404 NATUEB AND PROPERTIES OF SOILS 



much to retard the sulfur reduction which is constantly oc- 

 curring. Fertilizers, such as acid phosphate, ammonium sul- 

 fate, and potassium sulfate, may also be valuable sources of 

 sulfur. The amount of sulfur carried down in rain-water is 

 largely in the sulfate form and is quite variable, ranging from 

 a few pounds of SO3 yearly to the acre to over 160 pounds. 

 The rainfall addition at Ithaca,^ New York, is about 65 

 pounds of SO3 to the acre a year, while Stewart ^ reports a 

 yearly gain to the acre of 113 pounds at the University of 

 Illinois. The inorganic sulfur of the soil also constantly 

 tends to enter the sulfur cycle and must be reckoned with in 

 any study of sulf ofication. 



222. Loss of sulfur from the soil. — The loss of sulfur 

 from the soil under normal agricultural conditions occurs 

 in two ways: (1) losses in drainage, and (2) removal by 

 cropping. Unless such losses can adequately be met by ad- 

 ditions of sulfur or sulfur compounds, it is obvious that this 

 element will become a limiting factor in crop growth. The 

 figures ^ from the Cornell lysimeters are very instructive in 

 this regard. The soil used was a Dunkirk silty clay loam. 



AVERAGE ANNUAL LOSS OF SULFUR (aS SO3) BY PERCOLATION 

 AND CROPPING. CORNELL LYSIMETERS. AVERAGE OP 10 YEARS. 



Condition 



Pounds to the Aceb op SO, Lost Thkough 





Drainage 



Crop 



Total 



Bare soil 



Eotation 



Grass 



132.0 

 108,5 

 111.0 





132.0 

 149.5 

 140.2 



41.0 

 29.2 



* Wilson, B, D., Sulfur Supplied to the Soil iii Hain Water; Jour. 

 Amer. Soe. Agron., Vol 13, No. 5, pp. 226-229, 1921, 



* Stewart, R., Sulfur in Belation to Soil Fertility; 111. Agr, Exp. Sta., 

 BuL 227, 1920. 



^Unpublished data, Cornell Agr. Bxp. Sta., Ithaca, N. Y. 



