BOISE -- How much do you know about your dirt? Flowers not only need minerals and other nutrients, but the type of soil you have will make a big difference in the success of your garden.
KATVB master gardener Jim Duthie shows us a simple way to test your soil at home, so you can find out all the dirt on your dirt.
The success of any garden depends a lot on your soil. You can spend a lot of time and money to test the quality of your soil, but let me show you a simple and less-costly way to do it at home. All it takes is a canning jar with a lid, some water, and a sample of your soil.
Dirt is made up of mineral particles, water, air, and organic material, all mixed together in different sized particles.
The three main parts that we can see are clay, sand and silt. Depending upon where you live in southwest Idaho, your soil will be a different amount of each of those three things, and that can affect how your garden grows.
Clay makes up the smallest particles in the soil. They’re flat and sticky, and they pack close together. Clay drains poorly, and it takes longer to warm up in the spring.
Silt in the next largest component of the soil, and is made up of rock and mineral particles. It’s smooth and feels like flour when it’s dry, but becomes slippery when it’s wet.
Finally, sand has the biggest soil particles, and it’s very common here since we live in a desert. Sand particles are round, not flat, so water drains through quickly. But that means that the nutrients run-off quickly, too, so you have to add extra water and fertilizer with sandy soil.
The best garden soil is loam, which is a balanced mixture of all three of these soil components. The ideal ratio is 20-40-40, or 20% clay, and 40% each of silt and sand. If you have more sand, your soil is a sandy loam. Too much clay and sand and it’s a sandy clay.
We’re going to do a canning jar test to see how much clay, silt and sand there is in my soil.
Take a clean pint or quart-sized canning jar.
Fill the jar halfway with soil. You can take it from one location in your garden, or combine samples from more than one spot.
Fill the jar with water, leaving a little room at the top to shake it up.
Then tighten the jar’s lid and ring and get a good seal.
Shake the jar for a minute or so to insure that everything is suspended in the water.
Finally, let the jar sit for a few hours until the particles separate and the water starts to clear up.
Once everything has settled, take a look at the layers. The bottom layer will be the heavier sand and rock particles. Above the sand will be a layer of silt. And at the top is the clay layer. Floating on the very top is some lighter organic material.
Remember – you want a 20% clay, 40% silt and 40% sand mixture. I can quickly tell that the bottom layer is bigger than the others, so that means I have more sand than anything else. So I need to add some more organic material or fertilizer, and maybe even a little fine top soil.
One more thing -- take a look at the color of your soil. One of my samples is darker than the other. It has more organic matter in it, which is good. But the lighter soil means that I probably want to add more compost or other organic material before I start planting in it.
This easy test gave me a quick idea of the structure of my soil, and what I need to do to make it better.
You’ll get a much more detailed analysis with a soil testing kit, including the pH, and a breakdown of the different minerals and nutrients. You can also send samples of your soil to a lab, including your county extension office. Their standard test costs about $45 and it takes a couple of weeks to get the results.
Either way, you’ll have a more successful and productive garden when you’ve got good, quality soil, so you can grow it.
If you live along the Boise Bench, you probably have a heavy clay soil, so you’ll need to work in some gypsum, compost, manure and other organic material to break it down.
Many other areas in the Treasure Valley have sandy soil, especially in lower flat areas. Adding grass clippings, leaves and other organic matter, as well as some quality top soil, will make a big difference in improving the structure and fertility of your garden soil.