WATER OF SOIL IN ITS RELATION TO PLANTS 263 



mon field crops in general covers a range from 60 to 80 

 per cent of the water capacity of the soil. Mayer x 

 placed the optimum moisture content of wheat at 80 

 per cent of the water capacity of the soil, rye at 75 per 

 cent, barley at 75 per cent, and oats at from 85 to 90 

 per cent. Such estimates not only emphasize the range 

 of optimum moisture conditions, but at the same time 

 show the relatively high percentage of moisture necessary 

 for maximum crop growth. 



Granulation has considerable influence on the range of 

 optimum moisture conditions, since the better the granu- 

 lation, the better is the soil able to accommodate itself 

 to changes in water content without disturbance of 

 plant growth. The poorer the tilth of any soil, the 

 narrower does this fluctuating in optimum moisture be- 

 come. In moisture conservation and control a granular 

 soil is one of the first improvements to be aimed at. 

 Drainage, liming, addition of organic matter, and tillage, 

 by leading up to such a condition, increase the effective- 

 ness and economy of utilization of soil moisture. 



pflanzen. Forsch. a. d. Gebiete d. Agri.-Physik, Band 20, 

 Seite 53-109. 1897. 



1 Mayer, A. Uber den Einfluss kleinerer oder Grosserer 

 Mengen von Wasser auf die Entwickelung einiger Kultur- 

 pflanzen. Jour. f. Landw., Band 46, Seite 167-184. 1898. 



