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					Title                 Activities of Rhizosphere Microorganisms as Affected by
                              Application of Organic Amendments in a Calcareous
                              Loamy Soil. 1. Carbon Assimilation
Author/s              F. N. Barakah, S. H. Salem, A.M. Heggo and M. A. Bin-Shiha
                      Journal of
Contact Info.
Department
Major
Year of Publication   1995
Publisher             Arid Soil Research and Rehabilitation
Type of Publication
Full Text (Yes, No)   No
Key Words
Abstract                    The activities of soil microorganisms in the rhizosphere ( R
                      ) and nonorhizosphere ( S ) regions of alfalfa and wheat plants,
                      growing in calcareous loamy soil of Saudi Arabia, as influenced
                      by application of organic amendments such as sludge and wheat
                      straw, were studied in pot experiment for 7 weeks. The study
                      showed that counts of aerobic heterotrophic bacteria in the
                      rhizosphere soil of both alfalfa and wheat plants significantly
                      increased due to application of organic amendments accompanied
                      by a high decomposition rate for carbonaceous materials.
                      Application of sludge to the soil enhanced the rhizosphere
                      microorganisms during all experimental periods as compared with
                      those treated with straw. Strow manure clearly enhanced the
                      aerobic cellulose decopmosing bacteria, especially in the
                      rhizosphere region. The total microbial counts in the rhizosphere
                      of alfalfa were generally higher than those of the wheat plants in
                      the first and second weeks and at the end of the period,especially
                      when sludge was applied as an amendment . The densities of the
                      total fungi, actinomycetes, and sporeformers were slightly
                      affected by the rhizosphere soils, and the R/S ratios rarley
                      exceeded 2.0. Soil treatment with either sludge or straw
                      significantly increased the organic carbon and consequently, the
                      organic matter of the soil, especially in the rhizosphere region
                      with relatively higher values for those amended with straw.A high
                      carbon-to- nitrogen ratio of the amendment to the soil was
                      associated with slow decay of the organic matter. Ammendement
                      of loamy soil with sludge at the common rate(2%) enhanced the
                      microbial flora with no harmful effects to plant growth or soil
                      fertility and can be used safely on agricultural land.

				
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