[glenmonte]

I've always waited for a fairly warm day in the winter to take samples for a soil test. My thoughts were This gave the last fertilization time to be absorbed and I'd get the results back with time to plan for spring. Is there a better time or rationale?

 

[g-man]

I normally do it in March/April. Some soil amendments take time to move thru the soil.

 

[Virginiagal]

For year to year comparison, it's best to do it about the same time of year. There are seasonal variations in nutrients.

 

[glenmonte]

For year to year comparison, it's best to do it about the same time of year. There are seasonal variations in nutrients.

That's why I'm confused. I did one early winter (moved in during the summer), and want to compare. I think I'm going to do one around the same time AND in the early spring to see what happens during the winter and where the lawn season starts. After all, I'll have to put down dimension no matter what.

 

[ken-n-nancy]

I think I'm going to do one around the same time AND in the early spring to see what happens during the winter and where the lawn season starts.

Sounds like a very safe, conservative approach. I'm interested to learn what you find in the tests - please post the results.

What I don't have a good understanding of is the expected variation that would occur from test-to-test (due to test procedures, soil sampling variation, sampling of different representative soils, etc.) so differences you see in the two different sets of test results will be due to a whole lot of different factors, not just actual changes in the soil between the first test (collected in the winter) and the second test (collected in early spring).

Seeing the results would at least be interesting, even if though they won't necessarily allow any conclusions to be made from just one data point.

 

[Virginiagal]

Here's an article on seasonal variability:
www.ipni.net/ppiweb/agbrief.nsf/5a4b8be72a35cd46852568d9001a18da/39518d8891eaa74f8525707000071d89!OpenDocument

 

[glenmonte]

I think I'm going to do one around the same time AND in the early spring to see what happens during the winter and where the lawn season starts.

Sounds like a very safe, conservative approach. I'm interested to learn what you find in the tests - please post the results.

I certainly will. I may actually go so far as to use my local test, Logan Labs, and the poorly reviewed but highly marketed Unibest Soil Savvy (which actually provides he same numbers as Logan plus Nitrogen). I'm even up to do any other tests just to see how varied the results are in each season. Am I missing any other popular brands?

 

[BXMurphy]

It would be a fun experiment but I'm reminded of some wisdom that goes... The man with one watch knows exactly what time it is. The man with many watches is never quite sure of the time.

 

[monty]

It would be a fun experiment but I'm reminded of some wisdom that goes... The man with one watch knows exactly what time it is. The man with many watches is never quite sure of the time.

I'm with Murph on this one. It would be a cool experiment, but to me it seems impractical for coming up with a plan.

 

[Virginiagal]

If you want a list of labs, here is one from North American Proficiency Testing:
http://www.naptprogram.org/about/participants/all/
Keep in mind that different labs use various extractants and you cannot compare numbers if lab A uses Mehlich 1 and lab B uses Mehlich 3 (or Bray or Olsen or whatever). Also, you are not sending the exact same soil to different labs. It may be similar but it is not the same sample.

As for Soil Savvy, what you get is a one time recommendation for fertilizer. You won't know your overall shortages, won't get any recommendation for the rest of the year. It does not report cation exhange capacity, which is one of the most important things to know about your soil. There is no buffer test so a meaningful lime recommendation can be done if lime is needed. Also, they even say that the pH they report may be off by 0.5. it's a pretty useless test.

You get more meaningful results if you are consistent. Use a consistent depth, the same lab, same time of year and you can then track changes year to year.