92 



Journal of Agricultural Research 



Vol. XVII, No. 3 



Where elemental sulphur and calcium carbonate (CaCOa) were added, 

 0.3 gm. and i gm., respectively, of the above substances were mixed 

 with the soil or sand in each pot before planting. In the control receiv- 

 ing no added nutrients, 25 cc. of distilled water was added. The con- 

 centration of the salts per liter of solution were as follows : 



Gm. per 

 liter. 



Sodium nitrate 0-25 



Sodium sulphate 20 



Calcium sulphate 25 



The salts were dissolved in the same solution when more than one salt 

 was added to a pot. The sand cultures received the soil extract which 

 contained the additional nutrients as required. When the cultures 

 required further moisture, the same amount of water was added to each 

 of the pots. The soil extract was prepared by thoroughly mixing one 

 part of soil with two of water. The solution was allowed to stand over 

 night and then filtered through a porcelain filter. The clear filtrate was 

 sterilized by boiling for 15 minutes. Analysis of the soil solution as 

 given in Table II was made according to a method given by Stewart (25). 



TabIvB II. — Soil constituents found in soil extracts expressed as parts per million of the 



soil extract 



» Soil A=beaverdam; soil B=Medford loam; soil C=aatelope-clay-adobe. 



DISCUSSION OF RESULTS 



On examining the data in Table III it is noted that the weight of the 

 straw grown on soils B and C and receiving sulphur fertilizer is greater 

 than where no sulphur was used. An increase in weight of the crops 

 is also observed in the sand pots receiving additional sulphur over those 

 receiving soil extract plus sodium nitrate. The absence of plant food 

 in the original sand and the use of sterilized soil extract shows undoubt- 

 edly that sulphur acted directly in promoting this growth. The same 

 response of the soil to sulphur leads one to conclude that the sulphur 

 here too has acted directly in promoting the growth. This increase in 

 growth is also accompanied by an increase in sulphur content of the oat 

 straw. In soil A this increase from sulphur application is not obtained. 

 The weight of straw from the pots receiving calcium sulphate, sodium 

 sulphate, and sulphur in addition to sodium nitrate is no greater than 

 from the one receiving sodium nitrate only. In the sand pots receiving 

 added sulphur we find no increase in weight of straw over the one re- 

 ceiving no extra sulphur. This is not surprising when the sulphur content 



