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soil restoration

Soil degradation is one of the most pressing problems facing our planet. More than 80% of the world's farming land is 'moderately or severely eroded', with 75 billion tonnes of soil lost every year.

Over the past half-century, the intensification of agriculture has led to failure of soil structure and organisms, reducing it to little more than ‘dirt’ – a sterile medium in which little can grow without artificial fertilisers. It is a self-perpetuating cycle of destruction and chemical dependence. Without soil organisms and soil structure to retain them, water and nutrients leach away, and the soil compacts and becomes prone to erosion.   

Land degradation costs up to $10.6 trillion a year. In the UK, that cost is between £900 million and £1.4 billion a year – half of which is caused by loss of organic matter, over a third by compaction, and about 13% through erosion. The depletion of topsoil is so severe in the UK that in 2014 Farmer’s Weekly magazine announced we have only a hundred harvests left.   

However, a ‘regenerative farming’ movement is gathering pace, from naturalistic grazing systems to agro-forestry and ‘no-till’ (zero ploughing) agricultural systems, all of which focus on restoring soil structure and soil biology.  

Rewilding is part of this soil restoration movement – an approach particularly applicable to marginal land, like Knepp, where intensive farming is inappropriate and/or unprofitable. 

At Knepp we have seen life returning to the earth in a surprisingly short space of time post-industrial farming, suggesting that rewilding is a very effective, low-cost way of restoring depleted soils. A study of our soils by Cranfield University in 2018, compared to an arable control, showed a doubling of soil organic carbon, a doubling of soil microbial biomass, a recovered fungal/bacterial ratio and an increase in fungal biomarkers. These are major indications of both soil health recovery and carbon sequestration. In 2022 we are undertaking an extremely in-depth carbon analysis of our soils to work out exactly how much carbon they have stored over the past 20 years of ecosystem recovery.  

Earthworms are also a key indicator of soil health. Surveys of anecic, epigeic and endogeic earthworms at Knepp in 2013 recorded a total of 18 species. Using neighbouring farmland as a baseline, the comparison with Knepp showed an exponential rise in the populations of all three types of earthworm in all three areas of the rewilding project.  

Dung beetles perform a range of vital functions, including pulling down organic matter into the soil. In a study by the University of the West of England in 2018, Knepp was found to have 11,677 beetles compared to an organic control with only 518. Organic farms are thought to have 38% more dung beetles than non-organic farms (Hutton and Giller, 2003) due to reduced use of wormers and antibiotics. One hypothesis for Knepp so dramatically outperforming even organic farms is the diversity of herbivores in the system and the fact that the animals winter outside so there is no break in the availability of dung for the beetles which are active all year round. Twenty-one different species of dung beetle have been recorded at Knepp.  

Ants, too, increase the fertility of the soil, creating micro-habitats for numerous other species with their ant-hills, some of which, at Knepp, are now over a half a metre high.  

 The eruption of fruiting bodies of fungi across the land is another exciting indicator, demonstrating the spread of mycorrhizae through the soil. Mycorrhizae are the fungal filaments that convey water and essential nutrients to the roots of plants. They can extend for miles in the soil, an invisible web transmitting chemical communications between plants. Mycorrhizae can even mine rock, extracting minerals and bringing them into the plant food cycle.  

Encouraging, too, is the emergence in our post-arable fields of southern marsh, early purple and common spotted-orchids – plants that depend on an exclusive, symbiotic relationship with mycorrhizae.   

Further Information

Anderston, Bart. ‘Soil food web – opening the lid of the black box’. Energy Bulletin. (7 Dec 2006) 
Bathurst, Bella. ‘Kill the plough, save our soils’. Newsweek. (6 June 2014)

Case, Philip. ‘Only 100 harvests left in UK farm soils, scientists warn’. Farmers Weekly. (21 Oct 2014)

Cole, J., ‘The effect of pig rooting on earthworm abundance and species diversity in West Sussex, UK’. MSc thesis, Centre for Environmental Policy, Faculty of Natural Sciences, Imperial College London. (11 September 2013)

Darwin, Charles. The Formation of Vegetable Mould, through the action of earth worms, with observations on their habits. (John Murray, 1881)

Elio. ‘Mycorrhizal fungi: the world’s biggest drinking straws and largest unseen communication system’. Small Things Considered (a blog for sharing appreciation of the width and depth of microbes and microbial activities on this planet). (August 2013)

McKenzie, Steven. ‘’Alarming trend’ of decline among UK’s dung beetles’. BBC News. (17 November 2015)

Merryweather, James. ‘Secrets of the soil.’ Resurgence & ecologist, issue 235. (March/April 2006)
Merryweather, James. ‘Meet the glomales – the ecology of mycorrhiza’. British Wildlife, pp. 86-93. (December 2001)

Noel, S., Mikulcak, F., et al. ELD Initiative. (2015). Report for policy and decision makers: ‘Reaping economic and environmental benefits from sustainable land management’. Report for policy and decision makers, Economics of Land Degradation Initiative. (2015)

Montgomery, David R. and Anne Biklé. The Hidden Half of Nature – the microbial roots of life and health. (W.W.Norton & Co, 2016)

Ohlson, Kristin. The Soil Will Save Us – how scientists, farmers and foodies are healing the soil to save the planet. (Rodale, 2014)

Schwartz, Judith. Cows Save the Planet – and other improbable ways of restoring soil to heal the earth. (Chelsea Green, 2013)

Stewart, Amy. The Earth Moved – on the remarkable achievements of earthworms. (Frances Lincoln, 2004)

Van Groenigen, J.W., Lubbers I.M., et al. ‘Earthworms increase plant production: a meta-analysis.’ Scientific Reports, vol 4, article no. 6365. (2014).

Woods-Segura, James. ‘Rewilding – an investigation of its effects on earthworm abundance, diversity and their provision of soil ecosystem services’. MSc thesis, Centre for Environmental Policy, Faculty of Natural Sciences, Imperial College London. (September 2013)

Zaller, J.G., Heigl, F., et al. ‘Glyphosate herbicide affects belowground interactions between earthworms and symbiotic mycorrhizal fungi in a model ecosystem’. Scientific Reports, vol 4, article no. 5634. (July 2014)

Zhang, W., Hendrix, P.F., et al. ‘Earthworms facilitate carbon sequestration through unequal amplification of carbon stabilization compared with mineralization’. Nature Communications, vol. 4, article no. 2576. (2013).
‘Glomalin: hiding place for a third of the world’s stored soil carbon’Agricultural Research Magazine, US Dept of Agriculture(September 2002).

‘UK soil degradation’. Postnote no. 265, Parliamentary Office of Science and Technology. (July 2006).

‘UK dung beetles could save cattle industry £367m annually – bug farm boss’ Wales online. (27 August 2015)
Dung Beetles for Farmers  

Our 12+ Policy

Knepp Wildland Safaris and campsite are all about the quiet and patient observation of nature.

Some of the species we are likely to encounter are shy or can be frightened by loud noises or sudden movements. Our campsite with open-air fire-pits, wood-burning stoves and an on-site pond is unsuitable for small children.

For this reason, our safaris, holiday cottages and campsite are suitable only for children of 12 and over.

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