30 



LOUISE DOSDALL 



1. WATER CONTENT OF SOIL 



(1) Determination of maximum and minimum soil water content 



Two series of Equisetum fluviatile were run from November 4, 

 1916 to December 21, 1916 in soil-water contents varying from 

 roots submerged in water to a holard of 9% based upon the dry- 

 weight of the soil (see table 2). In series A the soil was sifted 

 through a 5 mm. screen to give uniformity while in series B the 

 soil was not sifted. In all other respects the series were dupli- 

 cates. Plants numbered 1 grew in an inch layer of soil covered 

 with three inches of water. Plants numbered 2 grew in porous 

 pots standing in water. The others grew in a four inch layer 



of soil (2500 cc.) in eight inch glazed jars. Buds of approxi- 

 mately the same size and with the same amount of rootstock 

 were used to plant in each pot so that none would have the 

 advantage of a larger stored food supply. The amount of 

 water added weekly was measured and recorded. A set of soil 

 samples was taken every two weeks. 



The plants in No. 5 and No. 6 withered when about 2 inches 

 above the ground while those in No. 4 grew to be 8 inches high. 

 Very few branches were developed and these dried at the tips. 

 The best plants were obtained in No. 1 and No. 2, those growing 

 in mud having slightly more branches than those with the roots 

 submerged. Thus, Equisetum fluviatile demands a high amount 

 of moisture in the soil, the range being from 23% to saturation 

 with the optimum at the highest concentrations. 



