101 
The first recorded yield from the unmanured plat, in 1844, was only 15 bushels, 
and the average of the first eight years (1844 to 1851 ) was only L71 bushels. 
It is also stated by the Bureau of Soils" that "by a simple rotation and change of 
cultural methods from year to year, with the change of the crop, the yield of wheat 
has been maintained practically constant for forty-Tour years," and the yields from 
a few selected years are cited as proof. The statement'' is made, for example, that 
"the yield of wheat has not been sensibly reduced, the yield, even when the roots 
were carted off and the land left in fallow, being 33j bushels in L883, as against 30£ 
bushels in 1851, 37| bushels in 1855, and 35 bushels in 1859." 
While it is true that. Sol bushels was the yield in 1883, and that some other very satis- 
factory yields have since been obtained, nevertheless, theoriginal data show that dur- 
ing the four courses, covering sixteen years (1S5:> to L867) the average yield of wheat 
was 30 bushels per acre, while duringthe next four courses, covering a second period 
of sixteen years (1868 to 1883) the average yield was 20 bushels, although in 1883 the 
yield was 33£ bushels, and during the sixteen-year period (1884 to 1899), the average 
yield has been 29 bushels. 
It is true that when not manured the average crop of wheat in the four-year rota- 
tion has been larger than where wheat was grown continuously, hut is the difference 
due primarily to physical conditions of the soil? All students of agriculture, practi- 
cal and scientific, not only admit, but have always advocated, that the physical con- 
dition of the soil is a highly important factor, and in my judgment the statement^ 
by the Bureau of Soils, "that fertilizers rarely take the place of efficient methods of 
cultivation and of cropping in increasing or maintaining crop yields," is at fault, in 
so far as it intimates that fertilizers may sometimes be substituted for good farming. 
Applications of plant food are not expected to retard, but to encourage, the growth 
of weeds. Fertilizers do not take the place of cultivation; their value is usually 
enhanced by cultivation, by means of which they are more thoroughly distributed 
and incorporated with the soil. 
The fact is that in this four-year rotation the wheat crop followed a year of fallow 
cultivation, and we might expect the one crop to utilize the total amount of plant 
food made available during the two years' time. That this is probably true is indi- 
cated by a further study of this rotation. 
Yield of crops grown in four-year rotation at Rothamsted < ! (roots, hurley, fallow, and 
wheat) root crop removed from land. 
Roots 
tons. 
Barley, bushels. 
Wheat, bushels. 
Applied — 
Applied — 
Applied — 
Number of course. 
No plant 
food. 
Nitrogen, 
phos- 
phorus, 
potas- 
sium. 
No plant 
food. 
Nitrogen, 
phos- 
phorus, 
potas- 
sium. 
No plant 
food. 
Nitrogen, 
phos- 
phorus, 
potas- 
sium. 
First e 
8.8 
19.7 
34 
37 
30 
30 
Second 
1.9 
2.3 
.1 
.4 
20. 1 
10.4 
4.4 
9.1 
32 
44 
35 
34 
38 
48 
6J 
45 
37 
36 
46 
38 
Third 
42 
Fourth 
53 
Fifth 
22 
1.2 
12.6 
36 
48 
36 
39 
Sixth 
.0 
2.6 
l.G 
1.6 
.0 
16. 6 
15.5 
22.5 
21 
21 
23 
29 
40 
32 
31 
34 
11 
21 
10 
34 
17 
Seventh 
29 
Eighth 
12 
Ninth 
37 
Average 6 to 9 
1.5 
13.7 
24 
34 
20 
24 
Tenth 
.9 
.8 
.5 
.8 
14.9 
21.6 
26.2 
17.3 
16 
16 
20 
11 
19 
20 
19 
21 
35 
32 
22 
27 
39 
Eleventh 
41 
Twelfth 
33 
Thirteen t h 
33 
Average 10 to 13 
.8 
20.0 
16 
20 
29 
37 
1.2 
15.4 
25 
34 
28 
33 
aU. S. Dept. Agr., Bureau of Soils Bui. 22, p. 56. 
&Ibid, p. 55. 
dbid, p. 60. 
d Memoranda of the origin, plan, and results of the field and other experiments at Rothamsted (1900) 
pp. 110, 111. 
e Clover instead of fallow in first rotation. 
