Soil through history
Human development since prehistoric times has been closely linked with an increasing ability to manage soil and other parts of the natural environment. During early attempts at soil management, areas of land were cleared of natural vegetation and cultivated for short periods. Once fertility started to decline, the site was abandoned and left to revert slowly to natural vegetation. Activity shifted to a newly cleared site.
Increases in population and the development of towns and villages encouraged people to remain at a single place for longer periods. This meant that some way of restoring soil fertility had to be found. One approach was to clear more land than was required and leave a part of it uncultivated or fallow. Another common practice was the addition of organic waste, from households or animals, directly to the soil. These remained the normal methods of land management until about 100 years ago. Since this time they have been less widely used, as inorganic fertilisers have developed. At first these fertilisers consisted chiefly of ground up rock (in some cases treated by simple chemical processes). In the second half of the twentieth century there has been an enormous development of inorganic fertilisers, offering a wide range of nutrient inputs.