I'm reading up on how to calculate TEC (Total Exchange Capacity), and I tested out my calculations using a recent soil test. My answer was drastically different than the published TEC. Problem is, I used the exact same formula on some other tests and it matched the published TEC on the test. So, is this test a misprint? The test says TEC = 17.45. I calculated 11.63.

http://s2.postimage.org/gpjxvx9k7/Soil_Test_BTEP_8_11.jpg

My calcs:

((3292/400)+(612/240)+(228/780)+(22/460)) / (100-(4.4+0)) = 11.63

You need to read some more. A lot more. You are missing a factor. This is why I won't publish my spreadsheets.

I didn't account for the soil sample depth. The constants I used assumed a 6 inch depth. That's why my numbers match for vegetable garden tests that were taken at 6 inches but not lawn samples taken at 4 inches.
Thanks for making me work for it

Correct.

Thanks for making me work for it

I'm glad that you took my posting well. If I tell you where you went wrong in your calculations, you learn nothing. If I tell you that the lab is right and you need to read some more, you learn your mistake and probably a few other facts, and you won't forget how they relate. I'd like to see a few more members getting serious about how all the numbers work, as it gets too busy in Springtime for Morph and I to handle all the interpretation work. But it takes time to get to the point where you can write-up stuff without someone checking your work. You're doing really well.

And even Morph won't touch most of the micronutrients. Iron being the exception, but you could raise most plants in soil mixed with iron ground to dust and no harm done.

I have a mound of pure limestone screenings that I used to backfill some post holes and as paddock topdressing, and the darn thing sprung a pretty assortment of weeds this summer.

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