PSYC 2450 Chapter : Society and Environment Reading Notes (wk 3).docx

• School: University of Guelph
• Department: Psychology
• Course: PSYC 2450
• Professor: Mark Juhasz

Document Summary

Chapter 3; the resources of the earth: sources and sinks. Soil is formed from minerals derived from the breakup and weathering of rocks combined with deposits of organic material derived from wastes and the dead and decaying remains of plants and animals. Soil is a variable mix of inorganic and organic compounds so is a living layer" of the biosphere. Topsoil layers are rich with nutrients necessary for primary producers to carry on photosynthesis. 98% of human food is produced on land. Agriculture increases the rate at which soil and silt is carried into the ocean>accelerating erosion of topsoil and nutrients>declining crop and livestock yields. 1990 (global assessment of soil degradation): reduced soil depth, water retention, organic matter (humus), reduced nutrients. Extensification= growth of food output from expanding cultivated land area. Growing irrigation of marginal and semi-arid land in mdcs and ldcs. Copious food production has led to farming that overdraws and degrades natural resources to maximize production.