Effect of Micronutrient-Based Integrated Use of Nutrients on Crop Productivity, Nutrient Uptake, and Soil Fertility in Greengram and Fingermillet Sequence Under Semi-arid Tropical Conditions

To identify the best combinations of micronutrient-based fertilization treatments in terms of crop yield and nutrient uptake, three field experiments with greengram−fingermillet as the test sequence with 12 treatments on micronutrient-based fertilization [with recommended nitrogen (N)−phosphorus (P)−potassium (K) fertilizer] were conducted during 2005 to 2007 in a semi-arid Alfisol at Bangalore. The effects of treatments on available soil and plant uptake of nutrients [N, P, K, sulfur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), boron (B), and molybdenum (Mo)] and yield of crops were assessed based on standard analysis of variance procedure. Using the relationships of yield with soil and plant nutrient variables, regression models of yield through soil and plant variables were calibrated and effects of variables on crop yields were assessed. The models gave high and significant yield predictability in the range of 0.87 to 0.98 through different variables. The model of plant uptake through soil nutrients indicated that soil S, Fe, and Zn had significant positive effects, whereas soil N, K, B, and Mo had negative effects on plant nutrient status in greengram. Similarly, soil P, Mn, and Zn had significant positive effects, whereas soil N, K, and Fe had negative effects on plant uptake of nutrients in fingermillet. Based on a relative efficiency index (REI) criteria, T2 for plant uptake and T12 for maintaining soil nutrients were found to be superior in greengram, whereas T2 for plant uptake and T8 for maintaining soil nutrients were found to be superior in fingermillet over years based on REI. The combined REI over soil and plant nutrients for both crops indicated that application of T8 for greengram and T2 for fingermillet could be prescribed for attaining maximum plant uptake of nutrients and productivity of crops in sequence, apart from maintaining maximum soil fertility of nutrients under semi-arid Alfisols.