Response to Zinc, Copper and Iron and their Critical Levels for Potato

Experiments were conducted in 16 fields for ln, 13 fields for Cu and 12 fields for Fe to measure their responses and determine their critical limits for potato (ev. Kufri Chandramukhi) on alluvial soil (Ustochrept). The responses were 56.0 per cent for zinc, 61.5 per cent for copper and 75 percentfor iron. Foliarspray of the micronutrients at 30 and 50 days was equally effective to the soil application. The critical deficiency limits for potato established by statistical procedure of Cate and Nelson were 0.75 mg kg⁻¹ soil of DTPA-Cu, 0.32 mg kg⁻¹ soil of DTPA-Cu and 6.6 mg kg⁻¹ soil of DTPA-Fe.