Buffering against changing climate

Even if you weren’t directly affected by the devastating floods of 2000 across much of England and Wales, you’ll agree the event was cause for concern.

 

Confirmed recently by scientists at Oxford University as the first weather event in the UK attributed to human-induced climate change, it marks the start of a tumultuous period that threatens crop profitability, warns Tim Wheeler, head of the Crop and Climate Group at the Department of Agriculture at Reading University’s Walker Institute.

“Advanced climate modelling research clearly shows that, in addition to a warmer climate, we are likely to see greater climatic variability, with flooding and droughts becoming normal events by 2050,” says Prof Wheeler.

“The heatwave that reduced average cereal yields across Europe by 10% eight years ago didn’t have an impact here due to its fortuitous timing between flowering and harvest. But we need to guard against such risk as they do in parts of the world where variability is already common.”

With more than 20 years’ experience of agriculture and climate change, Prof Wheeler has seen first-hand the adverse effects weather events can have on farm profitability and market share in different parts of the world.

He urges the whole industry to build resilience into cropping systems, which means addressing weather forecasting and plant breeding, as well as adopting responsive agronomy. That starts with soil management and reviewing inputs.

“It’s fair to say UK growers stand to benefit from the gradual rise in average temperatures in the short term. More carbon dioxide in the atmosphere and warmer growing seasons should increase UK cereal yields by about 10% by 2030, assuming varietal improvements keep pace.

“But for long-term solutions, we should look to areas where productivity has been affected by unpredictable weather, such as Australia. Or a few hundred miles south of here in continental Europe, where systems are more like our own,” says Prof Wheeler.

That doesn’t necessarily mean growing sunflowers or grain maize, but choosing crops that can be grown profitably at least risk.

“What’s clear is that plant breeders and growers should not second-guess the perfect variety of wheat or oilseed rape for 10 years’ time. We want to be developing and growing varieties that can tolerate extremes – arguably more important than gradual changes in average weather.”

Masstock agronomists are already assessing the best rotations, varieties and crop management strategies to mitigate yield losses to water shortages, particularly in the south and east of England.

Research development manager at Throws Farm, Colin Lloyd, believes the best way to manage the risk is to grow a balance of early and late-maturing varieties of cereals and oilseeds. That not only spreads the harvest risk, but also the workload.

“In wheat, early-maturing varieties are often used as a drought avoidance technique. Interestingly, in the past few seasons, late maturing varieties have been better able to take advantage of the summer rainfall that followed the early-season droughts.”

The company’s SMART Farm trials have identified differences between wheat and oilseed rape varieties in their ability to tolerate a range of environmental stresses. Some are less responsive to nitrogen fertiliser than others, which means they suffer less in seasons where nitrogen uptake is limited by drought.

In a trial on heavy land, the hybrid winter rape Hammer yielded 5.16t/ha at optimal levels and 3.8t/ha at sub-optimal nitrogen levels. At the same site, Excalibur yielded 5t/ha and 4.5t/ha, respectively, demonstrating a 19% yield advantage with limited nitrogen.

As a direct response to N availability problems in cereals last spring, Masstock’s senior development agronomist Andrew Richards has this season recommended growers on thinner and less fertile soils to apply more than the usual 40kg/ha top dressing, to ensure optimum availability from the start of spring.

“During last spring’s dry weather, wheat crops that received an early nitrogen dressing of 60-80kg/ha showed much better tiller retention. Indeed, many second wheats went on to yield much closer to first wheats than would normally be expected, mainly because they received 40% of their total nitrogen before the end of March.

“Ideally too, you want a rapidly developing variety producing extensive roots by spring to buffer against drought. If you start with a well-structured soil with a high organic matter content, that’s half the battle. Then you can fine tune inputs to maintain crop health with more confidence that you’ll receive a good return on crop investment.”

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