Displacement of Soil Solubles through Plant Roots by Means of Air Pressure as a Method of Studying Soil Fertility Problems 1

The intake of dissolved substances by plant roots growing in nutrient media is a subject of much scientific interest, but the many investigations on this subject have failed to explain satisfactorily the processes by which soil solubles are taken by plant roots and the relation which the nature and concentration of these soil solubles bears to soil conditions and the growth of plants. What is believed to be a new method of procedure for investigating the plant nutrients of the soil and the selective power of the living plant root is described in the following pages. The data obtained by the use of the method seem to justify its consideration as a means of investigating soil-plant nutritional problems. It is hoped that by its use some of the difficulties connected with research in this field may be lessened. Acknowledgment is due Paul J. Kramer (3) a as the idea for devising this method as, a means of studying soil-plant problems resulted from the reading of his article on the absorption of water by the root systems of plants. Briefly, the procedure followed consisted of growing plants in fertilized and in unfertilized soil. Subsequent to the growing of the plants, the tops were cut off and solution forced from the soil through the plant roots by means of ’air pressure and collected as it emerged from the stem stubs. In some eases the plant roots were killed with heat before the soil solution was forced through them. The solution was collected in consecutive portions, two to four in number, usually