24 THE FOOD OF PLANTS CHAP. 



The Soil should not have too much Water 



In order that we may have a healthy growth of 

 plants, the soil should be moist, but not saturated 

 with water, so as to form a swamp. This condition 

 is best obtained when the natural surface of the 

 water is at some distance below the surface of the 

 soil. 



A very simple experiment will enable us to 

 understand this. 



Experiment 18 



Fill a flower-pot with garden mould, first placing 

 some pieces of a broken pot in the bottom, and then 

 stand it in a pail. Now pour water into the pail 

 until it stands at the level of the top of the earth in 

 the flower-pot. 



The water will quickly rise in the pot and turn 

 the earth to mud. 



Now pour the water out of the pail, leaving only 

 two or three inches of water behind, and place the 

 flower-pot in the pail again. 



A great deal of the water will then drain out 

 of the flower-pot, but the earth in it will remain 

 moist as long as there is any water in the pail. 



The earth can evidently soak up the water 

 like a sponge or a piece of blotting-paper. 



To make sure of this, take another pot and fill it 

 with dry earth, and place it in a pail with two inches 

 of water. 



