 In the twentieth century Scottish agriculture became susceptible to the ups and downs of world markets. There were dramatic price rises in the First World War, but a slump in the 1920s and 1930s, in which perhaps 40 per cent of Scottish land changed hands, followed by more price rises in the Second World War. In 1947 annual price reviews were introduced in an attempt to stabilise the market. A series of Acts of Parliament followed, designed to give price support and grants to farmers. After the Second World War and the associated rationing, there was a drive in UK agriculture to greater production. This lasted until the late 1970s, resulting in more intensive farming. More areas of marginal land were brought into production with government subsidies. At the same time, the amount of forest was increased by a factor of three. There was increasing mechanisation of Scottish agriculture. The horse was replaced by the tractor and the combine harvester. This meant that farming became less labour-intensive. In 1951, 88,000 people worked in Scottish agriculture full-time, but by 1991 it had fallen to about 25,000, leading to more depopulation of rural areas. This helped make Scottish agriculture among the most efficient in Europe.
