Harper Adams Headline Wheat Forecast Specific Weight and Hagberg Down on Last Year

Posted 8 June 2007

Experts at Harper Adams University College forecast that the Great Britain national average specific weight for wheat will be 75.9 kg/hl. This is slightly below, but close to, the 1974-2002 mean of 76.1 and below last year’s 76.4 kg/hl.

It is also predicted that the Great Britain national average Hagberg falling number for wheat is to be 224s. This is below the 1974-2002 mean of 256s and well below last year’s 294s.  

The forecasting, which is likely to be correct two years out of three, has been co-ordinated and led by Dr Peter Kettlewell, Senior Lecturer at Harper Adams.

Dr. Peter Kettlewell said “The University College has studied the factors affecting the breadmaking premium over many years and we have found that Hagberg falling number has the largest effect on the premium. Every drop of 10s in national average Hagberg at harvest leads to a rise in the national average premium, over a whole year, of 1.5% of the feed price. Livestock numbers and the carry-over of wheat from the previous harvest year also influence premium, but these effects are less marked than the effect of Hagberg.”

He continues to explain “If the forecast of the wheat quality being lower than that of last year’s is correct, it will lead to a shortage of good quality wheat. This will create pressure for an increased premium.”

Experts at the University College have discovered that the North Atlantic Oscillation (NAO), a large scale climate phenomenon, strongly influences wheat quality. The problem of pre-harvest sprouting of wheat grain and low Hagberg falling number has been studied at Harper Adams for many years, and by chance it was noticed that the national average Hagberg falling number appeared to follow a pattern similar to that of the NAO which is a standard winter air pressure index over the Atlantic Ocean. There was a positive relationship between the NAO in the winter and Hagberg the following summer. The NAO was also found to affect wheat specific weight. These discoveries have been used to predict the quality of bread wheat in the spring.

The summer weather in the UK is linked to the NAO because the climate pattern the previous winter is driven by pressure difference between the air over Azores and Iceland. It has been found that if the pressure is high over Iceland, the weather is colder in Europe during the winter and there is more rain the following summer. However, if pressure is unusually low over Iceland, there are more storms in Europe, a milder winter and less summer rain.

The forecasting will assist farmers’ management decisions.  For example; a forecast of low quality will mean a high premium. Therefore, to minimise the risk of low quality and increase the chance of gaining a premium, farmers could harvest bread wheats early at high moisture and use the dryer, rather than risk waiting for the crop to dry in the field but suffer from pre-harvest sprouting.

For further details please contact Dr. Peter Kettlewell at pkettlewell@harper-adams.ac.uk