Today (5th December) is World Soil Day, a time to appreciate the importance of soil to our everyday lives. It has been estimated that soil contains 25% of global biodiversity! As R. Neil Sampson said in his book ‘Farmland or Wasteland: A Time to Choose’, ‘We stand, in most places on earth, only six inches from desolation, for that is the thickness of the topsoil layer upon which the entire planet depends’.
In 2010, soil degradation was estimated to cost £1.2 billion every year. Natural England research suggests that over half of the soil carbon in England is contained within the top 30cm of the soil. UK soils currently store about 10 billion tonnes of carbon, roughly equal to 80 years of annual UK greenhouse gas emissions!
Soil health is critical to an efficient and biodiverse farm. Only when we start thinking of soil as a living organism, rather than just a medium, do we start treating it with the respect it deserves. Like other living organisms, soils breathe and require adequate nutrition and water, not just inputs from a bag. A healthy soil should be 25% air, 25% water, 45% minerals and 5% organic matter.
What is organic matter?
Organic matter derives from living things. It is essential for the physical, chemical and biological function of soil, and fundamental for soil structure. Organic matter acts like a sponge and can hold up to 20 times its weight in water, making soil more resistant to erosion and drought. It is a key indicator of soil health. The organic matter off soils can be enriched by adding crop residues, farmyard manures, sewage sludge, compost, and by growing cover crops.
The role of cover crops
A cover crop is a non-cash crop that is grown with the purpose of protecting soil from erosion once the main crop has been removed and enriching the soil with organic matter. Cover crops aid the structure of the soil, enabling it to hold water and allowing the circulation of nutrients. Not only this, but a cover crop also provides useful habitat for wildlife.
How do Fair to Nature farmers look after their soils?
Fair to Nature farmers pay attention to the soils on their farms. Some of them have adopted min-till or no-till techniques when sowing their crops. This limits nutrient leaching and soil erosion and means the beneficial organisms in the topsoil are hardly disturbed. Farms are also using cover crops to prevent erosion and as a way of adding organic matter to their soils. Compost is also used in some areas, such as the RSPB’s Hope Farm, where trials into the value of spreading compost are taking place.