44 BOARD OF AGRICULTURE. 



not be growu ou land entirel}- destitute of the compouiuls of an}- one 

 of the substances, nitrogen, phosphoric acid, sulphuric acid, potash, 

 lime, magnesia or iron.* Oxygen and hydrogen can be furnished 

 from water, and carbon may come entirely' from the air. Nature 

 must have ever}' one of the above ingredients in order to construct 

 phiuts. But if the demand is absohite, what about the supply. To 

 state our former question a little more differently', — what one or ones 

 of these essential ingredients do plants fail to obtain from "run out" 

 soils? 



So long as it is a fact that poor crops are almost always the result 

 of a deficiency of the materials of growth, it is very necessary for 

 us to know just what is deficient, in order that we ma}' supply a 

 larger quantity of the material lacking. 1 have growing this year, 

 on the college farm, a piece of experimental corn. Some of the 

 plots received no manure this year, while others were manured with 

 a mixture containing bones that had been treated with oil of vitriol, 

 potash salts and dried blood. The corn receiving no fertilizer is 

 small and poorly eared, or with no ears at all, while that to which 

 was applied the above mixture is quite tall, and very fairly eared. 

 Had it not been for the drought, the latter would have been nice 

 corn. Evidently the mixture of substances applied furnished an 

 additional supply of those ingredients that were not present in the 

 soil in an available form sufficiently large to meet the demands of a 

 good crop of corn. The mixture contained phosphoric acid (in the 

 bone) , potash (in the potash salts) , and nitrogen (in the dried blood) , 

 as the essential ingredients. Sulphuric acid, lime and magnesia 

 were also present in the fertilizer. Besides the ingredients men- 

 tioned as present in the mixture, the plant took up oxygen, hydro- 

 gen, carbon, silica, chlorine, sodium, iron, and possibly small quan- 

 tities of one or two other substances. Experience has demonstrated, 

 however, that when a fertilizer supplies phosphoric acid, potash and 

 nitrogen compounds, nature can do the rest. To epitomize the 

 whole matter I will make the following statements : 



1. To grow fifty bushels of corn a certain quantity of a certain 

 number of ingredients are absolutely necessary. 



2. The soil and air can always furnish a sufficient quantity of a 

 part of these ingredients, while the supply of others in an available 

 form may become exhausted. 



* Chlorine and silica may be necessary in very minute quantities. 



