2 February 1996

nra concern at dangers brought by soil erosion

MAJOR land use changes in a river catchment can have marked effects on river water quality. In this respect, the increasing area of land used for maize-growing, particularly in southern England, has concerned us, writes Dr Robert Huggins of the National Rivers Authority.

A key concern are the off-field effects resulting from soil erosion. For example, in Dorset soil erosion has become so bad that the county council highways department held a special meeting to discuss soil on roads and has issued an advice leaflet with particular reference to maize growing.

For the NRA the threats to the river environment come from eroded soil which in rivers can cause turbid, muddy waters and can clog up salmon spawning gravels with soil. The NRA is concerned that this could affect salmon stocks. Eroded soil may also carry pesticide residues into watercourses and atrazine, which is commonly used on maize fields, could be a problem because of its persistence in the environment. Applying heavy dressings of slurry and manure to maize fields without incorporation into the soil may cause pollution when heavy rain washes the farm waste into watercourses.

NRA officers are currently considering the importance of non-point source pollution, particularly with regard to soil erosion. They aim to raise the awareness of their own staff to the effects of diffuse source pollution. Preliminary work identifies reduced tillage, buffer strips and careful fertiliser management as some of the most effective ways to reduce pollution from farmland. &#42