Soil structure and make up can be a science in itself, but not one that requires lab coats and complicated equations. All you need is a little 'know-how' that will allow you to confirm the soil structure you have available to you and what you can do to improve it if you wish to.
Some vegetables, such as carrots, do not grow as well in nutrient rich soil and are instead best planted in looser less fertile growing mediums such as sand, to encourage the root to push further into the ground. Therefore rewarding you with a larger carrot come harvest time.
Other plants, like hydrangeas and dogwoods, will grow well in water-retaining soils. It is these differences in the soil you have available that will play a part in deciding for you what plants your green space will contain.
Within this article we will look at one of the more simple but effective methods of gauging the makeup of the soil structure in your beds, known as ‘the squeeze test’. While there are other more involved methods of testing your soil, the squeeze test allows you to get a good idea of the sand, clay or loam levels of your planting area, with minimum fuss or equipment. Loam is soil made with a balance of sand, silt and clay.
Find a patch of soil in your flower or vegetable bed. It may be wise to do this exercise in a few different sections of where you're working, depending on the size of your plot, as soil can vary noticeably from one area to another.
Take up a good handful of soil (having dug it up a bit with a spade if necessary) and give it a firm squeeze, release your grip and see what you have in your palm.
Now we will look at different consistencies and tell you what you can do to improve them.
A tight hard ball: This means the soil you have is mostly made up of clay. Clay soils are made up of tiny particles that are stuck together to create large lumps that can be moulded with your hands without breaking up into smaller chunks. Clay soils will retain water and create a boggier planting environment, as there is little drainage.
They are also harder to penetrate and will seriously hinder a root vegetable's development. On a more positive note, a clay soil will contain a surprising amount of nutrients within it to benefit plants and there are a number of ways to improve the structure of it if you find yourself bogged down by it, which we'll explain below.
A ball with a ‘cakey’ consistency that falls apart when poked: Good news, you have a loam or silty soil. This is usually dark in colour and consists of a mix of sand and clay. Whilst this soil can still be compacted by machinery and being overly trodden on, it will have a good level of organic matter existing within it and retain enough water to keep most plants satisfied.
A handful of soil that collapses easily: This means you have a soil that is largely made up of sand. Sand is made up of comparatively large particles, which allow for lots of movement and large gaps that provide spaces for water and air to get between easily. For this reason, sandy soil is bad for retaining nutrients, but it will provide good drainage. Sandy soils can feel lighter in weight, be gritty to touch and be lighter in colour. To make improvements to the nutrient content of your soil and make it more workable when digging, there are a few things you can do which we will explore.
Sandy soil: Your best bet here is to dig during the late winter and early spring to improve the existing soil structure. Whether that be with manure, leaf mould or compost. Remember, not every plant will want or need to have a lot of nutrients available, such as lavenders and buddleia, but any nutrients that are in sandy soils are often quickly washed away. Fertiliser can also help provide additional nutrients to newly planted plants.
Loam or silty soil: While a loam or silty soil is favourable for planting it is best not to be complacent. You can still top it up with organic matter such as compost you have produced yourself and, in some cases, you may find adding either sand or clay useful to benefiting plants with any specific growing requirements.
Clay soil: One way of breaking up this hard to dig structure is by adding sand. Make sure to use horticultural sand which will be free of salt content that could damage plants. This naturally creates a less solid consistency to allow roots more oxygen and growing space. It is also possible with large areas of clay to introduce gravel, allowing for a draining soil structure that is more free. You can also make use of your composted material and add organic matter, both to improve the structure and add more nutrients to your growing area.