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87 Cards in this Set
- Front
- Back
What are the 4 functions of soil?
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Habitat Function (nutrition, microorganisms, growing space)
Regulatory function (buffer zone/storage) Archive function (fossils) Economics function (basis fir agriculture and forestry) |
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What are the 5 factors of soil development?
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Time, Climate (including water and temperature), Biota (human), Relief, Parent Material
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What factors influence relief?
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(Topography) slopes, morphology, how weathered the are becomes due to natural development
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What is the eq. for soil?
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Rock+Litter ((climate, relief)/(flora, fauana,human, time))
--> soil |
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What is parent material?
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Bedrock that provides the minerals that are necessary for soil development.
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What is the depth of weathering soils (tundra v tropical forest)?
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tundra least amt 5-50 cm
savanna most 100-200 cm |
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how is material physically weathered?
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Frost shattering, lossening/breaking
Caused by: insulation, temperatures freezing/thawing, water/ice, salt |
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How is material weathered physio-chemically?
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loamification, brunicifcation
Caused by: water, and humic substances |
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What different ways can parent material be weathered?
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Physically, physio-chemically, chemically
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What is brunicification?
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high amounts of iron in primary materials followed by oxidation which gives soils and a reddish/brownish color
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What is loamification?
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silicate weathering --> the neoformation of clay minerals and grain size decreases, leading to a finer soil texture
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What processes contribute to cambisoil?
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brunification and loamification
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What layers are present in the humic layer?
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L= litter
Of= partially decomp litter Oh= organic humuc Ah= mineral horizon |
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What is cambisol?
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Cambisols are developed in medium and fine-textured materials derived from a wide range of rocks, mostly in alluvial, colluvial and aeolian deposits.
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How is aggregation created?
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biologically and physio-chemically.
Excrements clay-humus-complexes by earthworms Developments of aggregates --> crumb structure PC: Clay and organic molecules, swell-shrink of clay masses. |
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What type of rock will decalcify?
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Limestone
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What is a universal effect of decalcification?
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secondary CaCO3 concentrations to all soil types
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What is podzolization?
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dissolved organic matter into metal-organic complexes to create podozol
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What is lessivation?
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Clay translocation, the movement of clay, creating luvisol
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What is gleysol ?
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a hydrologic soil gray/blue tinted soil with O2 and Fe/Mn-ion exchange
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What is bioturbation?
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The reworking of soils and sediments by animals or plants
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What is krotovina?
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filled in tunnels made by small animals
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What is peloturation?
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high levels of clay with extremely deep and dry crevies caused by shrinking/expansion(of water content)
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What is cryturbation?
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ice in the ground causing crevices, found in high elevations, affected by the permafrost table
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How do humans mix soil and why?
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Agriculture between 20-30 cm Ap = plowing
Top layer is homogenous |
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What is a typical soil profile?
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O horizon
A (first mineral layer) B C Bedrock (Organic Apples Bring Cheer) |
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What is hte definition of soil?
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Soil is a natural body consisting of layers (horizons) of mineral and/or organic constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical properties and their biological characteristics.
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Define histosols
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soils with thick organic layers
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What are soils with strong human influence by intensive agricultural use called?
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Anthorosis
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What is it called when a soil contains many artifacts?
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Technosols
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What are leptosols?
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shallow or extremely gravelly
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When soil has limited rooting due to shallow permafrost is called ________.
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a cryosol
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What are two examples of soils influenced by water?
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(just examples) gleysols and fluvisols
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A soil with stagnate water is a ...
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Stagnosol
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What is the German soil profile method called? What are the schematic 4 parts and what is it based on?
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KA5
A water regime 1. Terrestrial, 2. semi-terrestrial, 3. semi and sub- hydric,4.peat |
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What is peat?
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Runoff, partially decayed vegetation. Dark brown. (ombrogenic mires and topogenic mires)
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What is the single most important physical property of soil and why?
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soil texture
water potential, water holding capacity, fertility potential, sustainability for urban areas |
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What are 3 physical properties of soil?
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color, texture, structure
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What are three influences of soil color?
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OM content, water content, presence and oxidation states of iron and manganese oxides
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What do you know about sand?
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high porosity low, high drainage
high amount of quartz grains (dominating in rocks) low cation exchange capacity most soils are infertile and prone to drought |
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What do you know about silt?
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smooth and silky
retarins more water and plants, has a slower drainage rate than sand highly susceptible to erosion by wind and water higher potential to absorb irons, and silt holds more nutrients than sands |
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What is Loess?
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Silt dominated sediment of oblian orgin
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What do you know about clay?
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mainly weathered residuals and secondary silicats formed by mineral transformation and (re-)crstallization
important for chem/phyz processes. large water absorption intensive swelling/shrinking cycles |
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Are soil seperates and soil texture classifications the same?
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NO NO NO NO !!!!!!!
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What are some ways to determine the textural classes?
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-Field estimation (feel method)
-Lab ana. multiple protocols - laser defraction -sedigraph -lab particle size ana. |
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What are the 4 textural classes?
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sand, silt, clay, loam
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What methods can be used to determine physical properties of soil?
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Munsell color chart (color)
soil triangle (soil texture) |
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What is the international system for soil classification?
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FAO system
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What are the activities of soil organisms?
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-Burrowing and molding, activities of soil animals,
-Enmeshment of particles by sticky networks of roots and fungal hypae, -Producer of organic materials by microogranisms esp. bacteria and fungi, -influence of organic matter; supply of substances for biological activities |
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What is the significance of soil?
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-essential for water balance
-ground stability -ground water recharge -retention of pollutants -accessibility of nutrients for plant roots |
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What are the types of soil seperates?
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size division of mineral particles (sand, silt, clay)
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What is a soil aggregate?
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A group of soil particles adhering to oneanother, the smallest strucural unit, ped, of soil
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What is a ped, and what are different types of peds?
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unit of soil structure (such as aggregate, crumb, prism, block, granule)
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What is a colloid?
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substances of a very small particle size, either mineral (clay) or organic (humus), which have a large surface area per unit of volume. provided high cation exchange capacity and also exhibit and instability controlled by soil chemistry.
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What is cation exchange?
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The intercharge between a cation in solution and another cation on the surface of any surface active material, such as clay or organic matter.
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How is cation exchange capacity defined?
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The sum total of exchangeable cations that a soil can absorb. Sometimes called total exchange capacity, base exchange capacity, or cation adsorption capacity. Expressed in (cmol/kg) of soil (or of other adsorbing material, such as clay).
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What planning may be required for field work?
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Planning for fieldwork: lit, maps, sampling strategy, permission from public authorities, inform owner of the property, info about electrical lines, gas pipelines etc., equipment
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What is the importance of water in soil?
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-biological functions: plant growth, water supply and dissolved nutrient salts for plants, critical for livign organisms within soil and OM decay
-pedogenic functions:chemical weathering of minerals (clay formation), translocation of materials within soil -mechanical mizing of soils: desiccation cracks due shrink-swell, cyroturbation -physical properties: moderates soil temp, general hydrologic exchange (evapotrans), infiltration into ground water |
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Where are the options for water to go in soils?
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-surface run off
-percolation -old root channels and earth worm burrows (preferential flow paths) |
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Wat is capillary movement determined by?
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Pore size distribution
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How does the soil water potential move?
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From high to low energy states
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What are the forces (3) affected potential energy in soil water?
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Matric Forces: attraction of water to soil solides, absorption and capillarity
Osmotic forces: Attraction of water to ions and other solutes Gravity always pulls water forward (elevation) |
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What is the soil water potential?
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The work nesscary to move a certain volume or mass of water from a given point of a force field to another point
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What measurements are used to determine water content in soil water?
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Volumetric volume content (volume water/volume soil)
GRavimentric water content (m water -m dry/m soil) |
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Tensiometer, time-domain reflectometry, and a neutron probe are all methods to measure water in a __________ way.
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geophysical
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What are three qualitative descriptions of soil moisture?
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Max retention capacity
Field capacity Permanent wilting ppercentage |
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What is field capacity?
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The percentage of watter remaining in a soil two or three days after its having been saturated and after free drainage has practically ceased.
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What is the permanent wilting percentage of a wilting coefficient?
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The moisture content of soil, on an over-dry basis, at which plants wilt and fail to recover their turgidity when placed in dark, humid atmosphere.
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What is loam?
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soil composed of sand, silt and clay (40-40-20) and considered ideal for gardening and agricultural purposes. High water retention.
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What is the Munsell color system?
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A color designation system that specifies the relative degrees of the three simple variables of color: Chroma, Hue, Value
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What is particle size determined?
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The equivalent diameter of primary particles, as determined by sieving, sedimentation or any other method used in mechanical analysis of soil samples.
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What are the two degrees of organic matter? (According to their degree of transformation)
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1) Non-humic substances (litter): tissue structure still distinguishable
2) Humic substances: 3 classes (fulvic acids, humic acids, humins) |
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Define decomposition of soil.
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The biological process including physical breakdown and biochemical transformation of complex organic molecules of dead material into simpler organic and inorganic molecules
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What products are released during the decomposition of soil?
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CO2, energy, water, plant nutrients and re-synthesized organic C compounds
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What the speed of decomposition determined by?
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Soil organisms, physical environment and quality of the organic matter. Dead organic material will all compose.
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What is humification?
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the successive decomposition of dead material and modified organic matter resulting in the formation of a more complex organic matter (aka humic substances)
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What is mineralisation?
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The complete degradation by microoganisms into inorganic compounds (CO2, H2O) and the release of nutrients (Mg, Fe, N, S)
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What can resist against decomposition?
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Sugar, starch, proteins < cellulose < legnin, wax, resin, tannins
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What are the sub-classes of soil organic matter?
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Living organisms (function as a soil engine) and partially decomposed plant and animal residues (potential food for organisms, nutrient bank, buffer, energy)
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What are the 3 influences on soil color?
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OM content, water content, presence of Fe/Mn ions
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What is the definition of soil acidity?
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A quantitative term used to describe the total acidity in soils or soil horizons as a capacity factor
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Why is soil pH relevant?
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Soil quality, nutrient availability, plant nutrition, microbial and soil faunal activity
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What are differences between acidifying and alkalizing processes?
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Acidifying processes: produce H+ ions
Alkalizing processes: consume H+ ions or produce OH- ions |
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What are some soil acidifying processes? (Name at least 3, and their eq.)
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1) carbon acids (CO2+H2O-->H2CO3)
2) accumulation of OM 3) oxidation of nitrogen 4) oxidation of sulfur 5) plant uptake of cations |
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What are some soil alkalizing processes? (Name at least 3)
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1) Weathering of non acid cations from minerals
2) Accumulation of non acid cations 3) production of base production anions 4) CO2 and varbonates |
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What is pH buffering? Why is it important?
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The resistance to change by cation exchange, pedogenic oxides and hydroxides, and carbonate and silicate weathering.
Important because it ensures stability in soil pH and influences hte amount of amendments |
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What are anthropogenic influences that increase acidification rates?
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- Acidic deposition
- Land use - Fertilization - Mining activities |