440 On the Continuous Growth of Wheat on the 
Table XXVII. — Showing the PRODrcE of the last Two Crops on 
Plot 1G, which received for 13 Years in succession an Annual 
Dressing of Mixed Minerals, and Salts of Ammonia containing 
172 lbs. of Nitrogen ; followed by 19 Unmanured Crops. And 
for comparison, the produce of Plot 5, which received Mineral 
Manures only over the whole period. 
Plot 5- 
Plot 16. 
Plots 5. 
Plot 16. 
Minerals 
Minerals and 
Minerals 
Minerals and 
Alone. 
172 lbs. Nitrogen. 
Alone. 
172 lbs. Nitrogen. 
Dressed Corn in Bushels )>er Acre. 
Total Produce in Corn and Straw. 
1863 
5^ 
3017 
10,. 525 
9,348 
18G4 
51^ 
2462 
Minerals 
Unmanured 
Minerals 
Unmanured 
1865 
141 
32| 
2091 
5,007 
1806 
131 
i7i 
2303 
3,081 
1867 
9i 
14| 
1013 
2,512 
1808 
171 
22| 
2481 
3,503 
1800 
15| 
18? 
16J 
2543 
2,047 
1870 
181 
13J 
2564 
2,557 
1871 
Ill 
2207 
2,380 
1872 
123 
13^ 
2166 
2,387 
1873 
12f 
i2i 
1806 
1,921 
1874 
13 
111 
1674 
1,892 
1875 
H 
10^ 
1714 
1,829 
1876 
lOi 
11 
1429 
1,538 
1877 
111 
1570 
1,340 
1878 
13i 
2222 
2,181 
1879 
H 
1238 
1,154 
1880 
17? 
i4i 
2818 
2,383 
1881 
12| 
13i 
1709 
1,736 
1882 
12i 
101 
2057 
1,925 
1883 
1 l>Jl 
15? 
2147 
2,131 
With regard to the large crop grown during the first year after 
the manure was stopped, we are inclined to think it was mainly 
due to a certain portion of the salts of ammonia not having been 
washed out of tlie soil. The year of the last application, 1864, 
was one of exceptional drought ; in fact, it was the driest year 
we have ever experienced at Rothamsted since the commence- 
ment of our experiments ; and it is probably owing to this that 
a portion, at all events, of the produce was due. While the 
excess of produce obtained on plot 16, as compared with 
plot 5, during the next 10 years, is probably due to the slow 
decay and nitrification of the stubble, and underground roots of 
the very large crops grown on this plot for so many years. 
During the 13 years of the application of 800 lbs. of salts of 
ammonia, considerably more than 1000 lbs. of the nitrogen 
applied to the soil has not been recovered in the crops ; it is 
therefore hardly possible to suppose that the nitrogen contained 
