29 
Pickering ! found that partial sterilization brought about an in- 
crease in the solubility of the organic matter. An increase in the 
total nitrogen soluble in water and greater absorption of nitrogen 
by plants were also produced by heating. 
Lyon and Bizzell 2 observed that the action of steam heat at 2 
atmospheres pressure greatly increased the ammonia, in addition to 
increasing the water soluble inorganic matter. The nitrates were 
largely decomposed at this temperature and pressure. 
Russell and Hutchinson 3 have shown that by heating some 
Rothamsted soils at 98° C. for three hours a small increase in the 
ammonia content took place. The most remarkable effect of the 
partial sterilization, however, was in connection with subsequent 
ammonification. Ammonia began to be formed in the course of a 
few days, followed by a remarkable production of ammonia later on. 
Corresponding to the increase in ammonia subsequent to heating, 
an enormous increase in the numbers of microorganisms (bacteria 
and fungi) took place. Heating to 125° also caused an initial pro- 
duction of small amounts of ammonia, but no subsequent ammonifi- 
cation set in. The nitrates were little affected although nitrification 
was entirely inhibited by the treatment. From the fact that volatile 
antiseptics bring about similar effects, these authors believe that 
partial sterilization kills certain biological agents which, in the 
untreated soil, effectively hold in check the multiplication and activ- 
ity of the ammonifying organisms. After these inhibiting agents 
are destroyed the ammonifying efficiency of the soil rises rapidly, 
thus making available greatly increased amounts of nitrogen. 
Lodge and Smith 4 found that decoctions from soils show an 
increase in ammonia after steam sterilization at 15 pounds pressure, 
but a decrease in ammonia took place from the sterilization of the 
subsoil. 
Lathrop and Brown 5 found that the amounts of ammonia and 
total nitrogen soluble in water increased with an increase in the 
pressure under which the soil was heated. At 10 atmospheres 
approximately 40 per cent of the total nitrogen was rendered soluble, 
while the ammonia thus split off was found to vary from 7.83 per 
cent to 15.64 per cent. 
Recently Schreiner and Lathrop 8 published a comprehensive 
investigation of the effects of steam heat on soil organic matter. In 
this work they isolated from heated soils a number of compounds 
not found in the unheated soil. Among the compounds isolated a 
i Jour. Agr. Sci., 2 (1908), p. 411. 
* New York Cornell Sta Bui. 275 (1910). 
•Jour. Agr. Sci., 3 (1909), pp. 111-144. 
* Massachusetts Sta. Rpt. 1911, pt. 1, pp. 126-134. 
•Jour. Indus, and Engin. Chem., 3 (1911), p. 657. 
6 U. S. Dept. Agv., Bur. Soils Bui. 89; Jour. Amer. Chem. Soc, 34 (1912), pp. 1242-1259. 
