324 LESSONS IN AGRICULTURE 



pounds of water are necessary. It would, therefore, be 

 impossible to produce a crop year after year on the same 

 dry area. The question is not one of fertility of soil, but 

 of conservation of moisture. 



The conservation of moisture. By the system of 

 dry farming the solution of the problem consists in sum- 

 mer fallowing of the land, which means that the ground 

 is plowed as deep as possible and left to rest and absorb 

 all the rainfall it can. A person with a two-hundred 

 acre farm would by this method use only one-half of his 

 land at a time for crops and allow the other half to 

 lie fallow. A crop every year on all the land would 

 hopelessly dry up all the soil. In addition to the deep 

 plowing and summer fallowing, a loose surface mulch 

 must be kept over the fields to prevent the moisture from 

 evaporating. In this way the twelve or thirteen inches of 

 rainfall, characteristic of many semi-arid regions, is 

 caught and held to supply the moisture for the crop of a 

 single season. 



Certain crops have been bred up to be adapted to the 

 dry farming system, among which are the macaroni 

 wheat, Turkestan alfalfa, dwarf Milo maize, and Swedish 

 oats. At the present time wheat is the principal crop in 

 dry farming. 



Practical Exercises 



1. See Exercise 5, Lesson 46. 



2. How Moisture is Saved by the Dry Earth Produced by 

 Frequent Shallow Cultivation. 



Suspend a tin can from each end of a small stick four- 

 teen to sixteen inches long and balance over a nail driven 

 through a hole at the middle of the stick. 



