94 



Journal of Agricultural Research 



Vol. XVII, No. 3 



Table IV. — Weight of oat seed grown on soil and sand cultures 

 [Percentage of nitrogen is given on oats grown in soils A and B] 



Treatment. 



Soil.o 



Weight. 



Calcium sulpjiate . . 



Sodium nitrate 



Sodium sulphate. . 



Sodium nitrate 



Sulphur 



Sodium nitrate 



Calcium carbonate . 



Sodium nitrate 



Sodium nitrate . . . . , 

 Calcium carbonate . 

 No fertilizer 



Gm. 



[1-63 



I-I-44 



1-45 

 I. 62 

 I. 06 



•34 



Per- 

 cent- 

 age of 

 nitro- 

 gen. 



Weight. 



I. 72 

 1.79 



1. 46 



1-73 

 1.77 



2. 29 



Gm. 



1.25 



I- 13 



.96 



.76 



•52 

 .27 



Per- 

 cent- 

 age of 

 nitro- 

 gen. 



Weight. 



1-73 

 I. 71 



1.79 



2-53 

 2-33 



Ex- 

 tract A. 



Gm. 



0.85 



.92 



.82 



.61 

 .08 

 . 10 



Sand.o 



Weight. 



Gm. 

 O. 67 



•77 



.67 



•55 



Ex- 

 tract B. 



Ex- 

 tract C. 



Gm. 

 O. 71 



•55 



•38 

 •36 



Gnt. 

 O. 64 



.48 



■72 

 .26 



a A=beaverdain soil or sand; B=Medford loam; C= antelope-clay-adobe. 



The results on clover as given in Table V show increased yields in all 

 cases where sulphur was added to the soils. This increase is also seen on 

 the sand cultures receiving soil solutions from soils B and C, but not on 

 the sand receiving nutrients as soil A. The oats grown on soil A, as on 

 the sand receiving extract from A, did not respond to sulphur applica- 

 tion, but the clover did respond to sulphur treatment of the soil. How- 

 ever, the clover growing on the sand and receiving its plant food from 

 the soil extract did not show increased growth where sulphur was added. 

 Naturally one may attribute this difference to some other factor present 

 in the soil which was favorably influenced by the sulphur. Omitting 

 this important factor and observing the weights of the dry material grown 

 in the soil solution, there appears to be enough available sulphur in 

 soil A and in the soil extract to eliminate sulphur as being directly a 

 limiting factor as a plant food, while in the other soils the supply of 

 available sulphur seems to be limited in comparison to the other plant 

 food available. 



It is probable that the other factors acting here are the legume bacteria 

 which are present in the soil but not in the sand. The data in Table VI 

 show the increase in weight of the roots where sulphur was used, and 

 when the roots were examined the number of nodules, according to esti- 

 mate, varied directly as the weight of the roots. The roots of those plants 

 grown in the sand, of course, contained no nodules. Another reason why 

 the bacteria appear to be favorably influenced by the sulphur is the 

 noticeable percentage of increase of nitrogen in those plants grown on 

 soil receiving sulphur while the plants grown on sand do not show this 

 increase in nitrogen content. For this short period of growth the sulphur 

 apparently has a marked influence on the nitrogen content of the clover. 



