As part of its Soil Campaign, the Soil Association aims to increase organic matter in UK arable and horticultural soils by 20 per cent over the next 20 years to restore UK soils.
With the effects of climate change on the horizon, the ambition highlights the commitment of the arable sector to reducing atmospheric carbon while providing benefits for the farmer – a potential win-win strategy.
Peter Melchett, policy director at the Soil Association, highlighted some of the potential benefits of boosting soil organic matter.
He said: “An increase of 20 per cent, based on the UK average soil carbon density, means nearly 10 tonnes more soil carbon per hectare could be stored by 2035.
“Boosting soil organic matter could also increase the water holding capacity of arable farmland to 40,000-100,000 litres per hectare, reduce flooding and increase resilience to drought.”
Caroline Corsie, farm manager at the Worcestershire Wildlife Trust’s Lower Smite Farm, Worcestershire, has seen better water retention as a result of increasing organic matter content of soil.
She said: “Since 80 per cent of pesticides applied on UK farms end up in watercourses, using organic matter to retain water could benefit water companies as well as farmers.
“Our soils generally run out of water by the time it comes to grain fill or it runs out of moisture in spring, so we get capping because of low soil organic matter. This prevents us reaching our full yield potential.
“Since increasing our soil organic matter content, we are getting a further eight days of moisture retention per year.
“By growing cover crops alone, our organic matter levels have risen by 20 per cent over five years, from 2.5 per cent to an average of 3 per cent. Where we also apply compost or well rotted manure, we have doubled soil organic matter by 2.5 per cent, increased to 5 per cent over 5 years.”
Although it is a slow process, Mrs Corsie said she was convinced raising organic matter levels is a worthwhile process in terms of improving crop yields and health as well as creating additional environmental benefits.
She said: “There are so many different ways you can analyse soil, but if you can only do one thing, make it soil organic matter you measure.”
Organic matter originates from plants (for example, crop residues and roots) and animals (manures) and helps hold nutrients and water in soil. It also aids in reducing soil compaction and increasing the amount of rainwater a soil can soak up. In the UK, the amount of organic matter in our arable and horticultural soils is in long-term decline.
Source: Living Soils: a Call to Action, Soil Association
Source: Caroline Corsie