By Paul Brown / Climate News Network

    Trees planted as windbreaks for crops in Minnesota. (Eli Sagor via Flickr)

LONDON — Feeding the world’s growing population in a rapidly warming world will not be possible with modern intensive agriculture that relies on cutting down more forests to plant crops, according to new research.

The only way to produce enough crops and mitigate climate change at the same time is to adopt what the researchers have called agroforestry, a system of growing crops alongside trees and shrubs.

In a paper published in Sustainability journal, scientists from the department of crop sciences at the University of Illinois, US, say one of the most difficult aspects of the idea is changing farmers’ attitudes.

Adopting agroforestry

Matt Wilson, a graduate student who has been talking to farmers about the ideas, says that there are cultural barriers in the US to adopting agroforestry practices — barriers that do not exist in Europe and elsewhere.

He says: “We’ve had some farmers share sentiments like: ‘Why should I plant trees? My grandpa spent his whole life tearing trees out so he could put crops in.’

“There’s definitely some perception that trees are not good in a farm landscape. And trying to overcome that has been a challenge.”

But the research has shown that intermingling traditional grain crops with fruiting shrubs and trees can make more profit for the farmer, as well as combating climate change, habitat loss, improving water and soil quality, and reducing problems such as flooding and soil erosion.

The researchers do not dismiss research into high-yielding crop varieties and the contribution made by organic farming to greater sustainability and feeding the world.

However, they say that neither [can] do enough to provide sufficient food for the projected world population of nine billion. Nor will they help reduce the effects of climate change.

“We’re looking at economic strategies
to maximise profit
from the very beginning.”

With more than a third of the world’s land already given over to agriculture, there is likely to be more deforestation and habitat loss in an effort to feed this growing population — making a bad situation worse, according to Sarah Taylor Lovell, an agro-ecologist at the University of Illinois.

Lovell and Wilson advocate five agroforestry systems:

  • Alley cropping — growing crops between rows of trees;
  • Silvopasture — trees added to pasture systems;
  • Riperian buffers — trees planted between field edges and river systems;
  • Windbreaks — trees planted next to fields to shield them from the prevailing wind;
  • Forest farming — harvesting or cultivating products such as mushrooms, medicinal herbs or ornamental wood in established forests.

The plan is to produce a whole series of crops from the same land at different times of year — although some farmers were still resistant to the idea of trees because they feared these would shade crops and lower the yield,

But properly-designed systems would not do this, the researchers claim. For example, the combination of winter wheat and walnut trees in an alley cropping system works well.

“Winter wheat grows in the late winter or early spring, but the walnut doesn’t leaf out until late spring,” Wilson explains. “So, when you mix the two together, you’ve got the benefit of having two crops growing in different parts of the year.”

The researchers say that some of these practices are already being adopted in Europe.

Long timeframe

They accept that the long timeframe needed for trees to establish and mature may discourage some farmers, but they offer a strategy for the transition period.

In an alley cropping system with hazelnut and chestnut trees, for example, they suggest growing edible shrubs and pasture between rows of crops.

Farmers can expect to start harvesting and selling hay almost immediately, and will start seeing fruit production from the shrubs within a couple of years. Eight to 10 years after establishment, trees will begin producing nuts.

“We’re looking at economic strategies to maximise profit from the very beginning,” Lovell says.

Despite the challenges, the researchers insist the environmental benefits are worth the trouble.

“If you have trees in a system, you’re holding soil, preventing runoff, and ameliorating greenhouse gas emissions,” Wilson says. “At the same time, you are getting a harvestable product.

“This combination of environmental services and agricultural production makes agroforestry an exciting opportunity both to feed the world and save the planet.”

Paul Brown, a founding editor of Climate News Network, is a former environment correspondent of The Guardian newspaper, and still writes columns for the paper.

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