Pedosphere 6(2): 167--173, 1996
ISSN 1002-0160/CN 32-1315/P
©1996 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Study on water-soluble organic reducing substances: Ⅲ. Electrochemical properties of decomposition products of rice straw and their interactions with variable charge soils
WU You-Xian
Institute of Soil Science, Acodemia Sinica, P. O. Box 821, Nanjing 210008 (China)
ABSTRACT
      Some electrochemical properties, such as pH, Eh, and voltammetric behavior, of the decomposition products of rice straw and the interactions of these products with soils were studied. The pH, Eh, and amounts of organic reducing substances changed markedly during the 60-day anaerobic decomposition. pH decreased sharply to pH 5 on the tenth day and then increased gradually to 7 on the 45th day. The amounts of organic reducing substances increased almost synchronously with the fall of redox potential during the first 15 days. The differential pulse voltammetric (dpv) behavior changed not only in the peak current but also in the peak potential. The fractions with apparent molecular weights lower than 200 daltons appeared to be active in dpv behavior. The electric charge of organic reducing substances was closely related to the decomposition stage. The 6th day of incubation was the crucial time before and after which the major part of the components was negatively charged and positively charged, respectively. The group with a low apparent molecular weight and a negative charge was the main components responsible for the lower anodic peak potentials. They were oxidized first during the interactions of the organic reducing substances with soils.
Key Words:  electrochemical properties, organic reducing substances, rice straw, variable charge soils
Citation: Wu, Y. X. 1996. Study on water-soluble organic reducing substances: Ⅲ. Electrochemical properties of decomposition products of rice straw and their interactions with variable charge soils. Pedosphere. 6(2): 167-173.
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