352 MESSRS. J. B. LAWES AND J. H. GILBERT ON THE RESULTS OF 
Table XVII.—Average, per acre per annum, by Mixed Mineral Manure alone 7 years, 
after Ammonia-Salts alone 13 years; Plot 6. 
Average per acre per-annum. 
Plot 5. 
Ammonia- 
salts alone 
20 years. 
Plot 6. 
Ammonia-salts 
13 years, 
mineral manure 
7 years. 
Plot 7. 
Mineral 
manure 
alone 
20 years. 
Plot 6. 
+ or — 
plot 5. 
Plot 6. 
+ or — 
plot 7. 
Hat. 
lbs. 
lbs. 
lbs. 
lbs. 
lbs. 
First period, 13 years, 1856-1868 . . . . 
3317 
3425 
3914 
+ 108 
-489 
Second period, 7 years, 1869-1875 . . . . 
2257 
3502 
4040 
+ 1245 
-538 
Total period, 20 years, 1856-1875 .... 
2946 
3452 
3958 
+ 506 
-506 
Second period, per cent. + or — first period . 
-32-0 
+ 2-2 
+ 3-2 
Nitrogen. 
First period, 13 years, 1856-1868 . . . . 
57-8 
591 
56-9 
+ 1-3 
+ 2-2 
Second period, 7 years, 1869-1875 . . . . 
43 0 
4P9 
55-9 
-1-1 
-14-0 
Total period, 20 years, 1856-1875 . . . . 
52-6 
531 
56-6 
+ 0-5 
- 3-5 
Second period, per cent. + or — first period . 
-256 
-29-1 
-1-8 
Mineral Matter (Ash). 
First period, 13 years, 1856-1868 .... 
171-8 
1756 
254-5 
+ 3-8 
-78-9 
Second period, 7 years, 1869-1875 .... 
95-4 
189-2 
252-8 
+ 93-8 
-63-6 
Total period, 20 years, 1856-1875 .... 
145-1 
180-4 
254-0 
+ 35-3 
-73-6 
Second period, per cent. + or — first period . 
-44-5 
+ 7-7 
-0-7 
The sawdust applied on plot 6 during the first seven years being of little or no effect, 
the two plots, 5 and 6, each annually receiving the same quantity of ammonia-salts, 
were practically duplicates. On both, the produce was gradually diminishing, or in 
other words the effects of a given amount of nitrogen supplied was decreasing, and 
the character of the herbage was very greatly deteriorating. Hence, after 13 years, 
it was decided to continue the application of ammonia-salts alone on one plot only (5), 
to discontinue it on the other (plot 6), and to apply to it the mixed mineral manure, 
including potass, instead. The objects sought in the change were—to determine its 
effects, not only on the amount of produce, but on the character of the herbage, both 
as to the description of species developed, and the character of development, also on 
the chemical composition of the produce; and especially to acquire data in reference 
to the question whether any, or how much, of the nitrogen of the previous applications 
which had not been already recovered in the increase of crop, would be so under the 
influence of liberal mineral manuring ? 
