Relationships between soil characteristics and total and DTPA-extractable micronutrients in Inceptisols of Punjab

During the last three decades agricultural production in Punjab has increased manifolds. These gains in productivity have been confined to the Inceptisols, which cover about 60% of the geographical area of the state. An investigation was carried out to study surface and profile distribution of total and diethylenetriamine pentaacetic acid (DTPA)-extractable micronutrients zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe)] and their relationships with soil properties in nine different sub group of Inceptisols developed in Siwalik and alluvial plains of northwest India. The total contents varied from 39 to 99 mg kg(-1) for Zn, 16 to 47 mg kg(-1) for Cu, 2.04 to 4.54% for Fe, and 262 to 805 mg kg(-1) for Mn. DTPA-extractable contents varied from 0.08 to 1.28 mg kg(-1) for Zn, 0.20 to 2.36 mg kg(-1) for Cu, 0.91 to 32.0 mg kg(-1) for Fe and 1.50 to 43.8 mg kg(-1) for Mn. These micronutrients are higher in the fine fractions than in the coarse fraction. The content of total Cu, Fe, and Mn followed the patterns of accumulation, eluviation, and illuviation. Distribution of micronutrients with depth in these soils indicates that parent material and geomorphic and physicochemical processes control total content, and biological processes affect DTPA-extractable content. The total content of micronutrients increased with an increase in clay and silt and cation exchange capacity (CEC), whereas DTPA-extractable micronutrient increased with an increase in organic carbon content and CEC, and decreased with increasing pH. sand and calcium carbonate content. The total reserves of Zn and Cu showed an influence on availability of these respective micronutrients. The available micronutrient contents depended largely on the organic carbon content. The correlation between total amounts of Cu, Fe, and Mn suggested that they occurred together Among the various micronutrients, deficiency of Zn was widespread followed by Fe in the intensively cultivated Inceptisols.