COMMERCIAL FERTILIZERS 525 



of soil. He obtained increased growth in all treated soils 

 on which carrots, beans, celery, lettuce, sorrel, chicory, 

 potatoes, onions, and spinach were grown, the weight of 

 the crops on the treated soil being from 10 per cent to 40 

 per cent greater than those on the untreated soil. On 

 soils that had been sterilized before applying sulfur the 

 effect was much less, from which he concludes that the 

 beneficial effects were due to the influence of the sulfur 

 on the microorganisms of the soil. There may be some 

 question, however, w^hether this conclusion is justifiable. 

 Sulfur was found by BouUanger and Dugardin ^ to favor 

 ammonification in soils. Beneficial effects from the use 

 of free sulfur have also been obtained by Demelon,^ and 

 by Bernhard ^ among others, while von Feilitzen ^ found 

 it to be ineffective as a fertilizer. 



That free sulfur may, under some conditions, exert a 

 beneficial influence on plant growth must undoubtedly be 

 conceded, but how the action is brought about remains to 

 be conclusively demonstrated. Free sulfur is insoluble and 

 cannot be absorbed by plant roots. However it is readily 

 oxidized in soils ^ eventually producing sulfates with bases in 

 the soil and in this form may readily be taken up by plants. 



1 BouUanger, E., and Dugardin, M. Meeamsme de Taction 

 fertilisante du soufre. Compt. Rend. Acad. Sei. Paris, T. 155, 

 pp. 327-329. 1912. 



2 Demelon, A. Sur Taction fertilisante du soufre. Compt. 

 Rend. Acad. Sci. Paris, T. 154, pp. 524-526. 1912. 



3 Bernhard, A. Versuehe uber die Wirkung des Schwefels als 

 Dung im Jahre 1911. Deutsche Landw. Presse. Band 39, p. 275. 

 1912. 



^von Feilitzen, H. Ueber die Verwendung der Schwefel- 

 blute zur Bekampfung des Kartoffelschorfes und als indirektes 

 Dungemittel. Fuhling's Landw. Zeit. Band 62, Seite 7. 



2 Mares, M. N. Des transformations que subit le soufre 

 en poudre quand il es reponds sur le sol. Compt. Rend. Acad. 

 Sci. Paris, T. 69, pp. 974-979. 



