Published 2018-11-22

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Perennial crops better at withstanding extreme weather

The summer’s drought resulted in Sweden’s farmers getting significantly smaller harvests than usual. One exception was Anna Westerbergh, a researcher at the Swedish University of Agricultural Sciences (SLU) in Uppsala. The perennial varieties of barley and wheat cultivated on her experimental plot pulled through well.
‘They’ve had good vegetative and reproductive growth during the summer and haven’t been adversely affected in the same way as annual crops.’

The summer’s extreme weather revealed that our present agricultural system is vulnerable, and that food security is an issue for the future that concerns the whole of society.

In this perspective, AquaAgri is even more topical than before. This recently completed Mistra programme on aquaculture and agriculture had the aim of producing the food of the future.

Topicality particularly characterises the project, one of five altogether, designed to develop perennial crops. One advantage of these crops is that being able to develop their root systems over a long period enables them to withstand both drought and moisture better. Other pluses are that they can store more carbon in the soil, retain more of their nutrients and, not least, require less energy and work inputs from the farmer.

The drought showed that the theory was correct in practice, at least on one important point. The perennial crops that Westerbergh and her research colleagues grew on a farm in Vattholma, near Uppsala, endured the summer far better than related annual plants growing in the surrounding fields. They not only survived, but grew well.

‘I’ve never seen such a clear difference between annual and perennial cereals as this year. We haven’t watered the perennial cereal seeds we sowed last year at all, but they’ve still developed well. The seeds have grown and given a good harvest, and haven’t suffered the way the annual ones have,’ says optimist Westerbergh, lecturer and researcher at SLU in Uppsala, who heads the perennial crop project.

Even so, the road to a real breakthrough for cereals that do not need to be sown annually is long and winding. The main challenge is to develop varieties that yield harvests comparable to those of today’s crops.

‘But the summer convinced us of the importance of continuing to develop perennial cereal seeds, both for increased food security and to get more sustainable farming,’ Westerbergh says.

The problem is that present-day agriculture is unsustainable, with an adverse environmental impact, she says. Extending that thought, she believes we must move towards cultivation systems that include perennial cereals.

‘We face many challenges, but with today’s knowledge of genetics and various plant-breeding methods, our chances of succeeding are good and the benefits can be large.’

Advantages of perennial cereals based on grass studies:

  • Perennial cereals develop stronger root systems than annual ones, which enables them to absorb nutrients from the soil more effectively.
  • A plant that grows for several seasons binds more carbon in the ground, and reduces leaching of nutrients.
  • The perennial growth method also yields a major benefit in the spring. Then, the plants are already in the ground and can start growing as soon as the conditions are right. This gives them a longer growing season, which favours carbon and nutrient absorption, and also enables the farmer to get several harvests per year.
  • The developed root systems improve these plants’ capacity to survive both dry and wet conditions, while enabling them to be cultivated on less nutrient-rich soils and used as catch crops.
  • Since the fields do not need to be ploughed every year, there is less nutrient leaching to surrounding watercourses, and reduced greenhouse gas emissions. Energy and fuel consumption also decrease.
  • Reducing soil cultivation causes less disturbance of the ‘good’ microorganisms (bacteria and eukaryotes) in the soil, thereby improving its quality. Reduced soil cultivation also means that the soil is packed less hard than in the growing of annual crops, thereby reducing soil erosion.

Text: Per Westergård