Environmental Science: Soil 5.03 Understand basic environmental science practices and principles

Soil World’s 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 other horizons Typically darker colored because or organic matter Layer that has the greatest influence on crop production (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 uses such 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 large rocks

Soil Texture Texture refers to the size of soil particles Sand – largest soil particle Sandy soils have problems holding enough water for good plant growth, but they do drain well Individual particles can be seen with the naked eye Silt – intermediate size soil particle that can’t be seen with the naked eye Clay – smallest soil particle Clayey soils hold lots of water but may be airtight, infertile for root growth, and associated with wet soils

Soil Texture

Soil Structure Structure refers to the tendency of soil particles to cluster together and function as soil units called aggregates 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 rounded aggregates 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 Roman Numerals I – VIII Class I and II land is the best land for the most intensive cultivation of field crops with the fewest limitations and can be planted year after year Class VII land is very steeply sloping and best used for planting 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 soil erosion Crops are planted directly into the residue of a previous crop without plowing or disking An effective means of erosion control

Soil Conservation Conventional Tillage – uses tillage system that disturbs the soil surface by plowing, disking and/or harrowing Conservation Tillage – intermediate tillage system conventional and no-till