1. Agricultural, Pollution & The Environment
Leaving Certificate Agricultural Science
Agricultural, Pollution & The Environment

2. Learning Outcomes At the end of this section you should be able to:
Name the sources of pollution on Irish farms.
Define the term BOD and describe it’s importance.
Define the term eutrophication and describe how it can lead to a ‘fish kill’.
Describe the effects of the nitrate directive on when and how farmers should apply fertilzers.
Define the term biodiversity and describe ways farmers can encourage it on their farms.
Describe the advantages of hedgerow maintenance on farms.
Define organic farming and describe how it differs from conventional farming.
Describe the advantages of organic farming.

3. Sources of Pollution on Farms
The following are potential sources of pollution on farms:
Silage effluent – a by-product of silage production.
Fertilizer run-off – excess fertilzer washed away by rain.
Silage/Hay wrap – pysical litter.
Sheep dip – poorly stored or disposed of.
Slurry – dung & urine.
Milk
Dairy washings
Pesticides, herbicides and fungicides
Farmyard Manure -a mixture of bedding and dung.

5. Pollution of Watercourses
Organic pollutants are broken down by oxygen in water. Some substances are more pollutant than others.
The pollutant value of a substance is given by its BOD value.
BOD = Biochemical Oxygen Demand and is the amount of dissolved oxygen needed to break down organic matter in a 1 litre sample of water.
As pollutants enter watercourses the nutrients they contain can cause eutrophication.
Eutrophication is the enrichment of a habitat or environment with nutrients.

6. BOD Values of Agricultural Waste

8. Eutrophication
The addition of nutrients in water can lead to growth of algae known as algal bloom.
Algae grow quickly in the nutrient rich environment.
When algae die, oxygen in the water is used by bacteria to decompose the remaining organic matter.
This oxygen depletion means that other aquatic species such as fish cannot survive due to the lack of oxygen and die.
This is known as a fish kill.

10. The Nitrates Directive
As run off from fertilizers can cause water pollution, there are restrictions on when and where fertilizers can be applied.
The Nitrates Directive prevents excess nitrogen entering the soil by limiting the amount of fertilizer allowed to be spread.
It also bans autumn ploughing.
Farmers should not apply fertilizer if land is:
Waterlogged
Flooded
Snow covered or frozen
If heavy rain is due
Land is steeply sloped

12. Biodiversity
Biodiversity: All living organisms within an ecosystem; this includes plants, animals and micro-organisms
A diverse range of living organisms is important in an ecosystem in order to provide resources such as food, but also for recycling wastes and nutrients.
If habitats are destroyed, ecosystems can collapse and disappear rapidly, which in turn eradicates various plants, animals and other living organisms.

14. Encouraging Biodiversity
To encourage biodiversity on farms, farmers can:
Sow flowers and grasses in traditional hay meadows that produce seed to benefit wildlife
Utilise nature corridors to allow animals move under roads or railways.
Maintain hedgerows to preserve wildlife habitats.
Minimize use of pesticides and herbicides
Plant both coniferous and deciduous species in forest plantations

16. Hedgerows
The preservation and maintainance of hedgerows is important because:
Provide natural habitat for many species
Provide shelter to livestock
Food source to many mammals and insects
Form natural land boundaries
Improve growth of plants on sheltered side of hedgerow
Aesthetically pleasing

18. Organic Farming
Organic farming is agricultural activity which does not rely on chemical fertilizers, pesticides, genetically modified crops or livestock antibiotics.
Instead green manures, and farm rotations are implemented
Biological pest controls are implemented
Mechanical methods of cultivation are used to control pests and weeds
© Edco

20. Advantages of Organic Farming
The advantages of organic farming include:
Animals are free range and live in suitable conditions
Animals are reared on land free of chemicals
Crops are not genetically modified
Soil structure is protected by rotations
Waterways are not at risk of pollution
Habitats are maintained