Decomposition of the Iron, Aluminum, Zinc, and Copper Salts or Complexes of Some Microbial and Plant Polysaccharides in Soil
1966
Martin, J. P. | Ervin, J. O. | Shepherd, R. A.
Zinc, Copper, iron, and Aluminum salts or complexes of a series of bacterial and plant polysaccharides containing from 6 to 83% uronic acid units were prepared. The rate of decomposition of the metal-polysaccharide complexes or salts and the original polysaccharide preparations was determined in Greenfield sandy loam. Some or all of the metals exerted marked effects on decomposition rate and percentage decomposition at 8 weeks of the majority of polysaccharides tested. Specific effects of the metals depended on the polysaccharide. Zinc and Al exerted very little influence on decomposition of Azotobacter chroococcum polysaccharide for example, while Cu and Fe reduced decomposition by about 50%. A much smaller percentage of Zn, on the other hand, reduced decomposition of Karaya gum from 67% to 0 in one test and to 3% in a repeat trial. The Cu-salt of Azotobacter indicus polysaccharide was highly resistant to decomposition. After 8 weeks, 3% had decomposed compared to 29, 32, 16, and 16% for the original polysaccharide and the Al, Zn, and Fe complexes, respectively. With the exception of the Al combined with the Arthrobacter viscosus polysaccharide, all of the metals sharply reduced decomposition of A. viscosus polysaccharide and alginic acid but exerted very little effect on polysaccharides from Chromobacterium violaceum and a Bacterium sp. When added directly to the soil in concentrations equivalent to that in the metal-A. chroococcum polysaccharide complexes (75% uronic acid), the metals exerted no effect on decomposition of Bacillus subtilis fructosan.
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