Know your patch of land a bit better with these tests

by: COURTESY PHOTO - Homeowners in Washington County can dig into their own soil and investigate it for root structure, organic matter, moisture and other characteristics to get a handle on soil health.As you begin to understand the importance of soil health, you may want to get to know your own patch of land just a bit better. A professional soil test can be an accurate and thorough way to get a lot of information about your soil, but can also be time consuming and costly.

As participants in our recent agricultural soil health workshops learned, however, you can get in touch with your soil health by conducting a few simple tests at home.

The best way to get to know your soil is to grab a handful of it and investigate. Because healthy soil requires a fair amount of organic matter, you should be able to see bits of leaves, roots, woody debris and other organic matter throughout the soil. Remember that organic matter helps in nutrient retention and soil fertility, structure, and stability (and also to prevent soil erosion). Organic matter will also give soil that rich, earthy smell many of us associate with a walk in the woods or other heavily vegetated area. Soil low in organic matter will have more of a mineral, chalky scent. Healthy soil in our region will typically also have some moisture and should stick together when gently squeezed rather than crumble apart.

All soil contains a combination of sand, silt and clay particles as well, known together at the soil texture, which you can learn to identify by the feeling of smearing a small bit of soil between your fingers. Different soils contain these particles in different ratios, leading to some soils that hold water more closely and others that drain more quickly, among other characteristics. Sand particles, which are the largest particles, will feel noticeably gritty, almost like grains of salt. Silt particles will feel much smoother because they are quite a bit smaller than sand. Clay, being the smallest, will feel sticky to the touch. Feeling adventurous? Some say that tasting a small amount of your soil can really help hone in on the texture.

While you are looking at that clump of soil (which soil scientists call an aggregate, by the way), check for even bigger features such as large pores and earthworm tunnels. These are a definite indicator of excellent soil health — earthworm tunnels help create pathways for rainwater and nutrients to travel, and the chemical compounds they exude can literally help glue the soil together. Look also for strands of fungus known as mycorrhiza, which, believe it or not, are great for your plants. They help by making nutrients better available to the roots of plants and knitting the structure of the soil together.

These fungal mats can be most easily seen by rolling back mats of leaves on the forest floor, but aren’t always visible to the naked eye, so again you may need a professional soil test to help determine if their presence. Another good indicator of a healthy fungal community is the presence of its fruiting body above ground, mushrooms.

There are, of course, showier tests for soil health that you can conduct at home. In fact, we recommend many of these tests as quick assessment tools that a farmer can conduct directly in the field or back in the house with easily available, common materials. You can take the same aggregate you had collected to investigate by sight and smell, and test it to see how stable it is when submerged in water. An unstable aggregate will dissolve quickly in water when tested, whereas a stable aggregate will hold its shape for hours (in the case of one aggregate we tested in our office, for as long as 10 days even).

It is clear why a stable aggregate that holds its shape when soaked in still water would do a much better job of resisting erosion than less stable soils. Other tests may call for fancy tools — for example, testing for soil compaction (how pressed down soil has become by equipment, tilling, and foot traffic over time) is often done using a special tool called a penetrometer that is a bit on the expensive side.

You can conduct a similar test in your own soil, though, just using a hand trowel. Notice as you press it directly down into the soil how much resistance you face — areas with greater resistance under the same weather conditions (same recent rainfall and moisture) are probably more compacted. As soils become more compacted, the roots of plants struggle more and more to get a hold.

With these simple tests, you can begin to identify some of the challenges your soil may present in gardening. In some cases, you will want to plan your lawn and garden to fit the conditions presented. This is especially true for challenging soil textures, such as soils with a high clay content. It wouldn’t be practical to alter the soil texture of your entire lawn or garden to improve drainage, so you may need to select the right plant for these soils, which tend to hold more moisture over time. In other cases, your soil health tests will uncover specific actions you can take to improve soil health, from adding organic matter to keeping soil covered.

To learn more about these different techniques, contact your local soil and water conservation district office at

Jennifer Nelson is outreach coordinator for the Tualatin Soil and Water Conservation District.

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