The distribution of Zn, Cu, Mn, and Fe in the pedosphere varies with the genetic horizons that are evolved through soil-forming processes altering parent material. In Alfisols, the driving processes are eluviation and illuviation. Our objective was to determine the relationship of soil-forming processes with the distribution of total and DTPA-extractable forms of Zn, Cu, Mn, and Fe in Alfisols. Nine profiles, three each from concave hill slope in the Siwalik Himalaya, piedmont, and plain on a topo-sequence in Punjab, were sampled. Soil samples were collected from each horizon and analyzed for total and DTPA-extractable Zn, Cu, Mn, and Fe. Total content ranged from 36 to 113 mg kg−1 for Zn, from 12 to 42 mg kg−1 for Cu, from 210 to 586 mg kg−1 for Mn, and from 1.42 to 4.82% for Fe. DTPA-extractable content ranged from 0.22 to 2.30 mg kg−1 for Zn, from 0.30 to 2.58 mg kg−1 for Cu, from 2.80 to 86.5 mg kg−1 for Mn, and from 3.10 to 30.5 mg kg−1 for Fe. Total contents of Zn, Mn, and Fe were highest in the profiles of the piedmont, moderate in the profiles of the concave hill slope, and lowest in the profiles of the plain depicting their association with landform units. DTPA-extractable forms decreased with depth, increased with increase in organic matter, and decreased with increase in clay content. There were no correlations between total contents of Zn and Mn with soil separates, although total contents of Fe and Cu increased with increase in clay content. Invariably, illuvial horizons contained higher amounts of total elements than eluvial and subsoil horizons. Data showed that the landform units rule the profile contents and the pedogenic processes govern the distribution of the total elements, whereas organic carbon controls DTPA-extractable forms.
Department of Soils, Punjab Agricultural University, Ludhiana-141 004, India. Dr.B. D. Sharma is corresponding author. E-mail: email@example.com; firstname.lastname@example.org
Received July 22, 2003; accepted March 24, 2005.