Why Does Soil Structure Matter?

You can following every rule of successful gardening but none of that will matter if you have poorly structured soil. Using the wrong soil will waste all of the hard work you put into watering and fertilizing your plants. So, why does soil structure matter?

Soil structure determines how much oxygen, water, and nutrients your plants can get, which determines their growth rate. Compacted soil restricts oxygen and causes carbon dioxide to build up, which can kill your plants. Conversely, soil with porous aggregates is less prone to compaction, erosion, diseases, and pests that would otherwise threaten your yard and garden. 

The structure of dirt is complicated, so follow along as we explore why soil structure matters and highlight the ideal type to use.

Reasosn Why Soil Structure Is Important

1. Drainage

Perhaps the most important part of soil structure is that it dictates drainage, which refers to how quickly water passes across and through the dirt. This is critical to plant growth. Proper soil drainage ensures plants get enough water, oxygen, and nutrients. Poorly drained soil can smother roots and leave them waterlogged, causing root rot. A plant cannot thrive without healthy roots, and roots can quickly die once they become too mushy.

When dirt stays wet for too long, it becomes more vulnerable to pests and diseases that thrive on moisture. You can improve soil structure and drainage by adding organic matter, such as compost and peat moss. You can also find soil amendments meant to correct improper drainage at plant nurseries and garden centers.

2. Organic Life

Healthy soil contains tons of organic life, from earthworms and nematodes to tiny soil microbes. These natural organisms play a big role in soil structure, and without them, it will suffer. Healthy soil has pores that allow oxygen to pass through and support plants, worms, and microbes, making it easier for them to travel, reproduce, and eat. Compacted soil restricts oxygen, limits microorganisms’ movement, and leaves them vulnerable to fungi and disease.

Eventually, you won’t find as many earthworms, which are essential for healthy soil beds in many areas. Even worse, harmful microbes form in compacted soil, and can kill your plants. If you want to improve soil health and attract earthworms, improve its structure. Aerate your lawn and add organic matter to loosen the earth and attract healthy microorganisms.

3. Growth Potential

Soil structure plays a huge role in root health. The perfect scenario lets roots extend as far as they need to reach their full growth potential. Loose soil allows this, whereas hard, crusty, and dense dirt restricts growth. If your soil is crumbly and contains large pores, you don’t have much to worry about.

However, soil changes over time due to natural factors, like rain and erosion, as well as man-made factors, like heavy equipment. Excessive foot traffic and heavy equipment can compact soil and destroy healthy macropores, restricting root growth. Macropores and micropores are equally important, and plants need a balance of both. An imbalance can restrict root growth, airflow, and water drainage.

4. Gas Movement

Oxygen isn’t the only important gas in soil. Carbon dioxide is also needed. The soil must let oxygen in, but it must also let carbon dioxide escape. This gas exchange is vital to plants and the organisms within the same soil. When soil becomes compacted, oxygen can’t enter as easily, and carbon dioxide can’t be excreted.

Trapped carbon dioxide will eventually lower the soil’s oxygen level and harm the roots. The lack of oxygen and the excess of carbon dioxide will limit the roots’ ability to absorb important nutrients, like potassium and nitrogen. This happens if your soil is compacted and adds up to a mostly preventable problem that can wreak havoc on your yard and garden.

5. Erosion

Soil structure plays a largr role in the occurance of erosion. Extreme flooding can cause soil erosion even if the soil is healthy, but well-aggregated soil can hold its own and resist erosion far better than loose, structureless soil. Erosion is more likely in compacted soil, as water can’t penetrate it, so it rolls off the top. This washes the topsoil away, along with the important nutrients.

Planting groundcover plants and applying mulch can largely reduce the risk of soil erosion. The problem is that many people don’t know the signs of soil erosion, and can happen without them realizing it. Bare patches indicate soil erosion, but subtle signs, like surface roots and poor plant growth, also point to it.

6. Soil Acidity

Soil structure and acidity affect each other. For example, overly loose soil lets nutrients wash away, which can increase soil acidity, whereas compacted soil reduces acidity. Compacted, waterlogged soil often traps carbon dioxide, which can also increase soil acidity. Acidity itself also affects soil structure.

For example, excessive soil acidity disperses clay by reducing the electron binding, which then fills the pores and can cause compaction. Never prioritize healthy soil structure at the expense of perfect soil pH, and vice versa. Otherwise, one will affect the other, and you’ll wind up back at square one.

7. Pest And Disease Vulnerability

Pests and plant diseases are directly linked to soil health because many pests detect when plants release chemical distress signals when stressed. Unhealthy plants become vulnerable and divert their energy, leaving them open to diseases and pests. This can cause physical changes, such as splitting and cracking, which let pests and pathogens easy access to plants.

Pests and diseases don’t always point to poor soil structure. For example, many pests hitch rides on clothing, pets, and the plants that you buy from plant nurseries and garden centers. Similarly, some garden centers unknowingly sell diseased plants to customers who discover them when it’s too late. However, you should at least reconsider your soil health if pests and diseases take hold of your garden.

How Long Does Natural Soil Compaction Take?

Soil can naturally become compacted in 5 to 10 years if you leave it alone during that time. However, natural soil compaction can occur in as little as 1 to 3 years if you live in a rainy or snowy climate. For example, a harsh winter with many heavy snowsfalls can damage a lawn due to the weight. Similarly, consistent heavy rainfall can damage soil aggregates and reduce the pore space in the soil.

That’s especially true for relatively barren lawns and garden beds without many plants. Ideally, you should avoid putting heavy machinery on your lawn and in your garden bed after it rains or snows heavily. It’s also a great idea to restrict the foot traffic in your garden and on your lawn after intense weather. You can always aerate your lawn to address the problem, but you should minimize the risk as much as possible.

Summing It Up

Soil structure affects drainage, acidity, and the risk of erosion or compaction. Well-structured soil lets oxygen in to support the roots and microorganisms, and lets carbon dioxide out to maximize nutrient absorption. You can support your yard’s soil structure by applying mulch, using organic matter, and avoiding tilling.

Related Guides:

• How To Prepare Your Garden Soil After The Ground Thaws
• How Important Is Soil Temperature?
• Eight Signs Your Garden Soil Is Unhealthy