Soil is made up of all kinds of particles and minerals that give them their texture and feel. The way the soil is structured and maintaining a good structure in the soil helps support plant growth and health as well as ensuring good soil fertility.
What Is Soil Structure
Soil structure is the way the soil is organised. As opposed to what the soils materials which could include clay, silt, sand etc. the structure relates to how these materials are bound together and the way they are organised.
While the minerals that make up the composition of the soil is not really feasible to change in scale the structure of the soil is and by improving the soil structure you will ensure better plant growth and health.
Why Soil Structure Is Important For Plant Growth
Plants need water, air and nutrition to survive and flourish. These 3 things are provided to the plant through their root system.
Soils with poor structure have fewer air pockets or pores which in turn affects the nutrients in the soil and the drainage. All these fundamental building blocks for plant growth are impacted by the soil structure.
Plant roots require oxygen and air spaces in the soil provide this. Soils with poor structure don’t allow air to penetrate the surface and this has a big impact on how the plant develops and grows.
How Soil Structure Develops
In natural settings, the structure of the soil develops over time, largely caused by weather and temperature. Rain, freezing, thawing all contributes to make the soil swell, contract and break up which changes the soil “crumb”.
Root growth and decaying plant material also build over time to incorporate air pockets and organic material that improves the soil structure.
How We Can Alter Soil Structure In Gardens
Of course, in a garden setting, we want to improve the soil structure much quicker. In a natural environment, the soil structure will develop over many, many years. As gardeners we want this to happen much quicker.
People throughout history have known that working the soil can improve even very infertile areas.
Cultivation of the soil rapidly accelerates the process of creating structure in the soil. Digging and breaking up the soil creates air pockets and adding organic material creates pores and promotes good drainage as well as moisture retention.
Soil Structure Improves Drainage
A common sign of poor soil structure is standing water or waterlogging. Soil that is compacted with poor structure means there is nowhere for the water to drain.
If you find puddles form in certain spots simply digging over the area will do a great benefit by opening the soil structure.
There are, of course, other factors that will cause waterlogging such as heavy or clay soils that are more moisture-retentive but digging in organic material will alleviate problems of drainage at the same time as improving the soil for growing.
Improving Soil Structure
By far the simplest and most effective way to improve the soil structure in your garden is to dig in as much organic material as you can. No matter what type of soil you have, whether it is sandy, loam or clay organic material will open the structure, incorporate air and give the soil better drainage.
If The Soil Has Never Been Worked
If you know the soil has never been worked then digging it over is the first step.
I recently moved into a new-build home and there are always issues with the soil structure in this kind of scenario.
The problem is that heavy machinery, a small army of workers and building supplies will have compacted the soil all around the house. When I created my borders the first thing I did was dig down two ‘spits’ (depth of the spade) and broke up the clods of soil. This is known as double digging.
Double digging involves first digging down your border to the depth of your spade putting the first layer of topsoil to one side so you have a trench.
The next step is to take a fork and go back through the trench and break up the bottom to the depth of the fork. This is the second layer which gives it the name double digging.
Organic material such as compost, manure, leaf mould, etc. is then added to the trench and the soil is filled back in.
The soil is worked throughout the entire border this way and it will greatly improve the drainage, aeration and structure.
If The Soil Has Already Been Worked
If the soil has already been cultivated and dug over then mulching every year will maintain your soil structure.
Mulching or working the surface of the soil with a fork to introduce organic material will improve the structure. I mulch every year and what happens is the weather and worms incorporate this organic material into the soil. This maintains the structure in a far more natural way with a lot less effort on your part.