Science Buddies: "Ask an Expert"

Hello,

Could you please tell me how to measure Nitrogen in soil and how accurate it is?

Thank you Amy.

There are two main methods to measure Nitrogen in soil, so I'll explain each and its reliability. First, there is the Nitrogen soil strip which functions like a pH strip. The strip is a colorimetric (involving the analysis of color) method. There are several brands, but the necessary steps are to expose the test strip in the soil, to wait for a specified amount of time, and then to compare the color of the strip to a color chart on the back. This is very helpful, but the eyes can be unreliable in comparing color. Second, there are electronic probes which would come with directions often involving exposing the probe to the soil and then reading the instrument. These would be very accurate tools, but they come at a large price. Both methods are relatively easy as long as you read the directions and practice a couple times. I suggest that you research prices when making your decision.

On page 16 is an example of the first method. http://www.nrcs.usda.gov/Internet/FSE_D ... 044790.pdf
This is also a helpful video for the first method. https://www.youtube.com/watch?v=4gMVoLTRMvY
A simple online search will show the various types of electronic probes, which can go by other names such as "electrodes."

Hope it helps!