More large storms in the future, such as Storm Desmond, will increase the loss of valuable soil and nutrients from agricultural fields, according to new research published by a Lancaster University-led team. In the wake of Storm Desmond, and the wettest November and December since rainfall records began, farmers in the North West of England are once again struggling with waterlogged soil, livestock and crop loss.
Alongside the devastation caused by flooded homes and businesses, farmers also face the loss of an asset essential to their livelihood -- the soil itself.
In a new paper in the journal Science of the Total Environment, researchers investigating nutrient runoff from agricultural land warn that losses of soil and nutrients could increase by an average of 9 per cent by 2050, with some years washing off greater than 20 per cent more soil than the average year.
Professor Phil Haygarth of the Lancaster Environment Centre is leading the three-year, Natural Environment Research Council-funded study.
He said: "There always has been, and always will be, large variability in the weather between years, but there is undoubtedly a trend towards warmer, wetter winters which could result in increased water pollution from agricultural land."
Nutrients, such as phosphorus and nitrogen are essential to plant and animal growth, but too many nutrients cause excessive plant growth and algal blooms in rivers and lakes. These suffocate fish and other organisms and require costly remediation by water supply companies.
Fertilisers and manures washed off in storms are a major source of nutrients, with more than 60 per cent of the nitrogen and 25 per cent of the phosphorus in our rivers coming from agriculture.
Dr Mary Ockenden, Senior Research Associate at Lancaster University and lead author of the publication, said: "The research in this project highlights the importance of the largest and most intense rain events, which contribute more than 90 per cent of the soil loss and 80 per cent of the phosphorus loss in 10 per cent of the time. But longer periods of low rain fall during hotter, drier summers will also result in increases in nutrient concentrations and increased ecological risk."
The research in the paper combined analysis of high-frequency data from the Eden Demonstration Test Catchment programme, (a related collaborative project involving Lancaster University and partners) with site-specific rainfall projections for the future (UK Climate Projections 2009), to make estimates of phosphorus losses in the future.
The predictions incorporated both the uncertainty in the data and the natural inter-annual variability in climate.
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