MAFF is helping and encouraging farmers to adopt practices which avoid causing environmental pollution. Why the problem occurs A few key facts and figures demonstrate the importance of farming in Britain. British farmers produce three-quarters of the food we eat and look after much of the countryside we enjoy. As a by-product of all this activity, every year farmers spread about 200 million tonnes of animal manures and other organic farm wastes onto the land as fertiliser. Farm wastes such as animal slurry and silage effluent can cause pollution if they get into a watercourse, for example a river or a stream.
Chemical reactions take the oxygen out of the water that river life needs.
In the worst cases, river life is killed. To give an idea of the scale of the problem. . . Animal slurry, which contains manure and urine, can be up to 100 times more polluting than raw untreated domestic sewage. Silage effluent, that is the liquid produced when preserving crops harvested while they are still green so they can be kept for fodder, is even worse - up to 200 times more polluting. The problem of pollution from farming is greater in Wales and the west of England where most of the dairy farms are concentrated.