Effect of biochar and biological treatments on nutrient elements content (P, K, Ca, Mg, Fe and Mn) of Amaranthus in oil polluted soil

The presence of petroleum compounds in the soil causes environmental problems. Therefore, attempting to remediate contaminated soils is important. The present study was aimed at studying the effects of (1) different levels of biochar obtained from urban wastes and (2) the bacterium that degrades petroleum hydrocarbons on levels of nutrients in amaranth. The treatments were raw oil (0 , 2.5, and 5%; weight-based), biochar obtained from urban waste compost and fresh urban wastes (0, 1, and 2 %, weight-based), and bacterium (with and without Pseudomonas ). The results showed that with increasing the biochar level, the plant growth was promoted, with the highest values for growth parameters in plants treated with highest level of biochar. The dry and fresh weights of shoots in treatments with Pseudomonas florescence had statistically considerable differences compared to those in the other treatments. Overall, with the application of biochar and Pseudomonas, the levels of nutrients studied increased, and the maximum nutrient level was observed in the plants treated with the highest level of biochar. The highest P level (0.37%) was detected in plants treated with P1B0Ba1, and the lowest (0.23%) in plants treated with P2BM2Ba1. Moreover, the highest K level (5.16%) was recorded in plants treated with P2BM2Ba1, while the lowest (2.15%) was measured in plants treated with P0BM1Ba0 (no biological factor). The highest levels of Ca and Mg were found in treatments with biochar. The highest levels of Fe (1200.33 mg/kg) and Mn (441.5 mg/kg) were found in plants treated with P0B0Ba1, which had the biological factor, while the lowest was recorded in treatments where Pseudomonas florescence was absent. Accordingly, in order to increase the efficiency of soil remediation, it is recommended that organic matters, especially biochar, and bacterial treatments be exploited so that favorable conditions could be provided for plant growth and development.