22 FUNDAMENTALS OF AGRICULTURE. 



whenever a dry period comes on. It is of greatest 

 importance, of course, in those sections of the country 

 where the rainfall is light and the so-called dry farming 

 is based largely on a thorough use of this system of 

 mulching. It is, of course, necessary that the culti- 

 vation be not deep enough to injure the fine roots 

 of crops which often come comparatively near the sur- 

 face, especially during a wet season. Cultivation 

 should, therefore, be sufficiently shallow to escape this 

 danger. 



How to Influence Upward Movement of Capillary 

 Moisture. Not only is it possible in this way to pre- 

 vent the loss of moisture, but it is also possible to in- 

 fluence the upward movement of capillary moisture so 

 that in a dry season when the seed is placed in the soil, 

 moisture can be drawn up to the seed. This can be 

 accomplished by rolling the ground, since this firming 

 of the soil increases the upward movement of the mois- 

 ture. Following the rolling it is necessary again to 

 use the drag to produce the soil mulch so as to prevent 

 the loss of water altogether. 



EXERCISE. What kind of soil water can plants use? Which is 

 better: level or ridged cultivation? Why? 



REFERENCES FOR COLLATERAL READING. 

 THE SOIL. 



Yearbooks of the U. S. Dept. of Agriculture : 



1895 Reasons for cultivating the soil. 



1895 Origin, value and reclamation of alkali lands. 



1897 Some interesting soil problems. 



1899 Soil investigations in the United States. 



1902 The movement and retention of water in soils. 



1908 Soil mulches for checking evaporation. 

 Farmers' Bulletins, Nos. : 



187 Drainage of farm lands. 



192 Barnyard manure. 



262 and 329 Dry farming. 



266 Management of soil to conserve moisture. 



278 Leguminous crops for green manuring. 



320 Reclamation of salt marshes. 



326 Building up a rundown cotton plantation. 



371 Drainage of irrigated lands. 



