Keywords: soil protection; anaerobic digestion; sewage sludge; heavy metals; organic manure; plant nutrients
Application of organic materials such as manures, sewage sludge, compost and anaerobic digestate to land can bring both agricultural benefit and ecological improvement. It can provide valuable plant nutrients and maintain soil organic matter which is beneficial for the soil in many ways and which improves its functioning as a base for agricultural production. It also helps close the carbon and nutrient loops, recycling these resources to land. It is likely to be the Best Practicable Environmental Option in most circumstances, when carried out according to good practice. However, these materials often contain undesirable components such as heavy metals as well as potentially polluting plant nutrients such as nitrogen and phosphorus, so it is important that they are used in a way which ensures long term sustainability.
Regulation and guidance at EU and national level impacts on the use of organic material on agricultural land. In the UK, this is currently mainly aimed at ensuring that levels of heavy metals do no become to high and at controlling pollution of the surrounding environment. There are also UK government initiatives to promote the use of organic material to land; for example the support aimed at encouraging the development of anaerobic digestion techniques.
Dr Ã…sa E SjÃ¶strÃ¶m, Defra, Nobel House, 17 Smith Square, London SW1P 3JR, UK.
21 pages, 3 figures, 5 tables, 22 references.