New York Agricultural Experiment Station. 33i> 



stable manuro, tbe 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 fertilizerSv 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 1-3 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 



