Abstract

Cholarajan, and Vijayakumar R

The micronutrient status of rhizosphere soils of Thanjavur district, Tamilnadu was made at 9 different locations. The objective of the present study was to analyze the status of micronutrients and their relationship with various physiochemical properties. Soil samples were collected at a depth of 0-30cm and analyzed zinc (Zn), copper (Cu), iron (I) and manganese (Mg). The Zn, Cu, I and Mg ranged from 0.56 - 0.96, 0.57 - 0.96, 4.16 - 5.36 and 2.03 - 2.65 mg/kg -1 respectively. Nutrient management is an integral part of profitable agrisystems, but in some areas of Tamilnadu inputs of fertilizer and manure nutrients in excess of crop requirements have led to a buildup of nutrient concentrations that are of environmental concern. There is an increasing awareness of the need to pay greater attention to the role of trace elements in plant nutrition as we seek to explain the adverse effects of deficiencies and toxicities, and avoid suboptimal concentrations that limit the attainment of optimum economic yields of crops. But some elements can accumulate even as traces to concentrations that are toxic to the plant. For example, plant growth is adversely affected by excess manganese (Mn) and aluminium (Al) in many soils if they are allowed to become acid, or by nickel (Ni), cobalt (Co) or chromium (Cr) in acid soils derived from minerals in which there is a natural abundance of these elements. In other soils, concentrations of trace elements have increased as a consequence of human activity and such pollution often results in increased plant uptake with adverse effects on humans, as for example with cadmium (Cd). In these cases it is essential to ensure that the concentration of the element in the soil solution does not exceed an agreed critical value.