Rainfall research

Crop growth, drinking water and recreational watersports could all be adversely affected if predicted changes in rainfall patterns over the coming years prove true.

Scientists from Biotechnology and Biological Sciences Research Council (BBSRC)-funded North Wyke Research have found for the first time that the rate at which a dried soil is rewetted impacts on the amount of phosphorus lost from the soil into surface water and subsequently into the surrounding environment.

Dr Martin Blackwell, who is one of the project leaders, said: ‘Our preliminary results show that despite best efforts, the changing climate may limit our ability to mitigate phosphorus losses at certain times of the year, especially summer.

‘This is really worrying because high phosphorus concentrations in surface waters can lead to harmful algal blooms, which can be toxic, cause lack of oxygen during their decay and disrupt food webs. This can also affect the quality of water for drinking and result in the closure of recreational watersport facilities.’

Under laboratory conditions Blackwell and his team re-wet dried samples of UK grassland soil over different time periods, ranging from two hours to 24 hours using the same quantity of water.

The leachate – water that has washed through the soil – was then analysed for phosphorus. The study showed that the rate at which a dried soil is rewetted affects the concentration and forms of phosphorus lost in leachate, which could potentially contaminate rivers and lakes.

The research looked at only one soil type so it is not yet known whether other soil types would react in the same way. Blackwell and his team plan to examine that issue next.

Commenting on the findings, Prof Douglas Kell, chief executive of BBSRC, said: ‘If we are to ensure safe and sufficient food and water supplies in the future then we must be absolutely clear on the challenges that a changing climate presents us. Having this information now means that we can be prepared to deal with the consequences of altered rainfall patterns at a local, national and international level to secure harvests, and protect water supplies.’