324 
Journal of Agricultural Research 
Vot. IX, No. 9 
During the spring the ammonifying power of the soil which had 
received 25 inches of water is considerably higher than any of the others, 
while in the fall and summer the soil which received 37.5 inches of water 
is the greatest. The results collectively indicate that the irrigation 
water has increased the ammonifying powers of the potato soil. The 
ammonifying powers of all the plots are higher in summer than in either 
spring or fall. 
The nitrifying powers of the soil are much higher in summer than 
either fall or spring, and there is a relationship between the water ap¬ 
plied and the nitrifying powers of the soil. The water increases the nitri¬ 
fying powers of the soil. The highest results were obtained where 25 
inches of water were applied. 
For the potato land we note a decrease in the number of organisms as 
the water applied increases, but an increase in both ammonifying and 
nitrifying powers with increased water. So it would appear that the 
water has increased the physiological efficiency of the organisms without 
increasing the number. 
OAT LAND 
The oat plots received 37.5 inches, 25 inches, 15 inches, and no water. 
Otherwise they were all treated the same. The average results for the 
three years are given in Table XXIV. 
Tabl^ XXIV .—Number of colonies of bacteria , milligrams of ammonia, and milligrams 
of nitric nitrogen from soil receiving varying amounts of Water. Crop, oats. Average 
for 3 years 
NUMBER OF COLONIES DEVELOPED IN 4 DAYS ON SYNTHETIC AGAR PER GRAM OP SOIL 
Plot No. 
Water 
applied. 
Sampled 
May x. 
Sampled 
Aug. 1 . 
Sampled 
Nov. 38 . 
Average. 
Inches. 
43 .. 
37 * 5 
6,133,000 
6, OOO, 000 
4, 133, OOO 
5,422,000 
44 . 
25.0 
5, 700, 000 
4, 800, 000 
2,866,000 
4 , 455 > 000 
45 . 
15.0 
6, 200,000 
5, 133, 000 
4, 400, 000 
5, 244,000 
4<5 . 
None. 
7 > 533 » 000 
5, 967, 000 
6,000,000 
6, 500, 000 
MILLIGRAMS OP 
AMMONIA PRODUCED 
IN IOO GM. OF SOIL IN 4 DAYS 
43 . 
37-5 
56.8 
69-3 
49.6 
58.6 
44 . 
25.0 
53*3 
S 6 -3 
52*1 
53*9 
45 . 
15*0 
48. 0 
55 - 4 
46. 0 
49.8 
46 . 
None. 
48.8 
50.2 
44 . 7 
47*9 
MILLIGRAMS OP NITRIC NITROGEN PRODUCED IN IOO GM. OP SOIL IN 
21 DAYS 
43 . 
37-5 
i *7 
3*9 
2.1 
2. 6 
44 . 
25.0 
2. 2 
4 - 7 
.8 
2. 6 
45 . 
15.0 
i *7 
2. 0 
2*3 
2 . 0 
46 . 
None. 
4.0 
5*4 
6.8 
5*4 
