STUDIES ON THE RELATION OF AERATION AND CONTINU¬ 
OUS RENEWAL OF NUTRIENT SOLUTION TO THE 
GROWTH OF SOYBEANS IN ARTIFICIAL CUL¬ 
TURE 1 
R. V. Allison and J. W. Shive 
(Received for publication January 15, 1923) 
Introduction 
A study of the literature upon the relation between plant growth and 
oxygen pressure of the root environment shows that this relation is not a 
simple one owing to the complexity of the many variable factors involved. 
On the basis of our present knowledge it would be difficult to specify what 
should be the conditions, with respect of oxygen pressure, for optimum 
growth of a particular species in a given medium. It would be impossible, 
on this basis, to specify optimum conditions for plants in general, since the 
requirement of plants for oxygen in the sub-aerial environment has been 
found so distinctly variable among different species. 
The study here considered has been carried out for the purpose of further 
investigating the need of oxygen through aeration in the root environment 
with special reference to plants grown in sand and solution cultures, and to 
study in particular the effectiveness of a continuous flow of nutrient solution 
and constant aeration of the substratum in meeting this requirement. 
During the progress of the work the importance of considering the oxygen 
supply of the root environment in plant studies became apparent when it 
was observed how rapidly plants under favorable growth conditions are 
capable of exhausting the substratum of its store of dissolved oxygen, this 
being a matter of hours rather than of days when the roots of plants in a 
culture are surrounded by only a liter of nutrient solution which is not con¬ 
stantly aerated. 
Procedure 
The plan of the present experiment, briefly stated, involved a study 
of the growth of soybean plants (variety Manchu) in both solution and sand 
cultures under four distinctly different types of treatment as outlined be¬ 
low. Seed of high purity was obtained for this work through the courtesy 
of the Johnson Seed Farms, Stryker, Ohio. In the arrangement of the 
series, duplicate cultures of each of the four treatments, carrying three 
1 Paper no. 114 of the Journal Series, New Jersey Agricultural Experiment Stations, 
Department of Plant Physiology. 
554 
