as applied to the Growth of Wlieat. 531 
of dung required by wheat is nitrogen, as contained in nitric 
acid or in ammonia. If this be true in an exhausted soil, where 
the plant can only find its other elements in the soil as it 
gradually crumbles down, or in the atmosphere, it must be still 
more true in practical farming, where they will be supplied 
ordinarily by manures applied to the other crops of each course. 
I must admit, however, that as regards one element of farm- 
yard manure — the woody matter — the experiment is not con- 
clusive, because, though carbon applied as charcoal did not 
operate upon wheat, tlie ligneous matter contained in dung is 
more easily decomposed, and might be operative ; but as between 
the two leading articles of artificial manure, I mean the two 
Peruvian imports, guano and nitrate, it seems entirely con- 
clusive, because it shows that the two ingredients which guano 
does, and nitrate does not contain, whether applied separately, 
or whether in combination with nitrogen, do not increase the 
yield of wheat ; and this is worth remarking, because there exists 
still a latent suspicion that the pungent and compound animal 
excrement must contain more virtue than the inodorous mineral 
salt. 
Their effects, no doubt, will vary relatively with variations of 
heat and moisture ; but for corn crops nitrate appears a more 
certain top-dressing than guano. That it is sometimes more 
profitable is shown by the following experiment of Mr. Caird : — 
In the centre of a 50-acre field, he says, 1 acre was left without manure, all 
the rest of the field receiving 2 cvvts. of Peruvian guano per acre in autumn, 
at the time the seed was sown. The produce of the acre undressed has been 
tested against that of the adjoining acre, which received Peruvian guano, and 
this is the result : — 
£. s. d. 
1 acre, with guano, 32 bushels, 63 lbs. weight per bushel, 
at 6*'. 6d. per 60 lbs 10 18 4 
1 acre, without manure, 25^ bushels, 60 lbs. weight per 
bushel, at 6s. 6d per 60 lbs 8 5 9 
2 12 7 
Cost of 2 cwt. of guano in 1853 1 0 0 
Profit per acre, besides one-fourth more straw 112 7 
The inferiority in the quality of the unmanurod wheat, as shown by the 
weight per bushel, is worthy of notice, as well as the fact that the unmanured 
wheat was a week later in ripening than the other. 
The second experiment was made to test the value of nitrate of soda and 
common salt as a top-Hressing to wheat in spring, and the result in this case 
has been extremely profitable.* The wheat was sown in December, after a 
* It will be observed that, the nitrate having been used as a top-dressing in 
spring, and the guano at sowing time, the two experiments mentioned by Mr. 
Caird do not strictly admit comparison with each other ; nor will Mr. Pusey be 
understood as drawing any general conclusion from them. 
