SOIL WATER 77 



How Plants Drink. It is not easy to see 

 how it can take from 200 to 375 pounds 

 of water to make one pound of dry plants 

 unless one knows something of the way in 

 which plants drink. Only a small amount 

 of this water becomes a part of the structure 

 of the plant. Some plants are very succulent; 

 94 per cent, of the strawberry fruit is sweet- 

 ened water, 90 per cent, of the entire corn plant 

 is water, and 86 per cent, of the entire potato 

 plant is water. 



Even if the crop were 99 per cent, water 

 this would account for only a small portion 

 of the amount that is actually lost from the 

 soil during its growth. Most of this enormous 

 amount of water is lost by evaporation through 

 the leaves. Contrary to the old notion, plants 

 do not feed by sucking up tiny particles 

 of soil. The plant food in the soil is first 

 dissolved in soil water, as salt dissolves in 

 water; this is then drawn up through the 

 roots by a peculiar process of absorption called 

 "osmosis." The soil water drawn up by the 

 roots contains very little plant food; it is so 

 weak that we consider it pure water, and 

 we drink it as it comes from tile drains or 

 wells. Therefore the plant has to draw up 

 a very large quantity of water in order to get 

 sufficient food. 



After the plant has used the food in this very 

 weak fertiliser solution, the pure water is exhaled 

 through the pores of the leaves. Put a geranium, 

 or other potted plant, under a glass jar and note 

 how soon the inside of the jar becomes clouded 

 with the moisture given off by the leaves. The 

 soil in the pot may be covered with oil-cloth or 



