Is Soil Structure Important for Plant Growth? (Complete Guide)


Picture of Soil

Almost all of the global food production depends on soil. Also, it is home to a quarter of all terrestrial species on earth. Soil also plays a vital role in storing carbon and water that helps mitigate climate change and avoid flooding. It is undoubtedly one of the most important natural resources available to humankind. Other than just soil, its structure also plays a major role in plant growth.

The soil structure affects its ability to retain and transmit air, water, organic and inorganic substances that support root growth and development. It also plays an important role in improving soil productiveness, enhancing permeability, and preventing erosion.

A healthy garden needs healthy soil. So, it is essential to ensure that your garden’s soil has a good structure that can support plant growth. There are quite a few things that will help you understand, improve, and maintain the structure of your garden soil.

What is Soil Structure?

Soil structure refers to how soil particles (sand, silt, and clay) are arranged. Soil that has a good structure would empty spaces between these particles. This allows air, water, roots, and other organisms to move around easily.

Soil structure can influence its capability to sustain life and perform important functions like carbon, water, and nutrient cycling. By maintaining a good soil structure, you will allow air and water into the soil, which is essential for the healthy growth of plants. A healthy soil structure also promotes germination, emergence, crop yields, as well as grain quality.

Without a proper structure, the soil will suffer from waterlogging, anaerobic, and nutrient lock-up. This can eventually lead to stunted growth and even death of the plant.

A decline in the structure of the soil is usually associated with land use and crop management practices. However, changes in climate and biological activity can also impact the soil structure.

How Soil Structure Supports Plant Growth?

Soil offers the following to plants to ensure their proper growth:

Anchorage

Soil offers a home to the root systems of the plants that extend outward and/or downward and, thus, stabilizing plants.

Oxygen

The spaces present in between the soil particles contain air from which the plants acquire oxygen. Since the living cells use oxygen to break down sugars and release energy, these spaces are essential for proper growth.

Water

Other than air, the spaces between the soil particles also contain water that moves upward through the plants. Water helps the plant in cooling down while also carrying essential nutrients. Water also helps in maintaining the size of cells and ensured that the plants don’t wilt. And most importantly, waster serves as a raw material for the process of photosynthesis.

Temperature Modification

While water can help the plant cool down, the soil is a much better insulator that protects the roots from drastic fluctuations in temperature. This is really important, especially during excessively hot or cold months times of the year.

Nutrients

One of the most important ways in which soil supports plant growth is through the supply of nutrients. Other than this, it can also hold the nutrients added to it in the form of fertilizers.

Types of Soil Structures

Some of the most basic types of aggregate arrangements in soil are:

Platy

Picture of Platy soil

In this type of soil structure, the unite are flat and platelike. Usually oriented horizontally, the plates generally thickest in the middle and become thinner towards the edges. This structure is usually found in the soil’s subsurface, subjected to leaching or compaction by heavy machinery or animals. This is a structure that obstructs the downward movement of water and plant roots through the soil.

Prismatic

picture of prismatic soil

A prismatic soil structure is where the individual units are confined by flat to rounded vertical faces. These units are usually recognized by their distinctive vertical length, while the tops are generally flat. In this structure, the movement of water in the soil is mostly vertical. Thus, the supply of water to the roots as well as drainage is generally quite poor.

Columnar

Picture of columnar soil

The columnar structure is somewhat similar to prisms. Flat or slightly rounded vertical faces also bound them. However, the tops are usually very distinct and rounded as compared to the prismatic structure. Since this structure is extremely dense, plant roots cannot penetrate these layers. One can consider using techniques like deep plowing that will help restore some fertility in columnar soil structure.

Blocky

picture of hand full of blocky soil

As the name suggests, in a blocky structure, the units are blocklike or polyhedral. Flat or slightly rounded surfaces bound the units. The soil particles cling together in almost square or angular blocks and relatively sharp edges. Blocky soil structure can be further divided into angular blocky and subangular blocky structures (based on their sharp or rounded edges). Large blocks indicate difficulty in penetration and movement of water.

Granular

Picture of granular soil

Units that are almost spherical or polyhedral form a granular soil structure. Rounded or uneven faces bound them. In layman’s terms, they may look like cookie crumbs. This structure is commonly found in the surface soils of nutrient-rich and highly amended garden soils. They also have high organic matter content. This structure also has good absorbency and allows easier movement of air and water. Thus, it is a great structure to ensure the healthy growth of plants.

Structureless

Picture of structureless soil

Some soils lack structure. Soils that are structureless have no definite arrangement of the soil particles. Usually, sand and sandy-loam soils are structureless that have a single grain arrangement. Other than this, clay soils can also be referred to be structureless. This is when the particles create a massive structure with no small aggregates inside.

Factors Influencing Soil Structure

Certain elements and practices like compaction, excessive moving and handling of soil, screening, and excessive sodium can deteriorate the soil structure. As we know, heavy machinery can compact the soil making it less permeable to water. This can increase the probability of soil erosion and even flooding. High livestock densities can also do the same and damage the soil structure.

Other than this, factors like overworking the soil through tillage can also be quite harmful. This practice can also decrease the organic content and nutrients in the soil.

It is also known that a high proportion of sodium to magnesium and calcium can also cause the clay particles to repel each other when damp. This can reverse the process of soil structure formation. Excessive irrigation or salting roads can lead to high levels of sodium which can eventually cause the small organic particles to clog up and making the soil almost impermeable to water.

Other than these activities, there are also a few factors that can influence the structure of the soil in your garden:

  • Organisms (like worms and bugs) present in the soil
  • The amount of organic matter the soil contains
  • Any freeze/thaw that occurs with the soil
  • The amount of tillage performed with the soil
  • The presence and size of soil colloids
  • Water flow and movement

Checking Your Soil Structure

To improve the structure of your soil, it is vital to examine it first. For this, you can dig a 30- to 40 centimeter-deep hole while ensuring no spade marks along one side. Now, you need to examine the unmarked side of the hole by inserting a knife around a centimeter. The areas where you sense a greater resistance would indicate compacted zones.

Moreover, it would be best to look at the root development and any traces of worm activity. This will also give you an idea if the soil is well-structured or not. Restricted root growth or lack of activity usually indicates an issue with the soil structure that should be addressed.

Ways to Improve Soil Structure

With careful and proper management and certain practice, one can enhance and maintain the structure of the soil. There are a few interventions that can prove to be extremely beneficial for soil structure. Here are some simple and easy ways in which you can improve the structure of your soil:

Balancing the amount of organic matter in your soil

While lack of organic matter in the soil is a common issue gardeners face, excessive organic matter can also be an issue at times. Thus, it is important to maintain a proper balance of organic matter to ensure proper plant growth.

While deficiency of organic matter would result in a lack of nutrients responsible for plant growth, an excessive amount of organic matter in soil may stimulate the growth of wrong plants such as algae.

To increase the amount of organic matter in your soil, you can add fertilizers like manure to help soil regain its strength and even provide the plants with nitrogen which is crucial for their healthy growth. One can also grow cover crops to add organic matter to the soil.

On the other hand, if one needs to decrease the organic matter in your soil, one can try tilling and turning the soil. However, one should be careful to examine the soil very closely to maintain balance.

Increase Your Soil Organisms

The bacteria and those natural critters are essential for the soil. They are significant in stabilizing the structure and holding the soil together. Other than this, fungi also play a pivotal role in decomposing particles and ensuring healthier soil. One should encourage wildlife in their soil as well, such as earthworms. They serve as ‘ecosystem engineers’ that aerate the soil as they burrow their way underneath the soil.

Prepare Your Soil for Extreme Weather Conditions

When it comes to weather, there is very little that one can do. However, one can definitely prepare the soil for the upcoming drought, flood, frost, or the scorching sun and ensure that it is well-conditioned to face the adversities ahead.

For this, one can try growing cover crops, rotating your fields, working with more fertilizer, or improving irrigation or drainage.

Conclusion on Is Soil Structure Important for Plant Growth

Good soil structure is crucial for sustainable agriculture. And with the proper knowledge of your soil structure, you will be able to maintain and enhance the health of your soil, which will have a significant impact on water movement, regulating soil temperature, nutrient cycling, and thus ensuring proper plant growth.

We hope that these tips will help you improve the structure of your soil and grow healthy plants in your garden.

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Tony O'Neill

I am Tony O'Neill, A full-time firefighter, and professional gardener. I have spent most of my life gardening. From the age of 7 until the present day at 46. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

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