An agricultural study compares standard compost pile decomposition with a controlled silo composting method.
The table below shows the mass of the organic matter at the start and after 45 days45\text{ days}45 days.
MeasurementStandard compostSilo compostMass at start (kg)18001800Mass after 45 days (kg)8501450\begin{array}{|l|c|c|} \hline \textbf{Measurement} & \textbf{Standard compost} & \textbf{Silo compost} \\ \hline \text{Mass at start (kg)} & 1800 & 1800 \\ \hline \text{Mass after 45 days (kg)} & 850 & 1450 \\ \hline \end{array}MeasurementMass at start (kg)Mass after 45 days (kg)Standard compost1800850Silo compost18001450The mass of the standard compost decreased by approximately 21 kg21\text{ kg}21 kg per day. Calculate the average decrease in mass of the silo compost per day. Give your answer to the nearest whole number.
Carbon dioxide, a greenhouse gas, is released during decomposition and is responsible for most of this mass loss. Use your answer from part (a) to explain why the silo composting method might be better for the environment.
25 exam-style questions on OCR GCSE Biology 6.1 Monitoring and maintaining the environment, covering 6.1.1 Field investigation of distribution and abundance, 6.1.2 Human interactions and biodiversity, 6.1.3 Maintaining biodiversity, and 6.1.4 Environmental change and distribution of organisms. Each one has a worked solution and a mark scheme showing where the marks go.