HOME MAKURE. 65 



In many cases in which ammonia when first used proyed 

 beneficial, it now begins to lose its effect, and the reason 

 no doubt is, that by its means the phosphates existing in 

 these soils have been reduced in amount, while the am- 

 monia has accumulated, so that change of manuring is 

 needed. 



Artificial Manures. — Farm-yard manure is a '^ gen- 

 eral " manure ; whereas all artificial manures are more or 

 less '^special" manures, some of the most successful of 

 them being deficient in a great many of the most im- 

 portant elements of plant-growth. In addition to the 

 special food-supply yielded by them, they are, as a rule, 

 more active and give quicker returns than farm-yard 

 manure ; so that however rich the latter may be in the 

 constituents of crops, it is impossible, in the present 

 condition of agriculture, to do without large supplies of 

 artificial manures. 



The late Mr. Pusey experimented with a view to dis- 

 coverins: the extent to which farm-yard manure could be 

 profitably used. One acre of land, without manure, 

 yielded fifteen and a half tons of mangels ; a second 

 acre, with thirteen tons of farm-yard manure, }delded 

 twenty-seven and a half tons of mangels ; a third acre, 

 with twenty-six tons of farm-yard manure, yielded twenty- 

 eight and a half tons of mangels ; and a fourth acre, 

 with thirteen tons of farm-yard manure and two hundred 

 pounds of superphosphate, yielded thirty-six tons of 

 mansfels. So that while thirteen tons of farm-yard 

 manure gave an increase of twelve tons in the crop, 

 twenty-six tons of farm-yard manure gave only an in- 

 crease of thirteen tons in the crop, and thirteen tons of 

 farm-yard manure' with two hundred pounds of super- 

 phosphate gave an increase in the crop of twenty and a 

 half tons per acre. 



The artificial manure in this case is shown to have 



