Essential idea: Soil cycles are subject to disruption.
Intensive agriculture relies heavily on the use of artificial fertilisers to maintain high crop yields. The manufacture and the application of fertilisers is a major disruption to nutrient cycles. One consequences of this is the unbalancing of natural ecosystems around agricultural areas.
Understandings, Applications and Skills
|C.6.U1||Nitrogen-fixing bacteria convert atmospheric nitrogen to ammonia.|
|C.6.U2||Rhizobium associates with roots in a mutualistic relationship.|
|C.6.U3||In the absence of oxygen denitrifying bacteria reduce nitrate in the soil.|
|C.6.U4||Phosphorus can be added to the phosphorus cycle by application of fertilizer or removed by the harvesting of agricultural crops.|
|C.6.U5||The rate of turnover in the phosphorus cycle is much lower than the nitrogen cycle.|
|C.6.U6||Availability of phosphate may become limiting to agriculture in the future.|
|C.6.U7||Leaching of mineral nutrients from agricultural land into rivers causes eutrophication and leads to increased biochemical oxygen demand.|
|C.6.A1||The impact of waterlogging on the nitrogen cycle.|
|C.6.A2||Insectivorous plants as an adaptation for low nitrogen availability in waterlogged soils.|
|C.6.S1||Drawing and labelling a diagram of the nitrogen cycle.|
|C.6.S2||Assess the nutrient content of a soil sample.|
[Text in square brackets indicates guidance notes]
Hank from Crash Course introduces the Nitrogen and Phosphorous cycles
Mohamed Hijri in his TED.com talk offers a simple solution to the coming phosphorus crisis.
Presentation and Notes
The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.
Nature of science
Assessing risks and benefits of scientific research—agricultural practices can disrupt the phosphorus cycle. (4.8)