PRINCIPLES OF MANURING

MANURES

AND THE

PRINCIPLES OF MANURING

BY

C. M. AIKMAN, M.A., D.Sc., F.R.S.E., F.I.C.

FORMERLY PROFESSOR OF CHEMISTRY, GLASGOW VETERINARY COLLEGE, AND EXAMINER IN CHEMISTRY, GLASGOW UNIVERSITY; AUTHOR OF 'FARMYARD MANURE,' ETC.

THIRD IMPRESSION

WILLIAM BLACKWOOD AND SONS
EDINBURGH AND LONDON
MCMX

D. VAN NOSTRAND COMPANY
NEW YORK

All Rights reserved

TO

SIR JOHN BENNET LAWES, Bart., D.C.L., LL.D., F.R.S.,

OF ROTHAMSTED,

AND

SIR J. HENRY GILBERT, M.A., LL.D., F.R.S.,

FORMERLY SIBTHORPIAN PROFESSOR OF RURAL ECONOMY,
UNIVERSITY OF OXFORD,
WHOSE FAMOUS INVESTIGATIONS DURING THE LAST FIFTY YEARS
HAVE SO LARGELY CONTRIBUTED TO BUILD UP
THE SCIENCE OF MANURING,

THIS WORK,

EMBODYING MANY OF THE ROTHAMSTED RESULTS,
IS DEDICATED.

PREFACE.

When the present work was first undertaken there were but few works in English dealing with its subject-matter, and hardly any which dealt with the question of Manuring at any length. During the last few years, however, owing to the greatly increased interest taken in agricultural education, the demand for agricultural scientific literature has called into existence quite a number of new works. Despite this fact, the author ventures to believe that the gap which the present treatise was originally designed to fill is still unfilled.

Of the importance of the subject all interested in agriculture are well aware. It is no exaggeration to say that the introduction of the practice of artificial manuring has revolutionised modern husbandry. Indeed, without the aid of artificial manures, arable farming, as at present carried out, would be impossible. Fifty years ago the practice may be said to have been unknown; yet so widespread has it now become, that at the present time the capital invested in the manure trade in this country alone amounts to millions sterling. It need scarcely be pointed out, therefore, that a practice in which such vast monetary interests are involved is worthy of the most careful consideration by all students of agricultural science, as well as, it may be added, by political economists.

The aim of the present work is to supply in a concise and popular form the chief results of recent agricultural research on the question of soil fertility, and the nature and action of various manures. It makes no pretence to be an exhaustive treatise on the subject, and only contains those facts which seem to the author to have an important bearing on agricultural practice. In the treatment of its subject it may be said to stand midway between Professor Storer's recently published elaborate and excellent treatise on 'Agriculture in some of its Relations to Chemistry'—a work which is to be warmly recommended to all students of agricultural science, and to which the author would take this opportunity of acknowledging his indebtedness—and Dr J. M. H. Munro's admirable little work on 'Soils and Manures.'

In order to render the work as intelligible to the ordinary agricultural reader as possible, all tabular matter and matter of a more or less technical nature