of prob1errtS'-^.o the agronomist, as does also each climate and 

 each plant form. But it seems safe to predict that the correlated 

 system of physiological knowledge that is to result from this 

 cooperation will place in the hands of agronomists and agricul- 

 tural chemists many valuable facts and principles. Upon these, 

 with further experimentation in the field, may be built up a 

 greatly improved system of fertilizer practice and crop rotation. 

 The present project is therefore fundamental to the rational 

 advance of agricultural science and practice. 



The shortage of potassium in this country during war time 

 emphasized the need that our knowledge of the best ways of 

 using fertilizer salts in general should be increased and put on 

 a definite basis as rapidly as possible. This, together with the 

 high price of nitrogen-bearing fertilizer material, gave to this 

 project some of the characteristics of a war-emergency problem, 

 but the problem is exceedingly important and fundamental to 

 agricultural development in general. A concentrated effort 

 toward the building up of a reliable body of American scientific 

 results in this field may be regarded as higjily desirable from the 

 standpoint of national welfare. Also, the fact of cooperation 

 itself should benefit American science very greatly, and it may 

 be hoped that this general method of advancing knowledge may 

 eventually become much more common among democratic peoples 

 than has been the case in the past. Aside from war-emergency 

 matters, this is one of the aims set forth by the President of the 

 United States in his executive order establishing the National 

 Research Council on a permanent basis. 



This project itself contemplates only physiological studies, car- 

 ried on with water and sand cultures, thus avoiding many of 

 the complications introduced when agricultural soils are in- 

 volved. Besides determining as precisely as possible what are 

 the most favorable total concentrations and sets of salt propor- 

 tions for the various developmental phases of the plants studied, 

 it, is planned to include experimental studies of the relative de- 

 grees of^susceptibility to fungus attack Exhibited by the cultures 

 in different solutions. It is also planned to obtain chemical 

 analyses of the plants grown and to correlate these results with 

 the characteristics of the nutrient media used. 



The problem for any single plant is so complicated in itself, 

 and the amount of logically planned and carefully carried-out 

 experimentation required (before even tentative conclusions may 

 be attained) is so great, that it seemed absolutely necessary at 

 the start and for the present to restrict attention to a very few 



