What can I do in the short term?
Loosen compacted soil layers in grassland fields
WHY? When soil is compacted, the amount of water and slurry that can infiltrate into the soil is reduced. This means that there is a higher risk of losing these nutrients to the air or watercourses through runoff. If compaction is removed, then rainwater / slurry can percolate into the soil and be utilised by the grass crop. Soil aeration will be improved and result in roots being able to penetrate deeper into the soil, increasing nutrient uptake from deeper soil layers.
HOW? Loosen compacted soil by slitting / spike aeration (for shallow compaction) or subsoiling (for deeper compaction). Care should be taken in the timing of these operations, make sure the cultivation is done in moist soil conditions so as not to damage the grass.
WHAT ARE THE EFFECTS? Phosphate and sediment losses would be reduced by 10-50%. As a result of improved soil aeration direct nitrous oxide emissions are likely to be reduced and ammonia emissions reduced following slurry application (due to better infiltration).
WHAT IS THE INDICATIVE COST? £40/ha for topsoil loosening. If this was applied to 25% of grassland area this would be £10/ha. (2011)
Maintain / improve field drainage systems
WHY? Functioning drainage systems allow water to move through the soil profile allowing the soil to be maintained in a well drained condition. This will extend the window of opportunity for machinery operations and livestock grazing particularly in the autumn and spring. It will also minimise the risk of poaching, compaction and waterlogging and can reduce surface runoff. Poor drainage has a big impact on crop productivity and the management versatility of the land.
HOW? Actively maintain field drainage systems through jetting, reinstallation and moling drains.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be increased by 10-50% (compared with letting drains deteriorate) and as a result of these nitrate losses, ammonium and nitrite losses would also be increased. Direct nitrous oxide emissions would be decreased as the soil will be more aerobic. Phosphate and sediment losses would be increased by up to 10% as a result of greater losses through the drain.
WHAT IS THE INDICATIVE COST? £10/ha based on the need to mole drain 20% of the farm annually. (2011)
WHY? Maintaining field drainage systems and allowing them to function will reduce the risk of waterlogging, soil compaction, poaching and surface runoff.
HOW? Clean out ditches on a regular basis, this may include cutting vegetation in the bottom of the ditch to prevent flooding. It is good practice to also think about maintaining / improving field drainage systems (method above).
WHAT ARE THE EFFECTS? Nitrate leaching losses would be increased by up to 20% (this would also increase ammonium and nitrite losses as a result). Direct nitrous oxide emissions would be decreased as a result of more aerobic soil conditions. As a result of increased drainflow losses, phosphate and sediment losses would be increased by around 10%.
WHAT IS THE INDICATIVE COST? £18/ha based on contractor rates clearing 20% of ditches each year. (2011)
Fertiliser spreader calibration
WHY? Inaccurate fertiliser spreaders can result in inconsistent application of fertiliser across the field. Over application can result in increased nitrate leaching losses as well as reduced crop yields through lodging. This is a low cost method that will improve crop growth and reduce diffuse pollution.
HOW? Tray tests are used to determine the co-efficient of variation (CV) and accuracy of fertiliser spreaders. A low CV (less than 10%) ensures fertiliser is spread evenly and all parts of the field receive the recommended rate. Fertiliser spreaders should be checked at least annually and ideally whenever the fertiliser type is changed.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by up to 5% along with associated nitrous oxide emissions.
WHAT IS THE INDICATIVE COST? £150/farm based on average contractor rates. (2011)
Use a fertiliser recommendation system
WHY? Use of a fertiliser recommendation system to plan fertiliser applications will reduce the risk of applying more nutrients than the crop needs and will minimise the risk of causing diffuse pollution and air pollution. Maintaining an appropriate balance between different nutrients (N, P and K) is also important to maximise the efficient uptake of all nutrients and reduce environmental losses.
HOW? Use a recommended system (e.g. RB209, PLANET, Tried and Tested) to plan artificial fertiliser applications to all crops, do not exceed recommended rates. Time fertiliser applications to minimise losses and take full account of nutrients in manures.
WHAT ARE THE EFFECTS? Nitrate leaching losses and phosphate losses would be reduced by up to 5%. Carbon dioxide emissions would be reduced by a small amount due to lower fertiliser use and production.
WHAT IS THE INDICATIVE COST? A saving of £5/ha on grassland, and £10/ha on arable land based on a 5% reduction in fertiliser use. (2011)
Integrate fertiliser and manure nutrient supply
WHY? Studies suggest that farmers do not always make allowances for nutrients supplied in slurries and manures, when they are calculating fertiliser application rates. If allowances are made for these nutrients, in many cases this will result in a reduction in fertiliser inputs meaning reduced economic and environmental costs.
HOW? Use a fertiliser recommendation system (RB209,PLANET, MANNER)to make full allowances of nutrients supplied by organic manures. Use lab analysis to gain a better understanding of nutrient supplied by your home grown manures and slurries and deduct this from crop requirements when calculating artificial fertiliser rates.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by up to 10%, overall manure N use efficiency would be increased and artificial fertiliser N inputs reduced. Phosphate losses could be reduced by up to 10% (from applied fertiliser).
WHAT IS THE INDICATIVE COST? Savings of £5/ha on grassland and £30/ha on arable land based on greater allowances being made for manure nutrients and reduction in fertiliser inputs. (2011)
Do not apply manufactured fertiliser to high risk areas
WHY? By not applying fertiliser at any time to areas where it could easily be transferred to watercourses, the risk of nutrient pollution is reduced.
HOW? In areas in fields where there is direct access to a watercourse – don’t spread artificial fertiliser. These may include areas with a high number of open drains or next to ditches. In NVZs a no fertiliser spreading buffer zone of 2m from surface waters is compulsory.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by a small (2%) amount, soluble phosphate losses would be reduced by up to 10%.
WHAT IS THE INDICATIVE COST? £5/ha on arable land, £1/ha on grassland based on a small yield reduction on high risk areas. (2011)
Avoid spreading manufactured fertiliser to fields at high risk times
WHY? By avoiding fertiliser spreading at high risk times the available N and P for loss in surface runoff or drainflow is reduced. Surface runoff is most likely to occur where there is rainfall on sloping ground, or when soils are wet, frozen or snow covered.
HOW? Don’t spread N fertiliser between September and February when there is little or no crop uptake and there is a high risk of nitrate leaching loss. Closed spreading periods for manufactured fertiliser N already exist in NVZs unless a specific crop requirement can be justified. Make sure that you adhere to closed periods if you are in an NVZ.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by up to 5% and phosphate losses would be reduced by up to 10%.
WHAT IS THE INDICATIVE COST? £5/ha on arable land, £1/ha on grassland based on a small yield reduction as a result of delayed fertiliser application. (2011)
Do not apply P fertiliser to high P index soils
WHY? Phosphate losses from soil by erosion increases rapidly when soil P index reaches Index 4 or above.
HOW? Losses can be minimised by maintaining soil P levels at Index 2 or by allowing the P content of high index P soils to run down over time. Sample soils regularly to ascertain what your soil’s P index is. The run down of high soil P reserves is a gradual process; the full benefits will only be achieved in the longer term (more than 10 years).
WHAT ARE THE EFFECTS? Soluble phosphate losses would be reduced by up to 50%, and particulate phosphate losses by up to 30% over the long term.
WHAT IS THE INDICATIVE COST? Cost savings of £3-6/ha based on reductions in P fertiliser on high P index soils which are estimated to be on 10% of farm area. (2011)
Reduce field stocking rates when soils are wet
WHY? Soils are more easily poached and compacted when they are wet. Reducing livestock numbers or the duration of the grazing when soils are wet will reduce poaching damage and the potential for mobilisation and transport of pollutants to watercourses.
HOW? Poaching is likely to be more severe with cattle grazing than with sheep. Medium and heavy soils are more susceptible to poaching particularly in high rainfall areas. This is particularly applicable to livestock farms with high stocking rates where extended grazing or outwintering is practised.
WHAT IS THE EFFECT? Nitrate leaching losses would be reduced by up to 20% along with nitrous oxide through extended housing. Ammonia emissions would be increased by 20% through increased storage needs. Phosphate losses would be reduced by up to 10% (through lower poaching rates).
WHAT IS THE INDICATIVE COST? £0.70 – 1.80 / m3 of slurry based on additional silage production, floor scraping and slurry handling. (2011)
Move feeders at frequent intervals
WHY? Regular re-positioning of feed troughs reduces poaching around these points and reduces the quantity of excreta deposited in any single area, both of which can increase pollution losses in surface runoff.
HOW? Move feeders frequently, especially when soils are wet. Do not site them close (within 10m) to watercourses.
WHAT IS THE EFFECT? A small reduction in nitrate leaching losses, nitrous oxide and ammonia emissions due to less compaction and poaching. Phosphate losses would be reduced by up to 10%.
WHAT IS THE INDICATIVE COST? £10-30 / ha based on moving feeders fortnightly throughout the grazing season. (2011)
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)
Site solid manure field heaps away from watercourses / field drains
WHY? Keeping solid manure heaps away from watercourses and field drains reduces the risk of pollutant losses in surface runoff. This is a legal requirement in NVZ areas.
HOW? Don’t site field heaps within 10m of a watercourse or field drain. Benefits are likely to be greatest on medium / heavy soils where runoff risks are highest and field drains are likely to be present.
WHAT IS THE EFFECT? A small reduction in nitrate leaching losses and phosphate losses.
WHAT IS THE INDICATIVE COST? £1/ha based on additional time needed to plan the siting of manure heaps. (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? When stores are covered in an impermeable sheet there is a reduction in ammonia emissions as high as 90% from the store, although nitrous oxide emissions are likely to be increased during storage. Overall nitrate losses through leaching and ammonia emissions would be decreased. Effects on the 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)
Manure spreader calibration
WHY? Even application of manures ensures that all parts of the field receive similar amounts of total and crop available nutrients. Over application of N can result in greater potential for leaching losses and higher soil N levels.
HOW? Determine actual rate and evenness of manure applied by the spreader and adjust it to achieve the desired rate.
WHAT IS THE EFFECT? Nitrate leaching losses would be reduced by a small amount. Overall manure N use efficiency would be increased and manufactured fertiliser N inputs reduced. Phosphate losses would be reduced by a small amount from slurry applications.
WHAT IS THE INDICATIVE COST? £250 per farm cacluated using the farm typology for the study based on time to assess the evenness of manure spreading and field application rates. (2011)
Do not apply manure to high risk areas
WHY? High risk areas (e.g. next to a watercourse or borehole) are able to rapidly transport manure borne pollutants to watercourses.
HOW? Do not apply manure to field areas that are high risk e.g. directly adjacent to a watercourse, borehole, road culvert, shallow soils over fissured rock, or areas with a dense network or open drains or spring lines. These areas have a high degree of hydrological connectivity between the field and the watercourse. Do not spread slurry or solid manure within 10m of a watercourse or 50m of a spring, well or borehole. This is mandatory in NVZ areas.
WHAT IS THE EFFECT? Nitrate leaching losses would be reduced by a small amount (1%) and phosphate losses by around 2%.
WHAT IS THE INDICATIVE COST? £1/ha based on additional management time to plan manure spreading activities. (2011)
Do not spread FYM to fields at high risk times
WHY? When solid manures are spread under conditions where heavy rain post application could transport nutrients and manure borne pollutants to surface water systems the risk of pollution is increased.
HOW? Avoid spreading straw based FYM to fields at times with a high risk of surface runoff. High risk times will be most frequent in winter where soils are wet, particularly in high rainfall areas.
WHAT IS THE EFFECT? Nitrate leaching losses will be reduced by a small amount (up to 5%) along with associated in direct nitrous oxide emissions. Overall crop N use efficiency would be increased (by a small amount) and manufactured fertiliser N use reduced. Phosphate losses in run off would be reduced by a small amount.
WHAT IS THE INDICATIVE COST? £1/ha based on additional management time to plan FYM spreading applications. (2011)
FARM INFRASTRUCTURE CHANGES
Resite gateways away from high risk areas
WHY? Many fields have gateways located at the bottom of the slope and near a watercourse. Gateways incur increased activity, and re-positioning gateways away from watercourses would decrease the potential for sediment and nutrient losses.
HOW? Move gates away from high risk surface runoff areas to lower risk areas on upper slopes.
WHAT IS THE EFFECT? Nitrate leaching losses would be reduced by a small amount (1%) and phosphate losses reduced by 10%.
WHAT IS THE INDICATIVE COST? £2-4/ha based on a removal of gateways and replacement with back fenced hedging on around 30% of fields. (2011)
What can I do in the medium term?
Replace urea fertiliser with another nitrogen form
WHY? Urea and urea based fertilisers are associated with higher ammonia emissions than other forms of fertiliser N.
HOW? Replace urea or urea based fertiliser with another form possibly ammonium nitrate, ammonium phosphate or ammonium sulphate.
WHAT ARE THE EFFECTS? Nitrate leaching losses are likely to be increased by up to 5% and associated nitrous oxide emissions by around 20% as more mineral N is retained in the soil through reduced ammonia emissions to air. Ammonia and nitrite losses to water may be decreased by a small amount. Overall crop N use efficiency would be increased.
WHAT IS THE INDICATIVE COST? A cost saving of £5/ha as although urea is cheaper than ammonium nitrate per unit of N, higher ammonia losses from urea would result in a small yield penalty when compared with ammonium nitrate. (2011)
Incorporate a urease inhibitor with urea fertiliser
WHY? Urease inhibitors delay the conversion of urea to ammonium carbonate and this delay allows the urea fertiliser time to be washed into the soil, thus reducing the pH rise around the urea fertiliser. This means that ammonia emissions would be reduced.
HOW? Incorporate an inhibitor into solid urea or liquid urea / ammonium nitrate (UAN) solutions. This could be nBTPT which has been shown in trials to reduce ammonia emissions from solid urea by on average 70% and from liquid UAN by 40%.
WHAT ARE THE EFFECTS? Ammonia emissions would be reduced by around 70% from solid urea and 40% for UAN. As more mineral N is retained in the soil, nitrate leaching losses to water and nitrous oxide emissions to air would be increased by a small amount. Crop N use efficiency would also increase.
WHAT IS THE INDICATIVE COST? There is thought to be no net cost, as the costs were based on the inhibitor being added to the fertiliser at source and that the increased fertiliser costs were balanced by increased crop yields. (2011)
Use clover in place of fertiliser nitrogen
WHY? By using clover in grass swards, the need for artificial fertiliser N is reduced.
HOW? Incorporate clover into grass swards, to allow the clover to fix the N from the air. On high output systems which traditionally are reliant on fertiliser N, careful management is needed to ensure that grassland productivity is not compromised.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by up to 20%. There would be associated reductions in direct and indirect nitrous oxide and ammonia emissions.
WHAT IS THE INDICATIVE COST? Costs are based on productivity being maintained with the cost of establishing clover in grass swards being offset by savings in fertiliser. As such there is no net cost to the farm business.
Reduce the length of the grazing day / grazing season
WHY? Patches of urine deposited by grazing livestock are a major source of nitrate leaching losses and nitrous oxide emissions to the air. Reducing the time animals spend at grass reduces the amount of urine deposited.
HOW? Options include keeping stock inside during the night, or by shortening the length of the grazing season. This method will have the greatest benefit in autumn as collected excreta can be returned to the fields in a more uniform and less concentrated form via slurry spreading.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by up to 20% alongside nitrous oxide emissions. Ammonia emissions would be increased through longer housing periods by up to 20%. Phosphate losses would be reduced by up to 10% due to reduced levels of poaching damage. Methane emissions would increase as greater amounts of manure are stored. CO2 emissions would increase as a result of greater forage production and manure management activities.
WHAT IS THE INDICATIVE COST? £0.70-1.80/m3 of slurry, based on the additional scraping and slurry handling along with additional silage production to feed stock. (2011)
Extend the grazing season for cattle
WHY? Urine deposited by cattle at grazing rapidly infiltrates into the soil and is associated with lower ammonia emissions compared with higher emissions from urine deposition in cattle housing. The soil prevents a physical barrier to ammonia emissions compared with urine deposited on a concrete floor in the house.
HOW? Where soil conditions allow, extend the grazing season either earlier in the spring or later in the autumn. Soil conditions are likely to limit the potential of this method on many farms because of the unacceptable level of soil damage through poaching.
WHAT ARE THE EFFECTS? Nitrate leaching losses and nitrous oxide emissions would be increased by up to 20%; however ammonia emissions would be reduced by up to 20% through lower emissions at grazing. Phosphate losses would be increased by up to 10% as a result of greater poaching damage. Methane would reduce as smaller amounts of manure are stored.
WHAT IS THE INDICATIVE COST? A saving of £0.50 per m3 slurry based on the reduced need for scraping and slurry handling together with reduced silage production. (2011)
Construct water troughs with a firm but permeable base
WHY? Using a firm yet permeable based reduces poaching of the soil around water troughs. Also as the stock gather around the troughs there is a large volume of excreta build up which can be a source of nutrients and FIOs losses to water.
HOW? Construct permeable bases for water troughs to reduce poaching. If it is necessary to move an existing trough, there will be a need to install new pipe works.
WHAT ARE THE EFFECTS? A small reduction in nitrate leaching losses, nitrous oxide and ammonia emissions would be reduced as a result of less soil compaction, and phosphate losses would be reduced by up to 10% due to lower poaching damage.
WHAT IS THE INDICATIVE COST? £2-5 / ha based on constructing a concrete base for existing troughs. (2011)
Additional targeted straw bedding for cattle housing
WHY? Increasing straw bedding use will reduce the ammonia emissions from cattle housing by providing a physical barrier between urine and the air above the bedding, and by encouraging microbial immobilisation of readily available N.
HOW? Add 25% extra straw bedding to the cattle house and target this additional straw to the wetter or dirtier areas of the house. Further reductions in emissions may be achieved by adding more than 25% extra bedding, but there is a risk that too much bedding could cause the litter temperature to rise and lead to an increase in ammonia emissions.
WHAT ARE THE EFFECTS? Reductions in ammonia emissions of up to 50% can be achieved plus lower emissions during storage and following land spreading. Nitrate leaching losses and indirect nitrous oxide emissions will be reduced by a small amount. CO2 would be increased by a small amount because of additional straw use and increased FYM amounts that need to be managed.
WHAT IS THE INDICATIVE COST? £3/tonne of FYM based on additional time to remove and spread FYM and additional straw costs. (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)
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)
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 losses. 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)
FARM INFRASTRUCTURE CHANGES
Fence off rivers and streams from livestock
WHY? Trampling by livestock can erode river and stream banks and increase sediment inputs to watercourses. Livestock can also add pollutants directly by urinating and defecating in the water.
HOW? Preventing access to streams and rivers as water sources for livestock can eliminate this problem. Erect stock proof fences in grazing fields and on track ways adjoining rivers and streams.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by a small (2%) amount, phosphate and sediment losses would be reduced by up to 5%.
WHAT IS THE INDICATIVE COST? £5-15/ha based on the provision of wire fencing and water troughs. (2011)
Farm Track Management
WHY? Farm tracks can become conduits for nutrient and manure borne pollutants to be lost through surface runoff. On sloping land in wet conditions these tracks can become degraded quickly and form channels that will take large volumes of runoff. Waterlogged tracks can also cause damage to livestock including problems with lameness, mastitis, and teat and udder injuries.
HOW? Create well drained tracks with appropriate surfaces, avoiding routes with steep slopes, and avoiding directing runoff towards bare soil, roads or watercourses. Manage your tracks by improving track surfaces and repair damage promptly, and provide good drainage and divert runoff to adjacent grassed areas, soakaways or swales.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by a very small (1%) amount and phosphate and sediment losses by a small (2%) amount, manure borne pollutants would be reduced by a small amount.
WHAT IS THE INDICATIVE COST? £1-3/ha based on digging out a soakaway and installing drains across farm tracks, plus maintenance and clearing out every 4 years. (2011)
What can I do in the long term?
Allow field drainage systems to deteriorate
WHY? Drainage systems can accelerate the movement of pollutants from land to a watercourse by acting as an easy flow route. Allowing drainage systems to deteriorate reduces connectivity and the potential for these pollutants to be transferred into watercourses, although there would be an increase in surface runoff.
HOW? Allow existing drainage systems to naturally deteriorate over time. It is probable that with increasing soil wetness it would be necessary to reduce the length of the grazing season or to reduce the stocking rates.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be in the range 10-50%, as well as indirect nitrous oxide emissions, ammonia and nitrite losses. However direct nitrous oxide emissions would be increased as a result of wetter soil (through no drainage). Phosphate losses would be reduced by up to 10% provided that the stock were removed in wet conditions.
WHAT IS THE INDICATIVE COST? £10/ha for grassland based on estimated yield losses of 5-10% due to poor drainage. (2011)
CROP AND LIVESTOCK BREEDING
Make use of improved genetic resources in livestock
WHY? Incorporation of health and robustness characteristics into selected breeding programmes could result in improved nutrient use efficiency within livestock systems.
HOW? Use genetic manipulation to improve the lifetime efficiency of livestock systems. The more productive an animal can be during its life, the less impact it will have per kg of meat or milk produced.
WHAT ARE THE EFFECTS? Nitrate leaching losses, nitrous oxide and ammonia emissions would be reduced by up to 10% from manure management. Phosphate losses would be reduced by 10%, with potential methane loss reductions of up to 10%.
WHAT IS THE INDICATIVE COST? A saving of £8,500 per farm based on a 10% reduction in feed for the same level of productivity. This has been calculated using the farm typology devised for this study with a farm area of 146ha. (2011)
Reduce manufactured fertiliser application rates
WHY? Limiting the amount of N fertiliser that is available to crops will reduce the quantity of nitrate left in the soil post harvest. Limiting phosphate fertiliser will, in the short term reduce the amount of soluble P lost, and in the long term will reduce the amount at risk of loss as particulate P.
HOW? Reduce the amount of manufactured N and P fertiliser applied to crops below the economic optimum rate. This would have a significant impact on crop yields (other than legumes).
WHAT ARE THE EFFECTS? Nitrate leaching losses would be reduced by up to 10% (from a 20% reduction in N fertiliser rates) as well as reductions in nitrous oxide and ammonia emissions. Phosphate loses would be reduced by up to 10%, plus longer term reduction through reduced soil P status.
WHAT IS THE INDICATIVE COST? A reduction in gross margin at a cost of £1,200 on the farm typology used in this study. (2011)
Use nitrification inhibitors
WHY? Nitrification inhibitors are chemicals that slow the rate of conversion of ammonium to nitrate, so that nitrate is formed at a rate that is in better synchrony with crop demand (i.e. slow release) and will thereby increase N use efficiency and reduce nitrous oxide emissions and nitrate leaching losses.
HOW? Add nitrification inhibitors to applied artificial fertilisers, organic manures and grazed pastures or to grazing stock.
WHAT ARE THE EFFECTS? Nitrate leaching losses of up to 35%, and direct nitrous oxide emissions of up to 70%. Ammonia emissions to water and air may be increased by a small amount. There is ongoing Defra research into the potential of nitrification inhibitors to reduce emissions.
WHAT IS THE INDICATIVE COST? £20/ha based on purchase costs. (2011)
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? A cost of £1,100 per farm (using typology from the study) based on additional feed and management inputs. (2011)
Low methane livestock feeds
WHY? Developing a low methane diet for ruminants could significant reduce methane emissions as fermentation in the rumen accounts for about 80% of methane emissions from agriculture.
HOW? Formulate livestock rations to minimise the potential for methane production from rumen fermentation.
WHAT ARE THE EFFECTS? Still under development
WHAT IS THE INDICATIVE COST? Still under development
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 also 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 £8,000 per farm. (2011)
Outwintering of cattle on woodchip standoff pads
WHY? Ammonia emissions from urine deposition onto a woodchip standoff pad are likely to be lower than from a concrete yard or cattle housing due to rapid infiltration into the woodchip matrix. The woodchip present a low runoff risk.
HOW? Construct purpose built woodchip pads that include an impermeable liner and drainage collection system with a feeding area instead of winter housing.
WHAT ARE THE EFFECTS? Nitrate leaching losses are likely to be lower as a result of lower volume and N content of the leachate from the woodchip pads (compared with slurry spreading from cattle housing). Ammonia and nitrous oxide emissions at land spreading and ammonia from the woodchip pad are likely to be lower. Phosphate losses are likely to be lower as a result of the lower volume and P content of the leachate compared with slurry. Methane emissions will be reduced as stored leachate volumes are lower than from cattle housing.
WHAT IS THE INDICATIVE COST? £50/head of cattle based on the need to excavate to 0.75m depth, line the pad and install drainage. (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.
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.
WHAT ARE THE EFFECTS? Nitrate leaching losses would be increased by up to 50% and nitrous oxide and ammonia emissions at land spreading. On balance nitrous oxide would probably be reduced. Phosphate loss would be increased as a result of higher runoff risk.
WHAT IS THE INDICATIVE COST? Based on the farm type used for this study a cost of £3,000 has been assigned based on the installation of cubicles and construction of slurry storage tank. (2011)
FARM INFRASTRUCTURE CHANGES
Establish new hedges
WHY? Increasing the number of hedgerows can help to reduce sediment and associated nutrient losses by trapping and lowering surface runoff volumes. Hedges can also help to protect soils from wind erosion.
HOW? Plant new hedges along fence lines and use them to break up the hydrological connectivity of the landscape.
WHAT ARE THE EFFECTS? Nitrate leaching losses and nitrous oxide emissions would be reduced by a small (1%) amount, phosphate and sediment losses would be reduced by up to 20%.
WHAT IS THE INDICATIVE COST? £25-70/ha based on new hedge establishment, installing new gateways, and back fencing. (2011)
LAND USE CHANGE
Convert arable / grassland to permanent woodlands
WHY? There are only small losses of nitrate in drainage waters from permanent woodlands and the permanent cover provided by leaf litter mulch and vegetation minimises the erosion of soil particles and loss of phosphate in surface runoff.
HOW? Change the land use from agricultural land to woodland. This method is more applicable to marginal arable land with a high erosion risk and / or close to surface waters. This is an extreme change in land use and is likely to be suitable for areas where converted land would have amenity and conservation value.
WHAT ARE THE EFFECTS? Conversion to woodland would reduce nitrate leaching losses by around 90%. Nitrous oxide and ammonia emissions would be reduced by around 90% as no fertiliser N would be applied. Phosphate losses would be expected to be reduced by around 50% provided best management practices were adopted. Converting to permanent woodland would increase soil carbon storage.
WHAT IS THE INDICATIVE COST? £150/ha based on a whole life cycle cost / income over 75 years. (2011)