Field Experiments on Root-Crops. 
367 
to tlic young turnip plants. These are only a few examples, 
sliowinjif how field trials may lead men astray. 
Any one who reads the numerous testimonials which are 
given in good faith by highly respectable men in proof of the 
value of certain artificial manures that are all but worthless, 
must feel convinced] how difficult it is to ascertain^ by solitary 
experiments the money value of manures. 
In the present state of British agriculture the employment of 
artificial manures has become a necessity on most farms, and 
hence it is most desirable that the money laid out for artificials 
should be expended in the purchase of fertilizers which are 
really worth the price at which they are sold, and capable of 
answering the purpose for which they are used. In many in- 
stances farmers do not trouble themselves to enquire what are 
the most suitable fertilizing agents for particular crops on the 
kind of soil upon which the manure is to be used. Consequently 
they are not in a position to buy in the best market the special 
manuring matters which are required for a particular crop. If 
a farmer wishes to lay out money to the greatest ad vantage' in the 
purchase of artificial manures, he should discard the recommen- 
dations of competing manure manufacturers ; he should endea- 
vour to procure at the cheapest rate and in a separate form all 
the various fertilizing substances which are best adapted to a 
particular crop on a given soil, and to prepare himself the several 
mixtures which are sold under various names at a much higher 
price than that at which he can make them. 
•For the foregoing reasons, I have taken no interest in testing 
against each other, in the field, compound artificial manures, pre- 
pared by different makers. My object has hitherto been mainly 
to institute manuring schemes, which are calculated in the course 
of lime to elucidate general principles, capable of being reduced 
to practice by individual farmers. 
Adopting this course in all the experiments that have been 
carried out hitherto under my direction, I have seen no reason 
to deviate from the plan laid down for my own guidance. I trust 
that the experiments on which it is my privilege to report on the 
present occasion will afford useful hints to practical men in 
the selection of the various artificial manures which are required 
by a particular crop. 
Experiments on Swedes in 1869. — The first series of experi- 
ments on which I have to report was undertaken by my friend 
and former pupil, Mr. G. Y, Wall, jun., at the Lizards, near 
Sedgefield, Ferryhill, county of Durham, on a clay loam upon 
the Carboniferous geological formation. The field was divided 
into twelve equal and adjoining plots of of an acre each. 
The twelve plots were treated as follows, as regards manure : — 
