8/9/2019 TOWARDS THE THEORY OF APPLICATION OF BIOFERTILIZERS
1/8
Moscow UniversitySoil Science BulletinVol.50. No.2, pp.45-52.
1995
Vestnik MoskovskogoUniversiteta. Pochvovedenie
UDC 631.16:576.8
SOIL BIOLOGY
ON THEORETICAL SUBSTANTIATION OF THE USE
OF MICROBIAL FERTILIZERS
P. A. Kozhevin and S. S. Korchmaru
Poss ib le r e s t r i c t i on s i n he r en t i n ob t a in i
ng s t ab l e pos i t i v e e f fec ts f rom conv en-
t i ona l bac t e r i a l f e r t i l i zer s were cons ide red
. T h e use o f a na tu ra l mic ro b i a l com-
plex ex t r ac te d f r om a fer t i l e soi l by phy s ica l m
e t h o d s was sug ge s t ed as an a l te r -
na t i ve . E x pe r i me n t a l p roo f o f t he va l i d i t
y o f t h e p r op os ed so lu t i on a r e p ro v id ed .
The year 1897 can be regarded as an initial stage in the history
of the application of microbial fertilizers.
After Beijerinck succeeded in isolating a pure culture of nodule
bacteria, Nobbe and Hiltner produced and
put on sale Nitragin , a pr od uc t conta ining nod ule bacter
ia. Pa rad ox ica l as it is, mi crobial fertilizers were used
in many countries long before the world of micro orga nisms ha d
b een discov ered; thes e fertilizers were applied
as the earth taken fro m und er legumes on soils wit h low yield
of leg umi nou s crops. Along wi th Nitragin,
products based on cultures of various bacteria were broadly
advertized (as Alinite containing putrifactive
bact eria) . Microbial fertilizers were tou ted as th e gre ate
st discove ry of th e 20t h cent ury to boo st crop
yields. The use of bacterial fertilizers dates back to 1911,
when Bacteriological and Agricultural Station in
Moscow and Agricultura l an d Bacteriological Lab orat ory in
St. P ete rsb urg sta rt ed prod ucing Nitragin. By
that time it became obvious that microbial fertilizers were far
from being always efficient (Rudakov et al.,1938).
No serious analysis of rest rict ions an d failures ha d been ca
rrie d out, due to th e absen ce of reliable
methods of identification and enume ratio n of microbial popul
atio ns u nde r nat ur al conditions, on one hand,
and a trend towards the search for new microorganisms with a
higher efficiency, on the other. This approach
broadened the scope of microorganisms which could be of interest
from the viewpoint of the efficiency of
their agricultural use (Lyn ch, 1 987). Currently , pro mising
res ults obt ai ne d in th e field of gene engineering
regarding the possibilities of the development of new
microorganisms to make a revolution in agriculture
aroused deep interest amon g th e speciali sts. Th e only imp
edi men t could be th e necessity of th e analysis of
adverse implications (Tiedje et al., 1989). Th e prob lem rel
ated to t he esti mat ion of possible risks has not
been solved so far (Kozhevin, 1994; Zvyagintsev, Kozhevin,
1994); however, this most obvious (though far
from being the only one) restriction does not prevent the
emergence of promising genetic projects.
History develops in a spiral making geneticists think of
expectations which were engulfing people at
the tur n of the century. Despi te considerable endeavors being
mad e by a great nu mbe r of researcher s, the
problem related to t he use of microb ial fertilizers is still
far from b ein g solved. Therefo re, ne arly 100 years
after the beginning of the use of microbial fertilizers to
increase crop yield, quite urgent would be an attempt
at ecological analysis of the problem with possible
potentialities and restrictions to be revealed.
The very history of the application of microorganisms as
fertilizers showed that similar effects were
recorded in using diverse pop ula tion s with varying biological
an d technological pot entia ls. In this respect,
quite reasonable would be a tren d towards studie s of a group
of "p lan t growth stimu lato rs" comprising
not only nitrogen fixers (as nodule bacteria, azotobacter,
azospirillum), mycorrhiza, and other microorgan-
isms providing plants with phosphorus, nitrogen, and other
elements, but also microorganisms forcing out
undesirable populations with phytopathogenic and phytotoxic
effect from the rhizosphere (Shippers et al.,
1995 by Allerton Press. Inc.
45
8/9/2019 TOWARDS THE THEORY OF APPLICATION OF BIOFERTILIZERS
2/8
Basing on the information available doubts may arise as to the
usefulness of microbial fertilizers, the
more so, as yield increments are not always statistically
significant and usually do not exceed 15%.However,
in our opinion, the potentials of microbial fertilizers are far
from being exhausted. The doubing of the yieldin some cases may
serve as a proof of this assertion. The main problem to be solved
is instability of effects
and relevant restrictions.
The search and development of new microorganisms with a high
level of useful characteristics using
gene engineering technique is very important, but they have
certain restrictions researchers should be aware
of. Hopes for successful solution of all problems of
introduction using genetic methods are not justified. B
analogy one can speak of an unfeasible design of an aircraft
which could be the fastest, the lightest, having
the highest carrying capacity, reaching the highest altitude,
being the most reliable and cheapest. A real
design will always be a compromise due to existing restrictions,
with the final combination of characteristics
of even relatively simple designs to become clear only after
testing.
With the entire diversity of concept of ecological strategies of
microorganisms being the case, the mainidea is that a population
cannot maximize simultaneously parameters related to r- and
K-selection due
the principle of preservation (limited elasticity) (Kozhevin,
1980). An introduction of additional geneticinformation into a cell
will inevitably have an effect on the ecological strategy; in some
cases it will decreaseits competitiveness (e.g., plasmid as an
intracell parasite in connection with additional expenditures
forbiosynthesis), in other cases, may increase the risk of
undesirable implications (Kozhevin, 1992).
46
