Effects Of Fertilization And N-Fixing Bacterial Inoculation On Nutrients Of Coal Mine Spoil And Growth Of Black Locust (Robinia Pseudoacacia L.)

This study was conducted in greenhouse conditions to assess the effect of nitrogen fixing leguminous plant species, black locust (Robinia pseudoacacia L.), on the available nitrogen (N) and other soil nutrients such as phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) of the experimental coal mine soil. The growth and nitrogen (N) content of the plant grown in coal mine soil were also evaluated. Four treatments, including T-0-non-fertilized non-inoculation (control), T1fertilization, T-2-bacterial inoculation, and T-3-fertilization along with bacterial inoculation with three replications were used in the study. The results of the study showed that applied treatments significantly increased available N (NH4+-N and NO3--N) in the soil for black locust, as compared to control. Apart from control, NH4+-N was found significantly lower (1.75 ppm) at fertilized treatment, and NO3--N was recorded significantly lower (3.87 ppm) at inoculated treatment when compared with other treatments. Available P and K in the coal mine soil also increased significantly when NPK fertilizer was applied solely (30.7 mg kg(-1) available P and 0.76 cmol (+) kg(-1) available K), and together with inoculation (26 mg kg(-1) available P and 0.67 cmol (+) kg(-1) available K) to the plants but reduced at other treatments. The highest nodule volume (mL), number of nodules and nodule dry weight (g) per plant was documented 1.91, 27.65 and 0.60, respectively in black locust at rhizobia inoculated treatment. Fertilization and bacterial inoculation had positive effect on the growth of studied vegetative parameters of black locust as compared to control, except root dry weight. N content in plant also increased significantly when plants were treated by fertilizer and rhizobia inoculation. Therefore, it can be concluded that bacterial inoculation and fertilization in black locust species can significantly improve the fertility of coal mine soil as well as significantly improve the growth and nitrogen content of this legume plant while grown in coal mine soil. Hence, black locust could be a good option for the reclamation of degraded coal mine soil.