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Explain the term biological oxygen demand (BOD) - Leaving Cert Agricultural Science - Question b - 2016
Question b
Explain the term biological oxygen demand (BOD). Outline three farming practices that would help maintain a low BOD.
Worked Solution & Example Answer:Explain the term biological oxygen demand (BOD) - Leaving Cert Agricultural Science - Question b - 2016
Step 1
Explain the term biological oxygen demand (BOD).
Answer
Biological Oxygen Demand (BOD) refers to the volume of oxygen required by microorganisms to decompose organic matter in a water sample at a specific temperature over a defined period of time. In practical terms, BOD is usually measured in milligrams of dissolved oxygen consumed per liter of sample over five days at 20°C. This measurement is crucial for assessing the level of pollution in water; a high BOD indicates a high level of organic matter, which can lead to oxygen depletion and harm aquatic life.
Step 2
Outline three farming practices that would help maintain a low BOD.
Answer
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Slurry application at correct time: Applying slurry at appropriate times, such as avoiding rainy days, helps prevent runoff into waterways, which could otherwise increase BOD levels.
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Use of slurry tanks: Utilizing slurry tanks for the storage of animal waste minimizes direct discharge into water bodies, thus reducing contamination and maintaining lower BOD levels.
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Safe disposal methods: Proper disposal of dead animals and careful management of fertilizers, including avoiding overapplication, help in controlling nutrient runoff, thereby keeping BOD levels lower.