TRANSACTIONS OF SECTION K. 787 
During the fifties the volumes of the Association contain several important 
contributions from the two distinguished Englishmen to whom the world’s 
agriculture owes so much, Lawes and Gilbert. Their first contribution was made 
in 1851, and dealt with Liebig’s mineral theory, a subject with which their names 
will always be associated. They drew upon their rich store of experimental data 
to prove that the yield of wheat is much more influenced by ammonia than by 
minerals, and they gave it as their deliberate opinion that the analysis of the crop 
is no direct guide whatever as to the nature of the manure required to be provided 
in the ordinary course of agriculture. With the reservation ‘in the ordinary 
course of agriculture,’ the dictum cannot be questioned, though under the circum- 
stances of the continuous growth of wheat, as has been pointed out, conclusions 
indicated by the analysis of a crop happen to accord, at least approximately, with 
manurial practice. 
Field experiments or demonstrations, which have been such a prominent 
feature of the educational work of the past decade, appear to have been first 
introduced at the meeting of the Association in 1861 by Dr. Voelcker. 
While agricultural subjects have claimed a considerable share of the time of 
the Association, forestry has not been altogether overlooked. As early as 1838 
we find attention being directed to what has of recent years come to be a burning 
question—namely, the maintenance of our timber supplies. At that early date, 
when the industrial development of the country was, comparatively speaking, in 
its infancy, the estimate of our timber requirements was, in the light of present 
experience, amusing in its modesty. Captain Cook estimated that ‘100,000 acres 
of waste taken from the Grampian Hills for the growth of larch would in two 
generations not only supply the ordinary wants of the country, but enable us to 
export timber.’* Assuming a rotation of eighty years, this estimate postulates 
that the produce of some 1,200 acres, of a value of about 120,000/., was sufficient 
to make us independent of foreign supplies. Such is the estimate of 1838; now 
let us turn to the estimate of 1904. Dr. Schlich, in his volume on ‘Forestry in 
the United Kingdom,’ passes in review Britain’s timber requirements, and, after 
making allowance for woods like mahogany, teak, &c., which cannot be grown 
here, he comes to the conclusion that ‘if all these items are added up we find 
that we now pay for imports in timber... the sum of 27,000,000, all of 
which could be produced in this country.’ Assuming as before that the value of 
an acre of mature forest is 100/., it means that our imports are drawn from 
270,000 acres, and to maintain our supplies merely at their present level a forest 
area of more than 20,000,000 acres, worked on an eighty years’ rotation, is necessary. 
Although it has been reserved for the Cambridge Meeting of 1904 to witness 
the delivery of an Address from the Chair of an Agricultural Sub-section, this is 
by no means the first occasion on which an agricultural subject has furnished the 
theme for a Presidential Address. In 1880 the then Dr. Gilbert presided over 
Section B, and chose for his subject Agricultural Chemistry ; in 1894 Professor 
Bayley Balfour inaugurated the work of the Biological Section with an Address 
on Forestry ; while in 1898 the President of the Association focussed the vision 
of all thinking men on the greatest agricultural problem of all—the World’s 
Supply of Wheat. 
German Investigations on the Action of Conservation Agents on 
Farmyard Manure. 
Those who have followed the progress of Agricultural Science in Germany 
must have noticed how much attention has been given during the past ten years 
to investigating the changes that take place in farmyard manure during storage 
under varying conditions. The stimulus and funds for this work have for the 
most part been supplied by the German Agricultural Society, which in 1892 
resolved to carry through an exhaustive inquiry. For this purpose it enlisted the 
' Cook, On the Genera Pinus and Abies. 
* Bradbury, Agnew & Co., 1904, 
