Germination of Forest Trees 



55 



This diagram shows very strikingly the water retaining capacity 

 of these three soils. Not only' do sand and gravel hold less mois- 

 ture at the time of watering hut they lose a much greater per 

 cent, of it in the course of twenty-four hours than does loam. 



Diagram showing : 



□ soil moisture per cent, at time of watering; 

 ■ soil moisture per cent, twenty-four hours later. 



When we consider the amount of air space in these soils and the 

 amount of soil moisture each retains, the fact that loam usually 

 contains a great deal of moisture and very little air space and that 

 gravel contains very little moisture and a great volume of air 

 space is very strikingly shown. 



