A pot experiment was conducted in the green house ot National Research
Center to study the effect of organic manuring (composted town refuse) and organic
manure associated with dual biofertilizers on rhizosphere of taba bean plants, as well
as the enzymatic activities of soil as indicators to the biological activity. An empirical formula was suggested to evaluate the effects of different
treatments applied under the rhizosphere conditions. These effects could be indexed
by determining the Efficiency of Rhizosphere Treatment (ERT) i.e., the net effect of
rhizosphere treatment divided by the net effect of the same treatment in root - free
soil. Organic amendment (2% of composted town refuse) alone 0 r associated with
dual biofertilizers (Rhizobium /eguminosarum+ Phosphate dissolving bacteria) (POB)
wrer used. The rhizosphere effect and the ERT were periodically determined (2,4, 6,
8 weeks) for the unamended and amended soil respectively. The changes in soil
prganic carbon, total nitrogen, rate of C02 evolution, populations of total microbial
flora, Rhizobium /eguminosarum And POB, as well as soil enzymatic activities of
invertase, phosphatase, and dehydrogenase were used as chemical, microbiological
and biological parameters under these conditions. The results revealed that the biofertilizers treatment recorded the higher
figures of ERT for ali parameters studied as compared to the organic amendment
(CTR) alone or the unamended soil under the rhizosphere of faba been (Vicia faba).