Saturday, July 3, 2010

Perennial crops a win for food security

IT seems almost too good to be true: new wheat and rice varieties that are better suited to marginal land, that offer the hope of improving food security as well as the environment.
All our commercial grain and oilseeds are annuals. But perennial, or longer-lived, crops would need less cultivation, herbicide and fertiliser.

They could be grazed by livestock and sequester more carbon, and also increase food supply in a growing, hungry world.

Len Wade, strategic research professor at Charles Sturt University, has been interested in longer-lived crops since 1993, when he worked at the International Rice Research Institute in The Philippines and proposed the development of perennial rice.

Back in Australia he is focused on wheat. "If we had perennial wheat, which is the foundation of the cropping system, you really would have a chance to stabilise the system," he said.

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Professor Wade and Lindsay Bell, formerly with the University of Western Australia and now at CSIRO, have co-authored a number of papers on perennial crops.

The most recent, Increased Food and Ecosystem Security via Perennial Grains, written by a 29-strong international team, was published in Science last week.

The paper points out that although the world's population is growing, good agricultural land is not. It says there is an urgent need to increase food production, particularly on marginal land, with half the world's population relying on land that is at high risk of degradation from annual cropping.

"The paper is not just about feeding the world and improving food security, but about doing so in an environmentally sustainable way," Dr Bell said. "We grow annual crops on areas where our efficiency of production is pretty low and there are problems associated with that: soil erosion, salinity, nitrate leaching, decreasing soil carbon. All those things occur because we have mainly annual crops in the system."

Professor Wade said the original vegetation consisted of deep-rooted perennials that used the water and nutrients in the soil efficiently.

But when it was replaced with annual crops with shallower roots, the water balance changed, leading to problems such as salinity.

Perennials need less cultivation and less herbicide and they make more efficient use of fertilisers, all leading to fewer tractor movements, lower fuel usage and less greenhouse gas production. The deeper roots of the perennials also store more carbon and the plants can be grazed as part of a mixed farm system.

The challenge was to breed varieties that thrived in Australia, and were perennial and good seed producers, with other desirable wheat traits.

Work is being done in Australia on some US varieties, but Professor Wade admitted they may need to go "right back to the beginning and cross Australian wheat and Australian native grasses". He said perennial rice being developed in China was far more advanced. "They have perennials in the field that are agronomically suited upland and lowland that look good."

Professor Wade wanted to use the perennial rice on an Australian Centre for International Agricultural Research project he was working on in Laos. "The target in perennial rice is the fragile sloping uplands where they have slash and burn [agriculture]. There are huge erosion problems and there is overgrazing. The advantage of having perennial rice is it will stabilise the land and hold it, and provide some grazing and maybe some grain. I see perennial rice as being the poster child for perennial crops, in saving a really fragile part of the world," he said.

Under the green revolution, global cereal grain yields have more than doubled since 1960, while the area under cereal increased just 5 per cent.

World population is expected to reach nine billion people by 2050 and world food production will have to increase by 70 per cent to feed the growing and more affluent world.

The paper notes there has been a large investment in perennial biofuel plants to supply energy. It argues a similar investment in perennial crops could see commercially viable perennial grain

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