Researchers mixed equal masses of finely cut dead grass into eight containers of the same soil. Four containers were kept aerated and four were kept waterlogged. The containers were kept at the same temperature and contained no living plants.
The table shows the mean concentrations of nitrogen compounds in the soil.
| Soil condition | Ammonium compound concentration at day 0 / mg dm−3^{-3}−3 | Nitrate concentration at day 0 / mg dm−3^{-3}−3 | Ammonium compound concentration at day 21 / mg dm−3^{-3}−3 | Nitrate concentration at day 21 / mg dm−3^{-3}−3 |
|---|---|---|---|---|
| Aerated | 5 | 18 | 14 | 52 |
| Waterlogged | 5 | 18 | 29 | 6 |
Explain the changes in the concentrations of the nitrogen compounds during the 21 days. Suggest what would happen to the nitrate concentration in the waterlogged soil if this soil were then drained and aerated. Use the information in the table in your answer.
101 exam-style questions on Edexcel GCSE Biology 9.3 Material cycles and decomposition, covering 9.3.1 Cycling of materials through ecosystems, 9.3.2 The carbon cycle, 9.3.3 The water cycle, 9.3.4 The nitrogen cycle, 9.3.5 Indicator species and pollution, 9.3.6 Decomposition in preservation and composting, and 9.3.7 Rate changes in decay of biological material. Each one has a worked solution and a mark scheme showing where the marks go.