INTRODUCTION 



too slowly. The methods used in plowing, har- 

 rowing, and later cultivations fix the productive 

 power of a soil for the season in large measure. 



Control of Soil Moisture. The water in the 

 soil is a consideration that has priority over 

 plant-food in the case of agricultural land. The 

 natural strength of the soil is sufficient to give 

 some return to the farmer in crops if the moisture 

 content is right throughout the season. The 

 plant cannot feed unless water is present; the 

 process of growth ceases in the absence of moisture. 

 One purpose of plowing is to separate the particles 

 of soil to a good depth so that water-holding ca- 

 pacity may be increased. When the soil is com- 

 pact, it will absorb and hold only a very limited 

 amount of moisture. We harrow deeply to com- 

 plete the work of the plow, and the roller is used to 

 destroy all cavities of undue size that would ad- 

 mit air too freely and thus rob the land of its 

 water. Later cultivations may be given to con- 

 tinue the effect of the plow in preventing the soil 

 from becoming too compact, but usually should 

 be required only to make a loose mulch that will 

 hold moisture in the ground, and to destroy the 

 weeds that would compete with the planted crop 

 for water, food, and sunshine. 



[11] 



