'for Twenty Years in succession on the same Land. 
345 
been applied in the spring ; but as, unfortunately, the same quan- 
tities have not been applied for the two crops, no exact com- 
parison can be drawn between the results they respectively yield. 
Still, the evidence undoubtedly indicates that more increase has 
been obtained for a given amount of nitrate when applied to barley 
than to wheat. In this case, therefore, loss by winter drainage 
cannot account for the comparatively defective result with the 
latter crop. Part of it is probably due to the fact that the quan- 
tity which has been applied for wheat (550 lbs. per acre) is a heavy 
spring dressing ; and, owing to the great solubility of the nitrate, 
and the little power of retaining it which the soil possesses, there 
would be a greater loss by spring and summer drainage the 
greater the quantity applied. In confirmation of this view, Dr. 
Voelcker's analysis of the drainage from the nitrated plot after 
the manure had recently been sown, showed twice as much 
nitrogen as he found in any case of winter drainage from plots 
receiving the same amount of nitrogen as ammonia-salts. In 
many seasons too, the crop is too heavy and laid. For barley, 
on the other hand, only half the amount of nitrate is used ; and, 
consequently, there will probably be not only less loss of manure 
by drainage, but less loss of crop by laying. 
With regard to the supposition that there was probably a less 
proportional loss of nitrogen by drainage from the nitrate when 
applied for the barley than for the wheat, it should further be borne 
in mind, that although the manure is for both crops sown in the 
spring, yet it is in the one case on land in a close and consolidated 
condition, and in the other on soil rendered as light and open as 
possible by recent working, and hence offering a greater surface 
for absorption and retention of the manure. There is probably 
also a more active root-development in the upper layers of the 
soil in case of the barley than in that of the wheat. 
Whether or not the above suppositions afford an adequate 
explanation of the difference of result with the nitrate when 
applied to both crops in the spring, the difference in the case 
of the ammonia-salts applied for the wheat in the autumn, and 
for the barley in the spring, is at any rate much more conclu- 
sively accounted for. But there is another circumstance in con- 
nection with the point that should not be overlooked. 
The proportion of the nitrogen of the ammonia-salts which is 
recovered in the increase of produce being much greater in the 
case of the barley experiments than in those with wheat, there 
remains, of course, much less to be accounted for by accumula- 
tion in the soil, and by drainage. There is pretty certainly much 
less loss by drainage. And, so far as the few determinations of 
nitrogen that have yet been made in the soils of the barley plots 
enable us to judge, it would seem probable that there is less 
accumulation in the soil also, especially in the lower layers. If 
