Abstract
Micronutrients deficiency is a major limiting factor for increasing yield and productivity of major crops in India. Recent findings of multiple micronutrients interactions have evidenced the indispensable role played by micronutrients in plant nutrition. Though they are needed in smaller quantities, however, their availability in the Right amount, at the Right time, and for the Right crop has been a major limiting factor for improving the productivity and yield of Sugarcane in northern Karnataka state of India. This study was conducted to assess the level of Boron (B), Copper (Cu), Iron (Fe), Manganese (Mn) and Zinc (Zn) deficiencies in Sugarcane growing Vertisols of six micro-watersheds in northern Karnataka. The six selected micro-watersheds were intensively traversed and six representative pedons of standard dimensions were dug and horizon-wise soil samples collected and analyzed for various micronutrients using standard analytical procedures. Based on the optimum critical levels of micronutrients, B, Fe and Zn were deficient, ranging from 0.15 - 0.64, 1.23 - 5.92 and 0.11 - 0.64 mg⋅kg−1 respectively while Cu and Mn were in excess, ranging from 1.54 - 7.62 and 1.22 - 7.03 mg⋅kg−1 respectively. The distribution of B, Fe and Zn were inversely proportional to soil depth whereas that of Cu and Mn were irregular, which is an indication of the influence of pedoturbation in these soils. With the current rate of agricultural intensification, unbalanced fertilizer application, depletion of nutrients and no replenishment by smallholders, the results reveal that the current deficiency levels may increase further if appropriate and timely actions are not taken. We therefore recommend the use of site-specific nutrient management, balanced fertilizer application and good agronomic practices. These can enhance nutrient use efficiency in the study area.
Highlights
Studies have shown that Indian soils are characterized by large-scale deficiencies of primary (i.e. Nitrogen (N), Phosphorus (P), Potassium (K)) and secondary nutrients (i.e. Sulphur (S), Calcium (Ca) and Magnesium (Mg)) and micronutrients (i.e. Boron (B), Copper (Co), Iron (Fe), Manganese (Mn), Molybdenum (Mo) and Zinc (Zn)) [1]
The status of five micronutrient elements (B, Cu, Fe, Mn and Zn) in sugarcane growing Vertisols in northern Karnataka have been analyzed in order to ascertain whether these nutrients are in deficient, sufficient or excess quantities and the results are given in Table 1 and Table 2
Zn, Cu, Fe and Mn were more in the surface horizons than subsurface horizons, which may be due to the accumulation of these elements in the surface layer as a result of the regular turnover by plant and animal residues, higher content of organic carbon, lower calcium carbonate contents, better aeration and translocation of finer soil fractions leading to increase in the surface area for ion exchange
Summary
Studies have shown that Indian soils are characterized by large-scale deficiencies of primary (i.e. Nitrogen (N), Phosphorus (P), Potassium (K)) and secondary nutrients (i.e. Sulphur (S), Calcium (Ca) and Magnesium (Mg)) and micronutrients (i.e. Boron (B), Copper (Co), Iron (Fe), Manganese (Mn), Molybdenum (Mo) and Zinc (Zn)) [1]. Besides the primary and secondary nutrient deficiencies, crops suffer from deficiencies of one or more micronutrients in these soils, which sometimes create nutrient imbalances in plant nutrition. These nutrient imbalances have caused greater mining of soil nutrient reserves and depletion of soil fertility in many states of India. Studies conducted by various researchers including Wani et al (2011), Shivakumar and Nagaraja (2016), Krishna et al (2017), Sudhakar et al (2018) and Doran (2019) [3] [4] [5] [6] [7] have indicated a decreasing trend in micronutrient status in soils of Karnataka
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