220 
Journal of Agricultural Research 
Vol. XI, No. 5 
Table VI. —Percentage of organic carbon a in rings of Agaricus tabularis at Akron, Colo . 
Sample No. 
Location. 
Ring B. 
Ring 2. 
Ring 8 . 
Ring 6 . 
Ring 7. 
1. 
Outside. 
2.37 
2. 76 
3. 26 
2. 69 
2.97 
2. 
Youngest mycelium 
2. 58 
2. 87 
2.83 
2-93 
3-33 
3 . 
Dense mycelium.... 
2. 15 
3 - 17 
3 * 50 
2. 91 
3. 02 
4 . 
Below No. 3. 
2. 23 
2. 89 
3 - 79 
. 2.94 
3 - 05 
5 . 
Old dying my¬ 
celium . 
2. 23 
2. 73 
2.87 
3 - 23 
2. 81 
6. 
' Inside. 
2. 34 
2.45 
3-43 
2. 64 
.98 
<* For the determination of organic carbon the writers are indebted to Dr. E. C. Shorey, of the Bureau of 
Soils. The determinations were made by the moist-combustion method with sulphuric acid and potassium 
bicromate. 
One of the principal effects of the growth of the fungus mycelium in the 
soil is in changing the nitrate or ammonia content of the soil. 
Tawes, Gilbert, and Warington (1883) found more nitrogen outside 
the ring than either in the ring or inside the ring (Table VII). The same 
results were obtained for carbon (Table V) and the ratio of carbon to 
nitrogen was found to range from 11.2 to 11.7. They also determined 
the nitrates and found here a much greater amount in the ring than 
either inside or outside (Table VIII). From the results it was con¬ 
cluded that in fairy rings the nitrates of the soil were greatly increased 
and that the source of the nitrates was the organic matter of the soil. 
Table VII.— Mean percentages of niirogen a in the fine, dry fairy-ring soils , according 
to Lawes , Gilbert, and Warington ( 1883 ) 
Description of ring. i 
Percentage of nitrogen. 
Within 
the ring. 
On the 
ring. 
Outside 
the ring. 
Grove Paddock (May, 1874). 
Broadbalk (June, 1877). 
0. 262 
. 271 
. 226 
. 222 
•253 
O.274 
.300 
.244 
•253 
•257 
O. 287 
•315 
.274 
•259 
. 269 
Broadbalk (September, 1877). 
Park (September, 1877).. 
Park (April, 1878). 
Mean. 
.247 
. 266 
. 281 
Nitrogen “outside ,,= =ioo.. 
87.9 
94*7 
100. 000 
Ratio of carbon to nitrogen. 
ii -3 
11. 2 
11. 7 
a Nitrogen determined "by combustion with soda-lime.’' 
Molliard (1910) concluded that the mycelium acted directly on the 
humus of the soil and that the reduction of the organic matter of the 
soil gave rise to ammoniacal salts. The amount of ammonia found in 
different portions of the ring (fig. 1) is shown in Table IX. The greatest 
amount was found under the dead zone (III) and in the mycelium area 
under the outer stimulated zone (IV). No significant difference was 
noted between the inside and the outside of the ring. 
