Cation Exchange Capacities of Plant Roots as Related to Their Nitrogen Contents
1956
Mclean, E. O. | Adams, D. | Franklin, R. E.
This investigation included a total of 20 agronomic crops grown in gravel cultures to which ⅕ Hoagland solution was applied at regular intervals. In addition, six species were grown at three different nitrogen levels in the culture media, and one of the species was grown for two different lengths of time under the three nitrogen levels. Results obtained indicate that there is a rather high correlation (R = 0.866) between the cation exchange capacities of plant roots and their percentages of nitrogen. In general, as more nitrogen was supplied to a given species of plant via the growth medium, an increase in percentage of nitrogen in the plant was obtained, accompanied by a corresponding increase in the cation exchange capacity of the plant roots. Practical significance of the effect of nitrogen on the cation exchange capacity of plant roots would seem to be that through this mechanism all of the fertilizer and lime elements are inter-related in their effects on plant response. By affecting the exchange capacity of the roots, applications of nitrogen may thereby influence the recently recognized ability of plants to differentially compete with one another and with the soil for phosphate, potassium, calcium, and magnesium.
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