Soils and Soil Management 



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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 f 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.) 



95a. Rate of Loss of Water. Use three-pound tomato cans. 

 Put equal volume of air-dry soil of different kinds in each, and add 

 same amount of water to each. At 4 o'clock each day, note the 

 amount of water lost from each kind of soil during four separate 

 days, and calculate the per cent of total water lost for each day. 

 Record the results as shown in the following table: 



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. 



