Essential Idea:
Soil cycles are subject to disruption
Understandings:
- Nitrogen-fixing bacteria convert atmospheric nitrogen to ammonia
- Rhizobium associates with roots in a mutualistic relationship
- In the absence of oxygen denitrifying bacteria reduce nitrate in the soil
- Phosphorus can be added to the phosphorus cycle by application of fertilizer or removed by the harvesting of agricultural crops
- The rate of turnover in the phosphorus cycle is much lower than the nitrogen cycle
- Availability of phosphate may become limiting to agriculture in the future
- Leaching of mineral nutrients from agricultural land into rivers causes eutrophication and leads to increased biochemical oxygen demand
Applications:
- The impact of waterlogging on the nitrogen cycle
- Insectivorous plants as an adaptation for low nitrogen availability in waterlogged soils
Skills:
- Drawing and labelling a diagram of the nitrogen cycle
- Assess the nutrient content of a soil sample