New test to calculate N needs

The Illinois Soil Nitrogen Test (ISNT), a new tool to help farmers measure how much soil nitrogen (N) is available to corn, can now be purchased commercially.
    Cornell University is working with northern New York producers to calibrate and evaluate the test for New York conditions. The test identifies readily mineralizable soil organic N, organic matter and ammonium-N to predict if extra N is needed.
     Joe Lawrence, Cornell Cooperative Extension of Lewis County field crops educator, says the test can help farmers use manure better and keep from using too much fertilizer.
    The ISNT works better than the Pre-Sidedress Nitrogen Test (PSNT), Cornell says, because the results remain stable for two to three years, samples can be taken at a shallower depth and timing for taking samples isn’t as restrictive as for the PSNT.
     But Lawrence said producers need to know how soil samples are taken in order to use the ISNT and Cornell guidelines effectively.

Find more information in the Cornell Nutrient Management Spear Program fact sheets on the Northern New York Agricultural Development Program website. Go to the Crops section at <> .

•Agronomy Fact Sheet #35 Nitrogen Guidelines for Corn explains how N recommendations are derived.

• Agronomy Fact Sheet #36 Illinois Soil Nitrogen Test for Corn provides details on how to use the ISNT.

• Agronomy Fact Sheet #4 Nitrogen Credits from Manure details how to deduct manure N credits from the N application recommendations.

Find other resources through the Cornell Nutrient Management Spear Program website at

 Find forms for to submit samples for ISNT evaluation at Testing costs $15 per sample for ISNT and Loss-on-Ignition (LOI) organic matter testing; $10 when the ISNT is added as an extra test to the standard soil fertility testing package.