IOWA ACADEMY OF SCIENCE 
181 
conditions for growth were not favorable. As soon as the manure 
was added they multiplied because there were food and favorable 
conditions. Scientific researchers have demonstrated that bacteria 
have a great deal to do with preparing food for the higher plants. 
They produce decay of the organic matter in the soil. The carbon 
after numerous steps finally is changed to carbon dioxid, the pro- 
tein nitrogen finally takes the form of ammonia, nitric acid or free 
nitrogen. The higher plants obtain their nitrogen from nitrates, 
their carbon from carbon dioxid and even the mineral elements 
owe their availability largely to bacterial action. 
“The 1 greater part of the bases are taken up as nitrates and phosphates, and 
also as salts of the organic acids. Phosphoric acid exists in the soil in the form 
of insoluble basic phosphates, which under the action of organic acids are con- 
verted into neutral or acid salts which are soluble. Hence the production 
of organic acids by bacterial fermentation renders phosphoric acid available 
to plant roots. Carbonates unite with silica to form zeolites and these in turn 
are slowly decomposed by organic acids and their contained bases again liber- 
ated as organic salts. Thus by the combined production of carbonic, nitric and 
the various organic acids, through the action of bacterial life, we have all the 
necessary agencies at hand for the dissolution of the mineral elements of 
plant growth.” 
F. Dafert 2 and Kornauth, Vienna, Austria, report experiments 
with oats inoculated with alinit, Bacillus megatherium, B. subtilis, 
etc. The yield averaged 62.5 g. for the check which received a 
complete fertilizer, 66.2 g. where inoculated with alinit, 66.5 g. 
where inoculated with B. megatherium and 76 g. where inoculated 
with B. subtilis. 
We see that bacteria may play a prominent part in soil fertility, 
and the question is how much did they do in the case of the clover ? 
It may be that the manure by supplying food for the bacteria, 
or correcting the reaction of the soil, has produced a growth of 
bacteria which is favorable to the growth of the clover. There are 
undoubtedly more bacteria there in the soil. It may be that these 
have worked upon the plant food in the soil or the manure, and by 
this action made it more available for the clover. In the long 
run, bacteria undoubtedly do have much to do in the preparation 
of plant food and it would seem that in the case cited above that 
Bacillus subtilis helped the growth of the oats about 20%. If they 
are responsible for the better growth of the clover, it would seem 
that the clover would suffer if they were removed. 
1 F. D. Chester, Penn. Dept. Agriculture. Bui. 98. 
2 Experiment Station Record 16, p. 851. 
