A handful of dirt…or a vital ecosystem?
Monday September 5, 2022
Lynn Hill, Lynn Hill Garden Design
It’s so easy to overlook the importance of soil, after all, it’s always been there, under our feet. We build houses on it – creating streets and communities. It hosts forest, farmland, pastures, parks and gardens. It’s easy to think of soil as being static…as just dirt. But as we zoom in, we see it is teeming with life. Just one teaspoon of soil can hold more organisms than there are people on earth.
Soil is one of the most diverse ecosystems on our planet, a hotbed of biological and chemical reactions created through the interaction of plants, animals and microbes that live in the soil, along with those that live on it. It is these processes that underpin life on our planet as we know it. Soil first started to form around 400 million years ago. We’re looking at a span of around 3,000 years for fertile soil to be created from scratch. To top it up with just 1cm of new soil takes 200 to 400 years. It is definitely not a renewable resource and we are losing it much faster than it can recover. It is estimated that we are losing around an acre of soil every second which is why organisations such as the Soil Association Scotland are calling on all of us to take action to save it.
Why is soil important?
95% of our food relies on soil for its production. Soil anchors plants and feeds them so they can grow, farm animals are fed on plants and in turn, plants and animals are our main sources of food. Hence, soil is vital to our food security, which is rapidly becoming an issue. ‘Business as usual’ is showing itself to be unsustainable and governments across the globe are starting to grapple with how to make sure their populations get fed. The Climate Change Committee’s ‘Independent Assessment of UK Climate Risk 2021’ is just one of a plethora of voices warning our government that food security is a real and pressing issue in the UK. This is a global issue, to which the UK is not immune - and soil has a crucial part to play.
Combating climate change
Soil is one of our most important weapons against climate change. Soil stores carbon, through a process know as carbon sequestration. The UK’s soil holds nearly 10 billion tons of carbon, equivalent to the total global emission for the entire planet for a whole year. Globally, soils store more carbon than the atmosphere and all the world’s plants and forests combined.
Clean water and flood prevention
Soil actively filters our water and also helps to protect us from flooding. In the UK there are around 130 trillion litres of water stored in our soils. That’s more water than in all the UK’s lakes and rivers combined. When soil is healthy, it can store up to one and half Olympic size swimming pools worth of water per hectare. Poor soil doesn’t hold onto water in the same way, causing run off. This depletes it further and exacerbates issues of pollution as nutrients enter watercourses. And of course, water run off only adds to the issues of flooding.
Nurturing our soil
Soil depends on the relationship between microbes and plants to thrive, so the agricultural industry is fast learning the importance of ‘green manure’ and ‘cover crops’. These are plants that are grown so the soil is not left bare when food crops are harvested. We can learn from this in our gardens by using green manure (such as Vicia sativa) which keeps the soil in good condition, retaining nutrients and its ability to hold moisture.
Looking after soil in our industries…
There are codes of practice and guidance for the handling of soil within the construction industries, but they are often disregarded and are inadequate to truly help the matter. As a garden designer, I see compacted, impoverished landscapes far too often. We can… and should be doing more to protect it. Also - with a little creative thinking - we can do more than simply work to protect our soil. Our industries can lend itself to the solutions, by finding ways to nourish this vital ecosystem beneath our feet. Embracing and drawing from the new British Standard BS8683:2021 – Process for designing and implementing Biodiversity Net Gain will be a great reference point to start from. The Scottish Governments’ ‘Scottish Soil Framework’ identifies our current construction practices as a significant risk to soil health, so it is of vital importance that we address this.
…and in our gardens
Compost your food waste and add it to your garden. There are great ‘how to’ guides and videos on line, to get you started. And adopt a ‘no dig’ approach to gardening. This protects the life of the soil and helps reduce surface evaporation, helping it retain its moisture. You can use ground cover plants to smother the soil, for example creeping herbs such as creeping thyme (Thymus serpyllum) in a sunny spot or sweet woodruff (Galium odoratum) for the shadier areas. As mentioned, use green manure in the time gaps between planting, to avoid bare earth and mulch with well rotten, biodegradable mulches such as compost, manure or wood chippings to help boost the fertility and structure of the soil. And grow a diverse range of plants, including ones that are really beneficial to soil health, such as clover, legumes and trees.
“It is no exaggeration to say that civilisations rise and fall according to
the health of the soils on which they are built” …
“Soil is the heart and soul of our planet.
Put simply, we can't live without it.”
Soil Association 2021.