58 
Journal of Agricultural Research 
Vol. VII, No. 2 
series were superior to those in the soil-nitrogen series as is shown clearly 
in Table III, Group II, whereas in Table III, Group I, the highest per¬ 
centage of nitrogen transformed into nitrate was slightly in excess of 6. 
The corresponding figure for Group II is n, and several other soils, be¬ 
sides, approach that record. In general, it would seem that sulphate of 
ammonia stimulates nitrification in soils of the Bay area, while it depresses 
nitrification in the foreign soils. 
With dried blood the Bay area soils show a loss in nitrate production 
over that of which the soil is capable on its own nitrogen supply in over 
43 per cent of the soil types, so far as absolute quantities of nitrates are 
concerned. In a number of these cases, moreover, there is not only less 
nitrate produced than from soil nitrogen alone, but the soil’s original 
nitrate supply is lost besides. On the other hand, there are about 9 soils 
in the Bay area series which, on the basis of production of nitrate in the 
absolute sense, surpass any in the series with soil nitrogen alone, and, 
similarly, all but one in the sulphate-of-ammonia series. It may be 
noted, however, that none of these soils consists of coarse, sandy material 
with a small absorbent surface,and none contains less than0.073 percent 
of total nitrogen, nearly all of them containing considerably more than 
0.08 per cent. It is the last group of 9 soils showing naturally a number 
of good results on the relative basis in Table III, Group III, which reveals 
the highest percentage transformation of total nitrogen into nitrate yet 
noted with the Bay area soils in these experiments. The record is a 
15 per cent transformation in the case of the Yolo gravelly loam. One 
transformation of 12 per cent and one of 11 per cent are also noted, but 
all the rest are considerably below those figures. In general, it would 
seem that the heavier soils and such as are better supplied with nitrogen 
than the average of the Bay area series will give better results with 
dried blood than with sulphate of ammonia or soil nitrogen, but the 
rest (more than two-thirds of the total number) will not do as well with 
dried blood as with the other forms of nitrogen. 
Considering the cottonseed-meal results in the case of the Bay area 
soils, as set forth in Table III, Group IV, from the absolute amounts of 
nitrate produced cottonseed meal is to be regarded as of less value than 
dried blood from some points of view and of more value from others. 
To be more specific, no soil produces as much nitrate from cottonseed 
meal as does the Yolo gravelly loam from dried blood. On the other 
hand, there are less soils in the cottonseed-meal series than in the dried- 
blood series which are induced to lose in nitrifying power by the incor¬ 
poration of the fertilizer and none at all which lose part or all of the 
nitrate nitrogen originally contained in them. Relatively, the cot¬ 
tonseed-meal series is ahead of all others with the Bay area soils in 
that the largest amount of nitrogen transformed into nitrate is there 
noted. This record is attained by the same soil as that having the 
record in the dried-blood series and amounts to an 18 per cent trans¬ 
formation of the total nitrogen present into nitrate. The Pleasanton 
