Report of Experiments on the Growth of Wheat. 467 
of from 17 J bushels of dressed corn and nearly 18J cwts. of 
straw, to 20^ bushels of corn and 22f cwts. of straw, due to the 
application of the mixed mineral manure each year in conjunction 
with the ammonia-salts, instead of each year preceding them as 
on plots 17 or 18. 
In the greater amount of increase on 10b than on 10a, there is 
striking evidence of the permanent and lasting effect of the unex- 
hausted residue of the artificially applied mineral constituents, 
if only available nitrogen be provided within the soil. On the 
other hand, the greater amount of increase on plot 7 than on 
plots 17 or 18, shows the much greater effect of the mineral 
constituents when applied at the same time with the ammonia- 
salts. Nevertheless, there is no doubt that even plots 1 7 and 18 
received much more of all those mineral constituents that were 
supplied than was removed of them in the crops. The con- 
dition and distribution of the constituents within the soil, would, 
however, be very different in the two cases. 
The very interesting and important results which have been 
briefly passed in review in this Section, especially those to which 
the coloured Diagrams refer, may be still more briefly sum- 
marised as follows : — 
1. A somewhat heavy loam, of fair average wheat-producing 
quality, taken at the end of a five-course rotation since manuring, 
gave scarcely any increased produce of wheat in the year of the 
application when manured with a mixture of silicate of potass 
and superphosphate of lime ; but it gave a very considerable, 
though progressively diminishing, amount of increase, when 
afterwards manured for 19 consecutive years with ammonia-salts 
alone. 
2. It is obvious that, taken in the condition of practical 
exhaustion specified, the soil still contained an excess of annually 
available mineral constituents, relatively to the annually avail- 
able nitrogen supplied by soil and season without manure. 
When, however, large quantities of ammonia-salts were annually 
applied, the relative deficiency of mineral constituents became 
apparent, even as early as the fourth year of their application. 
3. When ammonia-salts were applied, the greater portion of 
the nitrogen remained unrecovered as increased yield in the crop 
for which it was employed. 
4. The unexhausted residue of nitrogen supplied as manure, 
was but very partially and very slowly recovered as increased 
yield in succeeding years, even when followed by the liberal 
application of such mineral manure as was very effective when 
used in conjunction with newly applied ammonia-salts. 
5. Mineral constituents supplied in the soluble form in the 
5th and 7th years of the experiments (though giving very little 
