On 26 February 1937, the 32nd President of the United States, Franklin D. Roosevelt, wrote to all state governors in the US. In his letter he made the case for effective soil management, including the powerful phrase: “The nation that destroys its soil destroys itself.”
His plea related directly to extreme climate events occurring in the US at that period. It also demonstrated political leadership in soil management and conservation to address the risk of its wholesale decline and degradation.
As Joe Biden, the 47th US President, visits Cornwall next month for the G7 meeting, he might note that soil degradation is still a critical and growing global problem. An increasing world population has added to climate pressures on soil, and its natural capital faces continuing decline.
Soil’s vital functions, and its vulnerability, are highlighted each year on World Soil Day; however, the conception of this event through the United Nations affirms that the torch of advocacy for soil health has passed from political leaders to non-governmental organisations.
The pressures on soil are clear, and predictions of a catastrophic collapse in the ability of topsoil to support food production have been put forward. However, their complexity and relatively low environmental priority create significant challenges to future management. It is claimed that the generation of 3cm of topsoil takes 1,000 years; meanwhile, in 2016, soils accounted for 55 per cent of landfilled waste in the UK.
Landfilling separates soil from its natural environment where, in addition to providing food security, it stores carbon, supports biodiverse habitats, and acts as a critical natural defence against flooding. Furthermore, peat, one of the best long-term carbon stores, is harvested at an alarming scale to enrich compost sold for gardening. On that basis, can we realistically expect to maintain the soil resources needed to provide for a growing human population and sustain critical ecosystems?
Prioritising soil conservation to optimise its natural potential requires a step change in how we value this resource. The UK government’s 25 Year Environment Plan aspires to the sustainable management of England’s soils by 2030, but the Waste Strategy for England ignores the loss of soils to landfills; the two issues are critically connected. Time is limited – we do not have the luxury of developing environmental stewardship strategies while waiting for soil to recover.
One potential solution to the loss and degradation of soil is the creation of soils from waste materials, where appropriate inert materials generated as waste are carefully mixed together to create a substrate with the characteristics of a healthy soil. Their uses include manufacture of topsoils for urban grasslands, and materials for high-value markets such as horticulture and agriculture.
An impressive example of infrastructure built using reconstructed soil is the Eden Project, which the G7 leaders may well visit during their stay in Cornwall. Here, almost 100,000t of reconstructed soil created on-site hosts a fabulous array of plants that flourish in a soil that is no more than 1m deep throughout. The soil was first deployed in 2001 and has provided us with an excellent laboratory to assess the potential of reconstructed soils and how they might be optimised for widespread use.
Reconstructed soils could reduce the pressure on valuable topsoils and support both sustainable development and food security. As the components of the soils can be varied, reconstructed soils could be developed to perform better than natural soils for their desired functions. A safe and high-performance soil that could be deployed for food growth would be a precious resource in our efforts to achieve environmental sustainability.
Regulation and policy must keep pace with scientific progress, and our latest international project on the feasibility of reconstructed soils made in England and France will investigate – and, where necessary, challenge – regulations that could be a barrier to the widespread application of this exciting environmental technology.
In declaring a climate emergency, the UK and other G7 countries have implicitly accepted that the trajectory of environmental degradation cannot continue. Human intervention to sustain and improve soil was an ancient practice in the Amazon basin and reconstructed soils can unquestionably be part of the solution to soil health and climate mitigation.
Responding meaningfully to this current challenge requires new ways of thinking; embracing the opportunities created by technological advances, such as reconstructed soils, could be a crucial part of our collective response.
Mark Fitzsimons is professor of environmental chemistry at the University of Plymouth.