Using the Late Spring Soil Nitrate Test In 2022
Antonio Mallarino, Professor and Nutrient Management Extension Specialist, Department of Agronomy, Iowa State University
June 7, 2022
This year corn planting was delayed due to an unseasonably cold spring, and at this time corn growth stage ranges mostly from the V2 to V6 across the state. Many producers had doubts concerning preplant nitrogen (N) application due to high N fertilizer prices, and now some are wondering about possible in-season diagnostic tools to assess a potential need for supplemental in-season N application.
Iowa research has shown that that the Late Spring Soil Nitrate Test (LSNT), or Presidedress Soil Nitrate Test (PSNT) as it is called in some other states, is a useful tool to assess if post-planting supplemental sidedressed N is needed. Extension publication CROP 3140 Use of the Late-Spring Soil Nitrate Test in Iowa Corn Production provides information about the sampling, research that helped with interpretation of results, and guidelines for N application when it indicates a need for supplemental N application. Also, last year’s Integrated Crop Management blog article Collecting Late Spring Soil Nitrate Test Samples further discusses soil sampling for the LSNT and includes a useful video concerning the soil sampling.