Soil Test For Organic Gardening
Why bother with a soil test?
A soil test is both easy and inexpensive and there really is no good reason for not getting it done. Without it you are just shooting in the dark and making wild guesses about what to do while wasting your time and money in the process. I know that the term ‘large garden’ is relative to your available space so let me state it this way. If you have a garden that is 500 square feet (10 feet wide and 50 feet long) and larger, having it checked is even more important. Why do I say that? Because with a garden of that scale you are going to be investing considerable time in preparation. You will also have the expense seeds and/or seedlings. With that much invested in your garden, not knowing the condition of what you are growing in is simply irresponsible. Getting it checked now will not only tell you what is low or missing - and you can be sure something is - but will allow you to ascertain how much you are going to need, which is just as important.
There is a principle in agriculture called Liebig’s Law of Minimums. Baron Von Liebig was a scientist that proved that your crop would not be any healthier than the lowest nutrient available. Having a deficiency in one area would effect the everything else.
Let us take the example of a low pH reading. I have seen a great number of cases in which there is an ample supply of Phosphorus but it is unavailable for the plants to use because the pH is too low. It becomes trapped in the soil due to an extra ion on the molecule. The only way to solve the problem is to add lime which will release the excess ions and raises the pH level. This is only one example of the many problems you can run into. You could fertilize very week and your plants would barely get enough nutrients to survive, let alone produce enough to harvest.
What does a soil test cost?
With a minimal amount of effort to obtain samples, postage and a laboratory fee you can get a basic report from a professional laboratory all for about $10.
How do I get a soil test?
Simply obtain a few samples totaling about two cups from the total area you intend to be working with. I recommend that you obtain your samples from a several different locations from the area in question. Whether it is a garden or a lawn, mentally divide it into about eight different sections and take a sample in each section. This will provide an “average” of the entire area and will help avoid a skewed reading. You can use a scrap piece of PVC or brass pipe at least one foot long. Wrap a piece of black electrical tape about two inches from the bottom to show the target depth. A hammer makes short work of inserting pipe without having to push. A piece of coat hanger will pop it out of the bottom. After you get all your samples together, pick out the stones, grass roots and whatever else is obviously not soil. Take approximately one cup of soil and place it in a zip lock baggie, squeeze out the air and zip it up. For good measure use another baggie and repeat the process. The you won’t have to give a second thought about it opening up during transit or getting contaminated.
Where do I get a soil test?
Now call your local county cooperative extension office. You'll find the listing in the county government section of your phone book. These people are very helpful and informative. It's worth the effort to visit your local office and getting to know them. Find a local office here
There is typically a one page form to fill out prior to shipping you sample to the state laboratory. Your cooperative extension agent will be able to assist you and may even have a pre-addressed box for you to use to ship to the lab.
Okay, I've got my report, now what?
The hardest part of this is interpreting what all that data means and knowing what to do. Most labs will include recommendations about what and how much chemicals need to be applied to your soil. These are standardized and included with the computer software that they use. Unfortunately these do not work for the organic gardener, that is why I have developed a set of guidelines specifically for organic gardening. They are free to use for your own personal use but may not be copied or reproduced in any way because they are copyright protected and vigorously enforced.
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