CHEMICAL AND BACTERIOLOGICAL STUDY oF wHEat soit. 103 
“beaker method” using 100 grm. portions of soil with 100 
mgs. ammonium sulphate was employed and the nitrates 
estimated at the end of four weeks by the pbenol disulphonic 
acid method. Two soils PB and PO were selected, and the 
nitrifying power estimated for December and March 
samples in March, using soil stored for three months in the 
ease of the former. The check was to see if the same 
result could be obtained for the nitrifying power of PB and 
PC for December samples when estimated in December 
and in March. The result is shown in Table VII as per 
cent. of ammonium sulphate nitrified. 




: | December samples; December samples} March samples 
Soil estimated in estimated in estimated in 
December. March. March. 
3h y aa o 
Pi oT oat 26°4 17:0 
PC 11-5 10:8 2°45 


It appears that close agreement is obtained for the 
December samples when experimented with at different 
times, and we see that the March soil is evidently quite 
different in this particular from the preceding samples. In 
this case there only remains the hypothesis that the soil 
has a varying nitrifying power. ‘To test this point the 
nitrifying powers of the monthly samples were estimated 
and assembled in Table VIT. 
Table VIL.—Percentaye Nitrification of (NH, )3SO,—July 1921 
to March 1922, melusive. 







| Dateof Sampling) Grass. | Lucerne.| PA | PB | PC | PD | 
| ae eae eer ch -b op ch 
July 14,1929 184 | 19-1 | 25-0 | 24-0 | 25-0 | 24-0 
Aug. 17 | 23-4 | 45:5 | 16-1 | 25-2) 16-0 | 84 
Sept. 15 Peed A) 3) PEr ih OOK EN ea one 8 
| Oct. 13 25:0 | 16-7 | 19:5 | 34-5 | 14:2 | 20-1>) 
Nov. 16 V2 all are tee a po ee alot ens yaa eS 
Dec. 15 | 15-2 | 155 | 18-6 | 27-7, |.11-5 | 16-5 | 
| Jan. 11, 1922| 26-4-| 17-9 | 30-2 | 32-1 | 33-5 | 19-8 
Feb. 15 bot0" | 8-4 10.7 2nB. | 9:9 
Mar.16 | 17:2 | 90 | 14-9 | 17-0 | 24-5 | 14-1 




