76 Elementary Principles of Agriculture 



A 



B 



Fig. 41b. Growth of rye in early spring. A, unfertilized; B, fertilized with 

 nitrogenous fertilizer. The leaching rains had robbed the soil of its nat- 

 ural store of nitrogen. Arkansas Experiment Station. 



ing than similar soils in northern climates. This fact 

 should suggest to farmers in southern climates their 

 need of greater attention to the use of cover crops. 

 (Fig. 41b.) 



QUESTIONS 



1. In what three forms does water exist in the soil? 2. Explain 

 capillary water. Hygroscopic water. 3. Between what per cents 

 of water content do plants grow most vigorously? 4. Can an irri- 

 gated field have too much water? 5. What becomes of the rains? 

 6. What can the farmer do to make use of a greater amount of 

 the average rainfall? 7. About how much water is used for every 

 pound of dry matter made by growing cotton, or corn? 8. Why is 

 soil drainage important? 9. How should open drains be made? 10. 

 What is a tile drain? 11. Why are foot-hill fields more productive 

 than hill fields? 12. Mention several ways of reducing the leaching 

 and washing of hillside fields. 13. Explain the theory of each 

 method. 



