UCSF 137 Lecture Notes - Lecture 10: Evapotranspiration, Homeostasis, M.2
11 May 2016
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Document Summary
Be familiar with nitrogen and phosphorus cycles and role of agriculture in them: 4 major environmental compartments. Water: most nitrogen sotred in the atmosphere as n2(g) Most p in environment stored in soil/rocks made available to ecosystem through wethering: limiting factors (why n and p) N and p in relatively short supply: haber-bosch process. Less water retention more erosion (loss of soil) Harvest (removes nutrients from system with crops) additional water moves through system due to irrigation clear fields -- bare fields more prone to erosion: how does lack of diversity contribute to need for pesticides. One plant means abundance of resources for pests in a monoculture. I. 3. lack of genetic biodiversity among the crops leaves them more vulnerable to disease/pests: basic needs of plants. J. 3. soil (p,n: crop plants, just like all species have range of tolerance, evapotranspiration. Water is pulled up through roots based on evaporation of water in leaves. L. 2. determines water/irrigation: bio needs of plants.
