94 
Journal of Agricultural Research 
Vol. IX, No. 3 
The value for K is sufficiently constant to create a strong probability 
that Mitscherlich’s mathematical expression (7) represents the relation 
between the quantity of roots supplied with an element and the amount 
absorbed. The results may therefore be taken as further proof that 
Mitscherlich’s formulation of the law of minimum is correct for ideal 
conditions. 
SUMMARY 
Tests were conducted in water cultures to see whether a plant could 
absorb a maximum amount of one mineral element which was supplied 
to only part of the roots if all other essential elements were supplied to 
all the roots. The absorption of nitrogen with rice and corn and of 
phosphorus, potassium, and iron with rice was tested in this way, one- 
half the roots being maintained in a nutrient solution lacking one of 
these elements. Tests were also conducted, varying the portion of roots 
in the complete and incomplete solutions. 
The results show that, under the conditions described, the plant does 
not absorb a maximum amount of the element, and the fewer the roots 
supplied with the element, the smaller the total amount absorbed. This 
applies when the total amount of the element supplied is equal to or in 
excess of the needs of the plant. A curve was plotted showing approxi- * 
mately what portion of the maximum absorption can be expected with 
any fraction of the roots supplied with the element. With nitrogen and 
phosphorus the total amount absorbed by plants with half their roots 
in the complete solution was 0.76 of that absorbed by plants with all 
their roots in the complete solution. The similar figure for potassium 
or iron was 0.66. Increasing the concentration of the element in ques¬ 
tion in the complete solution did not appreciably alter the results. 
The amount of the element absorbed per gram of roots increased 
greatly as the number of roots in the complete solution was diminished. 
The results are explained on the basis of the rate of utilization and 
transference of the elements in the plant. 
Attention is called to the bearing of these results on the method of 
applying fertilizers. 
The results obtained agree with MitscherliclTs formulation of the law 
of mimimum. 
LITERATURE CITED 
(1) Faack, Karl. 
1913. Untersuchungen fiber die Rolle einzelner Nahrstoffe im Haushalte 
hdherer Pflanzen. In Mitt. Landw. Lehrk. K. K. Hochsch. Bodenkul. 
Wien., Bd. 1, Heft 4, p. 443-509, 1 fig. Literaturverzeichnis, p. 509. 
(2) Frank, B. 
1893. Die Assimilation des freien Stickstoffs durch die Pflanzenwelt. In 
Bot. Ztg., Abt. 1, Jahrg. 51, Heft 9, p. 139-156. 
(3) Gils, P. L. 
,1913. Lime-magnesia ratio as influenced by concentration. Porto Rico Agr. 
Exp. Sta. Bui, 12, 24 p., 4 pi. 
