Improving the structure of our agricultural soils and returning unproductive agricultural land to permanent pasture will be a game-changer in the battle against rising levels of CO2.
According to the Royal Society, carbon capture by the world’s farmlands, if they were better managed, could total as much as ten billion tonnes of carbon dioxide a year – more than the annual carbon dioxide accumulation in the atmosphere.
The world’s soils contain 1,500 billion tons of carbon in the form of organic material. Increasing the quantity of carbon contained in soils by just 0.4% a year – through restoring and improving degraded agricultural lands – would halt the annual increase of CO2 in the atmosphere. This would go a considerable way to achieving the Climate Change objective of limiting the global temperature increase to +1.5˚C, while at the same time increasing global food security by improving soil fertility and stability.
The rise in soil function at Knepp has been dramatic. According to a study of our soils by Cranfield University in 2018 soil organic carbon has doubled since rewilding.
Carbon is also being sequestered in Knepp’s restored wetlands and woody vegetation. A study by Queen Mary University London in 2021 showed 3.7million square metres of new vegetation in the Southern Block between 2001 and 2019. A large part of this area is woody biomass – in effect, carbon.
The potential for rewilding projects like Knepp to provide carbon sequestration is of increasing interest to the UK government, legally bound to meet its ambitious target of reducing carbon emissions by 78% by 2035, on its way to net zero by 2050. This is why such a huge focus has been given to soil health and soil carbon in the new Environmental Land Management (ELM) schemes.
We have two major projects concerned with carbon sequestration ongoing at Knepp: Nancy Burrell, the daughter of Charlie and Isabella Burrell (co-owners of Knepp), is studying carbon capture values of new vegetation and woody scrubland across Knepp for her PhD at Oxford University. Simultaneously, we will be taking over 1000 soil cores from the Southern Block as part of a collaboration to build a verifiable carbon credit system that could be rolled out to rewilding projects across the country.