# Soil Testing



## Vol (Jul 5, 2009)

What happens with your soil sample when sent to be examined.

Regards, Mike

http://www.agweb.com/article/what-happens-during-a-soil-test-ben-potter/


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## IH 1586 (Oct 16, 2014)

Interesting. Wondering how everybody prepares their samples? I dry mine, break up the dirt clods, and remove all rocks and grass before sending them in. Just how I saw dad doing them, always wondered if I put to much effort into it.


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## hay wilson in TX (Jan 28, 2009)

*About the same as 1588's*

Problem is our potassium is mostly trapped in the damp clay lattice structure. In this form it is not available to the crop.

The drying destroys the lattice structure making potassium that is not available to the crop available to the chemistry of the analysis.

The lab has their reasons that are mostly valid. They take a two pound sample of 2,000,00 for even distribution of your minor sample. Then they extract a few oz of soil from your 2 lb 0 lbs. They grind it to a powder and stir, They then pull a few oz to represent our 2 Oz sample of 2,000,000 lbs.

The opportunity to find all the 1,000 ppm is fairly good. To find 60 ppm is a little tricky. To find all of >1 ppm is truly a miracle.

Plus some of the elements are highly mobile. Our dab in the dark may be when our 10 ppm has moved to a more friendly neighborhood.

For these reasons I have a great distrust of the accuracy of most results for the macro nutrients and even less trust for the micro nutrients.

I ask the plant what it has found. A system that is full of questions but still better than most soil analysis of clay type soils.

To avoid some of the accuracy problems I usually pull no less than 3 two pound samples to a small patch to more than 15 two pound samples for any thing over a few acres.
Then I take all the samples and average for a reasonable amount.

Do not tell the Lab but I have pulled three samples side by side for a one acre plot. Sent them off as three separate samples and then averaged the results. Seldom will the three side by side results be closer than 80% of the average of the three.

HERE a soil sample in the 320 ppm K range will tissue test down near 1% K.
To eliminate visual signs of potassium deficiency require a soil test in the 400 ppm K range.

Soils can be exciting.

Being in the hay business and knowing this soil I just assume a pH of 8. 8,500 ppm Ca, Plus 4% to 6% average 5% free lime. As well as a 50 CEC. 
Better yet I pull a hay sample from each cutting, and use the average for all the cuttings from that field to guess at the level for all the elements.

Not great because round bales will test lower in feed value than small squares, when baled side by side.
The test will be lower if I sample hay that has been baled a little too dry separate from hay baled at ideal humidity.

Two years ago I stopped baling one field, one round, before the humidity got too low. The next day I finished the baling. The hay baled the second day tested better than the hay baled the first day. ( I Knew the second day the stems were fully cured and started baling before the humidity got down to 70%)
The first day I started baling just as the air reached 70% Relative Humidity. The second day I started baling BEFORE the relative humidity was down to 70% Relative Humidity. The second day had a little less leaf shatter than the first day.

see http://www.wvu.edu/~agexten/pubnwsltr/TRIM/5811.pdf


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