THE BBOADBALK WHEAT BOILS. 
til 
NITROGEN AS NITRATES "NITRIC" NITROGEN . 
GENERAL DISCUSSION AND FULL STATEMENT <>F ANALYTICAL RESULTS 
ON THE BROADBALK SOILS. 
The greal classical researches that have been made at Kothamsted 
on the subject of nitrification — nature's way of providing food for 
new vegetable life from the debris of preceding Hf<' — are already 
well known to yon in substance. The subject was very carefully and 
thoroughly dealt with in the lectures delivered to you by Professor 
Warington in 1891, and the chief outcome of its study was again 
summarized in the course of Sir Henry Gilbert's lectures. Some 
apology — as indeed also in the case tin- preceding pages dealing 
with organic nitrogen — would be due from me for again traveling 
over ground that has been already explored ami explained, but for 
ihe fact that I am in the position of bringing before yon in these 
1893 samples the latest confirmatory evidence directly yielded by 
t he soil itself of many facts that were already known t<> us. Sir Henry 
Gilbert summed tip to yon the practical results of fifty years' continu- 
ous wheat growing under so many different manurial conditions; but 
lie was unable to give yon the results of the examination of the soils 
ai the end of the lift y years, for the samples, as I have said, were 
actually being collected while he was with yon. Then, as at ihe time 
of Professor Warmgton's Lectures, the 1881 samples formed the most 
recent complete set of liroadbalk samples that had been examined. 
The consideration, therefore, of the Later, ami much more complete 
results of the analyses of the lS!i:j samples, taken at the end of the 
first fifty years of ihe experiments, maybe regarded as a continua- 
tion (oomplet ion won Id be far too comprehensive a word) of Sir Henry 
Gilbert's review of the results of fifty years 1 work at Kothamsted. 
The conclusions deduced from the study of the determinations of 
nitric nitrogen in the 1 8!».'{ samples are not qualitatively different from 
those dedneed from the samples collected in 1SS1; but the plats in 
lSIK) were all twelve years older, and the evidence they have to give 
us is entitled to still more of the respect due to age than that gathered 
at the earlier period. 
It w ill be convenient to extract from Tables 11 and 12 the figures 
relating to nitric nitrogen, so as to have them before us in a more 
condensed form, and also a>> we go on to make further selected 
extracts from them for the purpose of comparing various plats one 
with another. 
