Environmental Science: Soil
5.03 Understand basic environmental science practices and principles Soil Worlds largest sponge Soil Profile A Horizon top soil
B Horizon subsoil C Horizon bedrock Soil Profile A Horizon topsoil
Surface layer of soil approximately 6 deep Usually contains more organic matter than otherhorizons Typically darker colored because or organic matter Layer that has the greatest influence on cropproduction (plant growth) Soil Profile B Horizon subsoil Subsurface layer
Most subsoil has an increase in clay content Layer that has the greatest influence on urban usessuch as building sites, septic systems, ect. Soil Profile C Horizon parent material (bedrock)
Releases water to the upper soil layers Contains larger soil particles including gravel and largerocks Soil Texture Texture refers to the size of soil particles
Sand largest soil particle Sandy soils have problems holding enough water forgood plant growth, but they do drain well Individual particles can be seen with the naked eye Silt intermediate size soil particle that cant be seenwith the naked eye Clay smallest soil particle Clayey soils hold lots of water but may be airtight, infertilefor root growth, and associated with wet soils Soil Texture Soil Structure Structure refers to the tendency of soil particles tocluster together and function as soil units calledaggregates that leave pore space to store air, water,nutrients, and allow root penetration Single grain associated with sandy soils Granular particles cling together to form roundedaggregates very desirable for all soil uses Blocky particles cling together in angular aggregates Typical of soils with high clay content Soil Classification Land capability maps are based on the physical,chemical, and topographical aspects of the land Soil Classification Land capability classes are designated by RomanNumerals I VIII Class I and II land is the best land for the most intensivecultivation of field crops with the fewest limitationsand can be planted year after year Class VII land is very steeply sloping and best used forplanting trees Class VIII land is best suited for wildlife and recreation Soil Conservation Two types of erosion
Sheet removal of layers of soil from the land Gully removal of soil that leaves trenches No till is a cropping technique used to reduce soilerosion Crops are planted directly into the residue of a previouscrop without plowing or disking An effective means of erosion control Soil Conservation Conventional Tillage uses tillage system thatdisturbs the soil surface by plowing, disking and/orharrowing Conservation Tillage intermediate tillage systemconventional and no-till