1894.] PUBLIC DOCUMENT — No. 33. 247 



those with relation to the eftect of the different forms of 

 nitrogen (ammonia salts, nitrates and organic nitrogen) on 

 the yield and character of grain crops and leguminous 

 plants ; * those to determine the economy of using natural 

 and commercial phosphates in the i)roduction of corn and 

 grain crops ; f experiments with permanent grass lands 

 (meadows ) . 



Of late our attention has been turned to a special study of 

 the effect of different forms of nitrogen and potassium oxide 

 on the growth of a series of prominent fruit and garden 

 crops, and the results of two years' observations regarding 

 the latter are already reported in detail upon preceding 

 pages (Field C). 



To explain the striking differences noticed in the yields of 

 some of those crops, in particular lettuce and tomatoes, when 

 raised with the assistance of either muriate or sulphate of 

 potash, it seemed advisable for confirmation of the results to 

 transfer the investigations to the vegetation house, where, 

 under better-defined circumstances, the special eftect of the 

 kind and form of the various articles of plant food supplied 

 could be more clearly demonstrated. A few notes regarding 

 the results thus far obtained are subsequently stated, to 

 invite co-operation on the part of persons interested in the 

 questions involved. 



Observations in the plant house with lettuce and spinach, 

 during the winter of 1892-93, were conducted as follows : — 



The soil used in the vegetation house was a sandy loam 

 taken a few feet below the surface from a locality which at 

 no time had received an additional sup[)ly of manurial matter 

 from an outside source. It was sent through a screen before 

 being used, to remove coarse vegetable matter (roots, etc.) 

 as far as practicable. The beds of the vegetation house 

 were divided into boxes thirty-two inches square and eight 

 inches deep. They were filled with the earth to the depth 

 of six inches, about three hundred pounds being used for the 

 purpose. 



* For details see annual reports of the Board of Control of the Massachusetts 

 State Agricultural Experiment Station for the years 1SS9-93. 



t For details see annual reports of the Board of Control of the Massachusetts 

 State Agricultural Experiment Station for the years 1800-93. 



