THE INFLUENCE OF PHOSPHATES ON THE ACTION OF 
ALPHA-CROTONIC ACID ON PLANTS 
J. J. Skinner and F. R. Reid 
Introduction 
The physiological effects of a-crotonic acid on plants and the action of 
nutrient salts in counteracting these effects have been studied in this labora- 
tory, and are reported in this paper. The investigation comprised a study 
of the effects of the compound on plants grown in pure distilled water and 
in nutrient solutions composed of phosphate salts together with sodium 
nitrate and potassium sulphate. Some preliminary tests of the compound 
were made in soil in pots, but this phase of the subject was not gone into 
exhaustively and the results will not be given here. 
a-Crotonic acid was isolated in this laboratory, ^ first from a sample of 
Susquehanna fine sandy loam soil from Texas. The soil was taken from an 
infertile spot in a field near Marshall, Texas. The infertile spots, which 
were devoid of all vegetation, had been observed for several years in this 
locality; the areas of these spots were gradually increasing. 
The soil in this district is described as a fine sandy loam, from 8 to i8 
inches deep, with an average depth of about 14 inches. ^ The sub-soil is a 
stiff clay of a red color or red mottled with yellow and gradually extending 
to a depth of several feet. The drainage is very poor because of the im- 
pervious nature of the sub-soil. The soil is deficient in lime or other basic 
material and is very poorly drained. It has been found to have a high re- 
ducing power and a low oxidizing power. The conditions for the accumu- 
lation of organic acids seem favorable. 
CH3.CH 
a-Crotonic acid 1 1 is produced from allyl cyanide, which 
HC.COOH 
is a constituent of mustard oil, and it has been isolated from pyroligneous 
acid obtained by the dry distillation of wood.'^ 
Crotonic acid is shown to be very harmful to plants in pure water and 
in nutrient culture solutions. With distilled water the compound in con- 
centrations as high as 200 parts per 'million killed wheat plants; in concen- 
1 Walters, E, H., and Wise, L. E. a-Crotonic acid, a soil constituent. Journ. Agr. 
Research 6: 1043. 1916. 
2 Van Duyne, C, and Byers, W. C. Soil survey of Harrison County, Texas, U. S. 
Dept. of Agr. Bur. Soils. Field Operations, 1912, p. 47. 
^ Kramer, G., and Grodzki, M. Uber die Sauren des Holzessigs und den Zusammen- 
hang derselben mit den sogenannten Holzolen. Ber. Deut. Chem. Ges. 11: 1356-1362. 
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