18 Maine Agricultural Experiment Station. 1918. 



The Plan of the Experiment. 



The investment of time and money was to be so large that 

 2 years of time looking over literature, consulting with the best 

 soil experimenters by letter and by visits to their operations 

 were used before the final plans were adopted. As these plans 

 are necessarily a compromise and cannot include all that one 

 could wish and as it is hoped that this investigation may extend 

 over many, many years of time the considerations that led to 

 the adoption of the plan are here given in considerable detail. 



The soil can be studied by growing plants in pots and under 

 conditions where the growing conditions — moisture, shade, and 

 the like — are under control or by growing the plants in the 

 field. While there are many advantages in the green house 

 method, if only one of these methods can be employed, the 

 advantages of growing the plants in the field offset its disadvan- 

 tages. 



In soil test experiments as heretofore conducted in this 

 country and abroad the general plan has been to decide some- 

 what arbitarily the amount of plant food to be used per acre 

 and then apply the nitrogen, phosphoric acid and potash, each 

 by itself, in combinations of 2. and finally all 3 combined in 

 these fixed amounts upon the different plots. The great weak- 

 ness in this plan is that one assumes at the start that the amounts 

 of the ingredients decided upon are the amounts best adapted 

 to the crop. A more logical method would be to apply each 

 ingredient to different plots in varying amounts from none 

 up to a point far beyond the amounts that would be likely to 

 prove beneficial. After careful consideration this plan was 

 adopted 



THE TRIANGULAR DIAGRAM. 



The triangular diagram as suggested by Schreinmacher, 

 which has been of great service to physical chemistry where 

 b)th theoretical and practical consideration of percentage com- 

 position of 3 component parts are concerned, has been adapted by 

 Schreinei* to investigations in plant nutrition where it is desired 



— Oswald Schreiner 



*Bureau of Soils, U. ; S. Department of Agriculture Bulletin 70, 

 Botanical Gazette, Vol. 1, No. 1, and elsewhere. 



