June i6, 1919 Sulphates Affecting Plant Growth and Composition 



89 



The action of sulphates upon soil bacteria has also been studied. Fred 

 and Hart (9) have shown small increases in the number of soil bacteria 

 and a slight increase in ammonification and carbon-dioxid evolution by 

 adding certain sulphates to the soil. A bacteriological investigation by 

 Janicaud (ij) indicated that sulphur had a favorable influence on the 

 development of bacteria in the soil. Pitz (20) reports no marked effect 

 on the number of bacteria found on agar plates, but he does report an 

 increase in legume bacteria from the use of calcium sulphate. Elemental 

 sulphur caused a decrease in the total number of bacteria that grow on 

 agar plates, but an increase in ammonification was accompanied by a 

 parallel decrease in nitrate formation. Boullanger and Dugardin (4) 

 state that the presence of small amounts of sulphur materially increases 

 the activity of the ammonifying bacteria. Ames and Richmond {2) con- 

 clude from experimenting on relation of sulphofication to nitrogen trans- 

 formation that the increase in ammonia which accompanied the decrease 

 in yield of nitrates when sulphur was oxidized can not be considered as 

 indicative of sulphofication having exerted a stimulating effect on am- 

 monification. A deficiency of base in the soil allows the ammonia 

 formed to neutralize the sulphur and it remains as ammonium sulphate. 



Certain soils in Oregon have responded greatly to the use of sulphur 

 and its compounds. In this locality greater crop production in many 

 cases has resulted from using gypsum than in using lime. Reimer {21) 

 of the Southern Oregon Experiment Station has obtained large increases 

 in alfalfa yield by the use of elemental sulphur. This marked effect 

 from the use of sulphur fertilizers suggested that it would be of interest 

 and practical value to carry on some greenhouse experiments in order to 

 study the effect of sulphur on early growth and composition of the 

 plants, and also to attempt to determine whether it acted directly in 

 supplying the plant with food or functioned in some other way. 



PLAN AND OBJECT OF THE EXPERIMENT 



For this work three Oregon soils, classified as a beaverdam, a Med- 

 ford loam, and an antelope-clay-adobe, and designated as A, B, and C, 

 respectively, in the tables, were chosen. The first was taken mainly for 

 its high sulphur content, the second one because it did not respond to 

 sulphur treatment in the field, while the third did respond to elemental 

 sulphur fertilizer. The results obtained on analysis of these soils are 

 given in Table I. The plants chosen were red clover, oats, and rape. 



Table I. — Percentage of constituents foun in soils 



Constituent. 



Potassium oxid (KjO) 



Phosphorus pentoxid (P2O5). 



Sulphur 



Calcium oxid (CaO) « 



Calcium carbonate (CaCOg)" 



Soil A. 6 SoilB.6 



349 

 183 



1.25 

 . 160 



•034 

 4. 02 

 None. 



Soil C.6 



o. 60 



. 027 



3-24 

 . II 



o Taken from analyses of soil sample when the field experiments were carried on. 

 'Soil A=beaverdam; soil B=Medford loam; soil C= antelope-clay-adobe. 



