How does climate uncertainty impact crop yield?

As harvest approaches, farmers and agronomists eagerly assess their crops to try and anticipate how crops will yield.

Yield estimates are important to inform forward selling of grain, plan storage, and update budgets.

According to Nicola Cannon, associate professor of agriculture at the Royal Agricultural University, there are “many factors that influence yield including management regimes and soil types but all of these factors are heavily influenced by the weather”.

“Weather is the determined by the day-to-day state of the atmosphere and is derived from a combination of temperature, humidity, precipitation, cloudiness and wind.

“Whereas, climate is the prevailing weather conditions of a region over a long period of time.

“On a seasonal basis, the UK is experiencing more extreme weather conditions which are impacting the yield and quality of crops grown.

Farmers and agronomists have to deal with ever increasing uncertainty of predicting, on an annual basis, how the fluctuating weather conditions will impact the growth of crops.

“The cumulation of these changes year on year are now recognised to have altered and the whole of the world is known to be impacted by climate change.

“Current and future cropping systems are going to be challenged by growing in increasing CO2 concentrations and temperatures, decreasing water availability, and an increasing frequency of extreme weather events.”

The challenge of farming in an uncertain climate

“Weather forecasting systems have improved in accessibility and reliability over the last twenty years but the major issue for farming is anticipating how reliable the forecast will be in both the short and long term,” she added

“For example, over the last two autumns, winter wheat establishment decisions have been a very fine balance between delaying drilling for blackgrass control and risking wet seedbeds and poor establishment conditions as seedbeds turned from very dry to prolonged waterlogging in a matter of a few days.”

How extreme weather impacts yield

Cannon continued:

“Extreme weather conditions normally cause a reduction in the yield of wheat regardless of when it occurs in the growing season.

“The UK climate projections predict warmer, wetter winters, and hotter, drier summers, alongside increased frequency and intensity of extremes.

Temperatures in the last decade were already 1º above pre-industrial levels recorded in 1850-1900 which may explain some of the greater variation observed in annual wheat yields.

“These changing weather patterns have already been influencing farm operations, with challenging autumn establishment conditions and often delayed pre-emergence herbicide applications turning into a less effective peri or post emergence application, wet springs limiting early access to land and keeping soils colder for longer,” she concluded.