Experiments on the Growth of Wheat. 
209 
consequently of the capabilities of growth without deterioration 
of the respective soils. 
The soil upon which the experiments now to be recorded were 
jnade, is described by Mr. Keary as a " light, thin, and rather 
shallow brown sand loam," but " resting upon an excellent marl 
which contains a large quantity of calcareous matter." And he 
adds that he has invariably found these light sand loams with the 
cbove subsoil " to be most productive and grateful for high farm- 
ing." In such a surface-soil, then, there will be combined the 
easily working qualities and the power of rapidly yielding up 
manurial matter of the so-called " light " soils ; whilst in its 
subsoil, we have much of the native resource of constituents 
and probably the power of absorption or retention of manurial 
matter also, of the so-called heavy soils. Still it is of the 
o;reatest interest, both in a scientific and in a practical point of 
view, to ascertain by actual experiment how far those chemical 
.substances which are employed with success for the increased 
growth of wheat upon heavy soils, can be used with advantage 
upon those of different descriptions : and these experiments are 
therefore of considerable value towards filling uji one gap in our 
knowledge on this subject. 
Here it may be suggested, that one very great desideratum at 
the present time is a few carefully-conducted experiments, not 
on too small a scale, to ascertain the result of the successive 
growth of wheat, on different descriptions of land, both un- 
manured and with a few well-selected artificial manures. How 
comparatively trifling would be the cost and trouble if one 
person only in each agricultural district in Great Britain would 
devote three acres of land in half-acre plots to the continuous 
growth of wheat for a series of years ; one portion being always 
unmanured, one manured with farmyard dung, one with mineral 
manures only, one with ammoniacal salts only, one with both the 
minerals and the ammoniacal salts, and another with rape-cake ? 
Yet such a simple series as this, carefully performed and accu- 
rately recorded, would in a few years furnish us with results 
which would be invaluable both in elucidating agricultural prac- 
tices as they are, and in affording a sound basis for deduction, 
with a view to improvement according to the variations of soil 
and climate. 
It may be well to mention, that with the exception of a sug- 
gestion as to the nature and amount of the manures to be applied, 
and the supplying of some of them from the quantities prepared 
for the Rothamsted experiments, these experiments at Holkham 
have been entirely under the management of Mr. Keary. That 
they have been conducted with extreme care and accuracy is, 
however, to those accustomed to make agricultural experiments 
VOL. XVI. P 
