Dairy
The main dairy farming areas are in south-west Scotland, where
conditions are particularly favourable for grass growth. The number
of dairy units has declined dramatically in recent times, due to
years of poor economic returns. There are approximately 198,000
dairy cows on about 1,800 holdings.
Like most farming, dairy farms handle a number of materials such
as fertilisers, oils, cleaning chemicals, effluents, manures and
slurries, veterinary medicines etc., which each have the potential
to harm the environment if not managed appropriately.
In recent years, a successful working partnership between the
farming community and SEPA has resulted in raised awareness of
pollution issues involving livestock farming. By providing advice
and good practice publications, and through improved compliance and
co-operation from farmers, there has been a marked reduction in
agricultural pollution incidents.
There are a number of issues relevant to diary farming, among
them:
Poaching and soil erosion on grassland
Poaching can be a problem when cattle are wintered on
grassland, particularly around gateways, feeding areas and watering
points. This can lead to risks of soil erosion and compaction.
Poaching can occur where the land is ‘cut-up’ through cattle moving
or tramping on wet soils. This removes the vegetative cover,
leaving the soil open to the elements and prone to being washed
away via surface water run-off.
Soil erosion can not only remove fertile top soil and clog up
drains etc., but can also lead to water pollution if the sediment
is washed into watercourses. Guidance is offered to farmers on how
to prevent soil erosion and compaction, in the 4
point plan 
, Farm Soils
Plan and the
PEPFAA code .
Livestock slurry and farmyard manure
In order to avoid poaching and damage to grassland, as well as
to improve productivity, many farmers house their cattle over the
winter months. The manure or slurry produced is collected and
stored prior to spreading to land as fertiliser. Livestock
manures and slurries offer a valuable source of plant nutrients,
including nitrogen, phosphorus and potassium.
Taking account of the nutrients applied to land as slurry or
manure, and the levels of nutrients already available in the
soil, and comparing them with the nutrient needs of the crop,
can often result in significant savings on inorganic fertiliser
use. Manures can also help increase the organic matter content of
soils thereby improving soil structure and fertility.
While slurries can be beneficial for plant growth and soil
nutrient levels they are relatively high in terms of Biochemical Oxygen Demand (BOD) and can pose
significant water pollution risks. Pollution risks can occur
at all stages of handling livestock manures and slurries including
collection, storage, transportation and land application.
In order to minimise pollution risks from steadings where
livestock are housed, any slurry that is produced is required to be
collected and contained. Further information is available from
the Control of Pollution (Silage, Slurry and Agricultural Fuel
Oil) (Scotland) Regulations 2003, SSAFO.
Spreading slurries to land can pose a significant pollution risk
if the spreading takes place close to watercourses or when the
ground is frozen or water logged. The rate and method of
application to land is also very important. There tend to be fewer
problems with solid farm yard manures from beef units. Guidance is
available to farmers on how to reduce the risks of causing
pollution from storing and handling livestock manures and slurries,
and can be found in the
PEPFAA code and
the 4
point plan .
Silage effluent
Any forage crop that is being made into silage (for feeding
cattle) will produce effluent. Silage effluent has a Biochemical Oxygen Demand (BOD) of around
65,000 mg/l of oxygen, and is one of the most potentially polluting
materials produced on farms. For example, a clamp or silo
containing 500 tonnes of unwilted (not dried) silage has a similar
polluting potential as the daily untreated sewage output from a
city the size of Aberdeen.
The quantity of effluent depends on the moisture content of the
crop being ensiled (stored in a clamp or silo):
- Grass ensiled at a dry matter content of 10–15% will produce
about 360–450 litres of effluent per tonne of grass ensiled.
- Grass ensiled with a dry matter content of 21–25% will produce
up to 90 litres of effluent per tonne.
It is therefore vital that cut grass is wilted for as long
as possible, before being stored.
Waste
Agricultural waste can pose significant risks to the environment
and human health if not managed appropriately. The types and
quantities of wastes will vary between farms. Common types of waste
produced on farms will typically include materials such as
packaging, tyres, oils and silage plastics etc.
Guidance on minimising waste produced on the farm and further
information is available from our agricultural waste guidance.