for Ttcenty Years in succession on the same Land. 
295 
Average annual Produce by Ammonia-saUs or Nitrate of 
Soda, with mineral Manure in addition. 
The first set of experiments to be noticed here, includes four 
plots, each of which has received 200 lbs. ammonia-salts per acre 
per annum, throughout the twenty years, but each with a different 
mineral manure in addition. The mineral manures, here used 
in admixture with nitrogenous manures, are the same as in the 
experiments with purely mineral manures, which have already 
been considered. As only much abbreviated descriptions of the 
manures can be given in the Table (see next page), they are 
described in full below : — 
Plot 2 A — 200 lbs. Ammonia-salts, and 3J cwts. Superphos- 
phate of Lime. 
Plot 3 A — 200 lbs. Ammonia-salts, and mixed Alkali-salts, 
— namely, a mixture of 200 lbs.* Sulphate Potass, 
100 Ibs.f Sulphate Soda, 100 lbs. Sulphate Magnesia. 
Plot 4 A — 200 lbs. Ammonia-salts, 3^ cwts. Superphosphate, 
and the " mixed Alkali-salts." 
Plot 5 A — 200 lbs. Ammonia-salts, 3^ cwts. ^Superphosphate, 
and 200 lbs.* Sulphate Potass. 
The produce is averaged over the first 10, the second 10, and 
the 20 years. The increase is calculated over the produce without 
manure, and also, in each case, over that by the corresponding 
mineral manure without ammonia-salts ; — that is 2 A over 2 O, 
3 A over 8 O, 4 A over 4 O,, and 5 A over 5 O. 
It is remarkable that, instead of, as without manure, with 
purely mineral manure, or with purely nitrogenous manure, a 
considerable falling off in the second compared with the first 
half of the total period, there is, with ammonia-salts and mineral 
manure together (though without silica), in each case a more or 
less increased produce of corn over the second compared with the 
first 10 years. On the other hand, there is in two out of the four 
cases a slight, and in a third a more considerable, deficiency of 
straw over the later period ; and it is only in that one instance 
that there is any material diminution in quantity of total produce, 
and then little more than 5 per cent. 
So far as quality of the produce is concerned, both weight per 
bushel of dressed corn, and proportion of corn to straw, are in 
every case higher over the second than the first 10 years. 
It has been concluded (p. 162) that the second period was, so 
far as the seasons themselves are concerned, the more favourable 
for the production of corn, but the less for that of straw and total 
produce. 
* .300 lbs. the first six years, 200 lbs. afterwards, 
t 200 lbs. the first sis years, 100 lbs. afterwards. 
