51 
Maintenance of Fertility. 
land then in barley, Mr. Prout omitted the usual application 
of nitrate of soda ; its absence was at once told in a much 
diminished crop. The variations shown in carbonic acid are, 
of course, associated with the variations in the amount of chalk 
(carbonate of lime) in different samples. No doubt this 
depends much upon the cultivation, the constant stirring of the 
land causing varying amounts of chalk to become mingled 
with the top soil. One other feature calls for remark, and 
that is, that there would seem to be some diminution going 
on in the amount of vegetable matter in the soil. This is 
what one would naturally expect in a soil thus used continually 
for corn growing, with no farmyard manure applied, but only 
artificials. Yet the amounts still present and supplied by the 
decaying stubble seem to be sufficient. 
As stated, none of the soils exhibit at the present time any 
lack of fertility, while an examination of their physical 
condition shows them to have improved in this respect. 
It may, therefore, be asserted, from the chemical side as 
well as the practical, that the system of continuous corn 
growing, as pursued by Mr. Prout, has brought about neither 
deterioration of the soil nor lessening of its productive power ; 
and, further, that it is a system which, under certain circum- 
stances, may be profitably adopted at the present day. 
Sawbridgeworth, Herts. W. A. PROUT. 
22 Tudor Street, London, E.C. J- AUGUSTUS YOELCKER. 
