Soil health matters

“We owe our existence to a six-inch layer of topsoil and the fact that it rains” - Paul Harvey*

^{*Paul Harvey (1978) US radio broadcaster}

Soil is the foundation of every farm business. It is a complex mix of organic remains, minerals, bacteria, fungi, gases and liquids. As well as forming a reservoir of nutrients and water for the sustenance of life, soils also play a critical role in major atmospheric cycles of life elements, including carbon and nitrogen. Its foundational status suggests that soil should have a much more prominent place in both farm management and agricultural policy, but its complexity, variability and inalienability have all contributed to fragmented and inadequate protection. This is long overdue for change. Both government policy and supply chain demands for regenerative practices are likely to push more farmers into positive soil health management.

In this Spotlight, we provide an overview of emerging national policy on soil health across the UK, analyse soil carbon schemes and assess how they might help improve soil health, and crunch the numbers on a conventional versus regenerative farm management approach.

SOIL HEALTH POLICY: AN OMISSION

The degradation of topsoils through erosion, compaction, sealing and loss of organic matter represents an enormous threat to human existence. Government estimates that over a quarter of the soil (four million hectares) in England and Wales is at risk of compaction and another 13% (two million hectares) is at risk of erosion. In terms of the opportunity, Scottish soils alone store over 50% of the UK’s soil carbon and across the UK soils are expected to play a significant role in mitigating greenhouse gas emissions. In part, this will be due to wider adoption of minimum or no tillage, which avoids the negative effects of cultivation on soil structure. The lack of a common framework for assessing soil health and its associated climate risks has been flagged as a major concern by the Climate Change Committee. Policy to monitor, protect and enhance soils in the UK is both urgent and important.

Between 1973 and 2018, agricultural and environmental policy was set by the European Union. Various attempts were made to establish a comprehensive framework for soils, but these were blocked by national governments who considered soil to be a territorial matter, unlike air and water, which are more obviously public goods. There is a vast range of regulation dealing with soil in various policy contexts, such as planning and waste, but no comprehensive framework for its protection. Most current regulation is derived from EU water or waste legislation; this is likely to be reviewed as part of post-Brexit regulatory reform, but the renewed focus on the strategic importance of soil health means the regulatory baseline and reporting burden is likely to get much tougher.

SOIL HEALTH CONSEQUENCES

Soil is a living catalyst for production and one that is featuring more prominently in farmers’ decision-making, as improved soil health increases the efficacy of inputs, reduces input need and makes soil more resilient to extreme weather events. Here are three ways that a more holistic soil health-focused approach has increased the profitability of farming:

1. Arable Blackgrass is a serious problem on many farms – across the UK herbicide-resistant blackgrass is estimated to reduce wheat yields by 5% and gross profit by £490 million per year. It thrives in cold, wet, anaerobic soil, so improving soil structure can reduce its competitiveness. The weed also prefers bacteria-dominated soils, so reducing cultivations can allow beneficial networks of fungal hyphae to address the balance.
2. Livestock Dung beetles perform about £473 million worth of work each year helping fertilise land and aerate soil, but their populations can be reduced by anthelmintic wormers. Adopting rotational mob grazing can reduce the need for wormers, while boosting the rate of livestock growth and soil organic matter formation.
3. Cover crops An AHDB study in 2020 found cover crops reduce margin in 95% of cases due to seed and establishment costs. Since then, the situation has improved as cover crops can unlock additional Sustainable Farming Incentive (SFI) income and carbon payments. However, while the short-term bottom line is important, cover cropping can significantly increase soil organic matter, leading to improved soil quality and mineralisable nitrogen supply.

UK SOIL HEALTH POLICY OPPORTUNITY

As UK agriculture and environment policy is devolved, each home nation is now developing its own approach to tackling the critical topic of soil health. Defra has been criticised this year for weakening its 2009 vision for all soils to be managed sustainably by 2030. The new target in the Environmental Improvement Plan 2023 may be lower, but it is more specific and enforceable. The table, below, sets out the different approaches being taken across the country.

LEADING THE WAY

Northern Ireland has commissioned a comprehensive soil baseline for the country. Covering an estimated 700,000 fields, farmers participating in the Soil Nutrient Health Scheme will get a detailed soil nutrient status, runoff risk maps, estimates of carbon stored in soils and biomass, and training on the use and application of the information. Due to the scale of the task, this is being rolled out regionally, with full coverage expected by 2026.

ASSESSING SOIL HEALTH ON FARMS

Farmers interested in understanding their soil health have access to practical tools such as the AHDB’s Soil Health Scorecard (see table below).

_{Read the articles within Spotlight: Soil below.}