Soil is probably our most valuable resource yet it is probably our least valued. It is also poorly understood and mistreated on a massive scale all over the country. However,there are many people that do treat their dirt with the respect it deserves, and I feel that if others had a better understanding then they too would begin to look after this vital resource. So let’s have a closer look at the soil beneath our feet.
What is soil? At its best, soil is an immensely complex living ecosystem, rich in life and biodiversity. Before the life can move in, first the dirt needs to build up. By dirt I am talking about the mineral content which is basically tiny pieces of rock. Our mountains have been worn away over millennia by the infamous British weather. Water gets into the cracks then freezes in the winter, expanding with such incredible natural force that eventually chunks of the mountain fall away from the steep rock faces. In the flooded white waterways large stones are smashed together violently until they break into smaller and smaller pieces. Eventually, as the river slows, incredibly fine splinters of rock settle out of the water to be deposited across our floodplains, so adding more nutrient rich sediment to the ever forming soil. This is just one possible pathway to the formation of soil.
The soils in our gardens contain sediments of different types and sizes. We place them into three main categories depending on the size of these particles – sand, silt and clay. The balance of these particles within the soil has a dramatic effect on the living organisms, including plants, which can live within it. Clay particles hold onto water and can assist in the nutrient uptake by plant roots, but too much and drainage becomes a problem causing many root types to rot. Sand particles improve drainage and create tiny air pockets providing oxygen for plant roots and other living organisms. Too much drainage and the soil will dry out quickly causing many plants to wilt and die. Generally speaking, what we want is soil that has a balance of all these particles to provide our plants with the perfect medium in which to thrive.
What happens when the nutrients in the soil are used up? This is where the other living organisms come into the picture. Plants were the first to move onto the land around five hundred million yeas ago. It is the plants that provide the bulk of organic matter in the soil. Decaying plant matter provides a food source for other living organisms. In fact, I have heard it said that there are more microorganisms living in a handful of healthy soil than there are people living on the planet. There is an alien world of tiny organisms busily going about their tiny little lives, feeding on decaying matter beneath our feet. As with all habitats there is a complex food web of interdependent living things, and all this eating leads to an awful lot of excreted waste. Look at a lawn and you might see the worm casts created by worms feeding on the cut grass. This worm poo is full of nutrients that are then washed back into the soil so that the grass can recycle them back into new growth. This recycling of nutrients is how plants continue to grow, year after year, for the last five hundred million years. If we understand this then we can help the plants in our gardens by recycling the nutrients back into our gardens such as using composting techniques.
As a professional gardener I have the privilege of working in a large number of very different private gardens. The owners of these gardens have very different styles of gardening. Some use herbicides and pesticides to protect their precious plants while others prefer a more wild or organic approach. When digging around in the dirt it isn’t difficult to see the effect of chemicals on the soil ecosystem. The soils that are left to their own devices are by far the richest in life, which can only be a good thing for the plants growing there, as all this life provides them with the nutrients they need to grow healthily. It is proof enough for me that if we look after (or in fact, leave alone) the soil habitat then we will be providing our precious plants with the perfect growing conditions. So, all we need to do is leave the soil alone. Is that it?
I wish it was that simple! There are many other factors that also need to be considered and I have tried to summarise my top five tips for a better soil below:
1. Before beginning any planting find out what your soil is made up of. If drainage is poor due to too much clay then add some horticultural grit. If there it is too sandy then add some organic matter to hold onto moisture.
2. Try not to dig up your soil if you can help it. When you dig up your soil you can be destroying a delicate ecosystem. The science of soil is not fully understood but many scientists believe that once damaged the soil habitat can take around one hundred years or more to repair itself, and in some cases it may never recover.
3. Don’t walk on the soil, especially when wet! When you walk on soil you are compressing it, forcing out the air between the particles. This air is necessary for the living organisms in the soil habitat. It provides the oxygen they require for energy. You will all know what happens to wet clay when you squeeze it together. When you walk on it then you will create an impenetrable barrier for plant roots so they will never be able to reach their full potential. Use stepping stones within the borders to allow access without damage to the soil structure.
4. Cover the soil. One of my old university lecturers likened bare soil to an open wound. Without the protection from plant foliage, heavy rain washes away soil particles. When it does penetrate into the ground it can then take nutrients deeper into the ground, away from the root systems of plants. On a hot day, the sun can bake the soil dry, so making it a very difficult if not impossible environment for living organisms to thrive. To prevent all this from happening fill in gaps with plants, or spread a thick layer of mulch over the surface of the soil. By using bark mulch or well-rotted compost, you will also be adding more nutrients to the soil to support the living system.
5. Garden organically. Resist the urge to use chemical fertilisers or pesticides. These can have a detrimental effect on the soil ecosystem that is so vital for a healthy living soil, as well as affecting many other organisms that visit your garden.
If we look after our soils we are looking after ourselves as well as the other living things we share this wonderful world with. It will also make sure you have a beautiful garden full of luscious plants and therefore lots of wildlife to watch, as they will also attract a plethora of living things to share our special living spaces.