There are many competing uses of soil. For example, should we preserve our soils for food production and use them mostly for farming; or should we enjoy our natural flora and fauna in the countryside and recognise that soils are important in this; or should we build on soils no matter what their fertility because people need houses to live in? Sometimes we have to make difficult decisions about how we use soils. Deciding whether to build on soils is a particularly difficult decision because buildings effectively seals them and prevent their use for any other future purposes.
It is becoming an increasingly difficult decision as to whether to build on land. In the United Kingdom this decision has been passed largely to the Local Council to decide whether covering of a piece of land with buildings should be permitted, though government ultimately has the power of sanction. The Local Councils have been helped by a number of Land Classification Systems in which the land is graded according to its quality. In these Systems there are up to 7 categories of quality of land. Grades 1 and 2 signify the best, most fertile land. This is land that should be reserved for agriculture and food production. Grade 3 land and above can be used for building and the higher the classification often the less opposition to building on it will be, unless other factors such as whether it is in an area of special scientific interest or one of particularly attractive landscape come into play. The Classification Systems have not led to all good land being saved from being built upon but they have certainly helped.
There is encouragement where ever possible to use land for building that for one reason or another is unsuitable for other purposes. Local Governments are generally more agreeable to the use of brown field sites for residential housing and different forms of industry. Brown field sites are those sites that have been used previously for industrial purposes. There is often reluctance to build houses on such sites because of the risk that they have been polluted or greatly disturbed during the previous industrial use. Instead there is a preference by builders for Green field sites where they occur on the edge of an existing urban development or in open country. Greenfield sites are those that have not been built on previously and are generally good agricultural land. The question is then raised should this land be preserved for agricultural or landscape amenity use in the future or can it be sacrificed for building. These are very difficult considerations and ones that have often been the cause of much argument and dissatisfaction.