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drainage, and a proper structural development, sufficient or- 

 ganic matter and deep and careful plowing, favor optimum 

 moisture conditions. Sucli moisture regulation means a low- 

 ered specific heat, rapid conductivity, and good convection. 

 The increase of soil organic matter may act directly in heat 

 control by darkening the color and thus increasing absorp- 



FiG. 46. — Curves sliowing the hourly temperature of a bare soil at a 

 depth of four inches and of the air just above the soil in Ger- 

 many, May 26. (Data from Wollny.) 



tion. A soil-mulch, being dry, not only may check evapora- 

 tion but at the same time may lower radiation. 



Any method of handling the land which tends to benefit its 

 physical condition, better its tilth and control its moisture, 

 tends at the same time towards a proper heat control. The 

 whole question may be summarized by saying that, if a farmer 

 adopts a proper system of moisture control and at the same 

 time employs methods that continually encourage a better 



