Reactions of Some Polyamine Polyacetate Iron Chelates in Various Soils
1956
Lunt, O. R. | Hemaidan, N. | Wallace, A.
The solution-solid phase distribution of Fe supplied as polyamine polyacetate chelates in several soils and clays at various pH levels was studied. In the pH range from 7 to 8, the disappearance of Fe from solution from clays and soils having moderate amounts or more of clays was much more rapid than is the loss of Fe from nutrient solutions in the same pH range. Clays apparently catalyze the hydrolysis reaction by which Fe is fixed in alkaline solutions. With a number of soils and clays, there was considerable loss of Fe from the soil solution under acid conditions. The process by which FeEDTA is fixed in acid soils is obscure, although Fe and EDTA were removed from solution at about the same rate. The rates of reaction indicated that simple surface exchange was not involved. Movement of Fe chelates in fine textured soils is slow. Organic matter content, wetting and drying, microbiological activity, and nominal quantities of salts in soils did not affect the loss of Fe from solution greatly. The recovery of fixed chelated Fe by plants was poor as compared to soluble chelated iron.
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