762 TRANSACTIONS OF SECTION M. 
It is to be hoped that the work of the Agricultural Economics Institute at Oxford 
will throw new light on the interpretation of experimental results from the 
accountancy standpoint. Finally, the soil surveys on which the colleges have 
seriously embarked will assist in defining the areas over which such results are 
applicable. It only remains for those of us who are responsible for the conduct 
of field trials to increase the accuracy of our results, and the steady accumula- 
tion of a mass of systematic and scientific knowledge is assured. It will be the 
business of the advisory staffs with which the colleges have recently been 
equipped by the Board of Agriculture and the Development Commission to 
disseminate this knowledge in practicable form to the farmers of this 
country. 
One more point, and I have finished this section of my Address. I have 
perhaps inveighed rather strongly against the publication of the results of single- 
plot trials. I quite recognise that the publication of such results was to a great 
extent forced upon those experimenters who were financed by annually renewed 
grants of public money. Nowadays, however, agricultural science is in a 
stronger position, and I venture to hope that most public authorities which 
subsidise such work are sufficiently alive to the evils attendant on the publica- 
tion of inconclusive results to agree to continue their grants for such periods as 
may suffice for the complete working out of the problem under investigation, and 
to allow the final conclusions to be published in some properly accredited agri- 
cultural journal, where they would be readily and permanently available to all 
concerned. This would in no wise prevent their subsequent incorporation in 
bulletins specially written for the use of the practical farmer. 
So far I have confined my remarks to subjects of which I presume that 
every member of the Section has practical experience, subjects which depend 
on the measurement of the yield per unit area. These subjects, however, 
although they have received far more general attention than anything else, by 
no means comprise the whole of agricultural science. Certain scientific workers 
have confined their efforts to the thorough solution of specific and circumscribed 
problems. I propose now to ask the Section to direct its attention to some 
typical results which have been thus achieved during the last twenty years. 
The first of these is the development of what I may call soil science. Twenty 
years ago the bacteriology of nitrification had just been worked out by Waring- 
ton and by Winogradski. The phenomena of ammoniacal fermentation of 
organic matter in the soil were also fairly well established. The fixation of 
atmospheric nitrogen by organisms symbiotic on the Leguminose had been 
definitely demonstrated. Fixation of nitrogen by free-living organisms had been 
suggested, but was still strenuously denied by most soil investigators. No 
suggestion had yet been made of the presence in normal soils of any factor which 
inhibited crop-production. The last twenty years have seen a wonderful advance 
in soil science. Our knowledge of nitrification and ammoniacal fermentation has 
been much extended. The part played by the nodule organisms of the Legumi- 
nose has been well worked out, has seen a newspaper boom, and a subsequent . 
collapse, from which it has not yet recovered. But the greatest advance has 
been the discovery of the part played by protozoa in the inhibition of fertility. 
The suggestion that ordinary soils contained a factor which limited their 
fertility emanated in the first instance from the American Bureau of Soils. 
The factor was at first thought to be chemical, and its presence was tentatively 
attributed to root excretion. Certain organic substances, presumably having 
this origin, have been isolated from sterile soils, and found to retard plant 
growth in water culture. It is claimed, too, that the retardation they cause is 
prevented by the presence of many ordinary manurial salts with which they are 
supposed to form some kind of combination. 
Contributions to the subject have come from several quarters, but whilst the 
suggested presence of an inhibitory factor has been generally confirmed, its 
origin as a root-excretion and its prevention by manurial salts has not received 
general confirmation outside American official circles. The matter has been 
strikingly cleared up by the work of Russell and Hutchinson at Rothamsted, 
who observed that the fertility of certain soils which had become sterile was at 
once restored by partial sterilisation, either by heating to a temperature below 
100° C., or by the use of volatile antiseptics such as toluene. This observation 
