Status and distribution of zinc in the soils of Thoubal District, Manipur India

Abstract

Twenty surface soil samples were collected from different paddy fields of thoubal district, Manipur to determine status and different forms of zinc in the soils. All the soil samples were acidic in nature with mean value of pH 5.49. The mean value of electrical conductivity was 0.07 dSm-1. The mean value of organic carbon was 2.13%. The mean cation exchange capacity, available nitrogen, available phosphorus and available potassium were 17.37 [cmol(p+)kg-1], 315.16 kg ha-1, 26.39 kg ha-1 and 240.11 kg ha-1 respectively. The studied soils were fine-textured that is clay in the textural class. The mean value of available (DTPA extractable) zinc was 0.82 mg kg-1. The DTPA extractable zinc show positive and significant correlation with CEC. A negative and significant correlation was observed with pH. On the basis of average concentration, the distribution of zinc in the soil order was: WSEX-Zn (0.38 mg kg-1) < CRYOX-Zn (1.31 mg kg-1) < MnOX-Zn (1.95 mg kg-1) < AMOX-Zn (3.04 mg kg-1) < OCx-Zn (3.16 mg kg-1) < Res-Zn (82.79 mg kg-1). All the zinc fractions showed positive correlation with EC, OC, CEC, available nitrogen, available potassium, clay; and negative correlation with pH and available phosphorus. WSEX-Zn and Res-Zn showed the lowest and highest concentration among the all zinc fractions, respectively. Different zinc fractions were found to be correlated to eachother, suggesting the dynamic nature of the equilibrium existing between them. The highest correlation among zinc fractions was found between residual and total zinc indicating the dependence of these forms on each other.