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This article in SSSAJ

  1. Vol. 22 No. 3, p. 225-228
    Received: Nov 5, 1957
    Accepted: Feb 5, 1958

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Water-Soluble Chelating Agents in Organic Materials: I. Characterization of Chelating Agents and Their Reactions with Trace Metals in Soils1

  1. M. H. Miller and
  2. A. J. Ohlrogge2



Water extracts of barnyard manure, dried and ground alfalfa, and animal feces were found to contain complexing agents which were capable of removing zinc from the soil. This zinc could not be removed by water or a potassium chloride solution, but could be removed with a cupric chloride solution. The complexing agents or combination of agents appear to be of plant origin, and were partially inactivated by incubation of the organic material prior to extraction.

It was shown by the principle of resin-exchange equilibrium that the zinc after removal from the soil was complexed by materials in the water extract of manure. There were at least two complexing agents in the extract, one or more of which formed a 2:1 type of complex and one or more of which formed a 1:1 complex, the resulting average being 1.55:1. The “apparent” stability constant of the combination of agents for zinc was found to be 7.8. The ability of the extract to complex zinc increased as the pH of the extract was increased. The formation of a chelate complex between the zinc and the chelating agents in the extract is postulated.

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