SCSC 301 TAMU Test 1 (Soil Science Test 1 Notes Set) Questions With Complete Solutions

Principle Components of Soil -Air 25% -Water 25% ^ (healthy soil composition, those two vary from 50-0% to 0-50%) -minerals ~45% -Organics ~5% (again healthy soil it varies) % are by volume not mass Soil Dynamic natural body having properties due to the combined effects of climate and biota as modified by relief acting on parent material over time. 5 thing that affect soil Active: -climate -biota Passive: -parent material -time Modifying: -relief (topography) Biosphere from roots to canopy, all things living Atmosphere from top soil on up Lithosphere from top soil down Soil from top soil to bedrock Functions of Soil Medium for plant growth -Nutrients -Support -Water -Oxygen (more absorbed through roots than leaves) Regulates water flow (erosion) Habitat for soil organisms (10^8-9 microorganisms in one gram of soil) Engineering medium (build with or on) Soil Profile a vertical section of soil through all its horizons and extending into the parent material Solum horizons A and B Soil Horizons layer of soil about parallel to the soil surface, differing in properties and characteristics from adjacent layers above or below it. Parent Material The bedrock that lies beneath the soil horizons. Can be termed either C or R. -C: bedrock can be dug when wet -R:solid rock Eluviated A horizons, clay moves out of it Iluviated B horizons, clay moves into it Pedon Smallest 3-d unit of soil measurmen