Pre-Sidedress Soil Nitrate Test (PSNT)

Definition - What does Pre-Sidedress Soil Nitrate Test (PSNT) mean?

In large, outdoor agricultural fields, a pre-sidedress soil nitrate test is a simple test that provides farmers a method of estimating the existing (available) nitrogen supply within the field's soil.

The pre-sidedress soil nitrate test (PSNT) is done by taking soil samples during the growing season. The samples of soil are obtained just beside the growing crop or plants.

The goal of doing a PSNT is to find out whether you have been overfertilizing or underfertilizing the crop with nitrogen, as a means to troubleshoot problems and avoid larger issues.

MaximumYield explains Pre-Sidedress Soil Nitrate Test (PSNT)

When used on corn fields, for example, a pre-sidedress soil nitrate test is done in the spring during the wet season and then repeated again during the corn’s active growing period when the crops demand for nitrate is usually at its highest. The test results can then be compared and specific fertilizer ratios can be applied to meet the plant’s distinctive growth requirements.

The PSNT, also known as the June Nitrate Test, was originally developed in the mid-80s by Dr. Fred Magdoff at the University of Vermont, who at first focused on dairy farms, where manure is frequently applied, and legumes such as alfalfa and clover are often planted. His goal at the time was finding a way to account for the available nitrogen that would be provided to the corn grown from those sources.

Different states have various methods used to analyze the pre-sidedress soil nitrate test results. Each method is distinct to the region where the crop is being grown and harvested.

Not all fields benefit from the PSNT test. Generally, fields that have been determined to naturally have a high nitrate content are ideal candidates for the test. Also, fields that did not sustain excessive moisture the previous fall and had only adequate rainfall in the spring and summer months can benefit from the test.

Fall-tilled fields, manure-laden fields, and those located on a south slope also benefit from the PSNT test.

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