432 On the Continuous Growth of Wheat on the 
In plots 10 a and 10 B, we have two parallel experiments. 
In 1844 both received an application of mineral manures, and 
produced a crop yielding 15^ bushels of wheat per acre. In 
1845, both received a dressing of salts of ammonia, which 
yielded a crop of 32 bushels per acre. 
From that time they have been treated as two separate ex- 
periments ; 10 A, from 1846 to the present time — a period of 
38 years — has received annually a dressing of salts of ammonia : 
while in 1846, 10 B was unmanured. In 1848, 10 B received 
a dressing of minerals, and the same amount of salts of ammonia 
as 10 A. In 1849, it received salts of ammonia alone, and in 
1850, minerals alone. 
The difierence between the two plots has therefore been as 
follows : 10 A has received one dressing of minerals, followed 
by 39 dressings of salts of ammonia : 10 B has received 
three dressings of minerals during the 7 years ; and for the last 
33 years both plots have been manured exactly alike, receiving 
salts of ammonia every year. 
In the following table will be seen (1) the produce of each 
plot separately during the first 8 years : (2) the mean produce 
of the two plots during each 8 years : (3) the mean of 32 
crops. 
Tablk XXIV. — Showing the Peodttce of 10 a and 10 b for each of 
the First 8 Tears of the Experiment, and afterwards the Average 
Produce in Periods of 8 Years ; 10 a receiving I^Iineral Manure 
in 1844, and for the last 39 Years Salts of Ammonia ; 10 b receiv- 
ing Minerals alone in 1844 and 1850, being unmanured in 184.6, 
and receiving Minerals with Salts of Ammonia in 1848. For the 
last 32 Years 10 b has received the same Manure as 10 a. 
lOA. 
lOB. 
lOA. 
lOB. 
Dressed 
Dressed 
Total Produce 
Total Produce 
Corn. 
Com. 
Corn and Straw. 
Com and Straw. 
bushels. 
bushels. 
Ibe. 
lbs. 
1844 
15J 
15i 
2120 
2120 
1845 
31? 
31i 
6246 
6246 
1846 
27i 
4 
4094 
2671 
1847 
25f 
25f 
4593 
4579 
1848 
19i 
25J 
3701 
4530 
1849 
32i 
32i 
4992 
5117 
1850 
27 
18 
4810 
3120 
1851 
281 
283 
5036 
4985 
8 years, 1852-1859 .. .. 
221 
27J 
4055 
4885 
8 years, 1860-1867 .. .. 
24 
27i 
4076 
4563 
8 years, 1868-1875 . . . . 
19 
20J 
3060 
3264 
8 years, 1876-1883 .. .. 
16i 
18J 
2618 
2935 
32 years, 1852-1883 .. .. 
20J 
23J 
3452 
3912 
