Materials spread on agricultural land include:
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manures and slurries from the farm or imported from other farms
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biosolids (sewage sludge) from sewage treatment works
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products from waste treatment processes such as composts and digestates
A range of organic materials can be spread on agricultural land to provide nutrients and organic matter to soil; it is a valuable fertiliser for farmers.
Different manures contain readily available nutrients to meet requirements of growing plants and the use of organic manures offsets the use of manufactured fertilisers and recycles valuable material back to land.
How odour is minimised
The Code of Good Agricultural Practice (CoGAP) guidance suggests that where livestock manures and organic wastes and treated materials are applied to bare soil or stubble that they are incorporated as soon as possible, and within 24 hours, to minimise odour and ammonia losses. Ploughing is the most effective technique to minimise odour in most circumstances.
This is a requirement in Nitrate Vulnerable Zones (NVZ), when landspreading waste-derived materials and some pig and poultry units which are permitted under Environmental Permitting Regulations.
Biosolids and their processing are closely regulated within the UK. The Sludge (Use in Agriculture) Regulations 1989 applies to the use of biosolids and includes the requirement to carry out testing of both the product and the soil. The industry has also created The Safe Sludge Matrix as a best practice guideline for the application of biosolids to agricultural land.