MANURE, ARTIFICIAL 213 



sivo and more widely distributed substances are dispensed -with in compounding a 

 manure, and those are selected which occur in soils only in minute quantities, a very 

 valuable and efficacious fertiliser is obtained, which possesses the great advantage of 

 containing in a small bulk all the essential fertilising substances of a large mass of 

 home-made dung. 



That the effect which every description of manure is capable of producing depends 

 on its composition is self-evident ; and as the different constituents which gener.illy 

 enter into the composition of manures produce different effects upon vegetation, it is 

 of primary importance to the manufacturer of manure that he should be acquainted 

 with the special mode of action of each fertilising constituent. 



We shall therefore make some observations on the practical effects, and the 

 comparative value, of the various constituents that enter into the composition of 

 manures. 



To guard against misapprehension, we would observe that, in one sense, all the 

 fertilising-agents are alike valuable ; for they are all indispensable for the healthy 

 condition of our cultivated crops, and consequently the absence of one is attended 

 with serious consequences, though all others may be present in abundance. Thus 

 the deficiency of lime in the land is attended with as much injury to the plant 

 as that of phosphoric acid. In this sense lime is as valuable as phosphoric acid ; 

 but inasmuch as lime is generally found in most soils in abundant quantities, or, 

 if deficient, can be applied to the land economically in the form of slaked lime, 

 marl, shell-sand, &c., its presence in an artificial manure is by no means a recommen- 

 dation to it. 



The principal constituents of manures are : 



1. Nitrogen (in the shape of ammonia, nitric acid, and nitrogenised 



organic matters). 



2. Phosphoric acid (bone-earth and soluble phosphates). 



3. Potash (carbonate and silicate of potash). 



4. Soda (common salt). 



5. Lime and magnesia (carbonate and sulphate of lime and magnesia). 



6. Soluble silica. 



7. Humus-forming organic matters (vegetable remains of all kinds). 



8. Sulphuric acid (sulphate of lime). 



9. Chlorine (common salt). 



10. Oxide of iron, alumina, silica (clay, earth, and sand). 



We have here mentioned these constituents in the order which expresses their com- 

 parative commercial value. 



1. Nitrogen. This element may be incorporated with artificial manures in the 

 shape of ammoniacal salts or nitrates, or nitrogenised organic matters. 



The cheapest ammoniacal salt is sulphate of ammonia ; the cheapest nitrate is Chili 

 saltpetre, or nitrate of soda ; hence sulphate of ammonia and nitrate of soda are 'exclu- 

 sively employed by manure manufacturers for the preparation of nitrogenised manures, 

 when no organic refuse-matters containing nitrogen, such as horn-shavings, bone-dust, 

 woollen rags, blood, glue-refuse, &c., are available. 



Nitrogen in any of these forms exercises a most powerful action in manure, espe- 

 cially when applied to plants at an early stage of their growth ; at a later period of 

 development the application of ammoniacal salts or nitrate of soda appears mucli 

 less effective, and sometimes even tiseless. For this reason nitrogenised manures, 

 such as guano, soot, specially-prepared wheat-manures, &c., ought to be applied 

 either in autumn or in spring, immediately after the young blade has made its ap- 

 pearance above ground. 



Ammoniacal salts, nitrate of soda, and decomposed nitrogenised organic matters. 

 have a most marked effect upon the leaves of plants ; they induce a rapid and 

 luxuriant development of leaves, and -may therefore bo called leaf-producing or 

 forcing manures. Grass, wheat, oats, and other cereals, when grown upon soils 

 containing abundance of available mineral elements, are strikingly benefited by a 

 nitrogenised manure ; but, on account of their special action, they ought to be used 

 with caution in the case of corn-crops, and always more sparingly on light than 

 on heavy land ; otherwise, fine straw, but little and an inferior sample of grain, 

 will be obtained. 



As a general rule, ammoniacal salts or nitrate of soda should not be used by 

 farmers in a concentrated state, and exceptionally only. However useful sulphate 

 of ammonia or nitrate of soda may be in a particular case, it ought to be re- 

 membered that generally such manures produce beneficial effects only in conjunc- 

 tion with mineral matters. If, therefore, a proper amount of available mineral 

 substances does not exist in the soil, it has to be supplied in the manure. Am- 



