PLANTS TAKE UP MOISTURE FROM THE SOIL 17 



stantly giving off water from their leaves. The largest 

 amount is evaporated in the hot sun and when an abun- 

 dance of water is supplied to the roots. Sometimes in a 

 drouth more water is evaporated from the leaves than is 

 being taken in by the roots. If this is continued for some 

 time, the plant wilts. This reminds us that the water in 

 plants gives the soft stems and leaves their stiffness. All 

 the food which the plant takes from the soil must first be 

 dissolved in water. It is estimated that 900 tons of water 

 are evaporated by each acre of corn plants during the grow- 

 ing season. 



In many seasons water is undoubtedly the limiting factor 

 in corn production. It has been found that the total yields 

 of corn for the corn belt may be predicted from the rainfall 

 during the month of July. It has been found that in an 

 average season an additional inch of rainfall retained in the 

 soil during July means an increase of $5,000,000 in the value 

 of the com crop in a single state. 



Unfortunately, rain does not always fall when it is most 

 needed, but by proper tillage and cultivation, large quan- 

 tities of moisture may be conserved until July. 



