Soils Chapter #4: Soil Climate


Radiant Energy

Radiant Energy & Heat Dissipation

The intensity of heating depends on the soil's...........


Material Density
Specific Heat Capacity*
Quartz 2.6 0.5
Rocks, (hard)
basalt, slate
2.4-2.5 0.5
Rocks, soft
1.8-2.0 0.3-0.4
Sand, dry 1.5 0.3
Sand, 40% water 1.9 0.7
Water 1.0 1.0
Air 0.001 0.003

  Thermal Properties of Materials


*Specific Heat Capacity: Amount of heat necessary to change the temperature of 1 gram of that substance 1oC






Soil temperature profiles fluctuate during
the day, especially in bare soil.



Movement of Heat Through Soil

Heat flows more rapidly through some media than others


Temperature gradient


Heat capacity and thermal conductivity in soils depend mostly on the soil's water content

           (A) Heat Capacity
          (B) Thermal Conductivity (K)
























    Turbulence will increase heat transfer







Controlling Soil Climates














Management of Soil Temperature

  • cultivation
  • heat capacity and thermal conductivity
  • mulching
  • transparent coverings can lead to large increases in soil temperature by.........





Lowering soil temperatures is sometimes desirable




Plant Process Optimum
Temperature (oC)
Wheat seed germination 4-10
Bedding plants seed germination 21-24
Pea seed germination 24
Corn seed germination 35
Minimum for corn seed germination 7
Root growth for most plants initiated 4-10
Cool-season grass roots stop growing 24*
Optimum potato growth 16-21
Optimum apple tree growth 18
Optimum citrus tree growth 25


* Cool Season Turf Grasses


Cool-season grasses that thrive in areas with cold, freezing winters and hot summers





These grasses grow best at air temperatures of 65-80oF (18-27oC)