I am going to depart from conventional wisdom here. I don’t think you always need a soil test. I know that is not a popular thing to say, and I have taken a little heat upon occasion. I’ll present my case and everyone can make up their own mind.
I don’t have any major objections to them. Sometimes it is helpful to see what your base point is. But you will begin amending soil from day one. Next year’s soil will not be the same as this year’s soil. You surely don’t need to have a soil test done every year.
Consider our local full service landscape companies that follow organic programs. They certainly don’t have time to wait for the results of soil tests before they can begin every job. They do a physical assessment and then apply soil building practices they have learned to depend on through time. You can do the same.
When you probably need a soil test
If you are new to a property, and have no idea what the previous ownership might have done to, or for, the soil, a soil test might be a good idea. But a basic soil test is still not going to return the information you really need to know.
A basic $10 public service soil test is going to tell you the soil pH, the Nitrogen (N), Phosphorous (P), and Potassium (K) levels, and a very few specific minerals such as Magnesium and Calcium. It will give you a recommendation of how much of each of these to add to your soil to support the type of plant you intend to plant in that soil. That’s pretty much it.
You can pay an additional amount to test for organic content, additional trace minerals, and soil structure, but you still will not receive the critical information that will give you the history of the soil as it pertains to contamination with pesticides, heavy metals, or hydrocarbons. It also won’t tell you if there are pathogens laying wait to devastate your best laid plans. Here is a copy of the standard TAMU soil test order form, and the tests that you can choose from. (http://soiltesting.tamu.edu/files/urbansoil.pdf).
To make things worse, the results shown in the report might not be as accurate as you hope. These labs must turn over a huge number of tests at a reasonable cost. The chemicals they use to break down the components are often the least expensive available and may not return the most accurate results. It’s close enough to identify major nutrient deficiencies, which may be all you are looking for, but these tests are quite limited. If you suspect an issue that could lead to health problems, you will need to seek out a private lab and be prepared to pay for the specific test you are interested in.
You also need a soil test if something is going wrong. If you consistently have trouble with a family of plants, and the symptoms or clues seem related to plant nutrition, a soil test can help you identify or confirm your suspicion so you can make appropriate corrections.
In my opinion, if things are going well, and you are on a solid organic soil building program, soil tests are an unnecessary expense and delay.
If I don’t get a soil test, what then?
You need to assess your starting point by observing the soil physically.
- What type of soil do you have – clay, sand, or loam?
- Is there sufficient organic matter available?
- Does it drain well?
Once you know these things, you can start a soil building program that you will follow for years. You will start with adding compost. Compost is the great equalizer and you will see us mention it over and over throughout the site. After that, you will start using natural, biologically active soil amendments. You will keep a continual layer of mulch on most of your beds. Nature will sort most everything else out. She’s been doing it for eons.
Start with a test if you wish, but if you REALLY want to know what is going on in your soil, you will need to send it to a lab endorsed by the Soil Food Web or endorsed by a local soil expert such as John Ferguson of Nature’s Way Resources. Bill Wyatt from Grace Outdoors recommends Logan Labs.