THE NITRIFYING EFFICIENCY OF CERTAIN COLORADO SOILS 
31 
from ammonium sulphate was 972 p. p. m. by No. 84,, a heavy clay 
niter soil; from ammonium chloric!, it was 428 p. p. m. by No. 97, a clay 
niter soil; from ammonium carbonate, it was 1148 p. p. m. by No. 97; 
from dried blood, it was 820 p. p. m. by No. 96, a sandy loam, normal 
soil. 
The average amount of nitric nitrogen produced by a positively re¬ 
acting soil in each series was as follows: Ammonium sulphate, 672 
p. p. m.; ammonium carbonate, 520.88 p. p. m.; dried blood, 431.50 p. 
p. m.; ammonium chlorid, 120.88 p. p. m.; check 59.30 p. p. m. 
The average amount of nitric nitrogen produced by a Colorado soil 
in the different series, all samples taken into consideration, positive 
and negative, was as follows: Ammonium sulphate, 484.26 p. p. m.; 
ammonium carbonate, 398.34 p. p. m.; dried blood, 341.30 p. p. m.; am¬ 
monium chlorid, 56.80 p. p. mi.; check, 51.30 p. p. m. 
The average amount of nitric nitrogen produced by a niter soil in 
the incipient stage, and a normal soil in each series was as follows: 
Ammonium sulphate, 710.6 p. p. m. for the nitre, 691.6 p. p. m. for the 
normal; ammonium chlorid 181.6 p. p. m. for the niter, 46.66 p. p. m. 
for the normal; ammonium carbonate, 507.6 p. p. m. for the niter and 
505.6 p. p. m. for the normal; dried blood, 405.14 for the niter, 519.6 
for the normal. The differences in the average gain from the sulphate 
and the carbonate are SO' small, 19 p. p .m. for the former and 2 p. p. m. 
for the latter, that we are reasonably safe in saying that our incipient 
niter soils and normal soils are equally efficient in nitrifying these sub¬ 
stances. In the case of the dried blood, the normal soils have out- 
yielded the others by 114.46 p. p. m. per sample. In the ammonium 
chlorid series, the number of samples under consideration is too small 
for the results to carry much weight; however, our figures taken for 
what they may be worth, indicate that the niter soils are superior to the 
normal, the former yielding an average of 34.94 p. p. m. of nitrate nitro¬ 
gen more than the latter. 
Considering the positively reacting soils, or those which showed an 
increase in nitric nitrogen above the controls, we find that 52.94 per 
cent, of them made their largest gains from the ammonium sulphate; 
33-33 P er cent, from the ammonium carbonate, 30 per cent from the 
dried blood and none from the ammonium chlorid; 41.17 per cent, made 
their second highest gains from ammonium sulphate; 38.88 per cent, 
from the carbonate; 15 per cent, from the dried blood and none from the 
ammonium chlorid 11.76 per cent, gave the third largest yields from 
the ammonium sulphate; 27.77 per cent, from the carbonate; 55 per cent, 
from the dried blood and o. per cent, from the chlorid of ammonium, 
21.74 per cent, of the soils produced less nitric nitrogen in the 
presence of ajnmonium sulphate than the controls, while 4.35 per cent, 
gave the same; 33.33 per cent, gave less with the ammonium chlorid 
than the checks, and 6.67 per cent, the same; 17.39 P er cent, yielded 
less from ammonium carbonate than the controls and 4.35 per cent, the 
same; 8.7 per cent, produced less from dried blood than the controls, 
and 4.35 per cent, the same. 
