OUR INVESTIGATIONS FROM 1898 TO 1901. 



GENERAL CONDITIONS. 



OBJECT OV TESTS. 



We have called attention on pages 323 and 327 to the methods 

 of using stable manure which are often practiced by gardeners 

 in forcing lettuce and to the investigations bearing upon this 

 subject which were published in Bulletin 146 of this Station. 

 The experiments which are now reported form a portion of the 

 series of investigations begun in 1895 concerning the selection 

 and preparation of soils for forcing lettuce and the economical 

 use of stable manure and commercial fertilizers for this crop. 

 In the fall of 1898 the experiments were directed to the question 

 of the use of nitrogenous fertilizers. It was decided to try com- 

 mercial nitrogenous fertilizers for forcing lettuce both with and 

 without stable manure. Director Jordan assisted in formulat- 

 ing the plans for testing th('se fertilizers. His counsel has also 

 been sought at various times during the progress of the work. 

 In the fall of 1900 Mr. Hasselbring became associated in the 

 work. He has assisted in taking notes and in preparing this 

 account of the experiments for publication. 



THE HOUSE. 



The experiments were conducted in the forcing house which 

 had been used for the preceding investigations. Its arrange- 



