ENV-0007 Lecture 23: Lecture 23- Soil
8 Nov 2016
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Document Summary
Dust storms became common place: technology turned to the the vast ogallala aquifer, a huge underground reservoir stretching from nebraska to north texas, filled with water that had seeped down for centuries after the last ice age. Constraints in soil use: climate change constraints, physical constraints, chemical constraints, because of these requirements, agriculture is feasible on a relatively small portio(cid:374) of earth"s surfa(cid:272)e, about 20%. Here climatic and soil conditions influence agricultural output. High levels of agricultural productivity are possible on only about 3% of earth"s surfa(cid:272)e. Soil formation: formed above by biological actions, formed below from break up of underlying rock, regolith is the parent material, mechanical weathering. Expands over time, forcing the rocks to move, causing large split, cracks. Physical grinding: soil formation starts in the unconsolidated material that lies above bedrock, which is known as the regolith.
