Part of the other 89% !
This figure (11%) includes incidents due to pesticides , fuel oil and other contaminants, the majority is due to livestock excreta and silage effluent. There are specific Codes of Good Practice governing the protection of soil, air and water, published by Defra, which are designed to provide guidance to farmers.
The Defra Codes of Good Practice
The Farm Practices Survey carried out in 2004, showed a small increase in the ownership of the codes between 2001 and 2004, with ownership varying with both farm size and type. In 2004, cereal farms had the highest ownership with 91% having at least one of the codes, whereas livestock farms had less than 70% ownership. Also, in the largest farms, only 13% do not own any of the codes compared with 36% of the smallest farms. A correlation with code ownership and membership of produce assurance schemes was also found.
Source: DEFRA/National Statistics, 2004
The chart below illustrates the substantiated agricultural pollution incidents in the UK in 1998.
Source: Taylor Nelson AGB plc (1996)
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Substantiated incidents of pollution from agriculture reached an all time high of 3329 in 1994 |
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This had fallen to 2111 by 1996 |
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Most cases came from slurry (17%) |
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Land run off (16%) |
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Dirty water (14%) |
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Category 1 incidents (high environmental risk) usually caused by catastrophic failure of slurry or effluent stores fell from 99 incidents in 1991 to 28 in 1996 |
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Much improved by grant aid for slurry stores and Control of pollutants regulations 1991 |
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The extent of possible groundwater contamination from earth walled slurry stores built before 1991 is unknown |
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Latest figures from the Environment Agency show the number of serious pollution incidents (category 1 and 2) to water, land and air has fallen to 85 in 2006 from 256 in 2000 (England and Wales). For more detail go to the Environment Agency website CLICK HERE. |
Pause for thought........In the chart above, what would fall into the unclassified category?
Sources of pollution:
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Pesticides |
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Animal carcasses |
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Organic manure |
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Slurry |
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Parlour/dairy/vegetable washings |
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Fertilizers |
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Waste milk |
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Sewage sludge |
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Silage effluent |
Air Pollution Detailed account of some of the issues regarding air pollution
Water Pollution This is constantly referred to throughout subject 3
Land Pollution Detailed account of the main issues regarding land contamination
Visual & Noise Pollution See 'pause for thought' below
Pause for thought......Are black polythene silage sheets and tyres a vital part of the countryside scenery or an 'eyesore' that should not be tolerated?
Left: Dairy farming adjacent to a housing estate can present problems. Right: Tyres, away from public view
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Dealing with Farm Waste
Livestock waste:
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Estimated 200 million tonnes undiluted excreta produced annually in UK |
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60% of this from grazing livestock, voided straight to grassland |
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Remaining 80 million tonnes collected from buildings for storage and spreading |
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Of this 50% handled as solid manure, 50% as slurries |
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Majority of total quantity of excreta is produced by cattle |
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Virtually all livestock waste is recycled to the land |
Storage:
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To avoid application to land in unsuitable conditions |
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Minimum of four months storage required in UK |
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All stores minimum of 10m away from a watercourse |
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Most excreta stored from 1-6 months |
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Solid manure storage not covered by legislation unless stored on concrete floor, then liquid effluent must be stored and treated as slurry |
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Approx. 15 million m3 of solid manure stored at any one time, 11 million m3 of which is in field 'heaps' |
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Most slurry stored in earth bank lagoons estimated total volume is 15.5 million m3 |
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5 million m3 stored in above ground circular stores |
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2 million m3 in weeping wall stores |
Above ground slurry store
Spreading:
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Farmers do not always take into account nutrient value of animal wastes when planning inorganic fertilizer applications |
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This often results in over-application resulting in increased leaching |
Farm waste management plans:
The code of good agricultural practice for the protection of water gives guidance for farmers on spreading and storage, by encouraging farmers to have a Farm Waste Management Plan:
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This identifies different land areas on the farm according to soil, slope, drainage and proximity to water courses |
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It identifies the amount of material that may be applied to the land at different times |
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A 10m 'no spreading' zone is recommended adjacent to water courses |
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A limit of 250 kg total N/year/ha is recommended from livestock manures |
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Majority of cattle farmers have sufficient land to stay within this limit |
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Many intensive pig or poultry units, that rely on purchased feeds, do not have adequate spreading area and have to rely on agreements with neighbouring units to stay within loading limits |
The plan should identify:
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The volume and nature of all wastes to be applied, including any arising off the farm |
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The periods when waste is produced |
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How much land is needed and available for safe spreading |
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The amount of storage required for periods when safe disposal is not possible or of nutrient benefit to the land |
Dirty water and manure disposal, an expensive agricultural necessity
The plan should contain:
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A map showing where and when land is available for spreading, identifying nearby water courses, land drains, springs, wells and any other sources of water supply |
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Identification of all areas of risk, taking into account soil type, slope, rainfall, access to the land and cropping or grazing constraints |
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An indication of the method of application and a description of the management and maintenance of the disposal system required throughout the year |
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A contingency plan for dealing with unforeseen emergencies or breakdowns |
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Treatment of livestock wastes
Anaerobic digestion
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Produces methane (biogas) as a fuel by anaerobic digestion |
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Only about 30 digesters in use on UK farms |
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Reduces waste's Biological Oxygen Demand (BOD) and odour release after spreading |
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Does not significantly reduce nutrient value or volume |
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Initial capital cost per animal unit is quite high and is only feasible when a very large number of livestock are raised |
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Debris in manure can cause major handling problems |
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Gas leaks are dangerous since methane is explosive at concentrations of 5 -15% in air |
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Pipe and valve corrosion can be a problem |
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The digester must be loaded frequently with a uniform quantity of manure, maintained at a uniform temperature, and kept relatively free of antibiotics in order for the process to occur properly |
CLICK HERE for anaerobic digestion case studies
Aerobic treatment (aeration):
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High electrical running costs |
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Significant reduction of odours both in store and after spreading |
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Low adoption rate in UK restricted to farms with specific problems i.e. odour complaints near to built up areas |
Slurry aerator, Sonning Farm, University of Reading
Mechanical separation:
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Widely adopted in UK |
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Enables easier and more predictable handling of solids an slurry |
Pause for thought........Animal waste, valuable resource or something that must be disposed of in the cheapest way possible?
CLICK HERE for definition of Biological Oxygen Demand
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Silage Effluent
Silage, covered and uncovered
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Approx. 38 million tonnes of silage made annually in the UK |
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17% of this is made in big bales |
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1 million m3 of effluent to be disposed of annually |
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Amount of effluent depends on weather and moisture content of the crop at harvest |
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Majority of Silage effluent (and dirty water etc) collected and mixed with animal waste slurry |
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A small proportion of silage effluent is collected and fed back to cattle |
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Very 'high risk' waste, controlled by 'The Control of Pollution (silage, slurry and agricultural fuel oil) Regulations 1991' which laid down standards for the structure of silos and effluent storage facilities |
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Silos built prior to this date may have deteriorated owing to corrosive nature of silage effluent |
| Big bales lower risk as the bags are sealed and the grass is generally harvested at a higher drymatter. The only controls are associated with the storage distances from water courses |
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Plastics and packaging
Plastic packaging for pesticides, fertilizers and contaminated plastic film (silage sheets and bags) represent a significant problem. Farmers often reluctantly resort to burning these materials, despite the fact that this practice is strongly discouraged in the Code of Good Practice for the Protection of Air. In 1997, the Producer Responsibility Obligations (packaging waste) Regulations were introduced. The intention was, to encourage plastics and packaging manufacturers to develop improved methods of minimising, reclaiming and recycling these products in the near future.
Plastics and packaging, another disposal 'nightmare'
Pause for thought......Recently, a well publicized scheme for recycling silage wraps and sheets failed. Why do you think this happened?
