ASSIMILATION OF NITROGEN, PHOSPHORUS, AND 
POTASSIUM BY CORN WHEN NUTRIENT SALTS ARE 
CONFINED TO DIFFERENT ROOTS 
By P. L. OIL'S, formerly Chemist , and J. O. CarrEro, Assistant Chemist , Porto Rico 
Agricultural Experiment Station 
INTRODUCTION 
In a former number of the Journal of Agricultural Research, 1 data 
were presented which showed that when the supply of an essential 
element is restricted to a portion of a plant’s roots the amount of this 
element assimilated is diminished. The relation between the fraction of 
the roots supplied and the amount of the element assimilated seemed to 
agree with Mitscherlich’s formulation of the law of minimum. Prac¬ 
tically the same factor was obtained for the assimilation of nitrogen as 
for the assimilation of phosphorus, potassium, or iron. These data, 
however, were all obtained for one general condition—namely, where 
part of the plant’s roots were in a complete nutrient solution and the 
remainder were in a nutrient solution lacking only one essential element. 
No tests were conducted with part of the roots in a solution lacking two 
or more elements. 
The present paper reports work which shows how the assimilations of 
nitrogen, phosphorus, and potassium were affected when half the roots 
of the plant were in a complete nutrient solution and half in a solution 
lacking more than one essential element; when the roots were divided 
between two solutions, each of which lacked one or two elements; and 
when the roots were divided among three solutions, each of which lacked 
one or two elements. 
Only nitrogen, phosphorus, and potassium were varied in these tests. 
It did not seem feasible to attempt to determine how the assimilations of 
calcium, magnesium, and sodium would be affected by localizing the 
supply, since relatively small amounts of these elements are absorbed 
by corn. Moreover, nutrient solutions lacking in these elements would 
probably be unfavorable for root growth. 
METHOD OF EXPERIMENTS 
The methods followed in conducting these experiments were very 
similar to those employed in the tests previously reported. 
Com {Zea mays I,.), was used in all the following experiments be¬ 
cause of the facility with which its roots could be divided among the 
1 Gile, P. L., and Carrero, J. O. absorption of nutrients as affected by the number of roots 
supplied with the nutrient. In Jour. Agr. Research, v. g, no. 3, p. 73-95, 2 fig. 1917. Literature cited, 
P. 94 - 95 * 
Journal of Agricultural Research, 
Washington, D. C. 
yn 
Vol. XXI, No. 8 
July 15, 1921 
Key No. B-17 
(545) 
