Two Sheffield-based academics believe that society will have to "rethink its attitudes" to genetic modification of food crops and accept the role of human excrement in producing more food. Dr Duncan Cameron and Jurriaan Ton of the University of Sheffield see both of these things as "inevitable" solutions to challenges facing agriculture, which include climate change, soil degradation, water shortages and a growing demand for food.

Analysis by scientists at the University of Sheffield showed that the UK's available soil has just 100 seasons of nutrients left in it. Furthermore, the problems associated with climate change are expected to increase uncertainty in crop performance, heralding new threats such as disease and drought.

In response to the multiplicity of pressures facing agriculture, the pair believes "UK farming's inevitable future will be a combination of genetically modified crops on organic farms fertilised by human waste."

The researchers said that careful cross breeding of plants for desirable characteristics during the green revolution resulted in highly productive crops, but that this had a downside; as a result of the breeding programmes, many plants lost important natural traits that allow them to interact with beneficial bacteria and fungi in the soil. They said that, as a result, today's crops are strongly reliant on external inputs such as fertilisers.

Scientists can now identify the exact genes that were lost during breeding programmes. Cameron and Jurriaan suggest these genes could be reintroduced using GM technologies, returning crops to their more communicative nature.

Biodiversity vs biotechnology

However, major development organisations, such as the UN Food and Agriculture Organisation have called for a push towards greater agricultural biodiversity, which they say would foster a wealth of beneficial traits, potentially helping growers face up to challenges that have yet to emerge. Most modern crops have been produced from a small range of closely related varieties, with consideration for their high yield or predictability eclipsing attention to their nutritional value, biodiversity or regional suitability.

The FAO estimates that over the course of the 20th Century the biodiversity of global agriculture shrank by 75 percent. The UN organisation's call seems to run contrary to the aims of the Sheffield scientists, who are pursuing an aspect of the 'high-tech' solution that these 'agroecologists' warn could further increase the precariousness of the current food system. Proponents of this view argue that seed banks and breeding technology will play a greater role in creating more robust crops than GM, which remains relatively rudimentary and has not been used for producing regionally adapted varieties.

Even so, Dr Cameron, from the University's Department of Animal and Plant Sciences, said, "We need to break the cycle that has led to many crops requiring the agricultural equivalent of spoon feeding, with chemical fertilisers and industrial irrigation. Whilst seemingly efficient, we are mollycoddling nature and this will lead to substantial yield losses due to pests and diseases."

He believes farming must transition towards organic methods which rely heavily on the natural breakdown of organic matter to replace nutrients taken from the soil by previous crops, protecting soils and reducing the impact of agricultural activity. Dr Cameron believes GM crops, engineered to replace the missing genes which could be limiting their success in organic-type systems, hold the key to food security.  

Fertiliser from human faeces

The final aspect of Cameron's vision is supplied by Professor Tony Ryan, who has been looking at the possibility of using human excrement as a fertiliser. He said, "Phosphorous and nitrogen are limiting nutrients both of which are found in human waste which scientists believe could be used more efficiently. People produce 1.5 tonnes of faeces and urine each year (400 kg of solid and 1100 litres of liquid); this could provide 20 kg of elemental PNK fertiliser and grow 200 kg of cereal. A human resource we cannot afford to waste anymore."

The prospect of using human waste as a fertiliser is not as far-fetched as it sounds. The method is already deployed in some developing countries, driven by water shortages and escalating fertiliser costs and Prof Ryan is adamant that all health risks can be eliminated from human excrement by proper composting.

However, the Sheffield scientists' view may prove to be a controversial one, especially in the organic movement. Organic farmers have fought fiercely and, for the time being, successfully to ensure GM crops cannot be certified as organic. In the UK, organic farming group the Soil Association maintains that advances in plant breeding technology mean GM crops are now effectively a costly distraction from moves towards food security.

The Soil Association maintains that "GM technologies have consistently underperformed, despite claims from the biotech industry that they are necessary to meet the 'perfect storm' of climate change, resource depletion and a growing global population." 

Reacting to the release of the UK government's agri-tech strategy at the beginning of the week, Soil Association spokesperson Tom MacMillan said, "While government has made clear this is an industrial strategy for the UK economy, some… are mistaking it as a strategy for feeding the world. There is already a resoundingly thorough international strategy for that.

"Known as IAASTD (the International Assessment of Agricultural Knowledge, Science and Technology for Development), it involved over 400 scientists and is supported by the United Nations and dozens of countries. It says the top investment priorities [for attaining food security] are agroecology and practical help getting products to market."

Nevertheless, Dr Cameron added, "Safeguarding food security for future generations is one of the biggest challenges for the 21st century. In a time of rapid environmental change we need new ways to intensify sustainable production and protect food crops."