Prevention of environmental pollution from agricultural activity: guidance
Code of good practice, giving practical advice to farmers and others on minimising pollution.
Section 4: the collection, storage and application to land of livestock slurries and manures
| Dos **1. Comply with the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 2003. **2. Notify SEPA at least 28 days before bringing into use any new, substantially enlarged or substantially reconstructed slurry storage facility, which together with existing storage capacity should provide six months storage unless otherwise agreed with SEPA. **3. Maintain a freeboard of at least 0.3m for above-ground slurry stores and 0.75m for slurry lagoons. **4. Collect all 'seepage' from farmyard manure and high-level slatted buildings as this is classed as 'slurry' under the 2003 Regulations. **5. Prepare and implement a Manure Management Plan (also known as a Farm Waste Management Plan). This is mandatory if specified by SEPA in the terms of a Notice served under the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 2003. *6. (i) Incorporate livestock manures within two weeks after spreading on stubbles. (ii) In areas prone to wind erosion, incorporation of livestock manures can be delayed. [GAEC measure 8] 7. Follow "The 4 Point Plan", which offers guidance on how to:
8. Consult SEPA if you are planning to use a waste treatment plant on your farm as it may require a consent, authorisation or permit to be sought. 9. Keep clean water and dirty water separate. 10. Minimise unroofed collection yards, feed passages etc. 11. Repair or replace roof gutters and downpipes that are broken or missing. 12. Regularly check effluent tanks, slurry tanks and slatted tanks to avoid overflow. 13. Ensure proper maintenance and repair of all slurry storage tanks, pipework and valves. 14. Be a 'good neighbour' and:
15.Locate any field heap of farmyard manure:
16. Spread livestock slurries and manures only when field and weather conditions are suitable to prevent water pollution. 17. Ensure that any agricultural contractor or company employed by you to spread farm manures and slurries on your land is suitably trained and competent to do so. Don'ts **1. Don't allow effluent to escape from middens, byres, high-level slatted buildings or roads used by livestock, as this is an offence under the Control of Pollution Act 1974 (as amended). **2. Don't allow dairy washings, parlour or byre drainage, or slurry spilled during handling, to enter clean water drains or watercourses. **3. Don't site any part of a slurry storage tank within 10m of any inland or coastal waters. 4. Don't store slurry or semi-solid manure in middens. 5. Don't forget that slurries and manures are a valuable resource and, if properly utilised, will save you money as well as protecting the environment. 6. Don't spread livestock slurries:
7. Don't cause direct and indirect entry of livestock slurry into the drainage system, especially with soil injection into fields with gravel backfilled drains. 8. Don't mix slurry with silage effluent in confined spaces, as dangerous fumes can be fatal. 9. Don't enter a tank unless all recommended safety procedures have been followed. 10. Don't spread when fields have been pipe or mole drained, or subsoiled over existing drains within the last 12 months. 11. Don't apply manures or slurries to any statutory conservation sites or other areas with a conservation, archaeological or historic value without prior notification to Scottish Natural Heritage (SNH) or Historic Scotland as appropriate. 12. Don't build a woodchip corral without carrying out a detailed assessment of pollution risks to surface and ground waters. Consult with SEPA about the site selection. |
Introduction
4.1 Livestock slurries and farmyard manure ("FYM") are valuable sources of organic matter and major nutrients such as nitrogen (N), phosphorus (P), potassium (K) and sulphur. They also contain magnesium and trace elements. Taking account of these nutrients can often result in considerable savings in inorganic fertiliser use. However, nutrients can be lost from manures and slurries during storage and spreading, posing a water pollution risk. Very rapid and severe oxygen depletion of the water can result, leading to fish and invertebrate mortalities for many miles downstream. Manure and slurry can also be associated with the microbiological contamination of inland and coastal waters and groundwater, potentially affecting compliance with environmental quality standards specified in EC Directives.
What legislation must be complied with?
4.2 The entry of slurry, manure or effluent from middens, byres, high-level slatted buildings or roads used by livestock to a watercourse or field tile is an offence under environmental legislation.
4.3 Farms at which slurry is produced are subject to the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 2003 ("the SSAFO Regulations"). For new, substantially enlarged or substantially reconstructed slurry storage systems, the Regulations require the provision of six months storage capacity for the farm as a whole. SEPA may accept a lesser period of storage but only where it can be demonstrated by a Farm Waste Management Plan ("FWMP") that this will not cause harm to the environment nor lead to a significant risk of pollution of the water environment.
4.4 Farmers operating within areas that have been designated as a Nitrate Vulnerable Zone ("NVZ") must also implement the mandatory measures contained in Section 6 as well as adhering to the requirements of the Action Programme Regulations relevant to their area. Further details are given in Guidelines for Farmers in NVZs produced by SEERAD in 2003. A summary of the statutory requirements of the Action Programme Regulations if you are farming within an NVZ is as follows:
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prepare and implement a fertiliser and manure plan
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ensure that adequate records are kept for land within NVZs relating to livestock numbers and use of inorganic fertiliser and organic manures
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organic manure application must not result in the nitrogen applied exceeding permitted rates in the NVZ Action Programme Regulations
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inorganic nitrogen fertilisers must not be applied during the closed periods specified in the NVZ Action Programme Regulations
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slurry or poultry manures must not be applied to sandy or shallow soils during the closed periods specified in the NVZ Action Programme Regulations
Fertiliser and Manure Plan
4.5 The Fertiliser and Manure Plan required for all farms in NVZs should:
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establish the quantities of livestock manures produced on the farm
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demonstrate sufficient storage capacity and land available for spreading
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contain an assessment of the nitrogen quantity available to grass and crops following application of organic manures
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contain an assessment of crop and grass requirement for nitrogen fertiliser in each field taking account of nitrogen supply from soil organic matter, crop residues and organic manures
4.6 A permit is required from SEPA for the operation of certain intensive pig and poultry installations to control the potential impact of manures and slurries on the environment. Further details are given in Section 13 of this code.
4.7 Establish from the local authority whether an Environmental Impact Assessment ("EIA") is required. If storageof manure on uncultivated or semi natural land is intended, which could lead to significant effects on the environment, an application under the Environmental Impact Assessment (Uncultivated Land and Semi-Natural Areas) (Scotland) Regulations 2002 may be required.
4.8 There are important health and safety issues and you should include the handling, storage and application of farm manures within the farm's Control of Substances Hazardous to Health ("COSHH") assessments. Further guidance is available in Health and Safety Executive publications.
What can you do to prevent pollution?
4.9 To address all of the pollution risks associated with manures, slurries and grazing animals, particularly in bathing water catchments, it is essential to follow the guidance in "The 4 Point Plan", the individual components of which are as follows:
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minimising dirty water around the steading
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better nutrient use
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a risk assessment for manure and slurry
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managing water margins
4.10 Following "The 4 Point Plan" will also help to maximise the nutrient value of manures and slurries. Guidance on adhering to the Plan can be obtained from the existing agricultural advisory network in Scotland. Copies of the Plan are available free from SEERAD Area Offices (listed in Annex A).
4.11 Pollution risk can occur at all stages of handling livestock slurry and manures, including collection, storage, transport and land application. At all times, the quantity of material requiring to be collected, stored and applied to land should be minimised. The risk of pollution occurring is usually higher with liquid systems than with solid based systems. Minimise the unroofed steading areas to which stock have access, or alternatively roof these areas where practical. Always separate uncontaminated water (for example, roof water) from dirty water and prevent it from entering the handling system. Repair or replace roof gutters and downpipes that are broken or missing.
4.12 Many farms have existing drainage systems to allow roofwater and run-off from roads and yards to discharge to local watercourses. This drainage can carry silt, chemicals, Faecal Indicator Organisms [FIOs] and other materials, thereby causing a risk of pollution. It may be possible to make use of properly sited and designed ponds to deal with this currently uncollected drainage and minimise pollution risks. SEPA should be consulted for further information.
Manure Management Plans (also known as Farm Waste Management Plans)
4.13 Farmers should draw up a Manure Management Plan (known for the purposes of the SSAFO Regulations as a Farm Waste Management Plan (FWMP)) and, if necessary, seek professional advice. In any event, there is a requirement under the SSAFO Regulations for all storage facilities to have six months slurry storage capacity, unless it can be demonstrated to SEPA's satisfaction through a detailed FWMP that six months is not necessary. It is recommended that details of all field applications be recorded including the site, rate, total volume and date of application. A Manure Management Plan or FWMP will establish the quantities of slurry and manure produced and safe methods of collection, storage and land spreading, and should include the following steps:
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establish the slurry and manure production schedule
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prepare a land availability schedule and field risk assessment for land application
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match slurry and manure production to land availability schedule
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calculate size of store required
4.14 There can be financial and practical benefits as well as environmental ones in having adequate storage capacity on farms. Slurries and manures can be stored until growing crops are best able to utilise the available nutrients and when soil conditions are most suitable. In this way the risk of run-off and leaching will be minimised.
Types of slurry, manure and effluent
4.15 Livestock slurry and manure are classified by the type of stock that produces it and the physical characteristic of the slurry and manure. Manures can be in the form of solids, semi-solids or liquids. Solid manures can be stacked but can produce effluent due to drainage and the leaching effect of rainfall. Liquids are materials, which flow readily, and semi-solid manures can be difficult to stack and tend to slump.
4.16 In the SSAFO Regulations, "slurry" is defined as:
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excreta, including any liquid fraction, produced by livestock whilst in a yard or building
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a mixture consisting wholly of or containing such excreta, bedding, feed residues, rainwater and washings from a building or yard used by livestock, dungsteads or middens, high-level slatted buildings and weeping wall structures, or any combination of these, provided such excreta is present
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of a consistency that allows it to be pumped or discharged by gravity at any stage in the handling process
4.17 It is important to understand this definition as it determines the regulatory requirements within the Regulations. For example, solid manure stores, dungsteads and middens are excluded but the liquid draining from these, as well as drainage from high level slatted buildings and weeping wall structures, is defined as slurry and must be collected and handled in accordance with the SSAFO Regulations.
Animal housing
4.18 The type of livestock housing system affects the physical characteristics of the manure or slurry. For instance, solid FYM is produced by the addition of straw or use of other bedding materials. Slurry is produced where housing and feeding systems use little or no additional bedding materials, and where excreta is scraped from solid floors or trodden into slats. Some systems such as straw courts use a separate scraped feed area to reduce straw use and these produce a combination of both FYM and slurry. All liquids produced from where livestock are housed must be drained or scraped to a suitable collection system. These liquids include drainage from passages and aprons used by livestock or where slurry is scraped, contaminated wash water from milking parlours and washdown (dairy, pig and poultry buildings), and drainage from traditional byres.
4.19 Drainage from high-level slatted buildings is included within the SSAFO Regulations definition of slurry, whereas the solid manure itself is not. Such drainage is therefore covered by the Regulations and must be suitably collected and stored prior to land spreading.
Woodchip corrals and stand-off pads
4.20 Woodchip corrals and stand-off pads are outside, uncovered, enclosures using fist-sized woodchips as a bedding layer. They are typically used to over winter beef cattle and, occasionally, dairy cows. Farmers are using such systems as an alternative to out-wintering and housing. Once in place, woodchip corrals and stand-off pads may be used to take cattle off pasture during wet weather so as to prevent damage to soil by treading.
4.21 Woodchip corrals are unsealed systems and are intended to drain freely to the soil / subsoil. As there is no intention to collect the drainage at the base of the woodchips, they are considered to have significant potential to cause pollution. Whether they do or not is dependent on where they are sited, their design, the prevailing weather and how they are managed. The principal pollution risks are to groundwater and local watercourses. Pollution of rivers occurs most commonly where field drains have been left beneath the corral or where run-off occurs due to build up of effluent in the corral itself. On free-draining sites, pollution of groundwater is of particular concern and the impacts are hidden from view.
4.22 Stand-off pads are sealed systems which rely on proactive management of the effluent produced at the base of the woodchip layer. The potential for discharges to reach groundwater should therefore be much lower than for woodchip corrals. In general, it is considered better that stand-off pads be sited on impermeable soils which can act as a barrier to the escape of effluent from the system. It is necessary to ensure effluent collection drains are installed for stand-off pads together with a tank that meets the requirements of the SSAFO Regulations.
4.23 Feeding arrangements for corrals and stand-off pads vary considerably. Given that feeding areas will be associated with most dunging and urinating by the animals, consideration will need to be given to the management of slurry and dirty water at these locations. Concrete yards will normally require a slurry storage facility that conforms with the SSAFO Regulations. For stand-off pads, this may provide an opportunity to collect the effluent from the base of the system.
4.24 Based on the above, stand-off pads are the preferred design in terms of specifically addressing pollution risks. SEPA may use a variety of legislation to prevent pollution from corrals or stand-off pads. This will depend on the risks at each particular location. The risks to groundwater may require existing woodchip corrals to be converted to stand-off pads and for advice to be sought on how best to do so.
4.25 Neither system should be constructed without carrying out a detailed assessment of pollution risks to surface and ground waters. Consultation with SEPA is advisable in most circumstances.
Livestock yards
4.26 Yards used for the collection and dispersal of livestock, together with feed areas, will become contaminated with slurry, bedding and feed residues. Whether these areas are roofed or unroofed, they must be designed so that all contaminated drainage is collected and contained. It is important that clean drainage from roofs and aprons is not allowed to enter the slurry collection system in order to reduce the volume of slurry to be applied to land. Avoid large unroofed areas and keep rainwater out of dirty areas.
Middens
4.27 Drainage from middens is included within the SSAFO Regulations definition of slurry, whereas the solid manure itself is not. Such drainage must be suitably collected and stored prior to land spreading. Escape of effluent from middens and aidle tanks to watercourses and field tiles is an offence under SSAFO. Slurry or semi-solid manure should not be stored in middens.
Feed storage and preparation areas
4.28 Drainage from feed areas is likely to be highly polluted and must not be discharged to a watercourse. Although this material does not normally contain manure or slurry, it can add to the volume of manure and slurry collected.
4.29 Unroofed areas pose a high risk of pollution during periods of rainfall. Where it is not feasible to direct and collect effluents into existing storage facilities, a separate tank should be provided. Tanks must always be appropriately sized, constructed and installed with regard to the type of effluent being stored.
Parlours and dairies
4.30 The drainage from parlour standings and the parlour pit must be collected and contained. Washings from these areas will be contaminated with milk residues, livestock excreta and cleaning chemicals. If included in the slurry system, the volumes produced must be taken into account in any calculation of the slurry storage capacity and land availability for spreading.
4.31 There can be occasions when it becomes necessary to dispose of milk on the farm. This can occur when bad weather prevents uplifting of milk or if milk becomes contaminated (antibiotics, chemicals, blood etc) or colostrum has to be disposed of from newly calved cows. Ideally, waste milk may be fed to livestock but it is advisable to first consult a veterinary surgeon, especially where the milk is contaminated or where large quantities are involved. Similar precautions should be taken before spreading contaminated milk on grazing land.
4.32 Milk is a highly polluting substance and should never be allowed to enter a watercourse. Waste milk should be diluted with water or slurry before disposing of to agricultural land. Dairy washings should be collected and stored in suitable stores. As the act of mixing milk and slurry may give rise to lethal or explosive gases, only small quantities of waste milk should be disposed of to the slurry system.
4.33 Milk should not be applied on sites with a high run-off risk. On suitable sites, the milk should be diluted 1:1 with water before application or mixed with slurry. The application rate should not exceed 50m3/ha (4500 gallons/acre) of diluted milk. The applications should be carried out in accordance with the principles set out later in this section.
Slurry reception tanks and channels
4.34 Where possible, keep the distance between the animal housing and slurry storage to a minimum.
4.35 Slurry can be transferred from where it is produced to the main storage tank either directly (via slats to storage tank) or via a suitable reception tank or channel from where it can be pumped or flow by gravity into the main tank. The system used will depend on the site, relative levels, type of slurry and storage used.
4.36 The SSAFO Regulations require that a reception tank is large enough to hold the maximum volume that could be produced over a 2-day period. This should include allowance for any washings, dirty water run-off and rainfall. Good management is essential to prevent overflow. To reduce the risk of overflow and ease operational management, a larger tank may be better. Tanks should be sited to minimise pollution risk in the event of overflow: they must be sited more than 10m from any inland or coastal waters and should be at least 50m from any spring, well or borehole.
4.37 Where slurry is scraped directly to the store, open areas of apron which can be contaminated should be minimised.
4.38 A freeboard of at least 300 mm must be maintained in all tanks (below and above ground). The freeboard on earth-banked lagoons/compounds must be at least 750 mm. Slurry should never be allowed to rise to rim levels as this is in breach of the SSAFO Regulations.
Choosing a storage facility
4.39 The type of storage facility required will depend on:
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type and volume of material to be stored
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topography, ground conditions and site area
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choice of constructional type
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cost
4.40 Storage capacity is determined by ensuring those periods of the year which are unsuitable for spreading are avoided. This should normally not be less than six months as required by the SSAFO Regulations.
4.41 The calculation of the minimum size for any slurry storage facility must include provision for:
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all livestock excreta produced during housed periods or at other times of the year (e.g. for dairy cattle)
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all other effluents directed to the system including dairy wash water, contaminated yard areas and any silage or draff effluent
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rainfall and freeboard on the storage tank(s)
4.42 Storage tanks can be constructed below or above ground. Below ground tanks may be open topped such as lagoons, above ground slurry stores or within a building and slatted.
4.43 Open-topped tanks and lagoons installed below ground must have appropriate protection to prevent access and risk of drowning in accordance with Health and Safety requirements. A childproof safety fence to a suitable height with lockable access gates will be necessary. Safe locations should be installed for access to agitate and remove slurry from the store. Permanent pipes can be installed to allow tanker emptying from outwith safety fencing and reduce risk to operators.
4.44 All slurry stores and reception tanks constructed after 1 September 1991 must be constructed and installed to the appropriate standard as referred to in the SSAFO Regulations. SEPA also has powers to ensure that all existing structures conform if they pose a significant risk of pollution or if they otherwise fail to comply with the requirements of the Regulations. It is strongly recommended that SEPA be consulted at an early stage when planning a system to establish any specific requirements. SEPA must be informed at least 28 days prior to the use of a new slurry store whether above or below ground. A Building Warrant Application must be made. The Planning Authority should be consulted in all cases to verify any specific requirements.
Design
4.45 The design and installation must comply with Schedule 2 of the SSAFO Regulations and to the constructional standards described by BS 5502 on Buildings and Structures for Agriculture (Part 50).
4.46 The base and walls of the slurry storage tank, any effluent tank, channels and reception pits, and the walls of any pipes must be capable of withstanding characteristic loads, shall be protected against corrosion and, with proper maintenance, must satisfy the requirements of the SSAFO Regulations.
4.47 Where a channel or reception pit connects by pipe to another container of lesser capacity which can overflow, two valves must be fitted in the pipe to minimise the risk of overflow should a blockage occur preventing closure of one valve. These valves must be kept locked when not in use and should be spaced at least 1m apart to minimise the risk of both valves becoming jammed open at the same time. Valves should be checked regularly and maintained in full working order. All channels and reception pits must be covered or fenced. Access openings for pumps and pipes should be guarded to prevent accidents. Covers must be designed to carry the loads to which they will be subjected. Access covers which can be easily opened or lifted should be kept locked.
Siting the storage facility
4.48 In selecting the site, consider all of the following:
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ensuring that the risk of pollution is minimised if slurry or effluent accidentally escape, including the risk to public and private water supply sources in the locality
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locating the storage facility at least 10m away from any inland or coastal water
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locating the facility in close proximity to the point of production of the manure or slurry
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making best use of relative ground levels for loading and unloading the store
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providing good access for handling equipment
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ensuring the safety of personnel and stock
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avoiding siting on 'made-up' ground
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causing a potential odour nuisance
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minimising the visual impact, including considering the potential for screening
Construction
4.49 To satisfy the standards set by the SSAFO Regulations, a high standard of workmanship is required. The contractor must be experienced in the use of concrete and other materials used in the construction process. The relevant design requirements are listed in sections BS 5502, BS 8007 and BS 8110. When considering substantially enlarging or reconstructing storage tanks, the resulting structure must satisfy the standards set by the SSAFO Regulations. It will therefore be essential to seek professional guidance prior to making a commitment to any work. In some instances, upgrading may be impractical due to the lower design criteria used in the original structure. SEPA may allow for substantial reconstruction of an exempt structure where the risk of pollution will be reduced. This is a matter for SEPA to determine on a site to site basis.
Temporary field heaps
4.50 Any temporary field heap of farmyard manure must be at least 10m away from any field drain or watercourse and at least 50m from any spring, well or borehole. Field heaps should not be sited on hardstandings, tarmac or disused roads.
System management
4.51 The person having custody or control of the management of any facility for the handling and storage of livestock manures and slurries must ensure:
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good operational standards are adopted (e.g. maintaining required freeboard)
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maintenance is carried out to retain the minimum performance requirements for at least 20 years (or the operational life of the store) as specified in the SSAFO Regulations
Maintenance
4.52 Practical and safe methods must be employed to allow all facilities to be inspected regularly for any signs of failure e.g. damage to surface coatings on steel and concrete structures, damage and failure of store walls and floor, leakage in pipes, connections and fittings. Note that harmful gases are generated at slurry stores and these have been responsible for both human and animal deaths in Scotland. It is essential that controls for pumps be situated so that they can be started and stopped without the operator entering buildings which may contain harmful gases. Stock or humans must not access buildings until appropriate actions have been taken to prevent risk of harmful effects. Such buildings should be well ventilated before entering. If it is absolutely essential to enter an area which may be contaminated by gas, operators should wear either an approved self-contained or airline breathing apparatus. Full training must be given in the use of this equipment before it is used. A notice should be erected at slurry stores warning of the danger of poisonous gas and that stores should not be entered without taking the recommended precautions. The following is a suggested procedure which should be carried out at least at annual intervals:
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clean any internal tank walls and floors. Be aware of the danger of toxic gases - use breathing equipment
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inspect walls and floors for cracking and surface erosion. Only the exposed external surfaces of slurry tanks should be inspected (see above)
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inspect all drains and channels for damage or deterioration
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check that all channels and pipes are free flowing
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check all safety arrangements
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list all repairs required and prepare a timetable to execute the work. This may involve diverting materials to other storage or providing temporary arrangements
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SEPA must be consulted with regard to any proposed substantial enlargement or reconstruction
Operational management
4.53 The following operational actions should be carried out with all systems:
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check tank storage levels at a frequency appropriate to its capacity, especially those receiving drainage from contaminated yards or uncovered silos where rainfall can fill the tank very quickly
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carry out regular spot checks at points where leakage may occur, such as joints in pipework connected to pumps
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check that external drains are running freely and are not contaminated
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check automatic pumping systems and carry out routine maintenance. Pumping systems which can be removed from a tank for inspection are most convenient and essential in situations where poisonous gas may be present
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check freeboard in tanks particularly after periods of heavy rain
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check parts of systems which may freeze during cold spells
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check tanks for the separation of contents which may lead to the build up of solids and loss of storage capacity. Above ground tanks require regular attention where surface drying can cause crust formation
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check all safety hatches after handling operations. Empty and inspect all tanks (taking appropriate safety measures) prior to animal housing
4.54 Persons having custody or control of slurry are responsible for informing those individuals who act on their behalf of the precautions to be taken to avoid overflow or spillage and the consequences of causing pollution.
4.55 SEPA must be contacted in the event of a pollution incident on its 24 hour pollution report line Tel. 0800 807060. All farm staff must be aware of the action to take in any emergency.
4.56 Appropriate training in the proper use of facilities and associated equipment is essential. The dangers likely to be encountered from moving parts on equipment and the presence of poisonous gases particularly from tanks within buildings during mixing of slurry must be emphasised. In slatted courts, livestock housed over the slats should be removed and the building well ventilated prior to and during slurry agitation. If possible, within buildings avoid the storage of silage effluent and slurry in the same tank at the same time as this can increase the risk of poisonous gases.
Land application and utilisation of livestock manures and slurries
4.57 Livestock manures and slurries are a valuable asset and should be applied to agricultural land in accordance with the principles set out in this section. The surface application rate should never exceed 50m3/ha (4500 gallons/acre) although normal application rates should seldom exceed 30m3/ha (2,700 gallons/acre) and any repeat application should not be made within three weeks. All applications should take into account the soil conditions and the amount of rain forecast so as to minimise the risk of run off and entry to a field drainage system.
4.58 Although the risk of causing pollution by spreading solid manures is lower than for slurries, surface run-off can still occur if rain falls shortly after an application. Surface application rates for solid manures should never exceed 50 tonnes/ha (20 tons/acre), and should be lower where soil and weather conditions are likely to increase the risks of pollution. Poultry manures should not be spread at rates exceeding 5-15 tonnes/ha (2-6 tons/acre) depending on nitrogen content.
4.59 The amount and frequency of applications should not be more than the nutrient requirements of the growing crop and take account of time of application and the residual value in the soil from the previous application.
4.60 Table 1 shows the maximum surface application rates which can be applied when soil and weather conditions are suitable to avoid run-off and minimise pollution. The rate applied in the normal course of slurry spreading in suitable conditions is generally between 25-30m 3/ha (2,200-2,700 gallons/acre).
| Table 1: Surface application rates in optimum conditions* |
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| Material |
Maximum application rate* |
Normal application rates |
| Slurry |
50 m 3/ha |
25-30m 3/ha |
| Manure (FYM) |
50 tonnes/ha |
30-50 tonnes/ha |
| Poultry Manure |
15 tonnes/ha |
5 to 15 tonnes/ha |
| Contaminated Water |
50 m 3/ha |
25-30m 3/ha |
| *Lower rates should be used in the event of inappropriate or difficult conditions and may also be required to ensure that crop nutrient requirements are not exceeded. |
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4.61 Repeat applications should not be made for a period of at least three weeks. This is a necessary requirement to allow the crop to utilise the available nutrients. Soil microbes breakdown and assist in incorporation of slurry and manure. More frequent applications would smother herbage and saturate the soil, increasing the chances of leaching and run-off.
4.62 Where there is insufficient suitable land for application on the farm, alternative options, such as waste treatment or the use of other suitable land close by, will require to be considered. Specific regulations may apply if slurry or FYM is to be transported from one farm to another.
Nutrient content
4.63 Livestock slurries and manures are a valuable resource. If correctly applied, they can save you money as well as protecting the environment.
4.64 Manure nutrient composition is affected by a number of factors including the type and age of livestock; livestock diet; method of manure handling and storage; extent of slurry dilution; and the type and amount of litter in FYM. Typical amounts of nutrients which are in a readily available form (i.e. can be taken up by crops and grass during the growing season following application) are given in Table 2 below.
| Table 2: Typical values of total NPK and available PK contained in slurry and manure |
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| Potential total nutrients |
Potential available nutrients |
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| % dry matter |
N |
P2O5 |
K2O |
P2O5 |
K2O |
|
| Slurry (kg/m3) |
||||||
| Dairy cattle |
10 |
4 |
2.3 |
4.3 |
1.2 |
3.6 |
| Young cattle 250 kg |
10 |
5 |
2.3 |
4.3 |
1.2 |
3.6 |
| Finishing cattle |
10 |
3.5 |
2 |
3.8 |
1 |
3 |
| Pigs |
10 |
6 |
4 |
3 |
2 |
2.5 |
| Manure (kg/tonne) |
||||||
| Cattle (fresh) |
25 |
5.5 |
3.5 |
8 |
2 |
5 |
| Pig (fresh) |
25 |
7 |
7 |
6 |
4 |
4 |
| Poultry Manure (kg/tonne) |
||||||
| Broiler/layer litter |
70 |
24 |
22 |
14 |
11 |
10 |
| Deep litter |
70 |
17 |
18 |
13 |
9 |
10 |
| Battery (fresh) |
30 |
15 |
14 |
7 |
7 |
5 |
| Note - for the purposes of this information P2O5 and K2O are used as units to describe |
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4.65 Further gradual releases of nitrogen and phosphorus from manures will occur in the years following application. A typical application of slurry in the spring will also usually supply sufficient sulphur for one cut of silage.
4.66 The available nutrient figures in the table indicate the nutrient content available to the crop grown following application. The N values in the table are a guide to the amount of N available for crop uptake when the manure or slurry is applied in the spring. Less N will be available if the manure or slurry is applied in the autumn or winter. The availability of N is variable and is affected by the rate and timing of application, the weather after spreading and the speed of incorporation into the soil.
4.67 The nutrient value of manure or slurry should be estimated from published data or supported by representative sampling and analysis of the manures and slurries from time to time. Dilution from rainfall, washings and bedding materials must be taken into account. The Fertiliser Series Technical Notes, produced by SAC, provide detailed information on the nutrient requirements of crops and grass, as well as the fertilising value of different types of manures and slurries and chemical fertilisers.
4.68 Livestock manures and slurries should be applied in amounts such that the nutrient content, particularly of N and P, can be utilised by growing crops. Excessive application rates can result in high N and P concentrations in the soil and an increased risk of water pollution. Soil analysis for pH, N, P and K should be carried out every five years or so to assess the nutrient needs of the soil.
Pathogenic micro-organisms
4.69 Manures can contain pathogenic micro-organisms (e.g. E. coli O157, Salmonella, Listeria, Campylobacter, Cryptosporidium and Giardia) which may cause food-borne illness. Factors such as the age, diet and management of animals, as well as regional and seasonal influences, affect the number of micro-organisms in manures.
4.70 The management and handling of farm manures, particularly the length of time they are stored, are important factors in the survival of micro-organisms. The method and timing of manure applications to land can affect the length of time that pathogens survive in the soil, and the likelihood of their getting onto food crops. In order to reduce any risks of food-borne illness resulting from the use of farm manures, there is a need for due diligence.
4.71 To reduce the risk of transferring disease to healthy stock, pasture should not be grazed for at least one month after spreading slurry or manure or until all visible signs of the solids have disappeared.
4.72 Pathogenic micro-organisms usually die out over time. The rate at which this happens depends on environmental conditions. In some conditions, they can survive for several months following the spreading of farm manures or deposition during grazing. They may also be present in dirty water, yard runoff and leachates from stored manures.
4.73 Pathogens can be killed either in the manure itself or after application to land. The main factors that will lead to a reduction in numbers are:
-
temperature
-
sunlight
-
soil pH
-
drying
-
time
-
soil microbes
Slurry and manure production schedule
4.74 All sources of manure and slurry should be identified to determine the type, quantity and nutrient content so that a schedule of slurry and manure production can be established. Sources include:
-
livestock excreta and bedding
-
contaminated washings
-
run off and drainage from contaminated aprons
-
silage effluent and feed residues
-
dairy washings and rejected milk
-
all other wastes which may be imported (e.g. sewage sludge, etc.)
"The 4 Point Plan" can help you with this.
Quantity of slurry and manure produced
4.75 Quantities of each type of slurry and manure and the time of production is calculated from current published data relevant to the farming system (see Appendices 1, 2 and 3 at the end of this section).
Prepare a land availability schedule
4.76 An annual schedule for application on available land should be prepared based on the annual cropping programme, land suitability and meteorological data.
Annual cropping programme
4.77 The annual cropping and land use programme determines when land may be available for the application of livestock slurries and manures. Consideration must be given to potential crop nutrient uptake, access periods and other effects of application (e.g. non-grazing periods following application).
Land suitability and field risk assessment
4.78 The land suitability for application of livestock manures and slurries is determined by topography, soil type and conditions as well as land use. A field risk assessment should be completed for each area intended to be used for application (An example is shown in Appendix 4 at the end of this section). All factors outlined below must be considered:
-
the proposed application site must be inspected before work commences to ensure it is in a suitable condition
-
during and after application, frequent inspections must be made to ensure that ponding or run-off is not occurring
-
it is also advisable that all drain outfalls be checked before, during and after application
Proximity of watercourses
4.79 An untreated strip at least 10m wide should be left beside all watercourses, to reduce the risk of direct contamination by run-off. Field dirty water irrigation systems should be operated so that there is no possibility of the spread pattern reaching within 10m of a watercourse. This distance may have to be increased on certain sites to reduce risk e.g. from wind blow or field slope.
Public health concerns
4.80 There are serious public health risks if harmful chemicals and micro-organisms (such as E. coli O157, Cryptosporidium) enter into water supplies. Application sites for livestock manures and slurries in proximity to public water supply sources, either surface or underground, may be restricted by Scottish Water byelaws preventing pollution of the water source. [Contact details for Scottish Water are in Annex C.] Private water supply sources should also be taken into account. An area is also unsuitable for application of livestock slurry and manure if it drains into a water supply channel or aqueduct, or where it lies in close proximity to an enclosed storage tank. Springs, wells and boreholes for drinking should be adequately fenced to prevent faecal contamination from grazing livestock.
Risk of flooding
4.81 Flooding of low-lying fields adjacent to watercourses can occur at certain times of the year. Application to these areas should be avoided when there is a risk of flooding, consideration should be given to previous flood patterns.
Groundwater
4.82 Applications to land can pollute water below the ground. The risk applies to any field where permeable soils directly overlie water-bearing rock formations, especially where there is a high water table or where the underlying rock formation is fissured. Note there are mandatory requirements in nitrate vulnerable zones (see Section 6).
Field drains
4.83 Drainage systems can present a risk of pollution as, under some conditions, liquid slurry can gain direct entry to the drains and from there to watercourses. There is a higher risk if the drainage system has only recently been installed, and in particular when permeable backfill has been used. It is important that all field and storm water drain positions and depth are known, in order to minimise the risks of direct entry of slurry and contaminated water.
4.84 Other recent soil disturbance such as moling or subsoiling also increases the risk of pollution via the drainage system. Slurry and contaminated water should not be applied to any areas where recent disturbance has occurred until the land surface has settled and the risk of direct entry of slurry and/or contaminated water to drains is reduced. An assessment should be made prior to making any land application and operators instructed to avoid the area if it is unsuitable.
4.85 Watercourses which may receive drainage containing slurry or contaminated water must be checked before, during and after any application. All pollution should be reported to SEPA.
Soil conditions
4.86 The quantity of liquid slurry that can be applied to an area without causing surface run-off is dependent on soil type and conditions including structure, moisture content, infiltration rate and surface gradient. As the permeability and infiltration rate of a soil decrease and the surface gradient increases, the risk of surface run off is increased. To minimise this risk, liquid slurry should not be applied at rates greater than the infiltration capacity of the soil and at no time during periods when a soil is waterlogged. This applies to both surface application and soil injection methods. The use of heavy, fully laden tankers in wet conditions increases the risk of soil compaction and damage, which will reduce the infiltration capacity of the soil and increase the potential for run-off.
4.87 Spreading slurries and manures at a time when conditions are not ideal also costs money later, in terms of remedial works to overcome compaction/tracking and the associated crop yield reduction or reseeding requirement.
Meteorological data
4.88 The design of any livestock storage system must take into account rainfall that enters the system and contributes to the volume to be handled. Both 'long term' and 'short term storm' rainfall events should be taken into account, to ensure adequate storage provision. This is to ensure that land application takes place when field conditions are suitable and the risk of pollution from the operation is minimised. Conditions which will minimise pollution risk also minimise field damage.
4.89 Full account should be taken of the weather (particularly prolonged wet weather) prior to any intended application being made and to the consequent field conditions. Effect on the risk assessment should be considered. A field that is normally suitable for slurry application and is a low pollution risk could become unsuitable and a high pollution risk following heavy rainfall.
4.90 Check local weather forecasting information prior to proposed application.
Frozen ground conditions
4.91 The application of liquid and semi-liquid livestock slurries to ground which is frozen to a depth of more than 50mm should be avoided. Ground that is frozen to a greater depth presents a high risk of run-off, especially on slopes. Application should not be carried out if the soil has been frozen for 12 hours or longer in the preceding 24 hours.
Periods of snow
4.92 Liquid and semi-liquid livestock slurries should not be applied to ground with snow cover, as there is a high risk of run-off during the subsequent thaw.
Wind direction and force
4.93 Wind direction and force will dictate days when spreading should be avoided to prevent air pollution from drift and odour affecting residential and other sensitive areas.
Proximity to sensitive habitats and features
4.94 Species-rich grassland, field margins and hedgerows are important habitats that need to be protected from manures and slurries. Buffer strips may act as a nutrient sink and this may reduce their wildlife interest. The effective width of the uncultivated margin will depend on topographical and/or soil characteristics. Farm manures and slurries should not be applied to Sites of Special Scientific Interest (including all National Nature Reserves and sites designated under European legislation) without prior notification to Scottish Natural Heritage (see Annex C for contact details).
4.95 Farmland may also contain sites of archaeological interest, some of which may be protected as Scheduled Ancient Monuments, and all of which are of conservation interest. Advice should be sought from local authority archaeologists and, especially for Scheduled Ancient Monuments, from Historic Scotland (see Annex C for contact details).
Rough grazing land
4.96 Many farms will have areas of rough grazing which may not be suitable for application of livestock manures and slurries. Many of these rough areas provide valuable habitats for wildlife and some have a rich and diverse mix of plants.
4.97 Such areas might include unimproved pasture, moorland, wet grasslands, machair, hay meadows, uncultivated field headlands and mires. Given the possible nature conservation value of such areas and the terms of the Environmental Impact Assessment (Uncultivated Land and Semi-Natural Areas)(Scotland) Regulations 2002 (EIA Regulations), advice should be sought from Scottish Natural Heritage before using them for the application of livestock slurry and manure. Rough gazing land that is of conservation value or is unsuitable for land-spreading equipment, or is considered as 'high risk', should be excluded from the available area.
4.98 Spreading of manures and slurries with the view to introducing intensive production on unimproved land requires an application to SEERAD under the EIA Regulations. The routine spreading of manures and slurries, where no change of land use was planned does not, however, require SEERAD approval under these Regulations.
Sloping ground
4.99 The application of slurry and manure on sloping ground should be carried out with care to prevent the risk of run off entering a watercourse. Also safe-working practices associated with vehicle operation on slopes must be followed at all times. Factors to consider include:
-
presence of watercourse at bottom of slope
-
soil type and condition
-
gradient
-
weather conditions (before, during and after application)
-
application rates
-
buffer areas must be used and sized to reduce risk of run off
-
avoid spreading manure on neighbouring fields if runoff will be a potential source of contamination of growing crops
Proximity of domestic dwellings and public buildings
4.100 Air pollution from livestock manures and slurries must be considered whenever there is a risk of public nuisance caused by odours or a potential risk to public health from harmful organisms. This applies to fixed installations such as slurry stores and middens, as well as to land spreading operations. When spreading, use low trajectory equipment. A 'good neighbour' policy should be adopted at all times.
4.101 Spreading of livestock slurry and manures should not be carried out:
-
close to domestic or public buildings
-
at weekends or public holidays
-
when the wind direction is towards public/residential areas
-
in areas designated for their conservation value
-
during the hours of darkness, unless this is not practical
-
close to public access areas, footpaths, picnic areas
-
on windy days
4.102 Further information on air pollution is given in Section 13.
Overhead electricity lines
4.103 Never spread slurry near or under mains electricity power lines. The conductivity of liquid manure and effluent is very much higher than clean water, and any electrical leakage down a jet of slurry from a tanker sprinkler or irrigator could prove fatal. The direction and strength of the wind and its effect on the spreading pattern will determine the clearance required between the spreading swath and the power line. Consult the local electricity company to establish a safe distance for broadcast spreading. Slurry may be applied near or under electricity wires by methods which do not involve the slurry being ejected into the air, e.g. gravity feed, slurry injection or a similar safe technique where there is no risk of slurry contacting or coming dangerously close to electrical conductors. Care should be taken in moving transfer pipe to avoid the dangers of direct contact with overhead lines.
Matching slurry and manure production pattern to land availability
4.104 The land availability schedule is matched to the slurry and manure production schedule. An account of slurry (and/or manure) collected is compared to that which can be viably spread taking account of all crop, stock and field constraints as outlined above.
Calculate storage capacity required
4.105 Adequate storage capacity is required to cover periods of the year which are unsuitable for spreading or land area which is not immediately available due to cropping and stocking programmes.
4.106 The amounts to be spread, the provisional periods at which spreading can take place and area available for spreading need to be determined.
4.107 Storage capacity requirement is calculated on the balance of slurry being collected versus the slurry able to be applied at periods throughout the year. The minimum storage requirement equates to the maximum accumulation of slurry at any time.
4.108 The store size calculated must include allowance for all rainfall onto the store (and any areas which drain into the storage system) during the storage period.
4.109 The overall storage capacity must enable a viable handling system to be operated and satisfy the requirements of the SSAFO Regulations.
Land application systems
4.110 Popular systems for spreading slurry and effluent are shown below:
-
tankers
-
umbilical feed systems
-
irrigation
-
injection
Tanker systems
4.111 Tanker systems must never be over-filled to avoid risk of spillage during filling, transit and unloading. Closure of valves should be checked after filling and emptying to prevent leakage during travel. The operator must determine and set the application rate taking full account of all the factors identified above.
4.112 The discharge system should produce a low trajectory-spreading pattern which will improve application accuracy, minimise the risk of odour nuisance and losses of ammonia to the environment. Excessive soil compaction by the tanker will be reduced by minimising the payload on each wheel and by fitting larger tyres to spread the load. Avoid spreading when the soil is wet and at risk of being compacted or rutted.
Umbilical systems
4.113 The umbilical system allows pumpable material (slurry and effluents) to be transferred without transport trafficking from the storage site to the field applicator. The system can effectively 'transport' slurry and effluent at high handling rates to a tractor mounted applicator in the field. Application rates can be controlled just as for a tanker by adjusting forward speed and pump flow rate. High handling rates do not mean high application rates. Application rates should be set as for tanker operation and can be as low as required and never higher than rates given in Table 1.
4.114 Effective systems must allow reliable control of slurry flow and transfer to the field via a pipe system which is both robust and reliable. Pipe routing and materials should be selected to reduce risk to watercourses in case of failure.
4.115 Careful planning of the operation is required in order to minimise risk as large volumes can be handled relatively quickly. A risk assessment should be carried out and full account taken of this for land application and for pipe routing from store to field.
4.116 Any water used for flushing should be treated in the same manner as the slurry and manure.
4.117 The system should be used to improve handling efficiency when field and weather conditions are appropriate. It should not be used to gain access to fields for land application when it would be otherwise unsuitable for tankers to operate.
Irrigation
4.118 Irrigation systems (including low rate irrigation systems) require regular checking to ensure automatic movement and speed of mobile irrigators is correct to avoid over-application. Application rate must be selected taking account of field conditions and crop cover. It is difficult and/or often impractical to achieve low enough application rates with static irrigators.
4.119 The responsibility for operation of the system must be given to a competent person who must check the field for signs of over-application, e.g. ponding, run-off, etc. Mobile irrigators must shut off automatically at the end of each run. Any water used for flushing should be treated in the same manner as the slurry and manure. Operators must be aware of potential odour nuisance and take any necessary action to minimise this.
Soil injection
4.120 Injectors can be supplied by tanker or umbilical systems. Soil type and structure, stones, slope and stage of crop growth will often limit the circumstances when and where injection can be successfully carried out. Applications of injected slurry should take account of the soil conditions and N required. Avoid injection into the backfill or infill over drainage systems, the subsoil below root depth, or into very light gravel soils. Work the injector across the slope, rather than up and down.
Use of contractors
4.121 You should only employ agricultural contractors to spread slurry and manure to land if they are competent and appropriately trained, aware of legal requirements and are prepared to follow the guidance in the PEPFAA Code. Always agree beforehand what responsibilities and measures the contractor will need to take to avoid pollution and odour nuisance and provide them with all essential information specific to your site.
Waste treatment
4.122 Normally the practices described in this Section should be sufficient to prevent or at least minimise environmental pollution and waste treatment systems will not be required. On some farms however, slurry handling and storage problems may be eased by separation of the solid and liquid fractions of slurries by using mechanical separators such as screen or belt presses, vibrating screens or centrifuges. However, a waste treatment system (such as constructed reedbeds, aerobic or anaerobic digestion or mechanical separation) may be necessary to deal with specific or severe problems.
4.123 The cost of providing and operating treatment systems can be high. Before deciding if these technologies are cost effective and are a practical solution for your farm, professional and specialist technical advice should be sought and also SEPA consulted as it may require a consent or authorisation.
Appendix 1
Typical values of undiluted slurry or manure produced by house cattle, pigs and poultry (adapted from the NVZ Guidelines)
| Typical volume of slurry/manure produced per day (m 3) |
||
| Cattle (per animal) |
% dry matter |
|
| Dairy cow (650 kg) |
10 |
0.064 |
| Dairy cow (550 kg) |
10 |
0.053 |
| Beef cow (500 kg) |
10 |
0.032 |
| Calf (100 kg) |
10 |
0.007 |
| Store cattle (400 kg) |
10 |
0.026 |
| Finishing cattle (500 kg) |
10 |
0.032 |
| Pigs (per animal) |
||
| Maiden gilt (90-130 kg) |
0.007 |
|
| 1 sow (130-225 kg) & litter |
0.011 |
|
| Weaner (7-18 kg) |
0.001 |
|
| Growers, dry meal (18-35 kg) |
0.002 |
|
| Light cutter, meal fed (35-85 kg) |
0.004 |
|
| Baconers, dry meal fed (35-105 kg) |
0.004 |
|
| Baconers, liquid meal fed at 4:1 (35-105 kg) |
0.007 |
|
| Poultry (per 1,000) |
||
| Laying hens (2,200 kg) |
0.112 |
|
| Broiler places (2,200 kg) |
0.045 |
|
| Broiler breeders (3,400 kg) |
0.167 |
|
| Replacement pullets (1,600 kg) |
0.021 |
|
| Sheep (per animal) |
||
| Adult ewe |
0.004 |
|
| Lamb (kept for 6 months) |
less than 0.001 |
|
Appendix 2
Typical amounts of bedding materail used per animal in livestock housing systems
| Livestock |
Housing system |
Litter used |
Typical amount used in 180 days (kg) |
| Dairy cows |
Cubicles |
Chopped straw |
120 |
| Sawdust, wood wastes |
150 |
||
| Dairy cows |
Loose housing |
Straw |
530 |
| Typical amount used per year (kg) |
|||
| Pigs |
Pens |
Straw |
102 |
| Poultry |
Deep litter |
Wood shavings |
1.0 |
| Broilers |
Deep litter |
Chopped paper |
0.5 (per bird per batch) |
Appendix 3
Quantity of cleaning water used by livestock (litres)
| Livestock type |
Cleaning system |
Range per animal/day |
Typical per animal/day |
| Dairy cows |
Cleaning milking parlour equipment, washing udders etc |
14-22 |
18 |
| With a power hose |
27-45 |
35 |
|
| Range per batch |
Typical per batch |
||
| Pigs |
Cleaning out pens after each batch |
16-24 |
18 |
Appendix 4
Example of a Risk Assessment for Manures and Slurries (RAMS)
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