True Soil - Environmental Geology - Lecture Slides, Slides of Earth Sciences

Download True Soil - Environmental Geology - Lecture Slides and more Slides Earth Sciences in PDF only on Docsity! SOILS Docsity.com Introduction • True soil science is relatively new – In the US • Less than 100 years • Most of the good information is less than 20-25 years old • Major impetus was the dust-bowl days of 1930- 33 • Originally conservation oriented – Europeans • Began worrying about soils in the late 1800’s • They ran out of land sooner than we did Docsity.com Factors in Soil Formation • Living Organisms – Plant and animal matter – Organic accumulation – Nutrient cycling • Plants maintain the type of soil they like – Plants take up the nutrients they need – Other stuff is removed – Needed nutrients are returned when plant dies • Locally, plants love acid soils – Acid-making nutrients are held in the biomass – Alkali elements are leached away – Soil remains acid Docsity.com Factors in Soil Formation • Living organisms (continued) – Profile mixing • Ants bring yellow subsoil to the surface • In Iowa, the upper meter of soil is completely overturned by earthworms every 75-100 years – Nitrogen fixation – Roots impart structural stability to soil Docsity.com Factors in Soil Formation • Parent Material – Material that breaks down to form soil • Often, but not always bedrock • Locally it is sand that was transported – Controls initial chemical and mineral composition • Carbonate valley soils are basic • Local soils are acidic • Soils formed on shales are clay-rich, never sandy – Influences rate and course of the weathering cycle – Floodplain soils are rich because new parent material and nutrients are added regularly Docsity.com Types of Changes • Translocations – Leaching—removal of material in solution – Precipitation—Deposition of material from solution Eluviation's—removal of material in suspension – Illuviation—addition of material in suspension • Transformations – Organic matter changing to humus – Weathering processes – Oxidation of carbon – Work of microbes and other organisms Docsity.com Soil Development • Surface exchanges – Material additions/removals – Energy – Biocycling – Water • Intrasolum translocations and transformations • Lateral gains and losses • Lower solum exchanges – Weathering adding material from below – Removal from below Docsity.com