DISTRIBUTION OF DTPA-EXTRACTABLE FE, ZN, AND CU IN SOIL PARTICLE-SIZE FRACTIONS

To examine the distribution of DTPA-extractable Fe, Zn, and Cu in clay, silt, and sand fractions; surface soils were collected from cultivated fields of North Dakota, South Dakota, West Virginia, Iowa, Ohio, and Illinois. Clay, silt, and sand fractions were separated after sonic dispersion of soil water suspension and analyzed for DTPA-extractable Fe, Zn, and Cu. In general, clay had the highest and sand the lowest amount of DTPA-extractable metals. Consequently, clay had the highest and sand the lowest intensity and capacity factors for these metals since DTPA micronutrient test measures both these factors. © 1979, Taylor & Francis Group, LLC. All rights reserved.