A new soil association report, released this week, warns that the UK’s reliance on nitrogen fertilisers could be damaging valuable soil resources. Although nitrogen fertilisers have resulted in higher yields and led to an increase in the affordability of food, its production relies on non-renewable natural gas, which could see fertiliser and, consequently, food prices rising again as resources become scarcer.

Nitrogen fertiliser can also be incredibly polluting; nitrous oxide, a greenhouse gas with 298 times more global warming potential that carbon dioxide, accounts for 54 per cent of the UK’s agricultural emissions. Nitrates leaking into water systems can cause eutrophication, where nutrients added to water ecosystems, such as fertiliser run-off or sewage, cause massive algal blooms which deplete oxygen in the water and kill off other aquatic life. The process has caused massive ‘dead zones’ off the coast of the United States and led to the creation of ‘nitrate vulnerable zones’ in the EU.

The Soil Association report reveals that a recent study by researchers at the University of Illinois has indicated that “In some circumstances, the use of manufactured nitrogen can cause the loss of soil organic matter by stimulating the activity of soil micro-organisms.” The report warns that, unless soils are managed carefully with appropriate inputs of organic matter, such a process and reduce soil’s ability to store carbon, hold water and store organic nitrogen. The results of the Illinois study still need to be replicated in further research.

Instead of relying on artificial nitrogen inputs, the Soil Association is encouraging the adoption of nitrogen-fixing legumes, which it maintains are better for the environment and better for soils. ‘Biological fixing’ of nitrogen is one of the key practices of organic systems that the Soil Association claims will ensure the approach’s resilience in the face of peak oil.

The organisation is calling for more research into how nitrogen behaves in legume-based systems to enable farmers to reduce reliance on finite artificial inputs. The subject has also recently been the subject of research by Nuffield scholars.

Soil health benefits from increasing recognition

The issue of soil health has received increasing attention in recent months. As soils take thousands of years to form, they are viewed by soil scientists as a non-renewable resource. In the EU, soil sealing and soil degradation are having a massive toll on available resources. In the UK, the last major study of soil, conducted in 2009, showed 2 million tonnes of topsoil in Britain is being eroded every year.

The All Party Parliamentary Group on Agroecology and the Food Ethics Council have organised a conference to discuss the lack of policies that exist to ensure protection of vital soil resources. The latest Food Ethics Council magazine deals with the issue of soil, which, although it is beginning to receive recognition from agriculturalists and policy makers, remains “undervalued” according to the Food Ethics Council.

Initiatives have been launched by major development organisations, including the UN Food and Agriculture Association, which has formed a global soil partnership and begun an initiative with research institutions to enable policy makers to implement strategies to conserve soil resources and introduce more environmentally friendly management practices ahead of the Rio +20 summit in June, where world leaders will discuss poverty and environmental degradation.

The full Soil Association report can be read here.