322 Reh'oht of the Houticultuual Dkpaktment of the 



Those portions of soil which received applications of 5 per ct. 

 of manure in combination with the commercial fertilizers always 

 showed a very great increase in yield over corresponding soils 

 which were treated only with the commercial fertilizers. Fur- 

 ther increase in the manure, however, was not followed by a 

 corresponding increase in the yield. 



When soils similar to those under test are used for the first 

 time for forcing a crop of lettuce, much more manure may doubt- 

 less be u'sed with profit than would be profitable where manure 

 has been used abundantly with previous crops. 



Where the use of manure is continued year after year on soil 

 originally not rich enough to force good lettuce the optimum 

 amount may be expected to decline first towards 10 per ct., 

 eventually to approach 5 per ct. 



The amount of manure which may be used with good economy 

 in forcing lettuce varies with the character of the soil and of 

 the manure, and al&o with the differences in prices received for 

 fancy lettuce and ordinary lettuce. For these reasons no definite 

 amount can be recommended. 



Repeated applications of excessive quantities of manure to the 

 same soil are not good economy. Manure is thus wasted and 

 the yield may be reduced. 



Where large amounts of manure were incorporated in the soil 

 for forcing lettuce the yield was increased by compacting the 

 soil. This shows that unfavorable effects which follow excessive 

 applications of manure may be caused in part, at least, by 

 thereby loosening the soil so much as to put it in an unfavorable 

 mechanical condition for the lettuce plant. 



The clay loam used in these experiments has always proved 

 superior to the light sandy loam for forcing lettuce when both 

 were fertilized with equal amounts of stable manure. 



INTRODUCTION. 



In forcing lettuce may nitrogenous commercial fertilizers be 

 used profitably either with or without the addition of stable 

 manure? This is a question of considerable importance to those 



