Soils Lecture 1 Intro PDF

10/7/2019 Soils are the naturally occurring mediums in which plants grow What are soils? In history great civilizations have risen and fallen dependen...

10/7/2019 Soils are the naturally occurring mediums in which plants grow What are soils? In history great civilizations have risen and fallen dependent Humans use plants for nutrition, building on the soils ability to supply food for it’s citizens materials, recreation, etc. 1  10/7/2019 We also rely on plants to maintain the The soil is a thin layer at the surface of the earth atmosphere…the photosynthetic reaction. (up to 1 meter deep) containing elements of: Lithospere – rocks, minerals, inorganic compounds Hydrosphere – water in various forms Biosphere – organisms and bioprocesses Atmosphere – air and other gases Soil is the support medium for plant growth Plants require water, nutrients and light - photosynthesis Only plant cells with chlorophyll can photosynthesize Simple carbohydrates (CHO) are produced and either used or stored CHOs are burned to produce complex nutrient compounds that contain carbon (C), hydrogen (H) and oxygen (O) Nutrients are absorbed by plant roots from the soil Respiration – reverse of photosynthesis, CHOs are converted to usable forms of energy Oxygen – critical to plant physiology, released during photosynthesis, used during respiration, can be the limiting factor in soil environment Ecological cycling –interactions and processes between the soil and the surrounding environment ie. Nutrient flow, hydrological cycle, organic decomposition, evapotranspiration 2  10/7/2019 Absorption/Transpiration Ideal Soil Composition Typically plants are 80-90% moisture by weight, less than 60% - death Organic matter – live and Water is absorbed by the roots from residual the soil Mineral matter – inorganic Translocated through the plant and Air – oxygen, CO2, other exits the leaf via the stomata pores - atmospheric gases transpiration Water – liquid, vapour Water contains dissolved soil These components act both nutrients that will be metabolized by independently and together the plant to determine behavior and properties of the soil. 3