Cultivation of Carrots and Cabbatjes. 217 
and green crops ; while Dr. Voclcker's recent investigations, 
reported in tlie paper referred to, tend to show tliat a large pro- 
portion of nitrogen in such crops is rather an indication of their 
immaturity than of their feeding value. The Doctor observes on 
this point : — 
" Kot many years ago a high percentage of nitrogen in hay, tnrnips, man- 
golils, and otlier kinds of agricultural produce, was regarded as a proot of their 
superior nutritive value ; but a thorough investigation, which I undertook on 
account of the frequent discrepancies in the calculated theoretic nutritive value 
of various articles of food, and the value assigned to them by practical men, 
has shown me that the higher proportion of nitrogen in one of two samples of 
hay, turnips, mangolds, &c., by no means indicates a higher feeding value, but 
the very reverse. I have been actively engaged for more than three years with 
an inquiry into the changes which roots nndergo in their various stages of 
growth, and especially when they approach maturity." 
I know that Dr. Voelcker's opinion is that the practical 
feeding value of different foods depends more on the relative 
amount of sugar than of nitrogenised matters. In his very 
instructive pamphlet ' On the Chemistry of Food,' he thus writes 
of cabbage : — 
" Indeed, no kind of «7rcew"'food cultivated on a large scale in the field con- 
tains so much nutritious matter as cabbage. Being much more nutritious, 
weight for weight, than turnips, and at the same time very succulent, cabbages 
form a valuable food for milk cows. Cattle are very fond of cabbage, and 
dairy cows fed on it and some haj' produce much and rich milk, and the butter 
made from the latter is free from the disagreeable flavour which it always 
has when cows are fed npon turnips. Cabbages, for this reason, are a 
valuable substitute for turnips, and dcs-^rve to be more extensively cultivated 
in England than they are at present." 
Dr. Voelcker states, in a letter to. me, that "one ton of dry 
matter of carrots is worth more than a ton of the dry matter of 
cabbages." 
Having disposed of our first inquiry, the second, as to tire 
comparative produce of food per acre, will receive various esti- 
mates in different parts of England. Every farm will, ho\\ ever, 
in the course of three or four crops, show what is its average 
acreable produce of cabbages, carrots, mangolds, and turnips. 
Dr. Voelcker has observed, in reference to the farm attached 
to our Agricultural College, which my farm joins, " the cal- 
careous soil in the neighbourhood of Cirencester, on the whole, 
is not favourable to the growth of these roots (parsneps and 
carrots), it being in most instances too stony and shallow." Yet I 
have grown 32 tons of the white Belgian carrot, the roots weighed 
Avithout the tops, and the tops, weighed separately, amounted to 
7 tons, — about 35 tons of mangolds, exclusive of leaves, and 24 
tons of swedes per acre. These crops were on fields in which 
we could plough seven or eight inches without meeting any 
