34 SOILS AND FERTILIZERS 



improved by rolling are not improved by subsoiling. 

 The additional expense involved should be considered 

 when subsoiling is to be resorted to. Experiments 

 have not as yet been sufficiently decisive to indicate 

 all cf the conditions most favorable for this practice. 



32. Fall Plowing followed by surface cultivation 

 conserves the soil water, by checking evaporation and 

 leaving the land in better condition to retain moisture. 

 If conditions allow, fall plowing should be followed 

 by surface cultivation. In some localities heavy winds 

 prevent this from being practiced. Evaporation may 

 take place from unplowed land during the fall, and in 

 the spring the soil contain appreciably less water than 

 plowed land. By fall plowing it is possible to carry 

 over a water balance in the soil from one year to the 

 next. 



33. Spring Plowing. When land is plowed late in 

 the spring there has been a loss of water by evapora- 

 tion, and the soil has not been able to store up as 

 much of the rain and snow as if fall plowing had 

 been practiced. 15 Dry soil is plowed under and moist 

 soil brought to the surface. If surface cultivation 

 does not follow, this moisture is readily lost by evapo- 

 ration, good capillary connection of the surface soil 

 and subsoil is not obtained, and the furrow slice soon 

 becomes dry. 



Per cent, of water in 14 



April 25th. Fall plowed Spring plowed 



land. land. 



From 2 to 6 inches 24.7 22.4 



" 6 to 12 " 26.6 2\.i 



" 12 to 18 " 28.8 26.5 



Average difference 2.37 per cent. 



