Inoculation, phosphorous and zinc fertilization effects on nodulation, yield and nutrient uptake of Faba bean (Vicia faba L.) grown on calcaric cambisol of semiarid Ethiopia

A field experiment was conducted in 2010 crop season with three factors: Inoculation (U = no inoculums and I = with inoculums), three levels of P (0, 20, 40kgPha-1) and three levels of Zn (0, 15, 25kgZnha-1) fertilizations. The experiments were laid in randomized complete blocks in three replications on calcaric cambisols to study effects of inoculation, P and Zn fertilizations on nodulation, yield, yield components, and the uptake N, P and Zn by the plant. Composite soil samples were collected one month before sowing and plant samples were taken both at 50% flowering and plant maturity. Findings showed that, the main and interaction effects of inoculation, P and Zn fertilization were found to affect significantly (P < 0.05) the root distribution and mass of nodules, the concentration of N, P and Zn in nodule, root and leaf tissues at 50% flowering, At maturity, P and Zn were found to significantly increase the root length, root fresh weight of the plant, and inoculation significantly affected the root fresh weight. Phosphorous and Zn fertilization improved the grain yield, pods plant-1, grain pod-1, number of branches, and the grain uptake of N, P and Zn nutrients. The combined application of inoculation, P and Zn fertilization increased the grain yield on average by 1.3 Mg ha-1. Phosphorous and Zn fertilization alone increased the grain P and Zn uptake by 1.1 and 2.7 × 10-2 kg ha-1, respectively, and the combined application of inoculation, P and Zn improved the N uptake of the faba bean grains on average by 40 kg ha-1. Thus, inoculating the legume with efficient and compatible rhizobium, and fertilizing it with P and Zn should be recommended to soils deficient in P and Zn, especially in alkaline calcareous soils.    Key words: Semiarid, nodulation, inoculation, zinc, phosphorus, yield, nutrient uptake, faba bean.