NRES 201 Lecture 2 Outline of Last Lecture II Definitions III Soil Exploitation a Dust Bowl b Black Blizzard IV Erosion in Illinois Outline of Current Lecture I What is soil II Soil Components III Functions of soil IV Soil as an environmental interface Current Lecture I What is soil a The upper part of the Earth s crust composed of mineral and organic matter and formed by the interaction of five soil forming factors which are i Climate ii Organisms iii Topography iv Parent Material v Time II How a soil looks in the field a Solum consisting of 3 horizons layers i O Organic ii A Plow Layer iii B Subsoil b C Horizon i Parent material but not yet soil c Regolith O A B C i Unconsolidated material that sits above bedrock loose material III Soil Components a The Solid Phase Composed of 1 Inorganic minerals a Primary minerals present in the original rock These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV V VI b Secondary minerals formed by weathering 2 Organic matter a Living organisms biomass animals plants microscopic b Organismal remains residues c Decay products humus ii Properties 1 Texture Proportions of particles by size a Sand coarse b Soil medium c Clay fine iii Organic Matter Content 1 There are many important effects on soil physical chemical and biological properties including a Aggregation of soil particles b Water storage and availability c Microbial energy source d Nutrient supplying power b The Liquid Phase i Characteristics 1 Water dissolved ions molecules and gases 2 Known as the soil solution 3 Medium for chemical and biological processes c The Gaseous Phase i Characteristics 1 Gases occupy soil pores not filled with water 2 Known as the soil atmosphere 3 Differs from ambient air by having a Less O2 b More CO2 c More Humanity Functions of soil a Medium for plant growth b Regulator of water supplies c Waste recycling system d Habitat for soil organisms e Engineering medium f Atmospheric modifier soil is changing the composition of the air we breathe and it is stabilizing the composition Pedosphere The outermost layer of the Earth where soil forms and life begins Environmental consequences of soil degradation a For the atmosphere i Dust storms ii CO2 enrichment soil loses organic matter b For the hydrosphere i Sedimentation ii Nutrient pollution
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