42 THE MOISTURE SUPPLY 



CONSERVATION OF MOISTURE 



Whether water is supplied to the land by rainfall, sprinkling, 

 or irrigation, it escapes rapidly by evaporation unless some means 

 are employed to conserve it. The most feasible means of retarding 

 evaporation of moisture from the soil is to break up the surface 

 layer into fine particles so that it will serve as a mulch and prevent 

 rapid evaporation from the undisturbed soil below. The breaking 

 up of the surface can best be accomplished by means of tillage 

 tools (Fig. 21). To be most effectual in conserving moisture, it 

 should be done as soon after a rain or irrigation as the soil reaches 

 workable condition (Fig. 22). The depth of tillage and the particu- 

 lar kind of tool to use will depend upon the crop, the type of soil, 

 and the climate. Deeper tillage is usually necessary in arid than 

 in humid regions. 



Thorough preparation of the soil before planting, so that it 

 is finely divided to a considerable depth, the presence of a large 

 amount of organic matter in the soil, and careful surface tillage 

 following each application of water, whether through rain or 

 irrigation, will enable the growing crop to secure the maximum 

 benefit from the moisture which reaches the soil. It is surprising 

 how much drought some crops can endure if the moisture present 

 in the soil earlier in the season has been intelligently conserved. 



QUESTIONS 



1. In what form can plants make use of plant food? 



2. What is the relation of water to rapidity of growth? 



3. Is irrigation of vegetable crops practicable in humid climates? 



4. What is the most recently developed system of irrigation for garden 



crops? Describe this system. 



5. Contrast the relation of irrigation to crop production in humid and in 



arid regions. 



6. What are some of the chief sources of water for irrigation purposes? 



7. How is the water conveyed from the source of supply to the field to be 



irrigated? 



8. Describe the process of furrow irrigation. 



9. Is the application or the conservation of moisture the more important? 

 10. Describe any irrigation system you have seen. 



