Have you ever wondered how healthy your soil is? There are three ways to get a handle on this question. Grow lots of different plants and if they grow well, your soil is healthy. Another option is to get a lab to analyse your soil, but standard lab tests only measure certain characteristics like nutrients and pH, and including more tests can be costly. The third option is to do the soil tests yourself.
This post is a collection of 10 simple DIY soil tests that you can do at home. Most require no equipment or purchase.
Improving Soil Health
Improving the health of your soil is a two step process. Step one is to measure the current health of your soil, and this post will help you do that.
Step two is to improve the soil. My book Soil Science for Gardeners provides a detailed discussion of soil, and has a section to help you create a personalized soil improvement plan.
Soil aggregation is a process whereby microbes combine the minerals and organic matter to form larger clumps of soil, called aggregates. A higher degree of aggregation indicates a healthier soil, which means more air and larger pores for root growth. That special black forest soil is highly aggregated.
The aggregate stability test measure the quality of your aggregates and the goal is to have highly stable ones. This video will show you to measure aggregate stability.
Microbes are extremely important for healthy soil but they are impossible to see or measure by the gardener. Microbes are the favorite food of earthworms and a higher number of earthworms indicates more microbes. An earthworm count is a simple way to estimate the number of microbes.
This test is taken from the book Soil Science for Gardeners.
As soil dries, earthworms move deeper in the soil and counts become inaccurate. Counts are also lower, early and late in the season. It is a good idea to test several times during the season and take an average.
Measure out a square foot of soil. Dig down 12 inches and remove all of the soil. Spread it out on cardboard or newspaper. Break up the soil and count all of the worms you find.
If your soil is healthy, you’ll find at least 10 earthworms per cubic foot (0.092 cubic meters). If you have less than 3, your soil is not healthy and needs major improvement. A number between these extremes means that your soil is OK, but there are things you should do to improve it.
Tighty Whitie Soil Test
This is a fun test that also measures the health of your microbe population. I have described this in detail in: Tighty Whitie Soil Test – A Brief Review. It sounds silly, but it does work.
Test Kits for pH
Test kits for pH will give you a very general idea of your pH. Kits and probes designed for home gardeners are not accurate enough to allow you to know how much soil amendment you need to change pH. Besides, in most cases it is better not to try to change your pH.
This will give you a review of some available kits: Soil pH Testers.
Kitchen pH Test
Cabbage Water pH Test
You can boil some cabbage to get a purple solution and then use it to measure pH. “Very acidic solutions will turn anthocyanin into a red color. Neutral solutions result in a purplish color. Basic solutions appear greenish-yellow.”
Although this test is fun to do with kids, it is useless for evaluating soil, because it provides no accuracy in the range you need.
Vinegar and Baking Soda
Add some vinegar to baking soda and it will bubble. If you add it to soil that has a lot of limestone in it, it can also bubble and such soil is usually alkaline. I put some vinegar on a piece of limestone from my garden and it made almost no bubbles.
Add backing soda to very acidic soil, it might also bubble, indicating the acidity.
The problem with this test is that most soil is near neutral and adding either vinegar or baking soda will not show bubbles. So this is a useless test for most soil.
Test Kits for Nutrients
Before you add fertilizer you should test the soil to determine its deficiency. You can get a lab test done, or use one of the home test kits designed for gardeners. The lab results are very accurate, but depending on where you live they can cost from $10 to $30 US. Home test kits are less expensive, but not nearly as good. This video reviews one of the more popular home test kits for nutrients, Rapitest, and compares the results to a lab test.
Ideal soil is 25% water and 25% air. As soil gets compacted the amount of both of these goes down, making it harder for roots to grow. New homes almost always have a compaction problem due to the heavy equipment that was used to build the home, but even walking on soil causes compaction. It is one reason grass has difficulty growing.
There is a simple, but effective way for the home gardener to measure the degree of compaction, as explained in this video.
Soil texture is a measure of the mineral components in soil – the sand, silt and clay. Sand makes soil gritty, and clay makes it feel smooth. Soil texture can be measured in several ways by home gardeners.
This first video shows you how to measure texture by letting soil settle in a jar of water. It also explains the soil texture triangle which will help you determine the type of soil you have.
This second video shows you some simple tests you can use to “feel” the soil. They are a faster way to determine soil texture, but they’re not as accurate. However, they provide more than enough accuracy for the home gardener.
The percolation test, or perc test, measures how well your soil drains. It is an easy test for the home gardener and requires no special equipment.