'2-22 
TliC Present S/a'e of Ac/ricvlfitre 
])revalence of this opinion was fitted to modify agricultural prac- 
tice in the matter of manuring, you will perceive a little not only 
of the practical value of chemical analyses generally, but how 
especially necessary the application of the higliest analytical skill 
really is to any sure progress in scientific agriculture. 
Did time permit, 1 might here, in connexion with this topic, 
satisfy you of the vast amount of work which chemical analysis 
has yet to do for the art of culture. It is conceded that the pro- 
portion of nitrogen in all our crops varies, and it is at present 
believed that their nutritive value varies accordingly; but the re- 
moval of a wrong opinion as to the cause of this variation, and the 
extent of our power over it, does not directly lead us to the right 
one. We have, in fact, still to inquire what are the limits of this 
variation in regard to every crop we grow — how it is affected by 
variety of seed, by climate, by manure, by soil, by mode of hus- 
bandry, by period of growth, by time of cutting or gathering, and 
many other circumstances. I can assure you that ten long and 
laborious lives will be insufficient to com})lete the researches 
which this one branch of the subject demands.* 
I should, however, be guilty of a serious omission ^^ere I to 
pass unnoticed in this place a paper, experimental and analytical, 
on the growth of turnips, by Mr. Lawes, which was published in 
a recent part of the Journal of this Society (vol. viii. p. 494). 
Of this pr.per, fur reasons which may be gathered from what I 
have stated in the previous part of this lecture, I consider the 
analytical of more importance than the experimental jiart, and 
among the analyses those to be of the most interest \a hich indi- 
cate the proportions of nitrogen contained in the turnip when 
aided in its growth by different manures. From these the general 
conclusion appears to be that where a field is in a condition to 
produce an average crop of turnips, the proportion of nitrogen in 
the crop may be increased by an ap])licati()n of manures contain- 
ing nitrogen. I According to Mr. Lawes's results, the proportion 
above v.hat is contained in turnips raised by means of farm-yard 
manure, may, by such application, be doubled. This result, as 
it stands, is very valuable and very interesting both in itself and 
* For a sketcli of some of the practical consequences to which such re- 
searches should lead, see two pamphlets by Sir Geoi tre Mackenzie, Bart., 
entitled ' Biief Remarks on the Growlii of Wheat Ibi- Seed/ and ' A short 
Plea for the Advancement of Scottish Ilusbaiuliy hy Science.' 
t I do not enter inio the refinement which Mr. I^avves endeavours to 
establish between the action of sulphate of ammonia and ra])e cake apj)lied 
sinajly or tcsjjether. It is a pity to si)oii good and fair conclnsicnis by the 
introduction of this and other doubtful refinements which are to be Ibund 
in Mr. Lawes"s papers, which are really valuable, not only for what they 
establish, but more so for what fhcy suggest in (he way of further research 
both in tile field and in the laboratory. 
