Environmental Impacts of Agricultural Land Use

What are the Environmental Impacts associated with Agricultural Land uses in the UK?

This is the second instalment in a series of blog posts which will identify and evaluate the typical environmental impacts associated with day to day farm processes.

slurry2

What is slurry? How is it stored and what are the relevant guidances and regulations?

Slurry is the combination of manure and water which is broken down over a period of time via bacteria. This processes cause gases such as methane, carbon monoxide, ammonia and hydrogen sulphide to be produced.

Slurry is typically stored in large tanks and within slurry lagoons and ponds. Minimum standards are set out for the use and design of slurry storage systems, which include effluent collection and drainage systems, bunding, distances from water courses, operational life spans and structural integrity for temporary and permanent structures.

If slurry is not stored within the aforementioned facilities and is used directly as a fertiliser, manure and slurry, are not classified as waste under Waste Management Regulations, even if they are used on a different farm to that upon which they were produced. However, the storage must still comply with associated regulations and legal controls.

  • Nitrate Vulnerable Zones (NVZ) Action Programme,
  • The Water Resources (Control of Pollution) (Silage, Slurry and Agricultural Fuel Oil) Regulations 2010 (SSAFO)
  • Relevant Scottish Legislation: The Control of Pollution (Silage, Slurry, and Agricultural Fuel Oil) (Scotland) Regulations 2003
  • UK guidance: Storing silage, slurry and agricultural fuel oil (9).

Good Agricultural and Environmental Conditions (GAECS) and Statutory Management Requirements (SMRs)

Cross Compliance are measures which were introduced to set baseline standards that farmers must meet in order to receive funding such as the Single/Basic Payment Scheme (11). Cross Compliance applies to farmers in the UK who are receiving payment under Common Agricultural Policy (CAP) (12). There are two basic elements to cross compliance: Good Agricultural and Environmental Condition (GAEC) standards relating largely to the protection of soils, habitats and landscape features; and Statutory Management Requirements (SMR) which are either pre-existing legislative requirements or those that Member States must implement under EU law. SMRs cover environmental, public, plant and animal health and, from 2007, animal welfare objectives. A list of GAECs and SMRs is given below. In order to assess the relevance of each standard to an individual farm, click here to register for Defra’s Self-Assessment tool. A full list of GAECs and SMRs are given in Appendix 1 of the Groundsure Agricultural Report.

The Department for Food and Rural Affairs (DEFRA) compiled a guide to cross compliance in England in 2015 (7). The document provides information and advice for claimants undertaking certain activities throughout the year and relates to different soil types. For example, you can apply organic rich manure (slurry) in January and February as long as you adhere to the SMR1 guidance, with August, September and October noted as the “start of closed period” for applying slurry.

The spreading of slurry must also comply with such guides as the Code of Good Agricultural Practice (COGAP) which stipulates that the use of slurry as fertilisers must not occur under the following conditions:

  • the soil is waterlogged;
  • the soil is frozen hard;
  • the field is covered in snow;
  • the field is cracked down to field drains or backfill;
  • the field has been pipe or mole drained or subsoiled over drains in the last 12 months;
  • heavy rain is forecast within the next 48 hours,

The COGAP dictates that manure or slurry should never be applied within 10 metres of any ditch, pond or surface water, within 50 metres of any spring, well, borehole or reservoir that supplied water for human consumption or for farm dairies, on very steep slopes where run-off is a high risk throughout the year, or on any areas where you are not allowed to because of specific management agreements.

The Health and Safety Executive (HSE) have compiled a factsheet which aids farmers in the management of slurry on farms (2). The factsheet provides guidance on a number of topics which will be briefly covered in the following paragraphs.

The HSE Fact sheet advises to avoiding exposure where possible. When slurry is disturbed (via agitation, pumping or emptying of a store) higher levels of gases are released, giving rise to sudden high volumes of gasses such as hydrogen sulphide. Gasses that are produced are be flammable, toxic, and can replace oxygen from the air causing asphyxiation. At low levels hydrogen sulphide gives off a smell of rotten eggs, however at high concentrations you cannot smell it (2). The gas is heavier that air so sudden exposure in poorly ventilated areas (tanks, pits and farm buildings) can be fatal. It is advised that a building or structure is ventilated for at least 30 minutes before it is re-entered.

In order to mitigate against potentially fatal incidents, farm workers must:

  • ensure there is an effective method of safely venting slurry gas away from the working area,
  • inform other site users including farm labourers, family members and contractors of what you are doing and understands the dangers (including suitable warning signs),
  • remove livestock and checked no one is present in buildings connected to the slurry storage system,
  • not stand over mixing points where gas may be emitted and to cover mixing points and reception pits in case someone is overcome and falls in,
  • avoid creating naked flames as some slurry gases are flammable,
  • never enter a slurry tank or slurry storage system unless you are equipped, trained and competent to use specifically breathing apparatus and safety lines.

Gas monitoring equipment must not be used on their own as gases can be produced quickly, before detectors can react. These detection systems also require expert maintenance, calibration and storage.

Slurry lagoons/pits must be suitably fenced to prevent children and escaped animals from falling in, with associated security gates to allow limited access. A tractor stop barrier should also be constructed on the scraping ramp. Fencing should be constructed of a suitable material and have an overall minimum height of 1.3m (see Figure 1). Further information on maintaining and installing fencing and scraping ramps can be reviewed in the HSE factsheet (2).

slurry fence

Edited from the HSE Factsheet- Managing slurry on farms.

As well as pits and lagoons, slurry can be stored in tanks and towers. The collapse of such structures can be avoided by planned maintenance of the plant and monitoring its condition. Indications that your slurry tower needs replacement or repairs include:

  • leaks,
  • bowing or cracking to the outer skin,
  • deterioration around joints,
  • spalling or flaking of the concrete layer of a tower, caused by corrosion of the metal reinforcing bars. This may also show as rust staining on the concrete surface, and
  • corrosion on either on the surface or the underside of concrete slats and concrete covers to pits.

If slurry storage areas need improvement or rebuilding, then BS 5502-50:1993 should be followed (8). This is the code of practice for design, construction and use of storage tanks and reception pits for livestock slurry.

What are the Environmental and Health Implications?

Environmental

Typical environmental impacts associated with the improper storage of slurry includes water pollution (surface and groundwater), air pollution (odours), eutrophication in rivers from ammonia and nitrate levels and increased levels of pathogens. Research suggests that Category 1 pollution incidents resulting from slurry decreased from 99 in 1991 to 22 in 1998. This has been attributed to heightened awareness for the need of improved and regulated storage facilities (10).

Health

Working with slurry can also have severe health implications and in some cases lead to death. The Health and Safety Executive (HSE) state that incidents involving slurry regularly occur on farms in the Great Britain. Such occurrences involve farmers and the general public being asphyxiated by toxic gasses such as hydrogen sulphide (2), drowning after a fall into slurry or lagoon or injuries resulting from collapsing of structures (3) (4). In September 2012, three people died on a farm in Northern Ireland due to a lethal build-up of noxious gases (1) and a young boy tragically died after being overcome by slurry fumes in 2014 (5).

Such significant fatalities and environmental impacts such as these highlight the need for regular maintenance and repairs to be undertaken.

Evidence and penalties for breaching regulations.

If the storage and use of slurry fail to meet regulations farmers can often be made to pay heavy fines. A farmer in Shropshire was ordered to pay £6000 by the courts after slurry was found to have contaminated a nearby brook (6). According to Environment Agency inspectors, the slurry had filtered through a hedge and was noted to spread on a nearby road. Areas reached up to 4 inches deep in some places. Officers also found that slurry was also discharging directly into a nearby brook. The article indicates that the farmer undertook slurry spreading on a day where there had been a significant amount of snow, causing the slurry to become more water logged. The spreading of slurry at this time did not comply with the Code of Good Agricultural Practice whereby it stipulates that the ground must not be frozen or waterlogged when slurry is spread.

 


References

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