New YorkK AGRICULTURAL EXPERIMENT STATION. oon 
stable manure, the latter being used in different amounts on 
different portions of soil. Although stable manure is very rich 
in nitrogen it contains other kinds of plant-food including 
important amounts of phosphoric acid and potash. Besides this 
it adds humus to the soil and changes its physical condition in 
such a way as to modify the soil fertility. For these reasons it 
cannot be classed as a simple nitrogenous fertilizer, and there- 
fore is not comparable as such with the other nitrogenous ferti- 
lizers above mentioned. 
In previous tests where manure constituted 33 1-3 per ct. by 
weight of the soil no increased growth followed the application 
of nitrate of soda but where it constituted but 15.5 per ct. of 
the weight the addition of nitrate of soda was followed by some 
increase in the crop. In view of these facts it was decided to 
try the nitrogenous chemical fertilizers on soils containing 15 
per ct. by weight of stable manure and compare the results with 
those obtained with similar applications ‘to similar portions of 
soil having greater amounts of manure and to others having 
less. For the first crop, therefore, manure in combination with 
chemical fertilizers was used on different portions of soil at the 
rate of 5 per ct., 10 per ct., 15 per ct. and 20 per ct. by weight, 
and on still other portions without chemical fertilizers at the 
rate of 33 1-5 per ct. by bulk. In the last mentioned instance 
part of the soil was compacted very firmly and the rest left loose 
without being shaken or packed at all, the object being to note 
to what extent the growth might be influenced by the difference 
in mechanical condition of the same soil mixture which was 
thus produced. 
For comparison with these, other portions of soil were given 
similar applications of the chemical fertilizers only, while still 
others received nothing. To each portion except the last and 
those which received one-third manure by bulk, phosphoric acid 
and potash were added in liberal quantities. 
The applications, whether of manure or of chemical fertilizers, 
were repeated in each instance for each succeeding crop of let- 
tuce in the same amounts as at first except that after the first 
