Soil Water and Water Quality
- utilization - removal of excess water - distribution of water
The Midwest, water problems are primarily related to:
coarse
What would drain faster, fine or coarse textured soils?
positive
a flooded soil puts a (positive/negative) pressure or potential on the water in the soil
tightly
as soil gets drier, it is held more (loosely/tightly) and thus is harder to pull away from the soil matrix.
ceased
at field capacity, water has _______ to flow out of the soil
loosely
at saturation, water is held (tightly/loosely).
zero
at the boundary between an unsaturated and saturated soil, the pressure or potential is _______
used all the water they can
at wilting point, plants have _______________________
adhesion
dominant force holding water to the soil surface
% water by volume = (volume water in soil/volume of soil) *100
equation for calculating % water by known volume
% H2O by weight = (wt water in soil/wt soil oven dried) * 100
equation for calculating % water by weight
% water by volume (unknown) = % H2O weight * Bulk density
equation for calculating % water for unknown volume
- water content & potential on horizons - soil strength & density - soil depth - root depth - soil layerin
factors affecting the amount of plant-available soil water
capillary rise
flow due to negative potential created by adhesion and cohesion
hydrogen bonding
hydrogen of one water bonding to the oxygen of another water
mulches
keep soil wet and reduces temperature fluctuations
fallow
kept free of plants, keeps more water in soil
double ring infiltrometer
minimizes lateral spreading, ensures downward vertical flow
% H2O FC - % H2O WP = % available H2O
plant available water equation
gravity
pressure disappears after water is drained away under the force of ________.
- leaching calcium - damages structures - speed up acidification of lakes & streams
problems of acid rain include:
transpiration
productive evaporation; builds biomass of plants through photosynthesis
acidic
rainfall water is naturally (acidic/basic)
irrigation
should be done on sandy/shallow soils
adds nutrients back into soil
sulfur and nitrogen from acid rain can be beneficial because:
gravitational flow
synonym for saturated flow
capillary flow
synonym for unsaturated flow
osmotic potential
the force with which an aqueous solution attracts water by osmosis
- matric potential - osmotic potential
the negative potential in soil is provided by these 2 sources:
silt > clay > sand
the order in which we expect to have the most capillary rise over an extended period of time
matric potential
the potential energy generated by the attractive forces between water molecules and soil particles
tension
the same as negative pressure or potential
prescription athletic turf
type of athletic grass that used moisture sensors to indicate root/plant needs and uses heating coils to prevent freezing in the ground water; uses suction pumps to get rid of excess water and has drains & subirrigation present
cohesion
water clinging to water
polar
water is a ______ molecule
both
water molecules are attracted to (negatively/positively/both) charged surfaces
-0.3 bars
water potential at field capacity
-15 bars
water potential at wilting point
- gravimetric - neutron scattering - resistance blocks - time domain reflectometry (TDR) - Tensiometer - watermark monitoring
what are 6 ways of measuring soil moisture?
- reduces frost heaving - reduces risk of damaging soil - increases oxygen in root zone - reduces heat capacity, helps growth
what are some advantages of draining excess water from a field?
- open ditches - tile drains - table control
what are three different drainage systems?
water pressure
what controls the rate of saturated flow?
allows soil to hold onto water
what does adhesion and cohesion allow soil to do with water?
- method of sewage & waste water treatment - reverse soil drainage
what is the purpose of a septic system?
- layers of fragipan - gleying - steep slopes - excessive drainage
what soil properties limit on-site disposal systems?
silt loam, clay loam, clay
which textures can hold the most available water?
concrete & pavements seal off soil so soil can't take in water
why does water move more rapidly in urban environments?
macropores
(micropores/macropores) drain faster under gravity
horizontal
In which orientation does the screen and sponges hold the most water (from demo)?