The future of farming: GM crops on organic farms fertilised by human excrement

Society will have to rethink its attitudes to GM technology and accept an inevitable role for human excrement in the food chain, according to scientists at the University of Sheffield.

The challenges of modern day agriculture are numerous - climate change, soil degradation, water shortages and growing demand.

A team led by Dr Duncan Cameron and Jurriaan Ton, from the University's Department of Animal and Plant Sciences, believes that UK farming's inevitable future will be a combination of genetically modified crops on organic farms fertilised by human waste.

The careful cross breeding of plants' characteristics during the green revolution resulted in highly productive crops. This has resulted in plants today being strongly reliant on fertilisers and many have lost the important natural traits that allow them to interact with beneficial bacteria and fungi in the soil.

Nowadays, scientists are able to identify the exact genes that were lost during breeding programmes. By using modern day GM technologies, these 'lost genes' can be put back and crops returned to their more communicative nature.

Further analysis by scientists at the University of Sheffield found that the UK's available soil has just 100 seasons of nutrients left in it.

Professor Tony Ryan has been looking at the possibility of using human excrement as a fertiliser. He says, ''Phosphorous and nitrogen are limiting nutrients both of which are found in human waste which the 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." (PNK is the abbreviation for for  phosphorus (P), nitrogen (N), and potassium (K) that are commonly used in fertilizers.

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. All health risks can be eliminated from human excrement by proper composting.

University of Sheffield scientists say a sustainable farming future also has to be more reliant on organic farming which relies heavily on the natural breakdown of organic matter to replace nutrients taken from the soil by previous crops.

Dr Duncan Cameron, from the University's Department of Animal and Plant Sciences, says, ''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.''

Global crop losses by diseases and pests have been estimated to amount up to one third of its potential production, whereas abiotic stresses cause further substantial crop losses annually.

The University of Sheffield team is developing new methods that allow these functions to be restored in combination with more sustainable management of agricultural land.

Dr Duncan 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. "