Soils and Soil Management 



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94b. Rate of Cooling of Dry Soils. The same boxes used in f 93a 

 may be used. Note readings when placed in sunlight at 8, 10, and 

 12. Then put in shade and note the temperature at 2, 4, and 6. 

 Which kind of soil cooled quickest? What soils retained their heat 

 longer? Do the soils that warm quickly cool quickly? What soils 

 would you class as "warm soils?" 



94c. Absorption of Heat by Moist Soils. Use same boxes of soils 

 as above, but add same amount of water to each, and make 

 readings when exposed to sunlight from 8 until 4. The cans or 

 boxes should be weighed at the beginning, and, when through 

 with the test in this experiment, weighed again for results in f 95a, 

 noting loss of weight in each. 



94d. Loss of Heat by Moist Soils. As above in H 94b. The same 

 boxes may be used. 



95. Soil Mulch. The rain falling on the surface 

 causes the many fine lumps of soil to crumble and 

 run together, and leaves the surface covered by a closely 

 compacted layer or crust. This condition of the soil is 

 very favorable for the rapid evaporation of the capillary 

 water. When the surface becomes dry, the water below 

 will move rapidly to the surface and the soil will soon 

 become dry. The thrifty farmer destroys this crust 

 just as soon as the surface layer can be harrowed or 

 plowed. He thus destroys the close capillary connection 

 formed between the surface and sub-surface soil. The soil 

 mulch should be two or three inches thick. (Fig. 36.) 



Fig. 36. How cultivation retards surface evaporation. The position of ground 

 water after fifty-nine days, and the per cent of water in the soil at different 

 depths. The shaded plots were cultivated. After King. University of 

 Wisconsin. 



