DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. oF 
Winogradsky’s solutions and also into flasks of sterile water, from 
which counts were made. The remaining portions of the samples 
were then emptied on clean sheets of paper in the culture room and 
left to dry under conditions as free as possible from chance contami- 
nations. Fifty-gram portions from each sample were removed for 
original nitrate determinations, and another equal portion was re- 
placed in the original containers, brought up to optimum moisture 
content with 5 cubic centimeters of 0.4 per cent sulphate of ammonia 
and distilled water, incubated for two weeks at 28° C., and the nitri- 
fication determined. A duplicate series to which was added a 2 per 
cent solution of calcium sulphate was prepared. At the beginning 
of the incubation period the total weight of the container and soil 
at optimum moisture was taken, and the loss from evaporation was 
restored with sterile distilled water at 3-day intervals during the 
incubation period. The results of the experiment appear in Tables 
IV and V. 
TaBLeE 1V.—Effect of calcium sulphate upon nitrification in samples of soil from plats 
300 and 310, Truckee-Carson Experiment Farm, representing poor soil conditions. 
Incubated 15 days at 28° C. 
NO CALCIUM SULPHATE ADDED TO SAMPLES. 
Nitrogen as nitrite (parts per | Nitrogen as nitrate (parts per 
| illion). © 
See | 
No. of | Depth of | mer: an | 
plat. soil. | 
| Original.| Final. Gain. | Original.| Final. Gain. 
Inches 
300 0-6 a2 5. 60 4.40 9.12 56.40 | 6.28 
6-12 2.0 3.12 1.12 7.68 00.00 | — 7.68 
12-18 1.2 1.68 | 48 | 6.14 00. 00 — 6.14 
18-24 .0 1.20 1.20 4.56 00.00 | — 4.56 
310 0-6 1.0 7.28 - | 6. 28 4.80 96. 00 91.20 
6-12 | 1.0 21075 1.10 1.60 00.00 | — 1.60 
12-18 1.0 80 — .20 4,32 00.00 | — 4.32 
| 18-24 | 1.0 20% | 20 3.07 00. 00 | — 3.07 
WITH 2 PER CENT CALCIUM SULPHATE ADDED TO ALL SAMPLES. 
, | 
300 ee ae 2.80 1.60 9.12 57.00 47. 88 | 
6-12 2.0 2. 80 “80 7.68 00.00 | — 7.68 | 
12-18 1.2 2.70 1.50 6.14 00.00 | — 6.14 | 
18-24 :0 .88 “88 4.56 00.00 | — 4.56 
310 0-6 1.0 4.00 3.00 4.80 | 96.00 | 91.20 | 
6-12 1.0 2. 40 1.40 160. | 1220 P= © 40 
12-18 1.0 1.68 68 4.32 0.00 4.32 
18-24 1.0 1.56 56 3.07 6/00 |e =23007 
a . —____ 
