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

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.

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.

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.

BOD Values of Agricultural Waste

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.

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

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.

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

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

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

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