A Simple Soil Science Test
You can help your soil support your plants, flowers, trees, shrubs, and lawns by learning what it is made of. Testing your soil involves a simple do-at-home science experience that you can complete in an afternoon.
Like many gardeners, I tend to focus my efforts at ground level. I weed, water, and mulch on a regular basis. I replace plants that don’t make it through various weather stressors and give a little TLC to those that did. But it turns out the interactions under the soil may be at the root of much that goes right—and wrong—for my lawn, trees, flowers, plants and vegetables.
Of course we all think about soil, right? That’s why we mulch and fertilize. But soil isn’t a constant: it gets depleted and if you don’t like what it’s doing to your plants, it can be changed for the better. The easiest way to get to know your soil better is to figure out what it is made of and what it is lacking. For that, there’s the mason jar test.
Why Test Your Soil?
Dirt may look pretty straightforward—dirt is dirt, right? But the soil in your garden beds and under your lawn is actually made up of several components: clay, sand, and silt, as well as water, air, and organic matter. The proportions of clay, sand, and silt are what determine how well your soil supports the things that are growing, how much moisture it holds, and how well it drains.
Of those three, clay and sand are the most familiar. When viewed up close and under a microscope, clay is the smallest mineral and it holds tight to water. The problem? Too much clay in your soil and you end up with a sticky, mucky mess that won’t drain and stays cold much longer in the spring than sand or silt.
Silt is the middle-size element in soil, while sand particles are the largest. Just like sand at the beach, sand in your soil drains quickly and has trouble holding onto essential nutrients that plants rely on. Translation? You have to water and fertilize lots more than you probably want to.
When silt, sand, and clay combine in just-right proportions, the result is loam. That’s the holy grail of garden soil, the black gold that will help your plants stay nourished, drain well, and retain water when needed.
If the percentages of sand, silt, and clay in your soil are less than ideal, you’ll also be able to feel differences in the soil. Sandy soil is gritty, and if wet it doesn’t hold its shape. Clay soil is sticky—think playing with clay when you were a kid—and holds together too firmly. Loam will feel rich and hold its shape when wet, but breaks apart into meaty pieces.
