Cassava (Manihot esculenta Crantz) is a perennial shrub and a tuberous root crop well adapted to poor soils and is relatively tolerant to drought, the crop is usually grown under marginal soil and climatic conditions and often with very limited inputs of fertilizers and pesticides. In India, cassava is cultivated in varied agro climatic and pedogenic environments. In Tamil Nadu, it is cultivated mainly for industrial uses, cassava is grown in black soils (Vertisols) and red soils (Alfisols). Cassava nutrient management by blanket fertilizer recommendations over wide areas and soil types over the past 40 years or so in India have resulted in significant yield increase. But when we extrapolate the results from experimental stations to farmers’ fields, the yield cannot be increased beyond a certain level due to the high temporal and spatial variability of soil and plant nutrients. Alleviation of micronutrient deficiencies to improve crop yields is difficult to large temporal and spatial variation in phyto availability of soil micronutrients. The easiest and most straight forward practice to correct micronutrient deficiency is to apply micronutrient fertilizers. Soil application of fertilizer is economically more affordable. Four field experiments were conducted to evaluate three different grades of micronutrient mixtures at graded doses for increasing the productivity and starch content in cassava under irrigated condition. The experiment was conducted in Factorial RBD replicated thrice with Main factor as micronutrient mixture grades (Grade I, Grade 2 and Grade 3) and sub factor as dose of micronutrient mixture (0, 10, 15, 20 and 30 kg ha^-1) in two different soils with calcareous and non-calcareous soil in Pethanaickanpalayam block of Salem district during Jan-Feb 2018. Observations on tuber yield and starch content were recorded in all the four experiments. Among the treatments, application of grade 2 micronutrient mixture at 30 kg ha^-1 application recorded significantly higher tuber yield (36.8, 35.2, 30.4 and 32.1 t ha^-1) and starch content (25.2, 32.0, 24.2 and 24.1%) respectively in YTP 1, MVD 1, Kungumarose and YTP 1 varieties at red non calcareous, red calcareous, black non calcareous and black calcareous soil respectively which was on par with the application of grade 2 at 20 kg ha^-1 application. Hence, application of grade 2 micronutrient mixture at 20 kg ha^-1 application can be recommended for getting higher tuber yield and starch content besides alleviating micronutrient deficiency and maintaining fertility of cassava growing soils in Tamil Nadu.

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