What to Look for When Assessing Soil Quality

You may think of the land you walk around on as just dirt, but it’s this dirt that makes up the thin sheet of the earth’s crust that supports life. And this dirt, also known as soil, is made up of a specific combination of organic remains and rock particles.

In Oregon, we even have very special soil — officially named Jory soil — that is the basis of our diverse environment and how this state has become the number one producer of Christmas trees and an award-winning region for Pinot Noir wines.

What to Look for When Assessing Soil Quality

However, while our soil is primed to support life, it varies dramatically and still needs to be checked on to ensure your Oregon trees and gardens flourish.

Here are seven key factors to look into when assessing soil quality.


A quick and easy way to assess the texture of soil is by getting down on the ground and feeling it between your thumb and forefingers. If the soil feels gritty, chances are it contains a significant amount of sand. On the other hand, if it feels greasy, it has more clay. But, now what?

You’ll want to create the perfect proportion of soil that contains less than 52% sand, 28-50% silt, and 7-27% clay; this is best known as loam, and it’s loam that will allow the earth to properly filter and retain the right amount of water and nutrients.


The color of the soil is one of the initial indicators of its health and quality. The color is formed due to the level of moisture, minerals, and organic matter present. Soil takes on various colors ranging from red, black, and brown to yellow and grey.

While red soil is considered to be well-drained with medium levels of organic matter, grey indicates poorly drained, waterlogged soil with low levels of organic matter.

The Munsell Soil Color Chart is generally used to evaluate and classify the color of soil.

Soil Crust

Soil crust refers to the thin, continuous layer of soil on the top surface. It develops when the soil surface dries out after rainfall or irrigation.

This hard and difficult to break layer is often considered a concern as it prevents water from infiltrating the soil, which leads to water erosion. It also leads to a reduction in oxygen diffusion, especially if the soil crust is wet.

The formation of soil crust can be prevented by maintaining a healthy growth of crops and adopting practices that increase both organic matter in the soil and aggregate stability.

Water Capacity

The amount of water that soil can store for Oregon trees is called water capacity. Considering water plays a major role in the growth of plants and trees, it is important for soil to retain enough water for agricultural purposes. Many factors such as the presence of rock fragments, organic matter, and soil compaction affect the available water capacity of the soil.

The water capacity of your soil is concerning if you are required to water it more than what is considered to be the typical norm in your region.

This can be corrected by adding more organic matter to the soil, which increases the water capacity. You can also maintain a higher salt concentration below the root zone to maintain increased levels of infiltration and reduce evaporation.

Organic Matter

A very important indicator of good soil health is the presence of organic matter because it influences a host of factors including soil structure, water capacity, oxygen-holding capacity, and nutrient storage. A healthy soil is rich in organic matter.

So, what is organic matter? It is comprised of plant and animal remains that have been subject to various stages of decomposition. The final, end-product is referred to as humus, which is the dark brown, spongy substance that forms an essential component of soils.

Organic matter provides nutrients to the soil along with reducing the chances of erosion. It keeps compaction levels low, reduces crusting, and increases the seepage of water while protecting the soil from pollutants and pesticides.

You can maintain levels of organic matter through irrigation methods, reforestation, keeping vegetative cover, and reducing tillage.


Many studies suggest that the presence of earthworms indicate healthy soil quality. This is because these tube-shaped worms thrive in soil that is rich in nutrients and organic matter.

They also play a critical role in maintaining soil health and improving farm productivity.

Earthworms benefit the soil structure through casting and burrowing, which helps store added moisture by the formation of water-stable aggregates. They also contribute to the nutrients in the soil as they feed on plant debris and promote water infiltration by loosening and aerating the soil.

You can encourage the presence of earthworms by increasing organic matter in the soil, keeping the soil moist, and reducing the use of fungicides that might repel them.

pH Level

The degree of pH levels indicates how acidic or alkaline the soil is. If pH levels are greater than 7, it is considered to be alkaline, while lower than 7 indicates acidic soil.

The pH level is an important indicator because it affects plant growth. For instance, when the pH levels are too low or high, plant growth is stunted.

The ideal condition is attained when the pH level is between 6.2 and 7.3. Assessing pH level will give you a clear indication of the steps you need to take to ensure ideal conditions are met for better plant growth and disease prevention.

It is important to constantly inspect soil quality to ensure healthy growth of Oregon trees and plants. If you are unable to assess it on your own, reach out to a professional tree service center to guide you through this process.

Soil supports life and ensuring you have the ideal loam will nearly guarantee your plants thrive in their environment.

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