('o)ititiiwits Growhig of Wheat and Barletf. 243 
a confirjuation in general respects in the experience at Woburn. 
At the same time certain difierences have been brought out 
between the two places which have I’endered the confirmation 
of the work very desirable. Chief among these is the influence 
of lime in the soil, the Woburn land being very deficient 
in this constituent. 
Having thus a common origin, it was both natural and 
desirable that, when the Woburn Experiments on the Con- 
tinuous Growth of Wheat and Barley were begun, the manurial 
plan adopted should be much the same as that of Rothamsted. 
Certain modifications and amplifications of the latter, which 
experience had shown to be desirable, were made, but, in the 
main, the same line of inquiry was followed. In this waj' 
it came about that the manurial treatment was independent of 
“ cost,” the object being to see what the different fertilisers used 
were capable of producing, apart from the variations caused by 
market changes in the purchase of manures or sale of produce. 
It was sought to establish data for calculating what increase 
of produce might be expected from the use of this or that 
constituent, rather than to determine directly what would “ pay.” 
So it happened that materials of comparatively recent introduc- 
tion, such as sulphate of ammonia and nitrate of soda, were 
employed in quantities which, to the present-day farmer, with 
corn hardly a “ paying ” crop at all, may seem prohibitive. 
Further, in the case of compound manures, the idea was 
mainly to supply all the constituents that the crops might 
I’equire, so that failure should not be due to the absence of any 
one or other, and that the differences in crop results should 
thus be attributable directly to the difference of manurial 
treatment. Accordingly, under “ mixed mineral manures ” 
were included superphosphate of lime, sulphate of potash, 
sulphate of soda, and sulphate of magnesia, these supplying 
phosphoric acid, lime, potash, soda, magnesia, and sulphuric 
acid, with small quantities of iron, alumina, silica, &c. ; 
similarly “ ammonia salts ” comprised not sulphate of ammonia 
alone, but also muriate (chloride) of ammonia. Farmyard 
manure, again, was not merely what was taken out of a yard, 
but was box-made manure for which definite quantities of 
cake, corn, roots, and chaff were consumed and known weights 
of litter used, so that, the nitrogen contents being approximately 
known, a fair comparison could be made with nitrogen in the 
other foi’ms of ammonia salts, nitrate of soda, and rape dust. 
Since these experiments began a good deal more knowledge 
has been collected as to the action of different manures and 
constituents of manures, and the conclusion of the thirtieth 
year of continuous cropping afforded a suitable opportunity 
for reviewing the original plan in the light of the experience 
