About N-Watch


Why was N-WATCH Created?  NWATCH was first conceived in 2009 when farmers in Southern Illinois were told they needed to reapply nitrogen for their crop following a wet 2-week period.  They had applied anhydrous ammonia within seven days of the prolonged wet period and the incorrect assumption was that all the N was lost due to denitrification.  Dr. Brown determined a way to determine whether or not the applied N was still in the upper profile and estimate the form and concentration found in the 0-1 ft.  The protocol created found the anhydrous band and showed farmers that a significant concentration of nitrogen remained in the soil profile, primarily as ammonium-N.  Ammonium-N is a reduced form of nitrogen and is not vulnerable to loss by leaching or denitrification.  Since it takes approximately 2-3 weeks for anhydrous ammonia to be converted to nitrate-N, it was a safe assumption that most of the applied N was still there.  Farmers that applied supplemental N to check for response reported no yield difference to the additional N.  It was concluded that if farmers could visualize the location of the applied band and have an estimate of N concentration (pounds/acre is a concentration… parts/2 million parts), then farmers should be able to develop a higher level of confidence with N management.  

What is NWATCH Based Upon?  N-WATCH is simply the Pre-sidedress Nitrate Test as described by the Late Dr. Fred Blackmer in the Iowa State University publication Pm-1714[1].  Added metrics include ammonium-N at 0-1 ft. and nitrate and ammonium-N concentration at 1-2 feet.  The Late Season Nitrate Test (LSNT) as described by Dr. Blackmer’s publication has been the focus of research projects over the past 17 years.  Dr. Fred Magdoff[2], University of Vermont, 1984, first described the protocol and how to evaluate the test results.  His research focused on a Pre-Sidedress Nitrate Test (PSNT).   The Late Fred Blackmer, Iowa State University, revised the protocol in 1989 and renamed it soon thereafter as the Late-Season Nitrate Test (LSNT).  The publication from Iowa State University (Pm-1714) is what all NWATCH reports refer to when attempting to interpret test results during the growing season.


  1.  Blackmer, Fred, R. Voss, and A Mallarino, 1997. Nitrogen Fertilizer Recommendations for Corn in Iowa, Pm-1714.
  2.  Magdoff, F.R., D. Ross, and J. Amadon, 1984.  A Soil Test for Nitrogen Availability to Corn, Soil Sci. Soc. Am. J. 48, pgs. 1301-1304

NWATCH Grower Data Agreement  To participate in the NWATCH program you will need to agree to the terms in the NWATCH Grower Data Agreement.


NWATCH Grower Data Agreement (PDF)


If you do not have a email address to use when creating a new site, please download and sign the data aggeement below and send to your adviser.

NWATCH Grower Data Agreement Signature (PDF)