PREFACE 



During the war period the Division of Agriculture, Botany 

 and Zoology of the National Research Council established a spe- 

 cial committee to attempt the organization of a nation-wide co- 

 operation among the research scientists interested in plant nutri- 

 tion. The project is of fundamental importance, and is to be 

 continued under the new Council. The purpose of this coopera- 

 tion is to hasten the acquisition of definite knowledge regarding 

 the salt requirements of a few representative agricultural plants, 

 and it is hoped thus to accomplish in a small number of years 

 what would usually require many decades. Experimenters are 

 earnestly requested to further this work in every way possible, 

 and it is hoped that at least part of the time of one research 

 worker in each laboratory where this kind of work is carried on 

 may be devoted to this project. If all of the time of one or more 

 persons can be devoted to the work, of course, that would be still 

 better for the progress of knowledge in this field. 



The need for some well-established, correlated, quantitative 

 knowledge of the salt nutrition of plants is clearly appreciated 

 by all students of this important subject, as is also the present 

 almost total lack of such knowledge. Our theories are incomplete 

 and vague, and the experimentation on which they rest has not 

 generally been such as to allow correlation between the different 

 pieces of work. - It is planned that the present cooperation by a 

 large number of experimenters will soon furnish a great body 

 of correlated information regarding the salt requirements of the 

 plants studied ; all workers in the project are urged to follow 

 the methods described on the pages following this preface, to 

 the end that all results obtained may be as truly comparable as 

 possible. While each cooperator will of course be perfectly free 

 to interpret and publish his results as he may see fit, the com- 

 mittee hopes to be able to bring all the contributions together 

 from time to time as the work progresses, so as to build up 

 rapidly a rather complete statement of the salt requirements of 

 each plant that is included in the, scheme. 



It is clear that this project is a physiological one, and that the 

 results obtained cannot be expected to furnish direct and imme- 

 diate information as to the fertilizer requirements of these plants 

 when grown on any agricultural soil ; each soil offers its own set 



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