Soil Temperature

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Soil Temperature

• NRSC 200

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Heat energy balance
Solar Radiation
Reflection
Thermal radiation
Heats soil air
Evapotranspiration
Night time
Day time
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Factors influencing heat absorption COLOR
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Aspect (angle of incident radiation)
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Reflection thermal radiation
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Frost heave
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Two related but distinct- concepts of soil
temperature
Thermal conductivity (K)
Heat capacity (c)
and
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Heat capacity (c) of the soil

• Soil heat capacity (or specific heat)
• Energy (calories or joules) required to raise the
  temperature of 1 g mass by 1 degree C.
• Some specific heat values
• Water 1.0 cal g-1 oC-1
• Humus 0.48 cal g-1 oC-1
• Quartz 0.20 cal g-1 oC-1
• Kaolin Clay 0.23 cal g-1 oC-1
• This means that it is about 5 x as hard to heat
  water as it is to heat dry soil (1.0 / 0.2 5)

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wall o water
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Calculating the heat capacity of a moist soil.
BOX 7.3 in text
Where c1 and c2 are heat capacities of dry soil
and water, and m1 and m2 are masses of dry soil
and water
Example Consider the heat capacity of a soil at
30 water content (i.e. 30 g water per 100 g dry
soil).
This means the dry soil will warm up in spring
nearly twice as fast as the moist soil (0.2
compared to 0.38).
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Energia house
Using the heat pump principle to harness soil and
water heat capacity
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Nuclear power?
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Two thermal phenomena make the foreground a poor
site for the cherry orchard.
Air drainage heavier cold as slide down slope
and collects in low spots.
Cherry orchard in MI
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Wind power in reverse!
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Light color -- high albedo Dry soil low thermal
conductivity
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The thermal conductivity (K) of soils
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The thermal conductivity (K) of soils
t1
t1
t1
t2
t2
Compact, wet High K
Compact, dry medium K
t2
Loose, dry low K
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Pair Share!
Explain what are these strange looking barns
along road in Idaho?
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Thermal conductivity (K)
Heat capacity (c)
and
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oC
oC
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Snow as insulator
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• Mulches
• Plastic
• Black
• Clear
• Organic
• Straw
• Compost
• Etc.

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33oC
43oC
37oC
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Effect of plastic mulch on soil temperature
http//www.fftc.agnet.org/library/image/eb332f4.ht
ml
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Mean daily temp.
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Effect of tillage on soil temperature
http//www.progressivefarm.com/html/figure2.html
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Enjoy the warming springtime soils!
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Extra slides follow
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http//aggie-horticulture.tamu.edu/extension/vegha
ndbook/appendix/table5.html
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Late fall on the high plains
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