Harper Adams University College Predicts That Summer Grass Growth Will Be Above Average

Posted 4 May 2007

Experts at Harper Adams University College forecast that grass growth over the period mid-May to end of September is to be above average in the Experimental Grass Growth Forecast. It is predicted that the average will be 6.5t dry matter per hectare compared to the median average growth between 1984 to 2006 of 6.2t /ha. In 2006 the cropping was well above average at 8.0t/ha. 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 the University College.
Harper Adams has worked with a number of agencies on climate research, investigating the impact of the North Atlantic Oscillation (NAO) on grass growth. The on-going project, using data from the past four decades, has ascertained that summer grass growth tends to be greater after a winter with a low index of the climate phenomenon NAO. A cold winter produces high levels of moisture (high soil moisture deficit) that leads to a better crop of grass, whereas, a warmer winter reduces the levels that has a negative impact on yield.
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 purpose of the research project is to improve grass utilisation and management through the forecasting of summer growth. The forecasting will assist farmers in spring forage management decisions.  For example; since forage maize is less susceptible than grass to summer drought a greater maize area could be drilled if below-average growth is forecast, therefore, ensuring sufficient conserved forage for the winter and save on bought-in compound feeds in the late winter.  A low yielding year has a significant impact on the industry. In 1996, following the lowest rainfall summer (between 1992 and 2004), the additional feed produced to supplement diet cost UK farmers an additional £30 million. This is in comparison to 1998 following the highest rainfall summer.
The University College is continuing the Experimental Grass Growth Forecasting Research to further develop and statistically validate models relating summer grass growth to soil moisture deficit and winter climate indices such as NAO.
For further details you can look at: http://www.harper-adams.ac.uk/groups/crops/grass/