Dr. Jenny Deakin:

The issues with phosphorus are the opposite to the nitrogen issue in the context of where the risky areas are in the landscape. The nitrogen issue is a freely draining soil problem in the south and south east. The phosphorus issues are driven by the poorly draining soils. The mechanism of transport for the nutrient from the farm to the stream is usually overland, with rainfall on hard surfaces, compact surfaces or poorly draining soils. While there are advantages in reducing the source load of phosphorus, it takes a tiny amount of phosphorus to cause a water quality problem relative to the amounts used on the farm. We would call for pathway interception measures, which break the pathway between the source of the phosphorus on the farm and the river. It is about finding the areas on a farm where the water flows when it rains because that water will bring the sediment and phosphorus with it. If you can intercept those with a buffer strip, hedge, pond or some sort of interception feature to hold back the water and let the phosphorus and sediment settle out, that is the way of approaching the phosphorus issue.