EXPERIMENTS WITH SPECIFIC MANURES. 189 



Conchmons. 



1st, Eveiy description of crop requires an ingredient 

 essential to its production, and without it such crop cannot 

 be raised in perfection. 



2d, If a soil does not contain in itself what is essential to 

 the growth of the plant upon it, it must be supplied throug'h 

 the medium of one or other of the specific manures. 



3d, The essential substance necessary to be added to the 

 soil, may be discovered by consulting- the nature and proper- 

 ties of the plant to be raised. 



4th, Nitrate and ammoniacal substances excel in the pro- 

 duction of straw, grass, or potatoes, and turnip tops, without 

 an equivalent production of grain or bulbs; so these sub- 

 stances should not be ap[)lied alone, but in combination with 

 others containing- phosphates. This is illustrated by the fact 

 that salt-petre refuse and nitrate of soda, applied with g'uano 

 or prepared nig-ht-soil and animal charcoal, improve their 

 individual production, either in quantity or weight, or in 

 both. 



6th, Salts which are sidphates produce grain in larger 

 proportions to their straw, than other salts which are nitrate 

 or ammoniacal. 



Gth, Bone manure, though dissolved in sulphuric acid, 

 may be greatly enhanced in value by the addition of ammo- 

 niacal substances ; hence it is inferred, that substances capa- 

 ble of imparting additional luxuriance to the foliage of 

 plants, largely administer to their necessities, and, combined 

 with phosphates, are highly advantageous. 



7th, Sulphuric acid is eminently beneficial to the potato 

 crop, and, in the experiment on that crop recorded in the 

 Tables, has proved itself a preventative of the disease called 

 " curl," having produced a healthy crop, when, from the 

 same seed, and otherwise treated in the same manner, the 

 other plants of the field were much infected with that disease. 



I am aware that some of these conclusions are mere 

 repetitions of ascertained facts, but truth is never injured by 

 repetition. Perhaps I should have added to the list of my 

 conclusions this one, that farm manure and guano, combined 

 in the proportion of 15 tons of the former to 3 cwt. of the 

 latter, is the proportion in which I have found these sub- 

 stances to succeed best; and as regards farm manure and 

 night-soil, the best proportion is, 25 tons of the former to 

 1;^ cwt. of the latter. This last result, however, may be 



