92 
Journal of Agricultural Research 
Vol. IX, No. 3 
It is obviously important to apply fertilizers in such a way that, so 
far as possible, all the roots of the plants will be supplied with the fer¬ 
tilizing element. The lateral diffusion of fertilizer salts in the soil being 
small, this can best be done by distributing the fertilizer uniformly over 
the whole area occupied by the roots. Whether a field plant will, with 
a portion of its roots, absorb all the fertilizing element applied depends 
on whether the quantity applied is sufficient for the needs of the plant 
and on various actions taking place in the soil, as leaching, fixation, 
etc. This work shows, however, that the optimum condition will be 
obtained by applying the fertilizer to all the roots. While the plant 
shows a degree of adaptation in its absorption as shown in these tests, 
it is not safe to assume that it will capture all the fertilizer wherever 
applied. 
Pig. a.—Possible relative rates of translocation of an element in plants with one-fourth and all their 
roots supplied with the element. 
In the preceding work it was not shown whether a plant can absorb 
a maximum amount of an element when it is available to a certain 
fraction of all the roots, as the lower, upper, middle, or different parts 
of all the roots. It is to be expected, however, that the results obtained 
in this work would apply equally to this similar condition. If the idea 
is carried a step farther, it would also be expected that a maximum 
absorption would be attained only when all the absorbing cells of a root 
were supplied with the nutrient. 
If the latter assumption is correct, a maximum absorption of the 
mineral nutrients from the soil would depend on all the nutrients being 
available throughout the soil. Since the plant for the most part obtains 
its nutrients from the aqueous film surrounding the soil particles, a 
theoretically maximum absorption would be obtained only when all 
the essential elements were present in all the soil films with which the 
roots came in contact. While this is plainly carrying the results actually 
