During the spring and in summer after harvesting, Environmental Health frequently receive complaints about agricultural odours in the district. Generally, the most common source of odour complaints relate to the storing and spreading of bio-solids (sewage sludge), animal manures and slurries (muck spreading). Prevailing winds can carry these odours some distance across fields and into residential areas. Muck spreading is recognised as standard agricultural practice, and as Dover and the nearby villages and towns are surrounded by a great deal of working farmland, such odour must be expected from time to time.
The spreading of pre-treated sewage sludge and the incorporation of manure into agricultural land is a perfectly lawful activity and considered the Best Practicable Environmental Option for disposal of such wastes.
It is not always possible to advise as to the expected duration or anticipated intensity of odours, as this can be dependent upon weather conditions.
Why do farmers have to spread in summer?
A frequently asked question is "Why do farmers have to spread in the summer months. Why not in winter when people are less likely to have windows open or be relaxing in their gardens?" Spreading can only be undertaken in fair weather. Working the soil in wet, cold or frozen ground is often unfeasible. The growing season dictates that most crops are harvested in summer and the incorporation of manures follows almost immediately. This is to replenish the soil ready for the following year.
Why is it that sometimes the smells from spreading are so awful?
Many of the complaints we receive about odour from spreading relate to the spreading of chicken manure (also called chicken litter). This is the material arising from intensive poultry farming where thousands of birds are keep in large sheds.
The smell could be reduced if the chicken manure was pre-treated prior to spreading (e.g. by aerobic composting) but this is rarely done in this country because of the costs involved.
Some odours arise from the spreading of sewage sludge. The practice of stockpiling and then spreading of treated sewage sludge is controlled by the Sludge (Use in Agriculture) Regulations 1989. This is regulated by the Environment Agency and overseen by Water UK and Ofwat. Sewage sludge is produced from the treatment of waste and consists of two basis forms, raw primary sludge (basically faecal material) and secondary activated sludge (a living culture of organisms that help remove contaminants from wastewater before it is returned to rivers or the sea). The raw primary sludge is transformed into biosolids using a number of complex treatments such as digestion, lime stabilisation, thickening, dewatering and drying.
Lime stabilisation is a a popular method of treating sludge and producing an alkali fertiliser for use in farming. The lime reacts with water in the sludge and produces heat. The increased temperature and pH kill pathogens.
What can the Council do about smells from spreading?
We will liaise with farmers to ensure they follow the Code of Good Agricultural Practice with a view to keeping disturbance to a minimum. If the farmer is acting unreasonably we shall look at enforcement action to minimise future problems.
We have worked with other local authorities to produce a Code of Practice for the Agricultural Use of Poultry Manure.
The National Farmers Union webpage also give guidance on odour control.
Tel: 01304 872428