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54 Cards in this Set
- Front
- Back
In the Soil loss equation define the symbols:
A= RKLSCP |
A: average annual soil loss
R: rainfall RUNOFF factor K: soil erodability factor L: slope LENGTH factor S: slope STEEPNESS factor C: COVER management factor P: erosion control factor |
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Factors that influence "K"
(soil erodability factor, normally ranging from 0- 0.6) |
stability if aggregates/organic matter
water infiltration rate particle size |
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How Does crop coverage help manage erodability?
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reduces surface puddles
intercepts rainfall helps maintain infiltration rate slows runoff residue returned to soil influences soil structure influences infiltration and permeability |
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What are the support practices that comprise "P" of the universal soil loss equation?
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contour tillage
Contour strip cropping Terracing |
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What is conventional plowing?
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moldboard
% of surface residue very low |
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Geologic erosion keeps up with the rate of _______.
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soil formation
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natural erosion is called ______
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geologic erosion
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Accelerated erosion is ____ to ____times greater than geologic erosion
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10x to 1000X
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Biggest causes of accelerated erosion?
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agriculture & grazing
in development when soil is often left bare for >1 year |
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the greatest loss of soil nutrient is from ....?
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the removal of crops
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#1 water pollutant?
What effects? |
water sediments
disrupted water habitats drinking water must be filtered bad for recreation (suspicious looking & smelling) navigation channels must be dredges affects photosynthesis and plant growth |
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What airborne pollutants can affect respiratory?
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clays ans silts can get deep into lungs
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Costs per year of wind erosion?
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8-40 billion on site
+ 10-30 billion off site |
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When sand skips along the surface and disrupts granular structure?
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saltation
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WEPP?
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Wind Erosion Prediction Program
uses climate, management, soil and topography to predict wind erosion |
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WInd erosion accounts for ____of soil loss in the US.
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1/3
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windbreaks are good for....
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slowing wind velocity for 10x the height of the windbreak.
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3 steps in water erosion?
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detach
transport deposit |
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raindrop speed?
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30 km/hr or 20 mph
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USLE is used for _____erosion.
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Sheet and Rill!
Not gully! |
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erosion where water moves in sheets and is hard to detect?
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sheet erosion
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erosion where small channels carve into soil surface?
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Rill erosion
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erosion where large channels are carved out and you need big machinery to correct it.
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Gully erosion
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T value is ....
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tolerable soil loss for a soil to remain productive indefinitely.
in tons/acre/year |
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the physical condition of soil as it relates to plant growth?
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TILTH
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purpose of tillage?
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planting seeds
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when a rock sits on a "pedestal" of sand and silt as a result of raindrop erosion?
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pedestal deflation
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2 types of plowing that leave some litter undisturbed?
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chisel plow, disk
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conservation tillage leaves > ___% surface litter.
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30%
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what does seed bed prep do?
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prvent crusting, compaction
encourage water infiltration and pore space |
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Steps in conventional tillage?
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moldboard plow + disk, drag, plant
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highest erosion from....
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fall plow
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fall plow causes highest erosion, tillage pan, platy to blocky structure, but benefits are...
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weed control, good seed bed prep, faster spring warm up
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is a dense layer beginning six to 10 inches below the surface
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tillage pan
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way to break up tillage pan?
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subsoiler- a chisel plow that vibrates deep in the soil and breaks it up.
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advantages of conservation tillage?
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reduce runoff
often comparable yields less time and money higher moisture retention |
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disadvantages of "No till"
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slower spring warm up, evap
highest density/compaction lowest pore space heavier reliance on pesticides hard to incorporate lime, fertilizers, manure, pesticides |
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nutrients movement through soil is called...
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mass flow
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waters polarity good for transportation os ....
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cations and anions
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resistance to flow...
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viscosity
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adhesion and capillarity result in _____in soils.
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Matric tension
waters attraction to a solid |
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SMT for OD soil
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-10K bars!
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SMT (Matric Tension) for air dry soil?
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-31 bars
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SMT for field capacity?
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-1/10 to -1/3 bars
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SMT at permanent wilting point
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-15 bars
plants have extracted all the water they can |
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what is gravitational water
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between field capacity and saturation
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Plant available water is between
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field capacity and wilting point
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anions and cations conduct electricity to determine soil moisture in a ________.
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gypsum block
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device which send out fast neutrons and measures slow returning neutrons to accurately measure soil moisture
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neutron probe
(used in research) |
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reflectivity
in also called.... |
albedo
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process of warming soil deeper and deeper
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conduction
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units of volume heat capacity?
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cal/cm3 per 1 degree C
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air has a _____heat capacity
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low!
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water has a _____ heat capacity
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high
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