Studied by 0 people
Looks like no one added any tags here yet for you.
what is soil colour?
it gives a lot of clues about the constituent materials of soil (e.g. darker = more organic, red = contains iron, etc.)
what is the munsell colour chart?
shows the different colour hues (specifically differences in yellow and reds in 10 yrs); up/down = different intensities and right/left = different 'chroma'
what is the texture chart?
its units measuring size - size is used to determine whether soil sample is clay, silt, sand and/or a combo; size class shows boundary between other grain size classes
what are the key boundaries of the texture chart?
between gravel and sand (2.0mm), between sand and silt (0.0625mm) and between silt and clay (0.0039mm); clays=mud and granule='fine gravel'
what is a structure?
plants (vegetation needs water and moisture that is dependent on these clumping patterns) and hydrology (water flow and water science)
what does clumping matter?
becausse it affect water infiltration (vertical = water can easily percolate down, horizontal = hard for water to get down)
the amount of water can affect its _____________
behaviour
what are the three types of water in the ground that soil can hold on to?
1. gravitational, 2. capillary and 3. hygroscopic
what is gravitational water?
water percolates and drains through the soil
what is capillary water?
roots grab the water that is surrounding them; this water is really good for plants and sticks around for a bit after rainfall
what is hygroscopic water?
water is adhered to the soil so well that it is generally not available to plants.
what are the main soils in canada?
chernozems, cryosols, podzols (fairly acidic forest soils) and solonetz (a lot of salt - not as productive as chernozems)
what is soil a combination of?
climate, vegetation, topography, humidity; all influence the type of soil you'll get
what is soil erosion a problem of?
soil production
what are the different types of soil erosion?
wind, water driven, sheet wash, rill erosion and gully erosion
what is sheet wash erosion?
water may flow as a sheet across the landscape and the water flows and erodes particals
what is rill erosion?
small rivulets of running water gather together and cut small channels -- shallow drainage lines less than 30cm deep (intermediate stage between sheet and gully)
what is gully erosion?
rills enlarge to form bigger channels too large to be removed by normal tillage -- channels deeper than 30cm deep that cannot be removed by normal cultivation
what happens as soil erodes?
we lose nutrients
what are soils according to dave montgomery?
strategic resources
how much land has been loss (apprx) according to dave montgomery?
about 480 million hectares of land lost
the past we are losing soil is not _____________
sustainable
soil is ____________ according to dave montgomery
self dynamic, self-identifying
bronze age (_________), dark age (__________), classical age (___________), and then modern age (_________)
popularity density rises, popularity density decreases, popoularity density rises and then popularity density rises again
what did thomas jefferson do?
created new plowing system to slow down erosion
when was the soil conservation service established?
mid 1930's
what is the soil conservation service called now?
national resources conservation act
the soil conservation act:
established the soil conservation service, which deals with soil erosion problems, carries out soil surveys, and does research on soil salinity.
did the soil conservative help soil erosion?
did NOT solve soil erosion, but is and was incredibly innovative; soil will NEVER grow at the rate it is destroyed
erosion rates and soil production:
soil eroded about an inch every 14 000 yrs (500mya), now it erodes an inch every 60 yrs while soil produces 1 inch every 500 yrs
how should we change our agricultural practices?
reduce subsidies for conventional, erosive practices, increase support for no-till practices and prompt practices that increase soil organic matter to both sequsester carbon and improve soil fertility
we are at peak _______
oil
can we make soil faster than nature does?
yes. takes organic matter and labour (adding organic matter BACK into the soil)
by the late 20th century....
1/3 of carbon added to the atmosphere since the industrial revolution came from degraded soil organic matter
GTc means?
gigatons of carbon
how much carbon does global soil emit?
1500 Gtc
how much carbon does global atmosphere emit?
760 Gtc
how much carbon does biomass decay emit?
60 GTc/yr
how much does fossil fuel emissions emit?
7 GTc/yr
capture of:
10% of biomass decay as biochar would offset glibal fossil fiel emissions
what is biochar?
charcoal used for agricultural purposes, bioenergy wastes and agricultural wastes could be converted. It has a lot of surface area and negative charge and so can hold a lot of nutrients on the surface
soil is a mystery: renaissance?
soil is a descipherable mystery
soil is a mystery: 19th centure?
chemical reservoir, medium to be fertilized as needed
soil is a mystery: modern machinery?
an industrial commodity to be used
soil is a mystery: finally?
soil is an ecosystem to be understood and worked with
restoring soils can help:
feed the world, climate change and public health
what is water storage?
storage of water on planet and movement of water between the "stores"
what are basic locations of water storages?
atmosphere (water vapour, clouds, etc.), surface of earth (oceans (not freshwater), lakes, glaciers) and ground (rocks, fissures, empty spaces in the rocks, soil)
what is the snowmelt run off?
water than runs off land surface into lakes,r ivers and oceans (as if in "storage)
snowmelt runoff precipitation:
any source reaching the ground (rain, snow, frost)
snowmelt runoff interception:
water being prevented by reaching the surface by trees/grass (doesn't land on ground, intercepts the rainfall and lands on leaves)
what is surface storage?
water held on the ground storage (puddles)
surface storage infiltration:
water sinking into soil/rock from the ground surface
what is soil mositure?
water held in the soil layer
what is percolation?
water seeping deeper below the surface
what is groundwater?
water stored in the rock
what is transpiration?
water lost through pores in vegetation
what is evaporation?
water lost from ground/vegetation surface (liquid to gas)
what is surface runoff (overland flow)?
water flowing on top of the ground -- a high rate of rain that soil can't infiltrate and percolate it fast enough
what is groundwater flow?
water flowing slowly below the water table through permeable rock
what is the water table?
the level below which the ground is saturated with water (the upper level)
what is base flow?
standard flow of water
what is sublimation?
solid to gas
what is porous/non-porous?
empty spaces in pores
what are no-pore spaces?
non-porous, non-permeable (can't get water through)
what are unconnected pore spaces?
porous non-permeable (can't get through readily)
what are connected pore spaces?
porous permeable (can get water through it)
what is porosity?
total volume of empty space in a material (total pore space divided by total volume)
what is permeability?
means water can be transmitted (permeability = r (size of pore spaces, pore connectivity)
what is "flat land"?
micro-topography
what is infiltration capacity?
the maximum rate at which rain can be absorbed by a soil
what is infiltration rate?
rate at which water enters the soil
what does infiltration rate depend on?
water input rate, infiltration capacity (texture fo soil or rock properties -- usually in relation to a dry soil), and moisture content in soil profile
what is the vadose zone?
the unsaturated zone above the water table
what is the groundwater zone?
the saturated zone
the water table....
is the boundary the separates the vadoes and saturation zones
what is throughflow?
water moves relatively quickly to river by surface runoff and throughflow
what is groundwater flow?
the slow movement of water through underlying rocks (follows a sort of pressure flow/path)
what is a drainage basin?
defined by ridges that separate (water) flow into adjacent ones (outlets = where all the water that lands would exist through)
Q(m3/sec) =
area (m2) times velocity (m/s) -- this gives discharge
Q =
stream discharge
what is stream discharge?
stream velocity times cross-sectional area
what is a hydrograph?
measures a stream's discharge over time
what is a rising limb?
a lot later than rainfall
what is lag time?
between when rainfall is happening and when the river is responding
what is the falling/recession limb?
discharge gradually goes back to it's previous base flow
snowmelt graphs _____
go on for longer
what are floodplains?
low flat valleys through which rivers flow (not as fast as the riverflow)
what is agricultural drought?
amount of precipitation at particular location varies year to year about some average, although there may be long-term changes
what is a drought?
period of drier-than-normal conditions that result in water-related problems
what is meteorological drought?
the degree of dryness compared to normal precipitation
what is agricultural drought (definition?)
links meteorlogical drought to agricultural impacts, accounting for soil and plant properties
what is hydrological drought?
related to the effects of dryness on surface and groundwater supplies
what is socioeconomic drought?
connects other types of droughts with their economic consequence
evapotranspiration (ET)
evaporation + transpiration
what is plant transpiration?
natural prcoess by plants
what is relative humidity?
the amount of water vapor present in air expressed as a percentage of the amount needed for saturation at the same temperature
what is dryland farming?
cultivation of crops without irrigation in regions with limited moisture (makes best use of soil moisture from winter precipitation or spring/summer rainfall
dryland farming includes:
wide spacing, strict weed control and crops suited to dry farming practices
what is irrigated farming?
artifical application of water to soil
Note
Flashcard