LESSONS FROM EXPERIENCE 325 



271. Limited Supply of Moisture. The conditions for 

 crop growth in the dry farm sections are most favorable 

 with one exception. The soils are rich in plant food and 

 the temperatures are favorable, 'but the supply of mois- 

 ture is below the amount commonly considered necessary. 

 A system must, therefore, be adjusted to make the most 

 efficient use of the moisture present. The chief ways of 

 doing this are conserving moisture by careful tillage and 

 the selection of crops and the use of crop management 

 methods that make the most economical use of moisture. 



The saving of a maximum amount of valuable moisture 

 is important to insure plant growth and also to make 

 available the plant food in the soil. Continuous cropping 

 results in low yields, chiefly because the valuable plant 

 food in the soil becomes used up. It is, therefore, neces- 

 sary to make light moisture demand occasionally in the 

 summer time in order that there may be heat, air and 

 moisture present to bring the plant food into condition 

 to be used by growing crops. The common method of 

 establishing these conditions is by means of the summer- 

 fallow. In many sections, the tendency has been to sub- 

 stitute cultivated crops, such as corn or sunflowers, in 

 place of the fallow. Where careful tillage is followed, 

 moisture may be conserved about as effectively in a corn 

 field as in a bare fallow and the feed produced is most 

 valuable in maintaining and adding to the number of 

 live stock kept. It, therefore, seems essential that the dry 

 farm field should be fallowed or planted to an intertilled 

 crop not less than two years in five. 



272. Early Maturing Crops. In many dry farm sec- 

 tions of the West, the heavy precipitation falls between 

 the first of April and the 15th of July. Under this con- 

 dition, it seems wise to plant crops that will make mast 



