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Understanding the behaviour of livestock manure multiple pollutants through contrasting cracking clay soils - WQ0118

The overall objective of this project is to improve our understanding on contrasting cracking clay soils of the interactions that occur between livestock manure multiple pollutant (i.e. nitrate-N, ammonium-N, phosphorus, sediment and microbial pathogens) loss processes and pathways to water, and to test practical mitigation methods.
In the region of 90 million tonnes of farm manures, supplying 450,000 tonnes of nitrogen (N) and 119,000 tonnes of phosphorus (P) are applied to agricultural land in the UK each year. These applications are a valuable source of plant available nutrients, however, they also pose a significant risk of diffuse water (and air)pollution. There is a recognised need to ensure that manure management strategies that aim to reduce one form of pollution (e.g. nitrate) do not exacerbate losses by another route (e.g. ammonium-N/phosphorus/faecal indicator organisms - FIOs), so called ‘POLLUTION SWAPPING’. To date, Defra’s work on ‘pollution swapping’ has largely been focused on free draining soils, reflecting the importance of these soil types above ground water drinking supplies. However, the processes controlling nutrient/FIO losses from drained clay soils are known to be markedly different from structureless free draining sandy soils. Moreover, proposed revisions to the Nitrate Vulnerable Zone-Action Programme (NVZ-AP) in England are likely to result in a ‘closed-period’ for slurry application on all soil types in late autumn/winter. This will substantially increase the amount of slurry applied in the spring and summer periods, which is likely to significantly influence both the amount and timing of nutrient losses to water (and air), and will have an estimated financial impact on the agricultural industry in excess of £500 MILLION.
Replicated field-scale farming system studies will be carried out utilising the Faringdon (Oxon.), ADAS Boxworth (Cambs.) and IGER Rowden (Devon) experimental platforms to quantify the impact of contrasting manure management strategies on diffuse water pollution from cracking clay soils. At Faringdon, the effects of contrasting slurry application timings to arable and grassland systems will be tested. At ADAS Boxworth, the effects of contrasting manure types and slurry application timings to arable cropping systems will be studied. And at IGER Rowden, the effects of contrasting slurry application timings and soil drainage status will be investigated. The manure inputs will be managed to be compliant with the revised NVZ-AP. For the arable systems, slurry applications will be limited to 50m3/ha and solid manure applications to a maximum of 250 kg/ha total N. On grassland, nitrogen inputs from manures and grazing animals will be equivalent to a total N loading of 170 kg/ha. At each site, the plots will be managed using commercial farm equipment. Slurry applications will be made using bandspreaders to minimise ammonia losses and to enable applications to growing crops in spring. On each of the grassland farming systems, there will be 1 or 2 cuts of silage followed by grazing by beef or sheep at a stocking rate of c.2.5 beef cattle or 15-20 ewes/ha. Inorganic fertiliser N applications on all systems will be applied to meet crop requirements (following RB209 recommendations) taking into account N supply from the contrasting organic manure applications. Manure application practices will comply with proposed revisions of the NVZ-AP and IPPC regulations.
Drainflow and surface runoff/interflow volumes will be measured continuously from each plot, using electronic flow measuring equipment, and automatic water samplers will collect samples on a flow proportional basis. The samples will be analysed for nitrate-N, ammonium-N, molybdate reactive P, total dissolved P, total P, FIO and sediment concentrations. N and P balances for each farming system will be calculated using measured inputs from applied manures and fertilisers, measured nitrate, ammonium and phosphorus losses to water, and MANNER-PSM estimates of ammonia and nitrous oxide emissions to air, ‘standard’ figures for N and P uptake by animals, and atmospheric deposition. The balances will enable differences in the amounts N and P retained within and lost from the farming systems to be quantified. The experimental measurements and system N/P balance data will provide information to assess the effectiveness of mitigation methods proposed in the Defra "DWPA User Manual". The results will also assist in the development of manure management systems that maximise crop N and P recovery, and minimise diffuse pollution of the water environment.
The data from this project will be used to refine and improve the field-scale nitrogen and phosphorus export algorithms underpinning the MANNER, NIPPER and NGAUGE models for nitrate-N, the PSYCHIC model for phosphorus, and will provide data for input to the FIO-FARM model (Defra project WQ0111). These refinements will improve the accuracy of model predictions of diffuse pollution from contrasting livestock farming systems and will directly feed into a range of other Defra projects assessing diffuse pollution mitigation methods (e.g. ES0203, WQ0106:DP-AII etc).
The results of these integrated farming systems studies will enhance the scientific evidence base used to underpin the development of strategies to minimise diffuse pollution of the water environment. Such an integrated approach is the only way forward in tackling diffuse-pollution from livestock manures and farming systems to ensure that Defra can meet it’s policy objectives of complying with existing and forthcoming Directives (e.g. NVZs, Water Framework Directive, Bathing Waters and Shellfisheries Directives, Freshwater Fish Directive etc.), and that the financial burdens placed on the agricultural industry to reduce diffuse pollution can be scientifically justified.
1. To quantify the effects of contrasting livestock manure management practices on diffuse water pollution (i.e. nitrate-N, ammonium-N, particulate phosphorus, dissolved phosphorus, sediment and microbial pathogens) at three contrasting cracking clay sites.

2. To identify ‘win-win’ and ‘pollution swapping’ situations with respect to minimising diffuse water pollution.

3. To test practical mitigation methods to reduce diffuse water pollution.

4. To refine the field-based export algorithms in existing diffuse pollution models widely used for policy support work for nitrate (i.e. MANNER, NIPPER and NGAUGE) and phosphorus (i.e. PSYCHIC and other associated models) losses from farming systems at field and catchment scales.

5. To provide a robust scientific evidence base to underpin Defra manure management policy implementation to achieve compliance with existing and forthcoming Directives (e.g. Nitrate Vulnerable Zones, Water Framework, Freshwater Fish, Bathing Water and Shellfisheries).
Time-Scale and Cost
From: 2007

To: 2012

Cost: £3,999,703
Contractor / Funded Organisations
Agriculture and Water Quality              
Sustainable Farming and Food Science              
Water Pollution              
Water Quality              
Water Quality and Use              
Fields of Study
Water Quality