Effect of cobalt, rhizobium and phosphobacterium inoculations on yield and nutrient uptake in summer groundnut (Arachis hypogaea L.) on alluvial soils

A field experiment was conducted at Students' Instructional Farm, Barajaguli, B.C.K.V., Nadia, West Bengal, to evaluate the performance of summer groundnut under alluvial soil with different types of inoculation and different levels of cobalt. The results indicate that soil application of cobalt at lower dose (0.21 kg Co ha⁻¹) was the best to enhance the yield and nutrient uptake of groundnut. Pod yield was the highest for inoculation with Rhizobium which was about 7.04 and 11.06% higher than that of inoculation with phosphobacterium and control, respectively. Nitrogen uptake increased over control, and was about 14.51 and 6.68% higher with C_0.21 and C_0.42, respectively. The highest uptake of phosphorus was by Rhizobium inoculation receiving C_0.21 level of cobalt. The average potassium uptake was bout 19.25 and 8.45% higher than control (no cobalt), with C_0.21 and C_0.42, respectively. Likewise, inoculation with Rhizobium and Phosphobacterium had about 47.90 and 28.76% higher K uptake as compared to no inoculation. The results indicated that soil application of cobalt at lower dose (0.21 kg Co ha⁻¹) was the best to enhance the nutrient uptake of groundnut. The combination of Rhizobium and cobalt @ 0.21 kg ha⁻¹ was found to be the best.