314 Report of Experiments on the Growth of Barley, 
but witli the mixed alkali-salts without superphosphate, and with- 
out any mineral manure at all, it is between and 3f lbs. That 
is to say, a given amount of ammonia-salts was more than one- 
and-a-half-time as effective when there was a liberal provision of 
mineral constituents, but especially of phosphates, within the 
reach of the roots, than when there was not. 
Assuming that, with otherwise favourable soil-conditions, and 
with an application of not more than 50 lbs. of ammonia per 
acre, an increase of 1 bushel of barley (52 lbs.), and its straw, 
may, on the average of seasons, be obtained for every 2 to 2 J lbs, 
of ammonia applied, still, it is seen that the amount may vary 
very greatly according to the characters of the seasons. Thus, on 
Plot 2 A, with superphosphate, only about 1^ lb. was required 
in the favourable seasons of 1863 and 1869, but in the bad 
seasons of 1853 and 1856, 5"36 and 4"48 lbs. respectively, were 
required. 
These great differences according to season occurred, it should 
be remembered, when only a moderate amount of ammonia-salts 
was used, and when it was employed under favourable conditions 
as to mineral manures. But even with the same moderate 
application, but at the same time less favourable soil-conditions, 
that is without superphosphate, or without any mineral manure, 
the differences in the amount required to yield a given increase of 
produce are very much greater. Thus, when the same quantity 
of ammonia-salts is used without any mineral manure (Plot 1 A), 
there is a variation in the amount of ammonia required to yield 
1 bushel of increase from 18'05 lbs. in 1859, to 2 25 lbs. in 
1871 ; and when with salts of potass, soda, and magnesia, but 
without superphosphate (Plot 3 A ), from 24'75 lbs. in 1859, 
to 218 lbs. in 1863. In fact, in 1859, there was scarcely any 
increase at all by ammonia-salts when not accompanied by 
phosphates ; and reference to the characters of the season, and of 
the growth (pp. 114-1 16), will show that there was probably 
defective root-development; a condition under which any defi- 
ciency of phosphates within a limited range of soil would very 
unfavourably affect the characters of growth. 
Lastly in regard to Series I : — Under each of the five conditions 
as to mineral manuring, the amount of ammonia required to 
produce a given increase of grain was very much less over the 
second than the first 10 years. It has already been shown that 
the last 10 seasons were the more favourable for the produc- 
tion of corn, and more especially so where superphosphate was 
used. But, as there was a greater falling off over the later years 
where the mineral manures were used alone, the f urther amount 
of produce obtained where the mineral manures and ammonia- 
salts were used together, which is reckoned as increase due 
