Field experiment conducted during 2004-05 and 2005-06 to study the effect of micronutrients viz., iron (FeSO4 @ 10 kg ha-1), boron (
borax@10 kg ha-1), Zinc (ZnSO4 @ 25 kg ha-1), molybdenum (ammonium molybdate @ 1 kg ha-1) and joint application of all micronutrients viz., Fe+B+Zn+Mo, alone and in combination with Rhizobium+PSB inoculation on symbiotic traits, grain yield and uptake of N, P, K, S, Zn, Fe and B by chickpea crop grown with one irrigation in Vertisol having 74.8 mg kg-1 Fe, 0.02 mg kg--1 B, 2.15 mg kg-1 Zn and 0.016 mg/kg-1 Mo in soil. Application of all micronutrients as well as inoculation significantly increased the nodule and total plant dry weight at 45 days of sowing. Grain yield was significantly increased by the application of molybdenum through ammonium molybdate @ 1 kg ha-1 which was 42.9% higher over the recommended dose of fertilizer alone. Combination of all micronutrients viz., Fe+B+Zn+Mo could increase the grain yield significantly to the tune of 25.3% over RDF alone. Microbial population viz., Rhizobium, PSB and uptake of nutrients viz., N, P, K, S & Zn, Fe and B was also higher under the treatment of RDF+ ammonium molybdate @1 kg ha-1 and the values were 43 and 26 X 103 per gram of soil and 58.84, 3.54, 41.37, 3.22 kg ha-1 and 48, 820 and 60 g/ha-1 respectively. Microbial inoculation could significantly increase the Rhizobium and PSB population and also the grain yield of chickpea (12.2%) over no inoculation. The study indicated the necessity of application of molybdenum wherever deficient in Vertisol under intensive (Soybean-Chickpea) cultivation of legumes as it is directly involved in biological nitrogen fixation through nitrogenase enzyme activity.
