Soil is the one of the most important elements of a successful vegetable garden. And be sure not to call it dirt, master gardeners (at least where I live) get sensitive about that. Dirt is what you track inside the house on the bottom of shoes; soil is the living matter that support the growth of grass, trees, bushes, and other tiny organisms that you can’t see outside.
What is soil?
Soil is a living, breathing thing that has many important jobs:
- Filters water (yep!)
- Habitat for living organisms (think earthworms, but there are thousands more!)
- Environment for plant growth
- Recycles waste products
And as you probably know, there are many different types of soil out there. Some areas may have loamy or sandy soil, while others are plagued with clay-heavy soils. Gardeners across the country (and world) have to first determine what they’re working with to know how best to plan their garden.
Most undisturbed soil is primarily made up of three layers:
- Topsoil– The topmost layer, and what you’re probably most familiar with.
- Subsoil– This layer usually has a bit more clay and less organic matter than topsoil
- Parent Material– This varies greatly based on where you live and even in your state, different regions will have different parent materials. Bedrock is an example of a parent material.
What makes good soil?
Good soil isn’t necessarily what comes in a bag from the hardware store. You may actually have some good soil in your own backyard, but before I tell you how to test your soil, let’s talk about what soil is made of. I mentioned earlier what soil does, but did you know that soil (much like a fancy cake) is made in layers? Yep, it’s true!
The most popular soil types found in backyards are:
- Sandy or Coarse Soil– This soil doesn’t hold water well, which also means that nutrients are flushed out of it easily. This type of soil means fertilizers will be a must.
- Clay or Finely Textured Soil– This soil does hold water and nutrients well, but it’s difficult to work with since it’s hard when dry and sticky when wet.
- Loamy or Medium Textured Soil– Typically this soil will have more organic matter in it and holds moisture relatively well. And since they also hold nutrients, this type of soil is fertile for growing.
Which of these sounds like what you have in your backyard? The next step to learning more about the garden soil in your backyard is to have it tested.
How to Test Garden Soil
Having garden soil tested is much more complicated than it sounds. It definitely doesn’t involve you buying a microscope and wearing a lab coat, though you certainly could if you wanted. My recommendation for soil testing is to use the resources of your state’s soil testing lab.
Get in touch with your local Cooperative Extension office and stop by for a soil testing box. Once you have the box, here’s what to do:
- Wait to take a sample when your soil is fairly dry. (i.e. not after a day of rain.)
- Dig down into your soil six inches and scoop out some soil.
- Then find another spot and repeat the scooping process.
- Fill your sample box with soil from around your garden for the best mix.
- Close up the box and fill out the paperwork that accompanies it, so you can give the lab the best information possible.
Can you submit more than one sample? Absolutely! I usually do at least two. One for my raised beds, and one for the area where my blueberries and figs grow.
How long until results I see my results? That depends. Most labs are busy in the late winter/early spring, so be prepared to wait several weeks during that time of year. The fall is a slower time, so if possible, send your sample in the fall for a quick turn around.
How to read a soil test report
- Note that my test was listed as a “vegetable garden” which is important, since soil test reports can give recommendations based on what you’re growing in that area.
- Ph– The Ph of the soil tells you how acidic or alkaline your soil is, and plants are sensitive to this in soil. As you can see on my sample, my soil Ph is a little higher than optimum. Since it wasn’t too alkaline, and I wasn’t planning to grow acidic soil-loving plants in this area, I just left it alone. But if you soil does need to have it’s Ph raised or lowered, check out this great article from Clemson University on “How to Change the Ph of your Soil.” Lime is typically used to increase the Ph of garden soil, and you’ll see on my report that they recommend no lime since my soil is alkaline.
- Nutrient Levels– The phosphorus and potassium index for my soil is on the right side of the report, and they were off the charts. I remember being very surprised by these results, but you just have to roll with it. Because there’s nothing I can do to really lower these numbers, you’ll notice that they recommend the only fertilizer I use be a 21-0-0. This means the fertilizer has no phosphorus or potassium added, since my soil needs none.
Soil testing at home
There are home methods of testing soil, though I haven’t used them myself. I prefer to let someone else do that for me, but if you’re interested in trying it out, there’s some great information and products out there. Here are some ideas:
- Soil Texture Test/Jar Test: For testing the texture of your soil (not the nutrients) try this step-by-step tutorial from Clemson University.
- How to Test Soil Ph at Home from Preparednessmama.com
- 3 Simple Soil Tests from The Farmer’s Almanac
If you try any of these out and love them (or not!) let us know below! I may need to just branch out and try them myself. Whichever method you choose, definitely learn more about your soil, so you know what you’re working with. Have a great day and happy gardening!