What can I do in the short term?
MANURE MANAGEMENT
Adopt (batch) storage of solid manures
WHY? FIOs die off during storage, as a result there are fewer microbial pathogens in the spread manure and lower nutrient losses in run off. The readily available N content of stored FYM is lower than in “fresh” FYM due to losses during storage which will lessen nitrate leaching losses and ammonia emissions.
HOW? Store fresh solid manure in separate batches for at least 90 days before land spreading. At present around 30% of FYM and 60% of poultry manure is applied “fresh” to land.
WHAT IS THE EFFECT? Nitrate leaching losses would be reduced because of the lower readily available N content of the manure and associated Nitrous Oxide and Ammonia emissions would be reduced at land spreading. Ammonia emissions would be increased during storage but by a lower amount. The effects on nitrous oxide balances at the farm scale are uncertain.
WHAT IS THE INDICATIVE COST? £1/t of solid manure based on construction of concrete pad / leachate collection facilities and associated areas for vehicle movements. (2011)
Cover solid manure stores with sheeting
WHY? Sheeting heaps provides a physical barrier preventing the release of ammonia from the manure to the air.
HOW? Cover heaps with heavy duty polythene sheet. This method is less appropriate for management systems that involve regular additions of manure to existing heaps. It is most effective when combined with incorporating manure into the soil when spread.
WHAT IS THE EFFECT? A reduction in ammonia emissions as high as 90% from storage when covered with an impermeable sheet, although nitrous oxide emissions are likely to be increased during storage. Overall nitrate losses through leaching and ammonia emissions would be decreased. Effects on balance of nitrous oxide emissions at farm scale are uncertain. Overall manure N use efficiency would be increased and artificial fertiliser N inputs reduced. Phosphate losses would be reduced due to the production of less leachate. Methane emissions would be increased due to the anaerobic conditions under the sheet.
WHAT IS THE INDICATIVE COST? £0.50/t of solid manure based on provision of plastic sheeting and additional management time. (2011)
What can I do in the medium term?
LIVESTOCK MANAGEMENT
Adopt phase feeding of livestock
WHY? Phase feeding allows more precise matching of feed rations to the individual animal’s nutritional requirements. Nutrients are therefore utilised more efficiently and less dietary N and P is excreted. This reduces the N and P content of manures, which reduces the potential for N and P loss.
HOW? Manage livestock in smaller groups on the basis of their feed requirements. Feed each group separately balanced rations matched to their needs.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by up to 5% and direct and indirect nitrous oxide and ammonia emissions reduced by up to 5%. Phosphate losses would be reduced by up to 10% and in the longer term particulate P losses would be reduced.
WHAT IS THE INDICATIVE COST? £0.75 /m3 of slurry based on collars being fitted to sows along with the use of feed dispensers. (2011)
MANURE MANAGEMENT
Increase the capacity of farm slurry (manure) stores to improve timing of slurry applications
WHY? The collection and storage of slurry allows for more flexibility in when you apply it to the land. This should help reduce the occasions where slurry has to be spread when soils or conditions are not right, increasing the risk of surface runoff and nutrient loss, and allow slurry to be spread when the crop can utilise the nutrients.
HOW? The expansion of facilities for collection and storage of slurry will allow for better timing of application. This method is most effective when it is also implemented with applying the slurry with a low level technique (e.g. band spreading or injection) and not applying the slurry to high risk areas.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by 10% and associated nitrous oxide emissions. Ammonia emissions would be increased by a small amount due to an increase in the slurry store surface area. Overall manure N use efficiency would be increased and artificial fertiliser N inputs reduced. Phosphate losses would be reduced by up to 20% through avoiding applications when runoff risks are high. Methane emissions would be increased as a result of longer duration of slurry storage.
WHAT IS THE INDICATIVE COST? £4/m3of slurry based on the construction of additional slurry storage. (2011)
Read more. For more help and advice on slurry and dirty water management please click here, or check out the Soils for Profit project page for further advice
Install covers on slurry stores
WHY? Covering slurry stores reduces ammonia emissions and by diverting rainfall the volume of slurry that is collected and has to be spread is reduced.
HOW? Fit open slurry stores with a cover (these can be either rigid covers fitted with a vent or a floating flexible cover. Ensure that you have planned how to remove the rainfall from the surface of the cover. It is a good idea to then inject or band spread the slurry when applying to the fields to further reduce ammonia emissions.
WHAT IS THE EFFECT? Ammonia emissions from stores have shown to be reduced using rigid store covers by 80%, using plastic sheeting by 60%, and using floating covers by 40%. Ammonia emissions following spreading would be increased due to the higher readily available N content and the higher dry matter content. Nitrate leaching losses would be increased by a small amount. Overall manure N use efficiency would be increased and artificial fertiliser N inputs reduced. Phosphate losses would be reduced where the cover diverts rainfall as there would be a lower volume of slurry to be spread.
WHAT IS THE INDICATIVE COST? £1.10 per m3 of slurry based on the installation of a store cover. (2011)
Minimise the volume of dirty water (and slurry) produced
WHY? Minimising the volume of dirty water produced reduces the volume to be stored and spread. Farms will then be less likely to run out of storage space and be forced to spread dirty water or slurry at times where there is a high risk of runoff.
HOW? Minimise the volume of dirty water produced by: minimising unnecessary dirty yard areas, avoiding excessive use of water when washing down yards, preventing unnecessary mixing with clean water from uncovered clean yards and roofs, or roofing over yard areas and covering dirty water and slurry stores.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by a small (1%) amount and phosphate losses by a small (2%) amount due to the better timing of dirty water and slurry applications through increased storage capacity.
WHAT IS THE INDICATIVE COST? £40/m2of roof, based on additional roofing over dirty concrete areas and diversion of clean water. (2011)
Read more. For more help and advice on slurry and dirty water management please click here, or check out the Soils for Profit project page for further advice
Adopt batch storage of slurry
WHY? FIOs (manure borne pollutants) die off during the storage of slurry. Adding fresh slurry to stores reinoculates the slurry with viable microorganisms and so the levels do not reduce. By batch storing the slurry for at least 90 days the risk of these pollutants entering water bodies via surface runoff is minimised.
HOW? Store slurry in batches for at least 90 days before land spreading, do not add any additional slurry to the store in this time.
WHAT ARE THE EFFECTS? Ammonia emissions would be increased by a small amount because of the greater surface area of the slurry. FIO loss risks to surface water would be reduced by up to 90% and the BOD losses by up to 50% from managed slurry.
WHAT IS THE INDICATIVE COST? £4 /m3of slurry based on the construction of additional slurry storage. (2011)
Compost solid manure
WHY? As part of the composting process the manure is “sanitised” and the readily available N content is reduced, lowering the risk of manure borne pollutants and nitrate losses when the composted material is spread to land.
HOW? Encourage the breakdown of solid manure by active composting. Turn the solid manure windrow twice in the first 7 days of composting to facilitate aeration and the development of high temperatures within the windrow.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced as a result of the lower readily available N content of the manure and the lower amounts of total N in FYM and poultry manure. At land spreading nitrous oxide and ammonia losses would also be reduced. Ammonia emissions would be increased during storage but by a lower amount. Effects on the nitrous oxide balance at the farm scale are uncertain.
WHAT IS THE INDICATIVE COST? £2.60 / tonne of solid manure based on the turning of FYM windrows twice using a tractor and front end loader. (2011)
Read more. For more information on the benefits of compost click here
Use liquid / solid manure separation techniques
WHY? Separating the solids from slurry means that the two different materials can be handled separately. This means that there is greater flexibility in manure management and application timing. This can be a useful method in helping farmers comply with N max limits in NVZ areas.
HOW? The use of a separator to remove the suspended solids from the slurry can result typically in a 5-10% reduction in the amount of pig slurry that needs to be stored.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by a small (2%) amount as there is less slurry to be handled and as such it is possible to get greater flexibility in application timing. The overall effect on ammonia and nitrous oxide emissions is uncertain. Phosphate losses are likely to be reduced by a small amount due to improved logistics of manure management.
WHAT IS THE INDICATIVE COST? £2-4 per m3 of slurry based on the cost of purchasing a slurry separator and a concrete pad to store the solids. (2011)
Store solid manure heaps on an impermeable base and collect leachate
WHY? The impermeable base and leachate collection prevents the direct loss of pollutants in surface runoff and drainflow. If manure heaps are stored directly on the soil surface leachate from the heaps will seep into the soil and / or flow over the soil surface in response to rainfall. Storage on an impermeable base will prevent seepage and accumulation of nutrients in the soil below the heap and will reduce soil compaction from farm machinery forming and spreading field heaps.
HOW? This method is of most benefit on farms with medium or heavy soil. Construct a concrete pad on which to store the heap. The leachate collected can be spread at a later date when soil conditions are suitable and the nutrients can be utilised by crops or be added back into the heap or into a slurry store.
WHAT ARE THE EFFECTS? A small (5%) reduction in nitrate leaching losses and indirect nitrous oxide emissions. Ammonia emissions would be increased as a result of conserved N in recycled leachate. Overall manure N use efficiency would be increased and artificial fertiliser N inputs reduced. Phosphate losses would be reduced by a small (2%) amount.
WHAT IS THE INDICATIVE COST? £1/t of solid manure based on construction of a concrete pad and leachate collection facilities, and areas for vehicle movement. (2011)
Transport manure to neighbouring farms
WHY? Where there is an excess of manures (and therefore of nutrients) manures can be exported to neighbouring farmland that may have spare livestock manure N capacity. This allows exporting farms to balance nutrient inputs with the capacity of the crops to use them.
HOW? This method will be most useful on farms in NVZs where livestock manure N loadings exceed 170kg total N per ha each year. It will be most easy to implement when receiving farm holdings are in close proximity.
WHAT ARE THE EFFECTS? A reduction in nitrate leaching losses on the exporting farm and increased (to a lesser extent) on the receiving farm with capacity. Ammonia and nitrous oxide emissions and phosphate losses would also be reduced on the exporting farm.
WHAT IS THE INDICATIVE COST? £5 / m3of slurry; £4/t of solid manure based on the need to transport manure over 5km. (2011)
FARM INFRASTRUCTURE
Establish tree shelter belts around livestock housing and slurry storage facilities
WHY? The tree shelter belt will disrupt air flows around the building or slurry storage facility reducing ammonia emission rates and will directly recapture a proportion of the emitted ammonia. The trees planted will also recapture a proportion of the emitted ammonia.
HOW? Plant tree shelter belts around livestock housing and slurry storage facilities. The effectiveness of the method in reducing ammonia emissions will depend on the height and canopy density of the shelter belt and environmental conditions. A shelter belt of sufficient height to be effective will take a number of years to establish.
WHAT ARE THE EFFECTS? Ammonia emissions could be reduced by up to 10%.
WHAT IS THE INDICATIVE COST? £800 for pig farms based on the establishment of a 30m deep shelter belt around the perimeter of the livestock building / slurry store over 20 years. (2011)
What can I do in the long term?
FERTILISER MANAGEMENT
Reduce dietary N and P intakes
WHY? Avoiding excess dietary N and P in the diet and / or making dietary N and P more available allows nutrient concentrations in the diet to be reduced without affecting animal performance. This will mean that the amount of N and P excreted either directly to fields or via handled manures is reduced.
HOW? Adjust the composition of livestock diets to reduce the total intake of N and P per unit of production. This may be achieved by restricting diets to recommended levels of N and P, or by changing the composition of the diet to increase the proportion of dietary N and P utilised by the animal. Benefits are likely to be greatest on dairy, pig and poultry units.
WHAT ARE THE EFFECTS? Nitrate leaching losses, nitrous oxide and ammonia emissions would be reduced by up to 10%. Phosphate losses would be reduced by up to 10% and in the longer term particulate P losses would be reduced.
WHAT IS THE INDICATIVE COST? £4,000 per farm based on the farm typology used in this study, calculated from additional feed and management inputs to avoid excess. (2011)
LIVESTOCK MANAGEMENT
Reduce overall stocking rates on livestock farms
WHY? Reducing the stocking rate reduces the amount of nutrients and manure borne pollutants in manures and slurries. Associated fertiliser N inputs and poaching risks would be reduced.
HOW? Reduce the total number of livestock on the farm. A smaller number of animals will produce less manure which would ease pressure on manure storage capacity and provide greater flexibility in application timing.
WHAT ARE THE EFFECTS? Nitrate leaching losses, nitrous oxide and ammonia emissions would be reduced by up to 20%, and phosphate losses reduced by 30%. Manure borne pollutants, methane, and carbon dioxide emissions could all be reduced by up to 20%.
WHAT IS THE INDICATIVE COST? Based on a loss in gross margin through a 20% reduction in livestock numbers, on the farm type used in the study a loss of £33,000 per farm. (2011)
MANURE MANAGEMENT
Frequent removal of slurry from beneath slatted storage in pig housing
WHY? Ammonia emissions from slatted floor pig housing occur from manure deposited on slat surfaces and slurry in the below slatted floor storage area. Frequent removal of this will reduce ammonia emissions from housing.
HOW? Farms with slatted floor pig housing could all potentially apply this method. Remove slurry completely twice per week to an outdoor store. Emissions can be further reduced by using a cover on the outdor store. There may be difficulties retro fitting existing pig housing.
WHAT ARE THE EFFECTS? Methane emissions from pig housing would be reduced by up to 25% There would be greater readily available N content of the slurry, as such ammonia emissions during storage and following spreading would be increased. Nitrate leaching losses and nitrous oxide emissions would be increased by a small amount. Overall manure N use efficiency would be increased and artificial fertiliser N inputs reduced.
WHAT IS THE INDICATIVE COST? £2 / m3 of slurry based on more frequent pumping out of underfloor storage and the provision of additional slurry storage. (2011)
Part slatted floor design for pig housing
WHY? Ammonia emissions from pig housing occur from both manure deposited on slat surfaces and also slurry below in the slatted floor storage area. Providing a solid floor lying area and a slatted floor dunging area can reduce ammonia emissions compared with a fully slatted design.
HOW? Replace fully slatted floors with a part slatted floor including a domed solid floor area and beneath slat slurry storage with sloping sides.
WHAT ARE THE EFFECTS? Ammonia emissions would be reduced by up to 50% from pig housing. There would be a greater readily available N content of the slurry and ammonia emissions during storage and following land spreading would be increased. Nitrate leaching losses and nitrous oxide emissions would be increased by a small amount. Overall manure N use efficiency would be increased and artificial fertiliser N would be reduced.
WHAT IS THE INDICATIVE COST? £2.50 / m3 based on replacing a solid concrete floor with part slats. There may be difficulties retro fitting existing housing facilities. (2011)
Install air scrubbers or biotrickling filters to mechanically ventilated pig housing
WHY? Ammonia is very readily absorbed in low pH solutions. This can be used to treat exhaust air from mechanically ventilated pig housing using acid scrubbers or biotrickling filters to remove ammonia, thereby reducing emissions to the wider environment.
HOW? Acid scrubbers typically use sulphuric acid in their recirculation water to capture ammonia as ammonium sulphate which can then be used on land as N fertiliser. In biotrickling filters ammonia is converted through microbial activity in the biomass held on the synthetic supporting material and in the recirculation water. The N in the recirculation water can be used on land as a fertiliser.
WHAT ARE THE EFFECTS? Ammonia emissions from slurry storage would be reduced by up to 90% from housing. Nitrate leaching losses and nitrous oxide emissions would be increased by a small amount. Overall manure N use efficiency would be increased.
WHAT IS THE INDICATIVE COST? £5.50 / m3 of slurry based on the installation of air scrubbers or filters. (2011)
Anaerobic digestion of livestock manures
WHY? Methane generated from livestock manures during AD can be used to produce heat and power, and to replace fossil fuel use. Methane emissions during subsequent manure storage prior to land spreading are also reduced.
HOW? Farms with significant numbers of housed livestock would be the most suitable for on farm installations because of the significant costs involved.
WHAT ARE THE EFFECTS? Methane emissions from slurry storage would be reduced, plus heat and power would be produced. An increase in the readily available N content of the digestate would increase ammonia emissions during storage and following land spreading. Nitrate leaching losses would be increased by a small amount. Overall manure N use efficiency would be increased.
WHAT IS THE INDICATIVE COST? £15,000 per farm type used in the study for the capital costs. (2011)
Change from a slurry to solid manure handling system
WHY? Solid manures are more easily stored than slurries and present less of a risk of pollutant loss during and following land spreading. Straw use also encourages bacterial immobilisation of readily available N resulting in a lower potential for ammonia emissions during housing, storage or spreading.
HOW? This method is potentially applicable to pig farms with housed stock that handle all or part of their manure as slurry. This method would entail changing from this system to one where animals are kept on bedding (e.g. straw) to produce solid manure.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by up to 50%, nitrous oxide and ammonia emissions at land spreading would be reduced as a result of the lower readily available N content. Phosphate losses would be reduced because of lower runoff risks. Methane emissions would be lower from solid manure systems. CO2 emissions could be increased through the additional handling of manure.
WHAT IS THE INDICATIVE COST? £73,000 for the pig unit based on changes to livestock buildings for housing, straw costs and additional labour requirements. (2011)
Change from a solid manure to a slurry handling system
WHY? Slurry based systems have a greater risk of pollutant losses during and following land spreading. However solid manures can contain high amounts of nitrous oxide that will be emitted from storage facilities and on bedding from housing, whereas slurry emits little or no nitrous oxide from slurry based buildings or stores.
HOW? Change from a system where the manure from housed animals is collected as a solid to one where animals are kept on a liquid based system. This system will require storage facilities that may not have been required for storage of solid manure.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be increased by up to 50% as well as nitrous oxide and ammonia emissions at land spreading as a result of the higher readily available N content of slurry. Ammonia emissions would be increased during housing and storage. On balance nitrous oxide would probably be reduced. Phosphate loss would be increased as a result of higher runoff risk. Methane emissions would be increased from slurry compared with solid manure storage.
WHAT IS THE INDICATIVE COST? Based on the farm type used for this study a cost of £27,000 has been assigned based on the construction of slurry storage tank. (2011)
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