176 BOARD OF AGRICULTURE. 



potash-containing silicieus soil constituents ; tliey render 

 thereby inherent sources of plant food move availalile and 

 improve the general physical conditions of the soil by 

 rendering it more mellow and permeable. As a direct 

 addition of plant food, they are .only in exceptional cases 

 of real importance, on account of a more general distribu- 

 tion of lime containing minerals in the soil. 



Marls and clayish marls, free from any perceptible 

 amount of potash and phosporic acid, act in the main sim- 

 ilar to the previously mentioned lime refuse. 



Earthy composts of various descriptions, if applied in 

 large quantities, frequently act very beneficially on exposed 

 portions of the upper part of grass roots, by protecting 

 them against an undesirable exposure to light and atmos- 

 phere, and thereby favoring the formation of new and more 

 numerous shoots. They benefit the inherent stock of plant 

 food only as much as they contain one or more of them 

 in an available condition, which is usually an unknown 

 quantity. Other substances, quite frequently of a mere 

 local interest, might be added to the previous list, if time 

 permitted. 



Most of these raanurial substances, it will be noticed, 

 are only temporary remedies, if any. They assist more or 

 less in economizing existing local resources of plant food ; 

 their general tendency of action defers the time of failures 

 and makes it more ruinous in the end. They may, however, 

 if used intelligently, quite frequently serve as valuable 

 helpmates in a more rational and more comprehensive 

 economical system of manuring grass lands capable of a 

 remunerative improvement. 



No system of manuring any of our farm plants can be 

 pronounced, to-day, efficient, which does not recognize the 

 necessity of compounding our manures with reference to the 

 special wants of the plant under consideration, as far as the 

 different kinds of plant food arc concerned, and at the same 

 time carefully considers its particular botanical and struc- 

 tural characteristics, as far as the duration of growth and 

 the development of leaf and root systems are concerned. 



Grasses are, comparatively speaking, large consumers of 

 plant food. Their long period of growth, supported by a 



