The fertility of the world’s soil is reaching a peak that will threaten global food supplies this century unless more is done to preserve the long-term viability of existing farmland, according to a group of leading scientists.
Soil erosion and degradation, combined with the loss of agricultural land to urban sprawl and a booming global population, is one of the most pressing issues facing human security in the 21st century, they said.
The “green revolution” of the past half century, where intensive farming based on agro-chemicals managed to boost food production significantly, will not be able to sustain the growing population this century without greater emphasis on soil preservation and fertility, they said.
Much of the most productive cropland today is due to the “domestication” of wild soils brought about by modern farming practices. But these domesticated soils are seldom able to maintain the quality of their wild ancestral stock, the scientists write in a review of global soil fertility in the journal Science.
1/7 Coastal systems and low-lying areas
Flood damaged streets in Queens, New York where the historic boardwalk was washed away due to Hurricane Sandy in 2012. The report predicts that by the end of the century “hundreds of millions of people will be affected by coastal flooding and displaced due to land loss”
2/7 Food security
Widespread drought devastated a corn crop on a farm near Bruceville, Indiana in 2012. The report forecasts that climate change will reduce median yields by up to 2 per cent per decade for the rest of the century
3/7 The global economy
The Evening Standard headline board showing the words 'Black Friday Shares Crash' in London in October 2008 in London. The report warns a global mean temperature increase of 2.5C above pre-industrial levels may lead to global aggregate economic losses of between 0.2 and 2.0 per cent
4/7 Human health
A child suffering from malnutrition and diarrhoea is seen at the Banadir hospital in the Somalian capital of Mogadishu in 2009. Climate change will lead to increases in ill-health in many regions, with examples including an increased likelihood of under-nutrition.
5/7 Human security
A Muslim migrant holds his son as they are detained at the Immigration Police Office on the Thai-Malaysian border in March 2014. The report states that climate change over the 21st century will have a significant impact on forms of migration that compromise human security
6/7 Freshwater resources
A villager walks through a parched paddy in Tianlin county, China in 2012. The report finds that climate change will “reduce renewable surface water and groundwater resources significantly in most dry subtropical regions"
7/7 Unique landscapes
Machair, a grassy coastal habitat found only in north-west Scotland and the west coast of Ireland, is one of the several elements of the UK’s “cultural heritage” that is at risk from climate change
“The efforts to improve the management and conservation of domesticated soils, and the preservation of portions of their remaining wild ancestral stock, will be among the most important challenges this century,” said Ronald Amundson, professor of environmental science at the University of California, Berkeley.
Between 1970 and 2000, an area of agricultural land the size of Denmark became urbanised and in the next 20 years an area the size of Mongolia – some 1.5m sq km – will be swallowed up by city development, the scientists said.
“Our most productive soils have already been exploited and that demand for food production will continue to increase,” they said.
Dr Amundson said farming practices through the ages have caused the accelerated loss of soil through erosion and nutrient removal and this is one of the primary game-changers for the long-term, sustainable production of the soil – the “living epidermis” of the planet.
“Ever since humans developed agriculture, we’ve been transforming the planet and throwing the soil’s nutrient cycle out of balance. Because the changes happen slowly, often taking two to three generations, people are not [aware] of the transformation,” Dr Amundson said.
One of the key threats to future food security is the supply of artificial soil fertilisers, specifically phosphorus and potassium, which have to be mined from reserves held in rocks and minerals. The US reserve of phosphorus, for example, accounts for only 1 or 2 per cent of the world’s reserves, and it is due to be depleted within the next 20 or 30 years, he said.
“This could create political challenges and uncertainties. Morocco will soon be the largest source of phosphorus in the world, followed by China,” Dr Amundson said.
“These two countries will have a great deal of say in the distribution of those resources. Some people suggest we will see the emergence of a phosphorus cartel,” he said.
Many of the artificial nutrients added to soil, including nitrogen, become pollutants when washed away. They should be recycled in the same way that paper, glass, tin cans and plastics are recycled from domestic waste, Dr Amundson said.
“We should be able to do this with soil. The nutrients lost can be captured, recycled and put back into the ground. We have the skill set to recycle a lot of nutrients, but the ultimate deciders are the people who create policy,” he said.
“It’s not a scientific problem. It’s a societal problem.”Reuse content