Influence of Ammonium Sulphate on Plant Growth in 
Nutrient Solutions and its Effect on Hydrogen-ion 
Concentration and Iron Availability. 1 
BY 
LINUS H. JONES and JOHN W. SHIVE. 
With six Figures in the Text. 
Introduction. 
T HE subject-matter reported in this paper is the result of a careful 
investigation of the use of ammonium sulphate in a complete nutrient 
solution as a source of nitrogen for soy beans during the early stages of 
growth. In so far as possible particular attention has been given to the 
effect of ammonium sulphate on the growth of this plant, the effect on the 
solutions in contact with the plant roots, and the influence which this com¬ 
pound has on the availability to the plants of different forms of iron. 
A previous study with wheat (20) along similar lines has been carried out, 
though not so completely. The methods of solution culture followed were 
those of Tottingham ( 37 ) and Shive ( 36 ), and these need not be considered 
here except as found necessary to explain the methods and conditions under 
which the various experiments have been performed. 
The ammonium sulphate was substituted for potassium nitrate in 
twenty representative solutions of the eighty-four comprising the Tottingham 
series, and run in parallel with the same solutions unmodified, all having 
a total osmotic concentration value of one atmosphere. At the end of each 
interval between two successive solution renewals the hydrogen-ion con¬ 
centrations were determined, and it was found that during the early stages 
of growth the plant roots in contact with the solutions containing ammonium 
sulphate cause these solutions to become more acid in reaction; other 
solutions become less acid, as many investigators have previously 
reported. 
Greater differences in plant growth are to be found with different forms 
of iron supplied to the plants in these solutions than with any other factor. 
1 Paper No. 115 of the Journal Series, New Jersey Agricultural Experiment Station, Department 
of Plant Physiology. This paper will appear in Rutgers College Studies, vol. i. 
[Annals of Botany, Vol. XXXVII. No. CXLVII. July, 1923.] 
