3 Soils Introduction The thin layer of soil at the earth’s surface is essential for maintaining life. This layer of soil is the basis of most agriculture around the globe. If soil is lost or degraded, the potential of an area to support both plant | 3 Soils Introduction The thin layer of soil at the earth s surface is essential for maintaining life. This layer of soil is the basis of most agriculture around the globe. If soil is lost or degraded the potential of an area to support both plant and animal life is greatly reduced. Whilst the actual definition of sustainable farming varies somewhat conservation and rejuvenation of agricultural soils are essential elements of any sustainable agricultural system. It is important to understand that soil is not the property of the land owner the lease holder or the tenant of the site. It is the property of everyone now and in the future. It may take many thousands of years for a soil to form but only a few years for it to be degraded or lost due to poor management practices. For this reason it is critical that the techniques we use to manage our soils will maintain them in a manner that ensures that they are at least as productive for future generations as they are now and hopefully are even improved. Growing media The growing medium is the material or space in which plant roots grow. This has traditionally been soil but with the application of modern technology we are provided with other options for growing media. There are three main options 1. Sustained Organic Soils. In nature the best soils contain at least 5-10 organic matter. Organic matter influences soil and water systems which in turn modify organic matter turnover and nutrient cycling. Maintaining the levels of organic matter in soils is a vital element of sustainable agricultural production. 2. Technologically Supported Soils. By adding fertilisers and soil ameliorants eg lime and by irrigating heavily technology enables us to grow almost anything in almost any soil. Unfortunately this is an inefficient use of resources and can result in serious degradation of soils as well creating further problems such as excess nutrients entering our waterways and causing problems such as algal blooms. 24 Sustainable .
