June i6. 1919 Sulphates Affecting Plant Growth and Composition 



95 



Table V. — Weight of clover and its percentage of sulphur and nitrogen on the different 

 soils and sand cultures obtained from the different fertilizer treatments 



Treatment. 



Sand .a 



Extract A. 



Weight. 



Per- 

 centage 

 of ni- 

 trogen. 



Extract B. 



Weight. 



Per- 

 centage 

 of ni- 

 trogen 



Extract C. 



Weight.6 



Per- 

 centage 

 of sul- 

 phur. 



Per- 

 centage 

 of ni- 

 trogen. 



Calcium sulphate. . 

 Sodium nitrate. . . . 

 Sodium sulphate. . . 

 Sodium nitrate. . . . 



Sulphur 



Calcium carbonate. 

 Sodium nitrate. . . . 

 Sodium nitrate. . . . 

 Calcium carbonate. 

 Sodium nitrate. . . . 

 No fertilizer 



Gm. 



k54 



49 

 63 



2.38 

 2.56 



2- 54 

 2-35 



Gm.. 

 0.38 



■36 



•24 

 . 22 



Gm. 



I. o 



0.467 



2. 14 



I. 92 

 I. 90 



493 



52 



2. 42 

 1.86 



o A=beaverdam soil or sand; B=Medford loam; C=anteIope-clay-adobe. 



b Plants were not thinned out. There was no growth in sodium-sulphate sodium-nitrate pot. 



It appears that the sulphur increases the nitrog"en content by stimulating 

 the activity of the legume bacteria causing greater nitrogen fixation. 

 The total nitrogen removed from the sulphured soils is three times as 

 great as from the unsulphured soils. These plants, of course, have grown 

 for only two months and whether the mature plant would show this 

 same ratio will have to be decided by further experiments. In comparing, 

 the nitrogen and sulphur contents of the clover grown in soil A at two 

 different periods as given in Table VII, there is a decrease in percentage 

 of nitrogen and sulphur from May i to June i . Perhaps the percentage 



