5.3.9 Percentage Yield

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Percentage yield measures the efficiency of energy or biomass transfer in ecosystems, particularly in agriculture or food production.

\text{Percentage Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100

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Actual Yield: The amount of product (e.g., crop, biomass) actually obtained.
Theoretical Yield: The maximum amount of product that could be obtained under ideal conditions.
Yield Loss: Differences between actual and theoretical yield arise due to factors such as pests, diseases, environmental conditions, or inefficiencies in farming practices.

Maximising Efficiency: Farmers aim to maximise percentage yield to ensure resources like fertilisers, water, and energy are effectively utilised.
Sustainable Practices: Managing soil health, crop rotation, and pest control to reduce yield loss while minimising environmental impact.
Reducing Energy Loss: Techniques such as using greenhouses to control conditions or employing high-yield crop varieties.

If a field theoretically produces 500 kg of wheat but the actual harvested yield is 400 kg:

\text{Percentage Yield} = \frac{400}{500} \times 100 = :success[80\%]

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Clearly identify actual and theoretical yields in calculations.
Show all working for percentage yield questions to avoid losing marks.
Relate percentage yield to energy efficiency in ecosystems where applicable.

Percentage Yield Simplified Revision Notes for A-Level AQA Biology