A study led by researchers from Scotland’s Rural College (SRUC) has found surface run-off and erosion are the principle sources of phosphorus loss in arable soils.

Phosphorus loss through drains has also been shown to be a key pathway, particularly in improved grasslands on soils with artificial drainage.

The research, which was funded by CREW (Centre of Expertise for Waters) and carried out in partnership with the James Hutton Institute, reviewed the current state of knowledge about various transport mechanisms which release nitrogen and phosphorus into the water environment.

These include surface run-off and soil erosion – some of which is exacerbated by soil compaction and structural degradation; the role of tramlines used for agricultural machinery; leaching through drain-flow; and hotspots which contribute greater than average pollutant loads due to the combined effect of land management intensity and soil properties.

Focusing on Scotland, researchers reviewed the scale and extent of each of these mechanisms, preventative measures and solutions to minimise losses, and the costs and impacts on water quality associated with these. They identified key knowledge gaps for future research, including the need to quantify diffuse pollution from ‘hotspots’ in fields within Scottish catchments and understand the impacts of recommended preventative measures and solutions on water quality.

Lead researcher, Joanna Cloy, said: “Improvement in water quality is important for society in general. However, the agricultural industry will also benefit from preventing loss of valuable soils and nutrients from their land, as well as improvements in soil health.

“The report outlined options for mitigating soil erosion and nutrient losses and the costs associated with different options. For example, good soil nutrient management, such as the use of a fertiliser plan linked to soil sampling for nutrient status and soil pH, is a simple and cost-effective measure for minimising pollutant losses.”

Knowledge transfer products, including a podcast and video for farmers, technical video and information sheets, have also been produced to communicate key messages about good soil management practices to farmers and landowners.