Up to a quarter of global food production could be lost by 2050 due to the combined impact of such problems as climate change, land degradation and water scarcity, the United Nations says.

The fall-off will strike just as 2 billion more people are added to the world's population, according to the UN Environment Programme (UNEP), which says cereal yields have stagnated worldwide and fish catches are declining.

In a new report, UNEP says a 100-year trend of falling food costs could be at an end and that last year's sharp price rises have driven 110 million people into poverty.

Prices may have eased from those peaks in many areas, but experts say volatility - combined with the impact of the global economic downturn - has meant little respite for the poor.

"We need to deal with not only the way the world produces food but the way it is distributed, sold and consumed, and we need a revolution that boosts yields by working with, rather than against, nature," says UNEP executive director Achim Steiner, who spoke at a major UN environment meeting in Kenya.

He says more than half the food produced worldwide today is lost, wasted or thrown away due to inefficiencies.
Improved efficiency could feed world

"There is evidence within the report that the world could feed the entire projected population growth alone by becoming more efficient while also ensuring the survival of wild animals, birds and fish on this planet," says Steiner.

The UNEP says world food prices are estimated to rise by 30-50% over the coming decades - while the global population is seen climbing to more than 9 billion from nearly 7 billion.

It says price regulations for commodities should be introduced and larger cereal stocks set aside to guard against price volatility. It also calls for "safety nets" to be established for those most at risk from hunger.

UNEP says more than a third of the world's cereals are being used for animal feed, and that this proportion is expected to rise to a half by 2050. It proposes feeding animals recycled food waste as an environment-friendly alternative.

Steiner says innovative solutions are needed, like in Niger, where UNEP experts are studying how to preserve the estimated 60% of the onion crop that rots before market.

"We have a very serious problem on our planet," he says. "Simply ratcheting up the fertiliser and pesticide-led production methods of the 20th century is unlikely to address the challenge."
China's farmers urged to green up

In related news, China's farmers are being urged to reduce their use of synthetic nitrogen fertilisers and change their farming practices.

Chinese researchers, publishing the Proceedings of the National Academy of Sciences, argue excessive use of nitrogen fertilisers has polluted China's groundwater, given rise to acid rain, soil acidification and increased greenhouse gas emissions.

"Persuading farmers to limit fertiliser inputs is difficult because many of them still hold to traditional opinions that higher crop yield will be obtained with more fertilisers," say Dr Xiao-Tang Ju at the China Agricultural University in Beijing and colleagues.

However, they stress: "Only by reducing fertiliser nitrogen inputs can degraded environments be gradually restored, enhanced and protected."

Overuse of synthetic nitrogen not only happens in China but in many other Asian countries that are under pressure to feed large and growing populations.

The researchers say farmers could reduce dependence on synthetic nitrogen by using more efficient recycling of manures and crop residues and legume crops in rotation to increase internal nitrogen cycling.

by:ABC Science