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Determining by Plant Response the Retention of Nutrient Ions by Soils 1
Author(s) -
Conrad John P.,
Adams C. N.
Publication year - 1939
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1939.00021962003100010004x
Subject(s) - citation , nutrient , library science , mathematics , horticulture , chemistry , computer science , biology , organic chemistry
essential elements have until now been largely determined by the procedures of analytical chemistry. We may logically reason from experimental data so obtained that retention should often be reflected in plant response in the field. To demonstrate retention by plant growth--primarily to make the teaching of this subject more concrete and more appealing--was the object of the writers in starting this study. With the general validity of the method evaluated by the data contained herein, and other similar data, the senior writer has continued to use it as a research procedure in investigating the reactions of a number of nutrient-containing compounds with several soils. The results of these studies will appear later. A method for poisonous substances worked out by Crafts 4 was first tried. By allowing a solution containing a toxic material to drip slowly upon a continuous column of dry soil in a demountable tube, he studied the retention in the various levels of the column. After each column was wet to the bottom, it was sectioned transversely with the successive sections being placed in a series of cannery tins and subsequently cropped to oats. Retention was judged by the injury to the oats. In preliminary trials with this method NaNO~, NH4OH, and (NH~) ~SO~ were used as test solutions. Plant response to the nitrogen contained therein demonstrated the non-retention of NO3 ions, while the NH~ ions were all retained in the very uppermost section of each of the respective soil columns. After these trials, a simplification of the procedure seemed esirable and at the same time possible without materially altering the results. In this simplification the writers have used an interrupted column of soil namely, a stack of pots, the drainage from the hole of one dripping down into the one below. This procedure introduces one more condition that makes it different from field conditions, but it has manifold manipulative advantages. Fig. ~ gives the main features of the procedure. In comparing the two methods, it is evident that practically all of the operations in handling the discontinuous column of pots are necessary, also, in the continuous column of soil with the further disadvantage that in the latter case these must be carried on with wet soil instead of dry. A great number of other manipulations, necessary with the continuous column, are not required in the column of pots.