So now you’ve decided you are going to grow something yourself. Fantastic! But where do you start? You start at the bottom. The foundation. The soil.
The soil is the life source of your garden. It’s an aspect of gardening that is often glossed over, yet the soil is where your plants get their water, nutrients and stability to grow.
There are a few key points you need to know about soil to help your plants thrive…
First of all – texture. The texture of your soil will determine how much water and nutrients your soil can hold. Texture is how much sand, silt and clay there is. A ‘clayey’ soil will be mostly clay and a ‘sandy’ soil mostly soil. There are, however, numerous other textures including loamy sand, sandy loam, loam, clayey sand, sandy clay loam….it’s a reasonable list.
In your garden, a loam is usually the best soil type. A loam has about 40% sand, 40% silt and 40% clay.
Texture is important because it affects so many other soil properties such as:
1. Water holding capacity – the more clay/silt in a soil, the greater amount of water it can hold.
2. Nutrient holding capacity – a straight sand holds almost no water or nutrients. A loam on the other hand will hold plenty of nutrients.
3. Drainage – the sandier the soil, the greater the capacity for drainage. This is why a straight sand holds minimal water as it’s lost to drainage.
4. Compaction – clay soil compacts more easily than sand. It is still possible for a sandy soil to become compacted, but it will take longer than a clay soil.
5. Organic matter content – a finely textured soil (i.e. more clay) can hold more organic matter than a sandy soil. This is because 1. clay particles are more ‘charged’ and can hold more organic matter and 2. decomposition occurs faster in a sandy soil.
To find out what texture your soil is you need to do the ribbon test.
Next comes soil structure. A ‘well structured’ soil will have about 25% air, 25% water and 50% solids. Quite frequently soil becomes compacted reducing the amount of air and water space. Plants need at least 10% air space to survive. This is in addition to the water in the soil. Without oxygen, the plant roots will suffocate.
You will know if you soil is compacted as soon as you try to dig into it. Compacted soil often resembles bricks. A great way to de-compact your soil is to use a garden fork to punch holes and ‘work’ the soil.
pH is important because it affects the availability of nutrients. Broadly speaking, if a soil has a pH outside 5 – 7, plants start to have trouble absorbing nutrients in the soil. This leads to a weak plant that is more susceptible to disease. You can buy a simple home soil pH test kit from most nurseries and test the soil yourself.
Alisa Bryce is the author of a recently released Organic Soil Guide. This guide teaches you what you need to know about soil to grow vibrant, healthy plants. It includes step-by-step instructions on how to assess your soil, what the results mean and what to do next.