272 REPORT—1°05,. 
croft ‘ wilderness,’ whereas the corresponding plot on Broadbalk contained 
25 per cent. Now, with no leguminous plants to act as collectors of 
nitrogen the considerable gains of combined nitrogen on this Geescroft 
land must be set down to the work of Azotobacter or kindred organisms 
which get their necessary supply of carbohydrate from the annual fall of 
the grassy vegetation, 
Taste IV. 
Accumulation of Carbon and Nitrogen in Soil of Land allowed to 
run wild for more than Twenty Years, 
Per cent. in Dry Soil 
—— Carbon Nitrogen 
| 1881-8 1 1904 1881-3 | 1904 
| Ist 9 inches . .| 1143 1-233 01082 | 01450 
Broadbalk | 2nd__,, ol 0-624" 0-708 00701 | 0-0955 
| Brat dati Store alt <O'464 0551 00581  0-0889 
1st 9 inches * 3 1111 1:494 01081 0 1310 
/ Geescroft 2nd A ° F 0:600 0°627 0:0739 0:0829 
peg © Sree ee ante 0-435 00597 | 0:0652 
1 Broadbalk, 1881; Geescroft, 1883. 
Broadbalk Geescroft 
1881 1904 1883 1904 
Nitrogen — lb. per acre. * p 5,910 8,110 6,043 6,978 
MS — Increase per acre, per 
annum, lb. 2 p —_ 97°8 — 445 
| Ratio of Carbon ta Nitrogen. 9-4 17 8:9 92 
| Ratio of Carbon to Nitrogen in 
Increase. 3 - é 5 — 2-9 _ 10:7 
The fixation of nitrogen must be an oxidising process, for no other 
natural reaction is likely to provide the energy necessary to bring the 
nitrogen into combination. This being so, some light is thrown on the 
process in nature by an examination of the ratio of carbon to nitrogen 
in the accumulations referred to above. At starting, the ratio of carbon 
to nitrogen in the organic matter of the two soils was much the same— 
a little less than 10 to 1—but the increase of carbon and nitrogen in 
the Broadbalk field, 7.¢., the organic matter which has accumulated in 
the interim, shows a ratio of only 3 to 1, while the corresponding accumu- 
lations in Geescroft field show a ratio not far removed from the 
original of about 11 to 1. In other words, where there has been the 
greater accumulation of nitrogen on the Broadbalk field, there has been 
the greater combustion of carbohydrate, so that the accumulation of 
carbon is actually as well as relatively smaller, Bacteriological tests 
