soil testing for organic gardening

I keep reading that everybody should test their soil before adding anything to it, so I decided to try to find a lab that would give me organic recommendations. Shouldn't be hard right? Well I just read that some labs frame their analysis in terms of the mineral content and others are looking at the organic content of the soil. Can't I get an analysis that tells me both? And since I live in Tx, it seems a good idea to find a lab in Texas. There is one in Edinburg, but I can't remember what kind it is, mineral or organic content.

Usually there is a standard test, which does the NPK and trace mins in your soil. Then you can add extra tests, such as one that looks at the amount of organic matter in your soil. This is pretty baseline information, but recomendations will be just for adjusting mineral composition, not soil health (these two, while tentatively linked, have little to do with each other, just as taking a multivitamin does little for the body if your diet is poor and you smoke).

The best indicator of soil health (in my opinion), which is what you're really after (unless you are concerned about heavy metal contamination, in which case they have extra tests for that as well), is the health and productivity of your garden plants. Watching them will give you the best indications as to what you're garden needs. I think there is a thread in the organic gardening forum that is entitled "Farmer vs. gardener fertilizing" started by CompostR, just down the list from the top. We all shared our thoughts and experiences on soil testing. Good luck
b

Good question, silverfluter.

Thanks Brambledad, I'll definitely go look for that thread.:)

silver - You can do some rough testing of the organic matter in your soil on your own. From my notes and experience over the years, here's what I have done:
Collect a soil sample - Get a large jar with straight sides and water-tight lid. Remove the grass, and thickest roots (about 1"), to reveal the soil. With a trowel, dig straight down about 7" deep, as if you were taking a soil core.
Fill the jar loosely about 3/4" full. Fill the jar with water to within about 1-1/2" from the top. Add a small drop of non-sudsing detergent if you have it (dishwasher detergent, for example) and shake the jar like mad. Allow to sit for 24 hours.

Observe: This is the fun part. The bottom layer will be sand (because it's heaviest) , on top of that silt (fine particles), then clay (slightly larger particles), then organic matter, then water and probably a few floating organics.
Now this is neat because it tells you something about the structure of your soil as well as the amount of organic matter. You'll need to estimate the percentage of each layer to the whole (ignore the water layer). For example, I could tell my sample was about 25% sand, 69% clay, and 6% organic matter (I honestly couldn't see a silt layer).

See this soil structure diagram (you have to scroll down a bit at the page) and you can roughly determine your soil type:

http://images.google.com/imgres?imgurl=http://www.scotland.gov.uk/Resource/Img/47121/0020508.gif&imgrefurl=http://www.scotland.gov.uk/Publications/2005/12/01130314/03147&h=415&w=385&sz=10&hl=en&start=2&tbnid=dBB2ykDrUXISQM:&tbnh=125&tbnw=116&prev=/images%3Fq%3Dsoil%2Bstructure%2Bdiagram%26gbv%3D2%26hl%3Den%26safe%3Dstrict%26client%3Ddell-usuk%26channel%3Dus%26sa%3DG%26ad%3Dw5

(You can find other examples of this diagram by searching "soil structure diagram" but this one is good because it shows percentages and is in color)

I have read 3-5% organic matter is sufficient for a farming situation. My own interpretation of that would be it's a minimum. Of course, you don't want a peat bog which would just be too acidic.
Personally, I love doing these kid science projects! : ) Let us know your results?

PS - I do my own soil testing (of nutrient levels and pH) with a LaMotte kit. I only do it once in a while when I just have to know!

That sounds like a really fun project CompostR. It'll be Monday before I can do that though. We'll be gone all day tomorrow working.

I thought I read somewhere that 6% organic matter was supposed to be very good. Can't remember where that was.

What is a LaMotte kit? I also read somewhere that the kits that you can buy at garden centers etc. are useless for testing alkaline soil. Since my chemistry is pretty weak, I can't remember why that is. I know our soil is alkaline, but I don't actually know the ph. Truthfully I'm a little afraid to find out what it is.:) What is your ph up there? I ordered a liter of EM1 and I'm hoping I can bring that ph down some atleast so the fertilizer and stuff will actually be used more by my plants.

Yes, I think 6% is good.

Here's a link to where I got the LaMotte kit:
http://www.gemplers.com/product/RLMB/Lamotte-Basic-Kit-NPKpH

They also have tests which just do the pH I think.

LaMotte also has a website if you're interested:
www.lamotte.com

Last time I tested my pH, it was 7. But, I question this result frankly. It was a while ago and I can't remember any details of how I collected the sample or ran the test. I'm vaguely remembering one should use distilled water for best results and maybe I didn't. I will be testing again soon. My guess is my soil is more acidic than 7 (neutral). I'm trying to grow blueberries and they like it acidic, so I'm going to dig in elemental sulphur to increase acidity. Compost increases acidity too.

I don't know why alkaline soil would be harder to test. Couldn't find any info on that. The LaMotte kit claims their test is reliable.

It's not quite thawed out enough here to start gardening (or soil testing) yet. It's "hurry up and wait" time!

Oh yes, I know the hurry and wait routine too well. I do that all year long.:) Thanks for those links.

Boy, 6%...I think our native soil is like .5% (that's point 5 per cent, yes). I guess that's from all that great compost you make, CompostR!

I dream of the day I hit 6%. I think I have one area that is around 4%, but I "cheated" by adding copious amounts of peat moss. Yes, sacrificing Canada for a little increase in productivity. Of course, I think E. Coleman once said that peat moss was an endless resource (he might of said that in the heady 80's, so I wouldn't hold him to it).
Ramblin'long,
brambledad

You're welcome, silver.

Hey, bramble - silver's using barley waste for compost - maybe you should head to the nearest brewery? ; )

CompostR
If I head to the nearest brewery, I'm sure I'll wind up feeling my soil is "Tahp Nosh" :>)

Weeeeell. I still don't have any beer mash.:( I'm not sure I can get any either. There's a local farmer who signed a contract with the brewery so I probably have to sweet talk the farmer into sharing his beer mash with me. I have even had time to find out who it is. Maybe we can trade sawdust for beer mash.:)

Let us know how it turns out!

The first time I saw that Soil Texture test was in school. We used "calgon" after taking some core samples from a few places in our yards. It was pretty amazing. Now I do it for all my clients along with using a LaMotte test for pH, N, P and K. As I am slowly convincing them all to go organic, their tests have been getting better each year. It is a slow process but worth it. Good soil health is everything!!