Soil fetility tests

[Treevly]

A university lab near me does soil tests. The list of tests include
pH, P, Mg, K, Na, Ca, Mn, Zn, Cu, and Fe. Why do they not include a test for Nitrogen? I thought that would be of prime importance.
Thanks.

 

[f-e]

The values you state, are unlikely to change. You can test in fall, then spread most amendments on the soil, and let winter take it in. The Nitrogen cycle is very fluid, and what's available at any one time, isn't a great indicator. You really need a history of tests, to know what your soil is doing. A few decades ago we couldn't test for it at all, so many farmers apply what they know a crop will want. Often in stages, as it can soon convert back n forth between available and unavailable compounds. But the layman explanation is that is simply washes away. Which a lot of it does. So misinterpreting a soil test could lead to a correction that wasn't wanted, and one that goes into the water table.

I'm no expert, but the field nitrogen cycle is well documented, or at least it looks so to me

 

[Drewsif]

Because nitrogen is variable. Even throughout a 24 hour period,levels are elevated at night. (hmm i wonder where is comes from)

Traditional farming doesn't add anything but nitrogen. Everything else is addressed by converting mineral via microbes. A fertility test was originally meant to show how fast microbes were breaking down unusable minerals into plant-usable forms,not how much npk you dump in a field.

 

[Treevly]

UPDATE: I aksed if Nitrogen could be tested as well, the reply was yes, but the N test was the same as the general basic test. That is, the basic soil fertility test for pH, Phosphorus, Potassium, Magnesium, is $20, and the Nitrogen test is $20 more. I accept that the N test must cost more for technical reasons, but do I want it? That raises another question: what am I going to do with a bunch of numbers anyway? What I would need is an explanation in layman's terms as to whether this stuff is Good Durt or Crummy Durt.