Depth-wise Distribution of Zinc, Copper, Manganese and Iron in Acid Soils of India and Their Relationship with Some Soil Properties

摘要

Micronutrient deficiencies in crops have been reported in recent years due to intensive cropping, loss of top soil by erosion, losses of micronutrients through leaching, excess liming of acid soils, less application of farmyard manure (FYM) compared to chemical fertilizers, growing high demanding modern crop culti-vars and use of marginal lands for crop production (Fageria et al. 2002). Micronutrient content in soils and capacity of soils to supply micronutrients in quantities sufficient for optimalcrop growth vary widely (White and Zasoski 1999). Deficiency of cationic micronutrients like zinc (Zn), copper (Cu), manganese (Mn) and iron (Fe) have been reported worldwide (Alloway 2008) and in Indian soils over the years (Takkar 1996; Singh 2001; Singh and Behera 2011). This deficiency is generally wide spread in high pH calcareous soils (Liu et al. 1983). However, Zn deficiency, low Cu content and high Fe content have also been reported in heavily weathered and leached acid soils developed from granite (Alloway 2008). Manganese deficiency also occurs on plant grown in over limed acid soils (Martens and Westermann 1991). Availability of micronutrients to crop plants is affected by many soil factors. The effect of those factors varies considerably from one micronutrient to another as well as in their relative degree of effectiveness. Among the soil factors, soil reaction pH and soil organic matter content are most important (Linday 1972). Soil pH affects solubility, concentration in soil solution,ionic form, and mobility of micronutrients in soil, and consequently acquisition of these elements by plants. Soil organic matter forms complexes with micronutrients and thereby increases micronutrient mobility and/or plant availability (Harmsen and Vlek