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Soil Facts

Page history last edited by dmjepson 9 years, 3 months ago

Hey everyone! So I guess the last study guide helped many of you, so I am making another one, sorry it took me such a while to upload, more info will be posted in next few hours. Please add/fix things if needed!

Good luck :)

-D

Soil: The unconsolidated cover on the surface of the earth (it is loose and poorly sorted). It is composed of mineral and organic particles, and air and water. Supports the nutrients neccessary for plant growth, which provides autotrophs for the food web. Ratio: Mineral matter 45%, Organic matter 5%, air 25%, water 25%. In one square meter of soil there are more than 10,000 bacterial and fungal types and 100-1,000 invertebrate types

Soil Bacteria: size of 1-2 micrometers, density of 109 cells gram soil. Diversity if 5,000 known species, millions are estimated. Biomass of 300-3000 kg/ha (wet)

Organic Matter: is the 'glue' that holds the aggregates together

Clay: Has a large surface area which allows it to adsorb a lot of water, retain nutrients and stick to other soil particles. (1/4 cup of clay has more surface area than a football field)

Properties of Soil Clays: Particles are stacked in layers like sheets of paper, each sheet has negative charges on it; need to be balanced by cations (positive charges)

Functions of soil for plants: Anchor roots, supply water and nutrients, air for roots.

Soil Texture: The mineral part of soil consists of sand, silt, and clay particles (these are in decreasing size)

Coarse textured, loose (more sand, less clay)

Fine textured, heavy (more clay, less sand)

Loamy (an even ratio of sand, silt and clay)

Soil Structure: The arrangement of sand, silt and clay particles to form larger aggregates; contains, organic matter, large and small pores.

large pores (spaces) are between aggregates and are filled with air in a moist soil

small pores are filled with water in in a moist soil

Plant Nutrients: Are obtained from the soil, comes from detritus (decaying plant matter) and a breakdown of soil minerals. Also humans add nutrients in the form of fertilizer, manure and lime and other synthetic forms.

Macronutrients: N,P,K,Ca,Mg,S (N,P,S are all anions)

Micronutrients: Cl,Co,Cu,Fe,Mn,Mo,Ni,Zn (Chloride is the only anion)

Anthropogenic Nutrient Additions:

-Commercial fertilizers: nutrients are quickly dissolved to go into the soil water, a form easily available for plants

-Lime: Dissolves slowly as it neutralizes soil acidity, releases calcium and magnesium

-Organic nutrient sources: Manure, compost and sewage sludge; decay and nutrient release is similiar to crop litter

Soil Water: a complex solution that contains nutrients, trace elements and complex organic molecules. These nutrients can be readily taken up by plant roots in this solution. If nutrients remained in the solution they could all be quickly lost from the soil due to factors such as run off and evaporation.

pH: Refers to the amount of free (H+) protons, it is a log rythmic scale pH of 1 being most acidic, 7 being neutral and 14 being most basic.

Adsorption: refers to the ability of an object to attract and hold particles on its surface. Solid particles in the soil have the ability to adsorb water, nutrients and other chemicals. Most important adsorbers in soil are clays and organic matter.

Cation Exchange Capacity: It is the function of pH and composition; is the total amount of cations that a soil can retain, higher the soil CEC the greater ability it has to store plant nutrients. As the amount of clay, organic matter and soil pH increases, the higher the soil CEC increases.

Chelate: is a liquid which binds to a site (usually around a macronutrient) makes it soluble (for metals). It is water soluble, can be leached out with heavy rains, it needs to be regulated, once put into a soil system it can move to a new system due to factors such as run off. (Example) Synthetic version is Miracle-Grow. Optimum time in a plant's lifespan to apply is during the peak of its growth phase (metal uptake phase occurs then) right before harvest

Rhizoremediation: using roots to clean soils and water; has a high surface area, an affinity for metals, promotes microbial activity, aerates soils, sediments and water, and releases exudates (nutrients). 40% of fixed carbon is done through roots (taking gaseous carbon

Metallophytes: Metal loving plants

Photosequestration Mechanisms: (a) Photochemical Complexation (b) Transport Protein Inhibition (c) Vacuolar storage

Phytoextraction Mechanism: The contaminent is taken up; dissolved in transpiration water or as vapor adsorbed through roots, it is translocated in xylem (or an intermediate from rhizodegredation); it is the sequestration of heavy metals (Pb,Cd,Cu,Zn,Co,Ni,Au,U,Pt) Utalizes metallopshytes to hyperaccumulate metals in aerial tissues

Phytostabilization: Is the immobilization of contaminants in soil and the waters through; absorption and accumulation by roots, adsorption onto roots, precipitation within the root zone, and stabilize contaminated sediments

 

 

 

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