How is nitrogen content measured in soil? 1

[TangoCharlie]

When a farmer sends in a soil sample, how does the lab determine the nitrogen content? Is it possible to measure it on-site? I know next to nothing in this area, so use small words.

 

[rockiologist]

I am not sure if it is possible in the field, but any environemental lab can measure the nitrite and nitrate (NO2 and NO3) in the soil. That is a realatively inexpensive test.

 

[TangoCharlie]

Right. Thanks, rockiologist. I know a lab CAN measure it. But HOW do they measure it?

 

[rockiologist]

TangoCharlie,

In the US most labs follow SW-846. I have attached a link to the nitrate nitrite test for you to see how it is run. I hope this helps:

Nitrate:

http://www.epa.gov/SW-846/pdfs/9210a.pdf

Nitrite:

http://www.epa.gov/SW-846/pdfs/9216.pdf

 

[TangoCharlie]

Thank you, Thank you, Thank you! Very helpful, indeed. Now we just have to figure out a way (probably not the 'lab' way...)to measure it in the field, on the fly, so to speak. Hmmm.

 

[rockiologist]

Tango Charlie

I was thinking you could try HACH field Equipment to test for nitrogen in field. It may be just an indicator, but maybe enough for you. Here is the link:

http://www.hach.com/hc/search.produ...zVKbWQxWlhOMFdFSklTRmd4TWc9PUJ6RTBOVFk1Tg==|.

If that does not workgo to:

http://www.hach.com

Type in nitrogen soil and see the results for soil fertility kit.

Hope this will help you in the field.

 

[TangoCharlie]

Thanks again.

 

[howardoark]

There are different forms of nitrogen and they won't all show up in the same test. Kjeldahl nitrogen is the stuff bound up in organic matter. Reduced nitrogen (nitrate, nitrite and ammonia) is the stuff farmers are interested in. Agricultural labs will give you the entire suite of analytes for $50.