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Research Bulletin No. 3 
of soil water available to plants, for growth and for the main- 
tenance of life, is approximately equal to the free water — the 
difference between the total water and the hygroscopic coefficient 
— in those portions of the soil and the subsoil occupied by the 
roots. For some plants the available water appears to be some- 
what greater and for others somewhat less than the free water. 
