Pollution from farming

Farming has been revolutionized in the past hundred years. In the 1890s, wheat was sown by hand, weeded by the hoe and harvested with the sickle and scythe, and about a third of the population were employed in some activity related to the growing of food. In 1945, 1 million people worked in farming in the UK, but by 1960, regular farm jobs had fallen to half a million; in 1994, the number had declined further to only 120,000 people. The largest single factor contributing to this change has been mechanization, in particular the replacement of the horse by the tractor. Harry Ferguson's prototype tractor arrived in 1933; by the mid-1950s, tractors outnumbered horses in the UK and now there are about half a million of them. The power of the tractor has increased greatly from Ferguson's prototype: it is estimated that modern farming requires the equivalent of 25 million horses.1

One of the consequences of this mechanization is the change in the size of the fields. If a farmer is working in a 2-hectare field with a 3-metre wide implement behind the tractor, one-third of the time is spent cultivating the ground whilst two-thirds is spent turning the machine around, going round the edges or going to another field. If the field is 40 hectares, however, two-thirds of the time is spent cultivating. For this reason, fields have been enlarged to accommodate the bigger machines and to increase productivity. The bigger fields are created by removing the hedges and fences. In the period between 1978 and 1984, 28,000 km of hedges were removed by farmers and only 3,500 km of new ones planted.

Surprisingly, although farmers have been creating bigger fields to maximize yields, the amount of land used for agriculture in the UK has declined in recent years. In 1980, 19 million hectares were used but ten years later this had been reduced to 18.5 million hectares. One of the reasons for this has been the introduction of the Set Aside Scheme introduced by the European Union. This scheme controls the amount of land used by farmers for growing cereals to prevent over-production. Farmers are given a 'ration' of land that they can use for cereals and any excess is set aside, i.e. it is undeveloped and left uncultivated. There has also been a shift in the type of cereals grown in the UK, with less barley (2.3 million hectares in 1980 down to 1.5 million hectares in 1990) but more wheat (up from 1.4 million hectares to 2 million hectares in the same period). Non-cereal crops such as oilseed rape also increased from 1 million to 1.4 million hectares during those ten years. The proportion of land put over to various types of agriculture in the UK is shown in Figure 12.

As well as the crops there have been changes in the proportion of livestock numbers and there are now greater numbers of sheep and pigs and fewer cattle. These changes for Scotland are shown in Figure 13.

Figure 12. Agricultural areas in different countries in the UK
Figure 13. Livestock numbers 1985 and 1995 in Scotland

In the UK as a whole in 1995 there were:

11.7 million cattle

42.8 million sheep 7.5 million pigs 141 million poultry

In order to optimize the yield of the crops sown, farmers apply many chemicals to keep pests at bay and artificial fertilizers to increase the growth rate and the size of the crop. All the livestock produce waste products - this is not a problem with the sheep that are outdoors for most of the time, but cows are now confined to stalls from October until March and their waste products have to be disposed of. In the UK, the annual amount of animal waste which is spread on to land to fertilize the soil amounts to 80 million tonnes.

The fertilizers, pesticides and animal wastes all pose threats to water quality because they are so polluting in different ways.

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