Paris: Small-scale "eco-farming" could double food production in many of the world`s poorest regions and also help fight climate change, according to a United Nations report unveiled Tuesday.
The spectre of world hunger looms ever larger as the global population continues to balloon, especially in the least developed nations.
Today more than a billion of the planet`s nearly seven billion people live at the edge of subsistence on less than a dollar per day.
Food prices have flared in recent years due to climate-related natural disasters, with the cost of several staple foods reaching unprecedented levels last month, according to the UN`s food price index.
By mid-century, when the global population is expected to surpass nine billion, food shortages will become even more critical as will the need for additional output.
But the key to boosting output in poor countries is a shift from mono-crops doused with chemical fertilisers and pesticides to more sustainable techniques that can both increase yields and repair the environment, the report said.
"We are not in a situation in which agriculture can only be about increasing production," said lead author Olivier De Schutter, the UN`s Special Rapporteur on the Right to Food.
"It must also be about limiting the impact on ecosystems ... and preserving agro-biodiversity. It must be about increasing the income of the farmers."
Conventional farming degrades soils, fuels climate change, is vulnerable to weather shocks, and relies on expensive inputs, he pointed out.
"It is simply not the best choice anymore," he said.
UN investigators searched scientific literature published over the last five years to identify agricultural techniques that work best in poor countries.
They found that small-scale and largely organic farms -- especially those with a diverse mix of crops and plants -- performed far better.
In development projects examined in 20 African countries, crop yields doubled over three to 10 years using these means.
Similar methods boosted output, on average, by 80 percent across 57 developing countries.
Beside growing more food, the sustainable approach slashed the use of chemical fertilisers and pesticides, saving farmers money, reducing pollution and allowing depleted soil to recover.
"It becomes essentially more affordable for poor farmers to farm because they will have to invest much less in order to buy the inputs they need," said De Schutter.
In Malawi, farmers who planted certain trees near their maize crops saw yields increase two-to-three fold.
The trees helped absorb nitrogen in the atmosphere, and fertilised the soil with nitrogen-rich foliage. At the same time, the tree roots oxygenated the earth and helped maintain ground moisture for nearby crops.
In combination with a modest dose of chemical fertiliser, this method increased yields even more, suggesting that the two techniques can sometimes complement each other.
Another programme in Kenya used some plants interspersed within crops to repel insects while other plants -- more distant -- were used to attract the pests a safe distance away.
Crop variety can protect subsistence farmers from disaster by pests or the weather, the report argued.
"Diversity on the farm creates an `agro-portfolio effect` -- you don`t lose all the crops at once," De Schutter said.
But in rich nations, he added, turning away from highly-mechanised industrial farming would likely reduce yields.
The study is one of many recent warnings that current agricultural practises are ruining life-giving ecosystems.
"The new reality is that the world is only one poor harvest away from chaos," said noted environmental expert Lester Brown, president of the Earth Policy Institute, and author of "World on the Edge: How to Prevent and Economic Collapse."
Others approaches to stemming a global food crisis include the use of genetically modified food, further industrialisation, and reducing production of bio-fuel crops to make way for food crops.