140 Report of Experiments on the Growth of Barley, 
had then been manured with 14 tons of farmyard-manure per 
acre per annum for twenty-five years in succession, owing to its 
vast accumulation of organic matter, and greater degree of dis- 
integration, porosity, and power of absorption, retained, near the 
surface, very much more water than that of either the closely- 
adjoining unmanured, or an artificially manured plot in the 
same field. 
In the same paper we recorded the fact, that a plot of 
permanent meadow-land which received annually mixed mineral 
manure, and a given amount of nitrogen as ammonia-salts, 
yielded in the season of drought of 1870, 23 cwts. of hay less 
than its average ; whilst, another plot, receiving annually the 
same mineral manures, and the same amount of nitrogen, but in 
the form of nitrate of soda instead of ammonia-salts, yielded, in 
the same season of drought, only IJ cwt. of hay less than its 
average amount, and about 26J cwts. more than the plot manured 
with the same mineral manure and the same amount of nitrogen 
as ammonia-salts. 
This result was assumed to be connected with the difference 
in the character of the two nitrogenous manures (ammonia- 
salts and nitrate of soda), in regard to their reactions upon the 
soil, and the consequent degree of rapidity and range of dis- 
tribution of them, or their products of decomposition, within 
it ; — the nitrate, or its products of decomposition, becoming 
much more rapidly distributed, and washed into the subsoil, 
whither the roots follow it. On examination it was found 
— that certain plants of the mixed herbage, having roots of a 
characteristically downward tendency, were much more prevalent 
on the plot manured with nitrate of soda, than on that manured 
with ammonia-salts ; that the subsoil of the nitrated plot was dis- 
integrated and permeated by roots to a much greater depth ; 
and that, accordingly, the lower layers of the subsoil had been 
pumped much drier by the action of roots, than the corresponding 
layers of the plot manured with ammonia-salts. 
These very interesting and significant facts point to the explana- 
tion of the much less prejudicial influence of the drought of 1868 
on the experimental barley-crops grown by farmyard-manure, and 
by mineral manure and nitrate of soda, than on those grown by 
mineral manure and ammonia-salts. In the case of the farm- 
yard-manure plot, the result was probably due to the great 
amount of moisture taken up, and retained, by the upper layers of 
the soil, from the winter and early-spring rains. In that of the 
nitrated plot it was, it is true, the first year of the application ; 
but, with the fair amount of rain in March, and the full amount 
in April, it is still probable that there would be a considerable 
distribution of the manure, and, accordingly, an increased 
