Getting Started with the Illinois Soil Nitrogen Test

  1. Identify fields for sampling.
    • a. Submit boundary file or plat map
    • b. Sample will be taken on approximately 2.5 acre grids or by management zones.
    • c. Soil samples will be taken from 0-12 inches and 12-24 inches for organic nitrogen analysis.
  2. Submit field history and cropping plan.
    • a. Improving nitrogen management relies on identifying the factors that are important for crop response and developing individual field recommendations.
    • b. Initial rates will be conservative although in many cases may allow for substantial nitrogen savings.
  3. Review nitrogen soil map and application map.
    • a. Apply nitrogen with variable rate applicator.
    • b. Evaluation rates can be included in map so future rates can be adjusted for localized field responses.
    • c. Map yields and analyze evaluation rates.
  4. ISNT map can be used for several corn crops. Use evaluation rates to adjust to optimum economic nitrogen rate. With previous map as a guide, resample to improve accuracy of organic nitrogen test and to track any changes in test values.

Lab Process

The basic process of the ISNT is described below:
  1. As soil samples first arrive at the lab, they are placed in the drying room and dried.
  2. Once the soil is dry, all of the cores are ground into a fine particle size to make the sampling process more accurate.
  3. A representative sub sample is weighed and placed in a plastic jar diffusion unit with a sodium hydroxide solution.  Within the jar, there is a boric acid catch system used to collect the nitrogen released from the sample.  Multiple samples are then placed in a draft proof thermal incubator to undergo the diffusion process.
  4. When the diffusion process is complete, samples are titrated to determine the amount of nitrogen released from the soil sample which gives us our ISNT value.
  5. The ISNT value is then joined with the sample locations to create an interpolated map of potential nitrogen release.
  6. Cropsmith has a database of nitrogen responses that is used to create variable rate nitrogen application maps.

Custom Soil Sampling

Cropsmith can do almost everything when it comes to sampling.  With GIS expertise from industry partners, we can grid sample a field in various sized grids, or work with a grower to develop management zones to be sampled individually.  Cropsmith also has specialized equipment which has the ability to sample cores down to 3 ft depths also in different core diameters.

Cropsmith utilizes specialized equipment while soil sampling.  Our custom jeeps have been retro fitted with hydraulic soil probes inside of the cab.