Knowing Your Soil

1 comment by Carter Westerhold

Are you like me, finding any excuse to get out in the yard and do some good ol’ yardwork? Probably not. If for some strange reason you are, this is the perfect time to orchestrate this year’s attack plan to have the best-looking landscape in the neighborhood. And it all starts with getting the dirt on…well, the dirt by getting a soil test.

A soil test will give you valuable information on the type and the amount of fertilizers you will need for the season. Knowing beforehand can make plants (including your turf) greener, healthier, and more resilient against pests and disease.

Doing a soil test is extremely easy. It all starts with picking up a soil test kit. (insert about test kit) Follow the kits instructions to get the most accurate results. Taking small samples from locations all around the landscape will help get you more cohesive results that will benefit the whole landscape. If you have a vegetable garden, it would be best to test it separately from the rest of landscape.

Getting the results are fun but without knowing a little background can be like deciphering a dead language. All you need to know is that there are three main things you need to pay attention to: pH, the macronutrients and the micronutrients.

  1. pH. This term may cause some traumatic flashbacks to high school chemistry, where you forgot to read the chapter last night and you have to run the mile in gym later this afternoon. Anyways, all pH tells us is how easy or hard our plants can access certain nutrients from the soil. If you haven’t done a soil test before, news flash: Southern Idaho’s soil is notoriously alkaline. Alkaline, or “sweet” sweet soil as people with bad taste buds call it means the pH is over 7. This means plants in our area generally will have a hard time getting nutrients like nitrogen, phosphorus, iron and manganese out of the soil. Applying sulfur pellets to your landscape can help lower your pH but this only works for a short time.
  2. Macronutrients. These are the big three nutrients all plants need. Nitrogen (N), Phosphorous (P), and Potassium (K). Yes, potassium’s abbreviation K. It’s Latin. These nutrients are so important to plant function that their values are plastered front and center on every bag and bottle of fertilizer. These three are the building blocks of plant cells and help keep important plant functions running like photosynthesis and not dying. In a very general sense, nitrogen helps make the plant green, phosphorus helps the plant produce roots (and fruits!) and potassium aids in plant metabolism.
  3. Micronutrients are the lesser but still necessary nutrients. Plants just need smaller amounts of these. In our area, iron is an important micronutrient. Because our soil doesnt have any! Many trees (like maples, birches, aspens) in our area become severely chlorotic (yellow) in the middle of summer because iron deficiency. If there’s one micronutrient to pay attention to, iron would be the one. But you already knew that because you looked at the chart!

Congratulations, you now have some context on how much your soil sucks. Now you need to figure out how to make it stop doing that. Looking at your test results, it recommends for x amount of square feet, you need y pounds of z nutrient. Perfect. Now that I have you nice and confused we'll move on.

Remember the numbers I was talking about earlier? The numbers you see on a bag of fertilizer tells you what percent of the bag’s weight is that nutrient.

For example: a 10-pound bag of 16-16-16 fertilizer is 16% Nitrogen (1.6lbs), 16% Phosphorus (1.6lbs), and 16% Potassium(1.6lbs). What the rest of the bag is depends on the fertilizer. Depending on your results, you may need to apply 2 or more different fertilizers. Be sure to follow the posted instructions for every bag of fertilizer you use. They made the stuff, so they’ll know best!

Want to know more, or need clarification? Email me at with any questions.

1 comment

  • Jane Miller

    Hi Carter, where do I pick up soil test kits? I have a fairly large yard and I’m fairly certain the soil may vary in different parts of the yard. Our front grass tends to struggle more so than the back grass even though 2 large dogs roam the back. Front gets far more sun than the back. Thanks for your help. After 30 years I finally decided maybe it would be a good idea to seek out soil testing! Retirement gives you more time for the details!

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