ABSTRACT
In the
present study, about 94% of the arable land had a phosphorus deficiency
(available P < 10 mg·kg-1). To
compensate for this deficiency, high amounts of phosphorous fertilization were
applied to soils to get better crop yield. In the past two decades, soil
organic matter has sharply declined from 34.8 g/kg in late 1980s’ to 12.0 g/kg
in 2010. The soil has moderate to high cation exchanging capacity (CEC) in the
range of 45 - 58 Meq/100 gm. The low soil organic carbon, high CEC and high
phosphorus fertilization could lead to poor heavy metal availability to plants.
Nevertheless, DTPA extractable concentrations were 40.5 mg/kg for copper, 35.5
mg/kg for iron, 134 mg/kg for manganese, 2.1 mg/kg for nickel, 2.6 mg/kg for
lead and 53.5 mg/kg for zinc. All the available micronutrients seem to be
adequate for plant growth. In terms of toxicity, the values of Cu, Fe, Mn, Zn,
Ni and Pb found in the present investigation were lower than those of above
critical value set by the international guidelines and other researchers.
Variations in heavy metal content in the soil were attributed due to
differences in land use types and disparity in organic sources amongst the
plant and animal composites. For better crop productivity, more organic matter
should be added to the soils. The traditional nutrient cycling practices, such
as manure application, allow crop residue to decay on fields, fallowing and
rotational cropping has to be followed to rehabilitate the soil and buildup
both macro-and micro-nutrients to their natural level.