[NATS 1840] - Midterm Exam Guide - Ultimate 16 pages long Study Guide!
6 Feb 2017
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Soil properties: tilth a soil"s ability to form a loose crumbly structure, depends on the amount of organic matter, in uenced by amount of biological (decomposer) activity in soil, good tilth also helps a soil retain moisture. Soil nutrients the nitrogen cycle: nitrogen abundant in atmosphere as n2, which plants can"t readily use. Available in usable form in soil as a result of transformation called nitrogen xing. Site a: till soil, added some water, hand weeding, hand harvest. Site b: till soil, adding water and organics, multiple groups, hand harvest. Modern challenge: good production must keep pace with rising population, human consumption of plants dominated by 15 species, human population tripled between 1950 and 1990 but yield per person increased. Site c: till soil, planting high-yield seeds, machine harvest, (this has a large fossil energy input, productivity increased, grain per person increased. Soil conservation (solutions: adding organic matter can help. Can be in the form of manure: no-till methods.
