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Everything to Know About Soil Compaction

Soil compaction can cause many problems in the garden bed and result in plants not being able to access the beneficial things they need from the soil in order to thrive. Plants need water, oxygen, and nutrients from the soil, and they take that in through their root systems.

If soil is compacted, soil particles are pressed together too tightly, collapsing the small pockets of air that are vital to healthy soil. When this happens, the plants’ roots cannot acquire the oxygen and essential nutrients that they need to grow. Follow our guide for everything to know about soil compaction and learn how to identify the problem, how to avoid it in the future, and tips for improving your soil.

Man's boot on shovel to dig through soil.

What Is Soil Compaction?

Soil compaction can wreak havoc in the garden bed, and since it happens below the soil surface, it can often be overlooked. Consider some of these gardening complications that are rooted in soil compaction, which gives some insight into why it is crucial to identify and remedy the problem.

  • Roots that cannot move freely through the soil vertically will seek out a more horizontal path. This can impact the plants around it and create shallow root systems where all plants have less access to nutrients.
  • Seedlings will struggle to push through the soil seeking the sunlight, which is necessary for their growth.
  • Compaction and lack of soil aeration can destroy mycorrhizae, the beneficial fungi that appear as white fibers.
  • Plants with taproots will not be able to penetrate the soil, stunting and deforming their harvestable roots.
  • Poor root growth means poor overall plant growth.
  • Soil will have low water retention.

How To Avoid Soil Compaction

Now that we know what soil compaction is and some of the ways that it can negatively impact our gardens, let’s identify some solutions.

  • When planting transplants, use care to plant them with an adequate depth and do not press the soil down around the plant with too much pressure. Instead, water the plant in well and allow the water to naturally cause the soil to hug the root systems of the plant.
  • Water with a gentle spray on your hose setting. If you are watering with too intense of a spray, this can pound down on the soil and result in compaction.
  • Avoid walking on or using equipment on the soil, especially when the soil is wet. The sheer weight of such activity causes soil compaction, negatively changing the soil structure.
  • Avoid tilling soil. Instead, mimic nature and layer soil amendments from the top and let roots and organisms manipulate the soil beneath the surface.
  • Amend soil with organic soil amendments regularly.
  • Plant cover crops when the garden bed is not actively in use. Roots will penetrate the soil and protect it from erosion. Some cover crops can release nitrogen back into the soil as they grow, improving the soil.
  • Add mulch to the garden beds to reduce the impact of heavy rain and add a cushion of protection to the soil beneath. Over time, the mulch will break down and improve the soil considerably.
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Soil Compaction Test

There are several ways that you can tell if you have a soil compaction problem. From general observations, soil tests, and garden devices, soil compaction can make itself known to gardeners in many ways.

Observing Soil Compaction

Keep a close eye on your plants and how your soil looks and feels. Sometimes making a note of these key elements can give you insight as to when soil compaction is present. Look for:

  • Dry Soil Crusting – Hard crusty layer on the top of the soil with moist soil beneath
  • Sunken Dips in the Garden Soil – Can be from too much water, footprints, erosion, or another compression.
  • Inadequate Plant Growth – Plants that are stunted, do not germinate properly, or fail to produce
  • Yellowing Plants – Discoloration of plant foliage and stems that are a result of inadequate consumption of water and nutrients.

Examine Your Soil for Compaction

Use a shovel to big up a clump of soil. If the soil has defined edges and stays together, then you likely are dealing with problems of soil compaction.

Use A Penetrometer to Detect Soil Compaction

You can use a gauged device that you insert into the ground, and it measures soil compaction in pounds per square inch.

Soil Compaction Squeeze Test

You don’t necessarily need a fancy device to determine if you have soil compaction in the garden and if it could benefit from amending. If you pick up some soil from your garden bed and give it a gentle squeeze, you can tell a lot about your soil.

  • If the soil sticks together cohesively enough to form a shape and is softs and crumbly, your soil is optimal, filled with organic matter and well-draining.
  • If the soil forms a pasty ball, it is a more claylike soil and more prone to compaction.
  • If the soil falls away, it is on the sandier soil. Sandy soil can also be compacted.
Woman planting vegetables in a box in her organic garden.

Tips for Improving Compacted Soil

Thankfully, there are ways to deal with the problem of compacted soil. The aim is to break up the soil particles and get lots of air and balanced moisture throughout the soil so that roots can move freely and get what they need to grow and produce.

  • Work the garden bed with a garden fork. This can be a difficult task in heavily compacted soil. Plunge the pitchfork into the soil and move the fork back and forth until you have broken up the soil particles, allowing air to penetrate.
  • Remove any random roots and debris that have impeded your garden bed. Snip them out and dispose of them in your compost pile.
  • Amend your garden soil with organic soil amendments using the layering method. You can also add things like compost, worm castings, earthworms, well-decomposed poultry manure, grass clippings, pumice, and more. These amendments will seep into the soil over time, significantly improving the soil structure.

Everything to Know About Soil Compaction

With everything to know about soil compaction, you can see the trouble it can cause for plants and microorganisms, depleting their oxygen supply and choking them out. Individual elements can compress the soil medium, negatively impacting plant growth and survival of beneficial soil microbes.

Adding organic soil amendments helps to create pockets between soil particles, which leads to a domino effect of great things in the garden. Water and air get where they need to go, giving plants’ roots access to everything they need to thrive. Adding organic soil amendments to your existing soil creates the optimal soil structure your plants need to flourish.


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