328 Report of Experiments on the Growth of Barley, 
barley ttan for wheat. The questions arise — What proportion of 
the supplied nitrogen is, in either case, recovered in the increase 
of crop ? What becomes of the unrecovered amount, if any ? 
How is it that more increase is obtained, and that there is 
apparently less loss, in the case of the barley than of the 
wheat ? 
In our first paper in this Journal, now more than twenty-five 
years ago, we pointed out that about 5 lbs. of ammonia in manure 
had been found necessary for the production of 1 bushel of in- 
crease of wheat and its straw. Frequently since, the question of 
the proportion of the nitrogen of manure recovered in the increase 
of produce obtained has been illustrated by results of the direct 
analysis of the produce. This was done, so far as barley is con- 
cerned, in the Report on the first 6 years of the experiments 
(Vol. xviii., 1858). In a paper " On the Annual Yield of 
Nitrogen per Acre in Different Crops," read at the meeting 
' of the British Association for the Advancement of Science held 
at Leeds in 1858, it was concluded that, with wheat and barley 
indifferently, rather more than four-tenths of the supplied nitro- 
gen was recovered in the increase. Again, in a paper " On the 
Sources of the Nitrogen of Vegetation, &c.,"* much the same 
estimate was arrived at for wheat, for barley, and for meadow- 
hay ; and estimates were also made in regard to some other 
crops. 
The subject is, however, one of such great importance, and 
the number of years over which the estimate can be made is now 
so much greater than formerly, that numerous new analyses have 
been made for the purposes of this paper. The nitrogen has thus 
been determined in the produce for 20 years (1852-1871), of 
six of the wheat, and five of the barley plots ; also, but for 3 
years only, in that of three of the experimental oat plots. For the oats 
the nitrogen has been determined in the grain and in the straw 
of each year separately ; but, for the wheat, and for the barley, 
respectively, a mixture has been made of the produce (corn and 
the straw separately) of each plot, for the 20 years, the quan- 
tity taken being in exact proportion to the amount of produce 
per acre each year. The whole was then ground up together ; 
so that the mixed samples respectively represent the produce of 
the grain and of the straw of each plot, for the 20 years. 
Table XLIV. (p. 329) shows the amount of nitrogen recovered 
in the increase of produce (corn and straw), and the amount 
not recovered, for 100 supplied in manure. 
For wheat, the plots selected are — that with 14 tons farmyard 
* 'Philosophical Transactions,' Part II., 1861; also 'Jour. Chem. Soc./ new 
series, vol. i., 18S3. 
