A couple of years ago I studied horticulture at my local college. I found the whole science of plants fascinating. One of the areas that has really captured me is soil. I know, when I looked at the course and saw a whole term devoted to soil I did think I was going to need a good supply of biscuits and tea to get me through it. Even our tutor picked up on the apathy in the class to the topic. How can soil be that interesting? Well there is a whole world of activity going on in your soil, or at least there should be if you want your plants to do well. And that’s the point, if you love plants you really need to love your soil.
So why is soil so important. Well, it provides an environment for the roots of plants to grow. Roots need to breathe, absorb nutrients and water and be able to push through the soil as they grow. A good soil will have enough spaces to hold air, water and nutrients and will be friable enough to allow the roots to move through the soil but will still have enough structure to give the plant stability. It will provide the right nutrients in sufficient quantities for a plant to grow and reach maturity.
But it is not just the roots of plants that are alive under the soil. A good soil will be teeming with life, although a lot of it is too small for us to see. From tiny bacteria and mycchorizal fungi, to nematodes and earthworms an enormous number of organisms are participating in a food chain where dead plants and organisms are being broken down releasing nutrients that plants can absorb and creating humus. Humus is the fully decomposed remains of organic matter and is so important because it can hold onto a lot of water and nutrients. Some organisms, types of bacteria, fix nitrogen gas from the air in the soil making it available for plants to absorb. Other organisms, particularly worms improve the structure of the soil, moving through the soil and creating channels which help to aerate the soil, improve drainage and provide spaces for roots to push through.
Soils are formed over a very long period of time from the weathering of rock and the gradual build up of organic matter and are made up of different proportions of clay, silt and sand particles. Predominantly clay soils suffer from poor drainage, good water and nutrient retention and tend to be slow to warm up in spring. Soil made up mainly of sand particles has very good drainage but as a result has poor water and nutrient retention but is quick to warm up in spring. The holy grail for gardeners is a loamy soil which has a good balance of all 3 particle types.
If you have a sandy soil or a clay soil you can’t do anything to change this but you can improve the soil to minimise the negative impacts of your soil type. So here are my tips for loving your soil.
- Don’t walk on your soil when it is wet or frozen. This leads to compaction, squishing soil particles together, making fewer spaces for air and water to flow. In severe cases plant roots will die and so too will all those organisms.
- Incorporate lots of organic matter. This will improve drainage on clay soils, hold onto nutrients and water on sandy soils and because it is dark in colour will help the soil to warm up more quickly in spring. It will also boost the numbers of organisms in your soil and contains nutrients that once broken down will be released for plants to absorb.
- Grow green manures. They will protect soil from erosion from heavy rain and wind and the roots will open up the structure of the soil.
- Try not to disturb the soil too much. Lots of digging isn’t just bad for the back, all those little creatures living in the soil don’t like to be disturbed.
- And finally, don’t use chemicals on the soil, whether it’s weedkillers, fertilisers or pest control they are all harmful to the delicate ecosystem of the soil. Earthworms, in particular are especially sensitive to these chemicals.