CHEMICAL AND BACTERIOLOGICAL STUDY OF WHEAT SOIL, 97 
seem to show a decrease at the end of winter and beginning 
of spring. Unfortunately the counts were not carried into 
the winter of 1922 and so the extent of the drop in total 
numbers for the winter season was not found. Tentatively 
a depression in the winter months may be postulated ex- 
tending into spring so long as the soil is in the sodden cold 
state it assumes in the wet colder months and then rising 
to more or less uniform levels in the hotter season. 
Total Nitrogen. 
A series of estimations were made of the total nitrogen 
in the various plots but it was found, as expected, that the 
variations from time to time were only such as might be 
due to sampling or experimental error. The following 
figures give the average result:— 
Surface Soil :—Grass ‘0557; Lucerne *0607%; PA °067%; 
PB °066%; PC ‘061%; PD ‘0635. 
Subsoil:—Grass °038%; Lucerne °039%; PA ‘038%; PB 
"041%; PC °0437; PD °045%, 
Judged by the usual New South Wales standards these 
percentages are merely fair. 
Nitrate Nitrogen. 
‘The results obtained for nitrate nitrogen during the ten 
months of the experiment have not given us a clear lead in 
solving the question of the nitrate supply to the wheat crop. 
The figures for the consecutive samplings are set out in 
Table IV, a double column showing parts per million and 
ibs per acre 9 inches of nitrate nitrogen. 
All the estimations were made by the phenol disulphonic 
acid method on 100 grm. portions of the air-dry soil. 
Several anomalies are evident notably for “Grass ”’ in the 
months of September and December, but these are most 
probably due to contamination since occasionally sheep 
were driven across this paddock. From the rest of the 
G—July 5, 1922, 
