| dc.description.abstract | Peat is the most commonly used carrier for
Rhizobiun. Although it is the best carrier identified
to date, it has some disadvantages: its suitability
varies depending on -the source and it is not
readily available in many parts of the world especially
the tropics. Alternative carriers of uniform composition
would therefore be of considerable importance.
Filtermud, a byproduct of white sugar factories, is
one such material which shows a lot of promise.
In this study the suitability of filtermud as
a carrier for legume inoculants has been assessed.
Five samples each of fresh and decomposed filtermud
were collected from five sugar cane factories in
Kenya namely, Ramisi, Miwani, Muhoroni, Mumias and
Nzoia. Australian peat used as a standard was
supplied by the Agricultural Laboratories, Sefton,
New South Wales, Australia.
The physico±chemical properties of filtermud
and peat were investigated. Fresh filtermud contained
high levels of ash and exhibited high-water
holding capacity compared to decomposed filtermud.
Peat and decomposed filtermud had higher pH values
(6.7 to 7.9) than fresh samples (5.3 to 7.0).
Extractable phosphorus, organic carbon content,
C/N ratio, calcium and magnesium content were all
significantly higher (P = 0.05) in fresh filtermud
than in decomposed filtermud. The total N level
in decomposed filtermud was higher than in fresh
samples. There was however no significant difference
between the levels of K and Na in the two types
of filtermud. Compared to filtermud, peat exhibited
a very low P content. However, the levels of total
N, organic carbon, K and Na were highest ~hile the
C/N ratio, Ca and Mg values were similar to those
of fresh and decomposed filtermud.
The plate"cou~t method was used for the enumeration
of rhizobia. Irrespective of the degree of
decomposition or source, filtermud-based inoculants
compared well as a carrier with peat-based inoculants.
This was judged from the growth and survival of
R. phaseoli strain NUM 406 within a five to six months
period during which cell densities of 108/g of carrier
were sustained for all carriers.
The effect of storage temperature on growth and .
survival of R. phaseoli strain NUM 406 and R. japonic
un strain NUM 504 was also determined using only
decomposed filtermud from Muhoroni and peat as
carriers. Storage at 40C did not significantly
increase rhizobial numbers while a maximum viable
count of 10 rhizobia/g of carrier was obtained
when inoculants were stored at 2800 for three mDnths.
No viable cells were "however recovered from inooulants
stored at 400C for one -month.
Based on rhizobial survival on seeds, it was
observed that 40% gum arabic was a better
sticker than 10% sucrose solution with both carriers
when sprinkler and slurry methods of seed inoculation
were adopted.
Tests on effectiveness were performed using
Rhizobium cultures applied as broth, peat-based and
filtermud-based inoculants. Nodulation and N2-
fixation were also assessed in Leonard jars under
greenhouse conditions. Soybean (Glycine m ax L.
Merrill) cv.
"Bossier" and the common bean (Phaseolus
vulgaris L.) cv. "Canadian wonder" were planted in
N-free vermiculite in Leonard jars. Measurements
of dry matter yield indicated that the effect of
inoculation with filter mud based inoculant did
not differ significantly (P = 0.01) from peat-based
inoculant.
From these investigations based on carrier
materials from Kenya, it has been concluded that
filtermud is a good carrier for inoculant production.
Filtermud is easily available in large qu?-ntities
at very low cost. | en |
