosion can be estimated using these performance measures.
Late Season Cornstalk Nitrate Test
Soil Conditioning Index
Iowa Phosphorus Index
Phosphorus Index- The phosphorus index was developed as a measure of phosphorus loss risk for applying manure and commercial fertilizer for regulatory purposes. It can be used by any farmer interested in tracking the risk of phosphorus loss, or environmental performance, of his or her operation. The phosphorus index considers erosion estimate, conservation practices, landform region, residue management, soil type and slope, soil test phosphorus, manure and commercial phosphorus fertilizer application, fertilizer application method, and subsurface drainage in the calculation of phosphorus loss risk.
Soil Conditioning Index- The Soil Conditioning Index (SCI) is an assessment tool created by the NRCS to estimate whether tillage and cropping systems will result in maintained or increased levels of soil organic matter. Soil organic matter is an indicator of overall soil health and productivity.
Fall Stalk Nitrate Test- The late season or fall stalk nitrate test was developed to monitor nitrogen fertilizer application program. Corn plants suffering from inadequate N availability remove N from the lower cornstalks and leaves during the grain-filling period. Corn plants that have more N than needed to attain maximum yields, however, accumulate nitrate in their lower stalks at the end of the season. Stalk nitrate concentrations can be divided into four categories; low (less than 250 ppm N), marginal (250 to 700) optimal (700 to 2000 ppm N), and excess (greater than 2000 ppm N).
Residue Measurement- Increased residue cover can minimize sheet erosion from the soil surface. Changing tillage practices to those that leave higher amounts of residue or modifying current practices to increase residue after tillage are encouraged. Residue cover can be measured using the line transect method.
