362 BOARD OF AGRICULTURE. 



fested when the same combination is suddenly and explosively 

 dissolved ; the diffei-ence being, that the force is expended less 

 quickly and in an entirely different direction. The idea of pro- 

 pelling plants into vigorous growth by the use of gunpowder, 

 may be a novel one to most of you, but it is one which may be 

 followed up without harm. 



If there be truth in the statement, it follows that saltpetre would 

 prove an effective manure ; and the results of its use when given 

 to plants show this to be the fact ; and not only because of its 

 combined nitrogen, but also because of its potash, which, so far 

 as its amount serves, is as good as if it were applied in wood 

 ashes. 



But it happens that the commercial value of saltpetre, for the 

 manufacture of gunpowder, of nitric acid, and for other uses in 

 the arts, is greater than its agricultural value. It follows, there- 

 fore, that it cannot be economically employed as a manure. 



This suggests a train of thought, which may be followed to 

 advantage with regard to various substances and compounds, 

 which are every year coming into more general use for fertilizing 

 purposes, and which may be grouped together under the term, 

 Commercial Manures. Can they all, or any of them, or which of 

 them, be employed with actual gain to the farmer who applies 

 them to his crops ? 



The agricultural value of any substance used for manure is in 

 proportion to its fertilizing efficacy, and determines what the 

 farmer can afford to pay for it. It does not necessarily conform, 

 in any measure,' to the price which the article commands in mar- 

 ket. Nor is it, when ascertained, a fixed amount. It is a vai-iable 

 quantity, less here and more there ; one amount in this field and 

 another in the next ; more on one kind of soil and less on another, 

 or on the same if it has been differently treated or cropped. In 

 some cases, the application of a bushel of gypsum is followed by 

 a return worth two, or three, or five dollars. This furnishes no 

 reason why a dollar per bushel should be paid for plaster, when it 

 can be had for a half, or a quarter of a dollar. Upon other soils 

 the application of gypsum is attended with no benefit whatever ; 

 and this, on the other hand, is no reason why the dealer should 

 sell gypsum below cost, for he may sell to those who do find it 

 profitable to apply to land, or he may sell to those who require it 

 for other purposes. 



In one sense it may be said that all manurial agents arc alike 



