agriculture, rivers and waste
Ref: W06

The waste products from both livestock and arable farming can lead to the pollution of rivers and fisheries if farmers are not very careful. Dairy farming, keeping pigs, sheep and chickens or growing crops such as wheat, maize, potatoes and other root vegetables can all cause pollution in rivers and streams. Pollution like this is often unintentional, but is nevertheless a real problem of agricultural land use.

Dairy cows
Free range chickens	Miscanthus, a modern alternative crop
Sheep in a barn	Farm tractor

• Organic Waste: The process that involves the rotting or break down of waste organic materials, such as plants and animal dung, can lead to the pollution of water. This is called organic pollution. On farms there might be manure heaps and slurry lagoons (W07d) that leak or silage clamps (W07f) with liquids slowly trickling out. If these liquids run into ditches or channels that lead to rivers or streams they will pollute the water.

Roadside muck heap

Cattle in a river

Black plastic wrap pile

• Fertilisers: Fertilisers are applied to the soil or plants to help the plants grow. Most fertilisers are made of a mixture of chemicals such as nitrates and phosphates (W07b).Any fertiliser not taken up by the plants in growing will find its way eventually to a river or stream and will then affect the plants that grow there. A small amount of fertiliser will help the aquatic plants to grow, but too much will destroy the delicate balance of nature.

• Herbicides and Pesticides (G1): Some chemicals that are used in farming practices can cause serious pollution problems more directly. Chemicals are used to kill weeds (called herbicides or weed-killers) and pests (called pesticides or insecticides). If these chemicals find their way into the water cycle the effects can be disastrous. Plants and animals that live in or close to the river (B09) could be killed and fisheries ruined.

• Sediments: Soil, fine sand and clays can be washed off the fields and riverbanks and pollute the river by filling the water with particles and covering the spawning gravel with sediment so that young fish cannot survive. Farm animals can churn up soils in the fields or damage riverbanks so that soil is eroded (worn down) and carried away in the water.

• Other farm waste: Black plastic silage wraps or fertiliser bags, empty medicine, pesticide or sheep dip containers, unused animal feed, rusty barbed wire, fence posts and broken gates are all agricultural waste that needs to be disposed of carefully.

Pollution of rivers can be caused by accident. For instance, pesticides or fertilisers might be blown by the wind or washed off the fields by rain and into the river. By taking precautions some pollution incidents can be avoided, such as a farmer building a dyke or bank around a slurry lagoon in case it overflows or leaving a wide margin beside a river when he is spraying crops in a field.

Don’t despair, there are solutions to pollution problems, but to find them the source of the pollution has to be found, and where and why it happened has to be understood. Some pollution problems are easier to solve than others. To learn more click on the key words below.

Some examples of these waste issues can be found on the Trust’s Demonstration Sites – visit the WRT website for information on Demonstration sites currently available for visits – www.wrt.org.uk