864 
Journal of Agricultural Research 
Vol. V, No. 18 
TabeE XIII.— Ammonification of casein on rotation plots in 1913 
Plot No. 
Quantity of nitrogen. 
Aug. is. 
Aug. 23. 
Aug. 26. 
Mom. 
68.38 
7 i- 5 6 
78 - 74 
74.89 
73 - S 3 
75 - 6 S 
74. 28 
Mom. 
60. 82 
63- 47 
69-39 
66.35 
64- 43 
68.15 
65. 21 
Mom. 
' 53- 67 
59 - 3 1 
64.03 
63-13 
60. 52 
63.46 
60. 97 
602.*. . 
606. 
607. 
600. 
OOI... 
004 ... 
TabeE XIV.— Yields of corn on rotation plots in 1913 
Plot 
No. 
Treatment. 
Yield per 
acre. 
601 
Continuous com. 
Bu. 
3°. 0 
53-3 
602 
2-year rotation: Com and oats. 
606 
3-year rotation: Com, oats, and clover.... 
68. 0 
607 
2-year rotation: Com and oats; clover turned under.. 
64. 0 
609 
2-year rotation: Com and oats; cowpeas turned under. 
60. 0 
901 
2-year rotation: Com and oats; rye turned under. 
63-3 
9°4 
4-year rotation: Com, com, oats, and clover. 
62. 6 
Comparing the results, it is apparent that the indications of fertility 
given by the ammonification studies were borne out by the actual crop 
yields. The rank of the soils both in ammonifying power and in crop 
production was as follows: 
Plot 
No. 
Treatment. 
Rank. 
606 
3 -year rotation. 
I 
901 
607 
9°4 
609 
602 
2 -year rotation; rye turned under. 
2 
2 -year rotation; clover turned under. 
2 
4-year rotation. 
0 
A 
2 -year rotation; cowpeas turned under. 
*r 
5 
6 
2 -year rotation. 
601 
Continuous com. 
7 
The results of these studies check those of previous years, therefore, 
and indicate that ammonification and crop production are very closely 
related and that the determinations of the ammonifying power of soils 
made during the growing season may show their relative crop-producing 
powers. 
The plots in this series, as will be noted, ranked differently each year, 
both in crop yields and in bacterial activities, but it is not purposed to 
enter here upon a discussion of the reasons for such variations. The 
seasonal conditions, especially as regards rainfall, were undoubtedly of 
