1882.] EXPERIMENTS WITH FERTILIZERS. 345 



more strictly scientific character; that they might be successfully 

 directed toward the study of some of the more abstruse problems 

 of soil fertilization and the nutrition of jJlants. It was for this 

 purpose that the special experiments were devised, and their re- 

 sults will form the chief topic of the present article. To explain 

 their plan and purpose I quote briefly from last year's report. 



THE FEEDING CAPACITIES OF PLAKTS. 



The experiments bring us face to face with one of the most 

 important problems with which agricultural chemistry has to deal, 

 the different capacities possessed by different plants for gathering 

 their supplies of food from soil and air, and the effects of different 

 ingredients of plant-food upon their growth 



A vast deal of experience in the laboratory and in the field 

 bears concurrent testimony to the fact, though we are still deplor- 

 ably in the dark as to how or why it is so, that different kinds of 

 plants have different capacities for making use of the stores of food 

 that soil and air contain. Thus leguminous crops, like clover, do 

 somehow or other, gather a good supply of nitrogen where cereals, 

 such as wheat, barley, rye, and oats, would haK starve for lack of 

 it, and this in the face of the fact that leguminous plants contain 

 a great deal of nitrogen, and cereals relatively little. Hence a 

 heavy nitrogenous manuring may pay well for wheat and be in 

 large part lost on clover. 



SPECIAL EXPERIMEXTS UPON THE EFFECTS OF NITROGENOUS 



FERTILIZERS. 



For the systematic study of this question, a special experiment 

 was devised in 1878, and conducted by a number of gentlemen. 

 Similar series were repeated in 1879, and with slight variations, 

 in 1880, and with some further changes suggested by experience 

 in 1881. The plan and purpose of the experiments are set forth 

 in the foUovsdng statements, prepared for the use of experimenters 

 of the season of 1881. 



Special Esperiments for Nitrogen Tests, 1881. 

 EXPLANATIONS. 



The Ohject of this experiment is to test the effects of nitrogenous 

 fertilizers in different amounts and combinations upon the growth 

 of the plant, and inferentially its capacity to gather its nitrogen 

 from natural sources. 



