a-CROTONIC ACID, A SOIL CONSTITUENT 



By E. H. Walters and Louis E. Wise, 

 Biochemists, Soil- Fertility Investigations, Bureau of Plant Industry 



In a preliminary examination of a sample of Susquehanna fine sandy 

 loam soil from Texas, which was made in October, 191 5, by Dr. E. C. 

 Shorey, who was at that time connected with the Office of Soil-Fertility 

 Investigations, an unsaturated organic acid was isolated. In a subse- 

 quent examination of the same soil by the writers this compound was 

 again isolated, and its identity with a-crotonic acid has now been 

 established. 



The soil was taken from an infertile spot in a field near Marshall, Tex. 

 The infertile spots, which are devoid of all vegetation, have been observed 

 for three years in this locality, and the area of these spots is gradually 

 increasing. 



The soil in this district is described as a Susquehanna fine sandy loam, 

 from 8 to 18 inches deep, with an average of about 14 inches (8). 1 The 

 subsoil is a stiff clay of a red color or red mottled with yellow and gray 

 extending to a depth of several feet. The color of the soil is prevailingly 

 gray, but for a few inches above the subsoil it has a reddish cast. Be- 

 cause of the impervious nature of the subsoil, the drainage is very poor, 

 and special methods of soil management, with the object of producing 

 better drainage, have been recommended and to a limited extent prac- 

 ticed. This soil is deficient in lime or other basic material and is very 

 poorly drained. It has also been found to have a high reducing power 

 and a rather low oxidizing power. It therefore seems to present opti- 

 mum conditions for the formation and accumulation of organic acids. 



In the isolation of a-crotonic acid an alkaline extract was obtained by 

 treating the soil with an aqueous 2 per cent sodium-hydroxid solution 

 for 24 hours at room temperature. The extract was made slightly acid 

 with sulphuric acid and filtered. The acid filtrate was then extracted 

 with ether and the ether extract was evaporated to about 200 c. c. and 

 shaken up with a concentrated solution of sodium bisulphite to remove 

 aldehydes or other substances which combine with this reagent. 



The bisulphite solution was drawn off and extracted several times 

 with fresh ether. All of the ether extracts were then combined and 

 slowly evaporated to a brown sirup in a small crystallizing dish. At 

 this point the dish was covered with a watch glass containing ether and 

 maintained at a low temperature on a steam bath. A white crystalline 

 solid gradually sublimed on the watch glass. The sublimed substance 

 was dried between filter paper and recrystallized from petroleum ether. 



1 Reference is made by number to "Literature cited," p. 1045. 



Journal of Agricultural Research. Vol. VI, No. 35 



Dept. of Agriculture, Washington, D. C Sept. 18, 1916 



fk G— 94 



(I043) 



