Nitrate-Nitrogen (NO3-N) is the amount of available nitrogen, tested as nitrate, present in the soil at the time it was analyzed in the laboratory. Because of it’s solubility nitrate can leach rapidly from the soil under wet soil conditions. This mobility makes it difficult to predict how much nitrogen will be present throughout the growing season. However, a sample collected in the spring can provide some guidance on how much additional N might be needed as a side-dressing to supply all the crop requirements.
To convert the results from ppm into pounds/acre (lbs/acre) use the following formula:
Sample depth (in inches) X 0.333 = conversion factor (CF)
CF X NO3-N ppm = NO3-N, pounds/acre
Soil test = 7 ppm NO3-N
Sample was collected to a depth of 6 inches
6 X 0.333 = 1.99 This is the conversion factor (CF)
1.99 X 7 ppm = 14 pounds/acre of NO3-N