SSSAJ Grow Your Career with SSSA
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Published in Soil Sci Soc Am J 16:134-137 (1952)
© 1952 Soil Science Society of America
677 S. Segoe Rd., Madison, WI 53711 USA
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by McLean, E. O.
Right arrow Search for Related Content
PubMed
Right arrow Articles by McLean, E. O.
Agricola
Right arrow Articles by McLean, E. O.

The Effect of Humus on Cationic Interactions in a Beidellite Clay1

E. O. McLean2

ABSTRACT

Previous studies of cationic interactions have been made for the most part using relatively pure clay minerals. This has been a logical place to start, but to be of maximum practical benefit in solving agronomic problems sooner or later the resulting principles must be projected back to the natural soils. Too little is known about the relationship between ionic activities in plant media and nutrient uptake. But certainly one would not expect close correlation between these activities in pure clay and nutrient uptake from a soil high in this particular clay mineral unless there were no other substances present which possess exchange properties capable of interfering with activities and interactions caused by the clay mineral. In this connection it is obvious that the effect of humus on the cationic activities and their inter-relationships is of utmost importance.

As a follow-up to a similar study made previously with relatively pure beidellite clay, the present study has dealt with mixtures of 10 parts of the same clay to 1 part of crude humic acid. The activities of K, Na, and Ca in homoionic and in biionic systems were determined using the clay membrane electrode technique.

The results obtained are summarized as follows:

  1. The exchange capacity of the clay-humic acid systems was only 73% of that of the sum of the component parts.
  2. Since the base saturations of the biionic systems were made up on the basis of the sum of the exchange capacities, the actual exchange capacities were exceeded somewhat.
  3. This relatively higher base saturation in the clay-humus systems resulted in higher activities of the cations in all cases than in the clay alone.
  4. In spite of the higher activities in the clay-humic acid systems the interactions of the cations were very similar to those in the clay alone.
  5. If the clay-humic acid systems studied can be considered as somewhat analogous to the situation in the field, this relatively small interference by the humic acid may possibly indicate that information gotten from similar studies with pure clay could be projected with some degree of assurance to a whole soil which contains a predominance of that particular clay mineral.
  6. Evidence is presented in support of the contention that the loss in cation exchange capacity as a result of interaction of the component materials was due to a loss of exchange capacity by the humic acid rather than the obstruction of exchange spots on the clay.

NOTES

1 Research paper No. 1025, Journal Series, University of Arkansas, Fayetteville, Ark. Published with the permission of the Director of the Arkansas Agricultural Experiment Station. Presented before Sections I and II, Soil Science Society of America, State College, Pa., August 28, 1951.

2 Assistant Professor of Agronomy.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
The SCI Journals Agronomy Journal Crop Science
Vadose Zone Journal Journal of Plant Registrations
Journal of Natural Resources
and Life Sciences Education		 Journal of
Environmental Quality
Copyright © 1952 by the Soil Science Society of America.