Journal of Agricultural Research 



possible in all cases to determine how well crops will grow in a soil of 

 known alkali content. 



In view of the great practical importance of the subject as well as its 

 scientific interest, considerably more information should be gathered on 

 the relation of alkali in soils to crops. The limits of endurance of each 

 crop for each salt in the different kinds of soil should be fixed with much 

 greater exactness. 



It was in response to this need that the work reported in this article 

 was undertaken. 



REVIEW OF THE LITERATURE 



The effect on plants of the salts classed as alkali has been the subject 

 of much investigation, but the greater part of this work has been done in 

 solution cultures rather than in the soil. By using water cultures an 

 attempt has been made to limit the great number of factors that exist 

 in the soil, where some of the salts are neutralized and others are absorbed. 

 The work of Loew (i6),^ Kearney (12-14), Harter (7, 14), Cameron 

 (5, 13), Breazeale (1-2, 5), Dorsey (6), Osterhout (20-21), True (26), 

 McCool (18), and others in this country and numerous workers in Europe 

 has added many facts to our knowledge of the action of single salts and 

 balanced solutions on plants grown in water cultures. These workers 

 have shown the great toxicity of salts Hke magnesium when used alone 

 in a water culture and how this toxicity may be reduced by the presence 

 of other elements. 



The facts obtained in these experiments have increased our knowledge 

 of plant physiology and the fundamental nature of alkali; but conclu- 

 sions drawn from them should not be too definitely applied to the action 

 of alkali as it is found in the soil. 



For example, in solution cultures the salts of magnesium when present 

 alone are very toxic, while if added to a normal soil they are no more 

 toxic than a number of other salts. Again, Kearney and Cameron (13) 

 concluded from their work with solutions that "the toxic effect of inju- 

 rious salts is due very much more to the influence of the cathions (derived 

 from the basic radicle) than to the anions (furnished by the acid radicle)." 

 This may be true for solution cultures, but it certainly does not always 

 hold for salts added to soils, as the results in the present paper will 

 show. 



It is desirable, therefore, in studying the effect of soil alkali on plants 

 to use soil as a medium in which to grow the plants, even though it is 

 somewhat difficult to watch all the factors involved. 



In 1876 Toutphoeus (9), and Henri Vilmorin (9) about the same time, 

 published results of experiments showing that chemical fertilizers when 

 added to the soil in too large quantities inhibit the germination of 

 seeds. 



' Reference is made by number to " Literature cited," p. s^-S3- 



