Do you know what’s under your feet? If you’re reading this outside, the answer is no – because it’s estimated that upwards of 90% of the organisms residing in the soil are unknown to science. Healthy soil is a microscopic Times Square of bustling activity and nutrient cycling.
While we have next to no understanding of the species present in the soil, let alone the cycles they participate in, we have some tests we can run which give us some windows into the world of the soil. Think of them as a peeks through various manhole covers present in streets across the planet – they give you a glimpse, but you can’t climb through the manhole to see the full context.
Why are these glimpses important? Well, we may be missing a large chunk of the context for HOW plants grow, but we do have a somewhat better sense of what soil conditions they need to grow well. Obviously as farmers we want our plants to grow well, so the more we know about our soil the better.
Now, different labs offer different tests that tell you different things about your soil biology, and I’ve found that looking at all the tests a given lab offers tells you a lot about their approach to soil health. If a lab offers mostly chemical testing – think levels of NPK, micronutrients, pH and organic matter with a Haney test or a 24 hour CO2 tossed in at the end, that shows that their analysis and recommendations will come through an elemental lens. If they only offer one or two types of tests, then that’s an indication that they’ve either chosen to specialize in that one test, or they think that one test gives them a full view of what’s going on. In short – all tests are wrong, some are useful, and the usefulness of the results you get depends very much on the biases of the lab you do your testing with.
One company I’ve found that focuses on soil biology and offers a nice combination of tests is Earthfort. When you send them a soil sample, you can get insight into ion exchange (electrical conductivity), total biomass of fungi and bacteria, total living carbon, nitrogen carbon and overall nitrogen, biomass of only aerobic fungi and bacteria, protozoa counts and nematode counts.
You may notice one big test that’s not in this list – the Haney test. For many folks, the Haney test is considered the gold standard of soil biology testing. So I asked Earthfort why they offer the tests they do, and got a response that simply cemented my opinion of the company: “We test for soil biology as an indication of soil health, productivity, and function. Tests, like the Haney test, will tell you what is in your soil but not why or how it got there. Microbial interactions are crucial for nutrient cycling through the processes of decomposition, mineralization, nitrogen fixation, nutrient immobilization, and chemical transformations of nutrients present in the soil… so, testing for bacteria/fungi/protozoa/nematodes will help you understand what processes are actually happening in your soil based on the microbial populations and interactions taking place. Knowing your microbial populations is essentially learning about the potential your soil holds versus what is present in that moment.”
Earthfort’s tests will give you a solid understanding of your soil’s biological activity. It’s not a full picture of your soil’s health, but you can stitch the results together to get a decent snapshot of your soil at the time you took the samples, as well as a guess at what your soil is capable of. If you pair these results from Earthfort with some traditional chemical soil analyses and a few plant sap and tissue analyses throughout the course of your growing season, you’ll have as good an understanding as is reasonable to expect – remember, every test result is a peek through a manhole cover, and we’re missing 90% of the information about the world we’re peeking at. But having those glimpses into your soil health helps to set you up for success as a grower.