350 Beport of Experiments on the Growth of Barley, 
which amounts at least must be attributed to the residue of the 
mineral manures supplied now more than 20 years ago. 
The wheat experiments afford other illustrations of the lasting 
effects of certain mineral substances applied as manures ; but 
owing to the very unusual exhaustion of the mineral constituents 
of the soil by the application of ammonia-salts alone so many 
years in succession in the cases above cited, the point is suffi- 
ciently forcibly brought out to render it unnecessary to adduce 
further evidence of the same kind on the subject. 
The evidence afforded by the analysis of the produce, of the 
soils, and of the drainage waters, is, however, perfectly consistent 
■with that of the field results. 
Thus, numerous analyses of the ash of the grain and the straw 
of the produce of the experimental wheat plots show that of Plot 
lOa to have become relatively deficient, more particularly in 
phosphoric acid, but to some extent in potass also, during the 
later years. 
Again, Baron Liebig's son, Hermann von Liebig, who had 
asked to be provided with samples for investigation, has partially 
analysed the soils from some of the Rothamsted experimental 
wheat plots ; and so far as the important constituents potass and 
phosphoric acid are concerned, he finds the amount of these 
much greater, especially in the upper layers of the soil, the 
greater the supplies by manure. 
Lastly, on this point. Dr. Voelcker's analyses of the drainage 
waters show, that very much less of potass passed off in that way 
than of either soda, lime, or magnesia; and also very much less 
of phosphoric acid than of sulphuric acid or of chlorine ; in fact, 
there is comparatively little loss by drainage of either. 
The facts brought out in this Section may be briefly sum- 
marised as follows : — 
1. When either ammonia-salts, or nitrate of soda, or nitro- 
genous organic matter in tlie form of rape-cake, or farmyard 
manure, was applied for either wheat or barley, a considerable 
proportion of the nitrogen so supplied remained unrecovered in 
the increase of the crop for which the manure was employed ; 
nor was the whole recovered in many succeeding crops. 
2. When ammonia-salts were applied in the autumn for 
wheat, a much less proportion of their nitrogen was recovered 
in the increase of crop, than when they were applied in the spring 
for barley or for oats. 
3. Analysis of the soils to the depth of 27 inches, showed that 
there was a considerable accumulation within that depth, of the 
nitrogen of manure which had not been recovered in the increase 
of the crop ; but that a still larger amount remained to be other- 
wise accounted for. 
