286 SOILS: PROPERTIES AND MANAGEMENT 



and during a good part of the time attained a difference 

 of 10 per cent. The effect of this was to reduce evapora- 

 tion by from 53 to 63 per cent on different days in July, 

 in spite of a higher temperature inside the tent. (3) The 

 direct effect of this was to increase the moisture content 

 in the soil in spite of a larger crop growth under the tent. 

 These differences are shown by the following curves (see 

 Fig. 45), which represent the percentage of water in the 

 soil to a depth of nine inches from June 13 to August 1. 



Fig. 45. — Curves showing the percentage of moisture in a sandy soil to 

 the depth of nine inches inside and outside of a loosely woven tent 

 over a period of about fifty days. Heavy line, moisture inside of 

 tent ; broken line, moisture curve of soil outside of tent. 



Not only was the tent effective in preventing evapora- 

 tion and thereby increasing the average moisture Content 

 of the soil, but the soil was able to maintain a more uni- 

 form content, due to the freer movement and adjustment 

 of the capillary water under the tent — conditions more 

 conducive to rapid crop growth. 



204. Level cultivation. — The velocity of the wind 

 next to the ground may be checked by ridging the soil. 

 It is doubtful whether this practice conserves moisture, 



