228 MISCELLANEOUS FARM SUBJECTS 



must be broken by cultivation as soon as possible ; otherwise, evapora- 

 tion will go on so rapidly from the surface of the soil that far more 

 moisture will be lost than was gained through the rain. 



Retaining Moisture in the Soil. When dry land soil has been 

 loosened to a good depth to form a reservoir, and it is porous and 

 fine grained, the water from a rain slowly moves downward through 

 it until absorbed, and each minute grain of earth becomes covered 

 with an invisible film of moisture. 



When these minute grains of soil are in close contact with one 

 another, there is a constant movement of the water in the films 

 surrounding them, the water flowing from a wet grain to a dryer 

 one. After a rain the sun and the wind dry out the surface soil and 

 carry away the moisture contained in it. Then the water from the 

 damper soil below moves upward to wet the surface grains and is in 

 turn evaporated. This movement continues in land not cultivated 

 and extends to a depth of many feet, often, in a dry time, taking 

 out of the soil in a week moisture equal to more than an inch of 

 rainfall. 



When the surface soil is stirred after a rain, the tiny grains are 

 separated so that the water does not easily pass from one to another. 

 The movement of the moisture is checked and evaporation is greatly 

 reduced. Such shallow cultivation is called an earth mulch, because 

 it has a similar effect in holding the moisture in the soil as that 

 effected by a mulch of straw or a covering of boards. 



The dry land farmer's supply of moisture for his crops depends 

 upon his skill and judgment in maintaining an earth mulch over 

 his cultivated fields. No set rules can be given. He should study 

 the principles governing the absorption and movement of water in 

 the soil, as here given, until he thoroughly understands and ap- 

 preciates them. Tnen he can intelligently conduct the farm opera- 

 tions for maintaining the earth mulch. The deeper the earth mulch, 

 the better it will prevent evaporation from the soil. For cultivated 

 crops a general rule, with many exceptions, is to keep the mulch 

 three inches in depth. With trees, four to six inches is better. Seeds 

 must be planted below the earth mulch so that they will be in moist 

 eoil and the mulch must not be so deep as to prevent the young 

 plants from coming up. With growing wheat and other grains, 

 the mulch must not be made so deep as to put the roots in dry soil. 



A good rain packs the loose surface soil and destroys the earth 

 mulch. It is necessary to pulverize the ground quickly after every 

 such rain to restore me earth mulch, as a week's delay may mean 

 the loss of water equal to an inch of rainfall. Light showers do not 

 usually destroy the mulch. 



On account of the winds, evaporation is very rapid just after 

 the frost goes out of the ground in the spring and an earth mulch 

 should be established as soon as the ground is dry enough to^ work. 

 Evaporation is very rapid from stubble fields after the grain has 

 been cut, and an earth mulch should be made with a disc harrow 

 as soon as the grain is shocked. Where the surface is hard, the 

 earth mulch will have to be made with a disc harrow; where the 



