Hma. Magid et al., THE INTERRELATIONSHIP BETWEEN MICROBIAL NUMBERS, APPLICATION RATE ANDBIODEGRADATION PRODUCTS OF 2 ORGANIC MANURES IN A SANDY SOIL, Arab Gulf journal of scientific research, 14(3), 1996, pp. 641-657
The relationship between microbial numbers and rate of application and
biodegradation products (mainly CO2 and NH3 evolution) of chicken man
ure (C.M.) and municipal refuse (M.R.) was determined using the data o
btained during field incubation studies under centre-pivot sprinkler i
rrigation in Central Saudi Arabia. Microbial numbers increased with in
creasing rate of manure application and with incubation time. Maximum
microbial proliferation coincided with the optimum (feasible) rates of
application of both manures with respect to CO2 evolution previously
reported by Abdel Magid et nl. (1993). In microbial growth rate terms
the effect of the optimum rate of application was more pronounced with
C.M. than with M.R. at the 16th week of incubation. After 16 weeks, h
ighly significant correlations were obtained between microbial numbers
and rates of treatment application, cumulative CO2 and cumulative NH3
. The highest rates of CO2 and NH3 evolution coincided with the optimu
m rates of application of both manures. A laboratory study of the effe
ct of temperature on NH3 evolution during the biodegradation of C.M. r
evealed that at high rates of application the magnitude of the tempera
ture coefficient (Q(10)) Of NH3 evolution is affected by the rate of a
pplication irrespective of temperature. At application rates higher th
an the optimum biodegradation was insensitive to temperature. The resu
lts obtained confirm our previous findings that the optimum economic r
ates of application of C.M. and M.R. occur between 8.25 to 16.5 and be
tween 16.5 to 33.0 tonnes/ha, respectively.