Feeling virtuous about breakfasting on organic muesli? In case you feel you've done your bit to save the planet with the eco-friendlier option, a new study will provide some food for thought. It says that intensive agriculture may be less damaging than organic farming.
The study, which involved researchers from 17 organisations across the UK, Poland, Brazil, Australia, Mexico and Colombia, says that land efficient systems must be used to prevent further conversion of wilderness into farmland. Agriculture that appears to be more eco-friendly but uses more land may actually have greater environmental costs per unit of food than “high-yield” farming that uses less land, the study says.
The study, which was published in the journal Nature Sustainability, argues that intensive farming techniques have got a bad name because they are thought to create disproportionate levels of pollution, water scarcity and soil erosion. But actually, it is because of intensive agriculture that virgin tracts may be saved the plough, even as the food needs of the world rise.
The scientists put together measures for some of the major “externalities”—such as greenhouse gas emission, fertiliser and water use—generated by high and low-yield farming systems, and compared the environmental costs of producing a given amount of food in different ways. Previous research compared these costs by land area. As high-yield farming needs less land to produce the same quantity of food, the study’s authors say this approach overestimates its environmental impact.
The study goes a step ahead. Not only does it emphasise that wild lands are saved with intensive agriculture, but that this option also produces fewer pollutants, cause less soil loss and consume less water. These are radical conclusions since it is the generally accepted belief that while organic agriculture may have lower yields, their carbon footprint is also smaller as they involve better water management, and do not pump in harmful pesticides and fertilisers into the soil.
“Agriculture is the most significant cause of biodiversity loss on the planet,” said study lead author Andrew Balmford, Professor of Conservation Science from Cambridge’s Department of Zoology. “Habitats are continuing to be cleared to make way for farmland, leaving ever less space for wildlife. Our results suggest that high-yield farming could be harnessed to meet the growing demand for food without destroying more of the natural world. However, if we are to avert mass extinction it is vital that land-efficient agriculture is linked to more wilderness being spared the plough.”
The study analysed information from hundreds of investigations into four vast food sectors, accounting for large percentages of the global output for each product: Asian paddy rice (90 per cent), European wheat (33 per cent), Latin American beef (23 per cent), and European dairy (53 per cent).
Examples of high-yield strategies include enhanced pasture systems and livestock breeds in beef production, use of chemical fertiliser on crops, and keeping dairy cows indoors for longer. The scientists found data to be limited, and say more research is urgently needed on the environmental cost of different farming systems. Nevertheless, results suggest many high-yield systems are less ecologically damaging and, crucially, use much less land.
For example, in field trials, inorganic nitrogen boosted yields with little to no greenhouse gas “penalty” and lower water use per tonne of rice. Per tonne of beef, the team found greenhouse gas emissions could be halved in some systems where yields are boosted by adding trees to provide shade and forage for cattle.
In the dairy sector, too, the researchers felt that for the same output of milk, organic systems in Europe cause at least one third more soil loss, and take up twice as much land, as conventional dairy farming. Phil Garnsworthy from the University of Nottingham, said, “Across all dairy systems we find that higher milk yield per unit of land generally leads to greater biological and economic efficiency of production. Dairy farmers should welcome the news that more efficient systems have lower environmental impact.”
Co-author Dr David Edwards, Senior Lecturer in Conservation Science from the University of Sheffield, said: “Organic systems are often considered to be far more environmentally friendly than conventional farming, but our work suggested the opposite. By using more land to produce the same yield, organic may ultimately accrue larger environmental costs.”
“These results add to the evidence that sparing natural habitats by using high-yield farming to produce food is the least bad way forward,” said Balmford.