The crops that protect rivers

Affinity Water is working with the Farming and Wildlife Advisory Group Southeast on cover crop demonstration trials. Their aim is to reduce the use of nitrogen fertiliser on crops which can seep into water in the aquifer. By working with farmers in the catchments, we aim to reduce the need for expensive water treatment processes to remove the nitrate from the water.

One trial, being undertaken at a farm in the Alkham Valley, aims to show the benefits of sowing a cover crop such as oil radish or mustard, versus leaving the soil bare over winter. Agricultural trials have demonstrated that cover crops retain nitrogen in the plant over winter and this is then released when the plant is incorporated into the soil in the spring. Locking in these essential nutrients in turn may reduce the overall requirements for fertiliser the following season, reducing the amount which can reach the aquifer. Having a cover crop sown instead of leaving the ground bare over winter also reduces soil runoff and so can also reduce silt reaching the aquifer which can make it cloudy.

Samples of water are collected from porous pots which are drilled in to the soil amongst the cover crops so that the concentration of nitrate that is washed through with rainfall can be recorded.

The results from the first year of the trials showed that the nitrate concentrations were much higher under the control plot of stubble than the plots where cover crops were growing, which suggests that this method does have potential to reduce nitrate loading in the catchment. We are now in our second year and hope to continue for a further year.

Protecting the environment and our natural water resources is fundamental to everything we do. By developing partnerships with farmers and other stakeholders, we raise awareness of the issues affecting water and support initiatives to reduce diffuse pollution from agriculture and industry.