Verification of Critical Limit of Zinc in Selected Soils of Southern Karnataka for Finger Millet (Eleusine coracana L.)

A pot culture experiment was conducted with finger millet (GPU-48) with twelve different levels of zinc containing soils of selected zones of southern Karnataka to determine the critical limit of zinc in soils and crop. Among the different soils studied, significantly highest dry matter yield (27.00 g/pot) was recorded in ZARS, Mandya soil having 2.60 mg/kg of native Zn with application of 1.00 mg/kg fertilizer Zn, whereas the lowest dry matter yield of 11.68 g/pot was recorded in pathakote soil having 0.35 mg/kg of native Zn without application of any external Zn. But the highest Zn content of 103.13 mg/kg in finger millet shoot was recorded in ZARS, GKVK, soils having 1.65 mg/kg of soil Zn, where 1.00 mg/kg of Zn was applied through fertilizer whereas the lowest shoot Zn content of 44.38 mg/kg was noticed in Pathakote soil has 0.35 mg/kg of native Zn, without application of any external Zn. The critical limit of zinc for soil was worked out by plotting the DTPA extractable Zn against relative yield (Cate and Nelson's graphical method) calculated from yield obtained in pot culture experiment. Similarly, critical limit of zinc in finger millet crop was calculated by plotting shoot zinc content against relative yield. The critical limit of Zn was found to be 0.66 mg/kg for soil and 54.00 mg/kg for finger millet crop.