EXPERIMENTS WITH NITROGEN FERTILIZERS 23 



When this comparison of nitrogen fertilizers was begun, the manufacture of 

 nitrogen compounds from nitrogen in air was impractical because of high cost. 

 At the close of the comparison, such compounds were being made in enormous 

 quantities. At the present time, synthetic fertilizers are being produced from 

 atmospheric nitrogen at such low cost that those used in these experiments may 

 become obsolete in practical agriculture. 



The value of Field A to agriculture is its history of the diversity of results. 

 Back of any subsequent work upon it are authentic records of each plot, of which 

 no similar records were to be had when the field was laid out. 



There is now nearly ended a comparison of a succession of graminaceous 

 crops with rotations in which such crops alternate with legumes. The experiment 

 is directlj^ dependent upon the records of the plots without nitrogen, from which 

 more nitrogen has been removed in crops than adjoining plots have received in 

 fertilizers. 



Field ex-periments should be planned primarily to afford the investigator an 

 opportunity to test under practical conditions, on a small inexpensive scale, those 

 theories, principles, and processes which have been developed under controlled 

 conditions in the laboratory and vegetation house. To depend upon such ex- 

 periments to furnish the information and data upon which practices and theories 

 may be based and developed is not justified and is sure to prove disappointing. 

 Where such work has been continued for a long period of years without change, 

 it has resulted in the accumulation of a large mass of records which could not 

 be interpreted in terms of much agronomic value. An intelligent program 

 requires variation in the details of treatment and management in conformity 

 with the changes in economic conditions operating in those relationships. 



(The main redeeming feature in the plan for field investigation as developed 

 at Massachusetts State College is the evidence of sufficient courage on the part 

 of those in authority to be willing to change the program from time to time to 

 keep pace with new developments in farm and industrial practice. Had it not 

 been for such courage, the few conclusions possible after this fifty-year period of 

 detailed and accurate work would, no doubt, have proved more limited. F. J. S.) 



Publication of this Document Approved by Commission on Administration and Finance 

 3M-12-32. No. 6992. 



