عنوان مقاله [English]
Background and purpose: Soil and plant contamination with heavy elements due to industrial activities has adversely affected human health and has received much attention in recent decades. Heavy metals can endanger soil, plant and human health by entering the soil cycle and food products. In order to reduce the harmful effects of heavy metals on the soil ecosystem and food pollution, a factorial experiment was conducted in three replications in a completely randomized design in a greenhouse. The aim of this study was to investigate the effect of different amounts of natural biochar and poultry manure on the fertility of zinc and cadmium elements in a contaminated soil.
Materials and Methods: In order to conduct this research, first different levels of poultry manure (zero, 0.5, 1, 2, 4 and 8% by weight) and natural biochar (zero, 2, 4, 6, 8 and 10% Weight) were added separately to a contaminated soil. Then, 4 levels of incubation were applied to the moisture capacity of the farm (1, 2, 3 and 4 months). At the intervals mentioned from the pots, sub-samples were prepared and transferred to the laboratory. After drying in the oven at a temperature of 50-55 ºC was taken pH, EC, the total and absorbable amount of zinc and cadmium elements in them.
Results: Comparison of mean effects of incubation and poultry manure and biochar levels showed that with increasing consumption level and incubation, soil pH decreased by 3.9% and 1.4%, respectively, and EC amount by 36.5 and 10.4 percent increased. There was a statistically significant difference between the control treatment of the control or the zero level of poultry manure and biochar with the treatment of 8% of poultry manure and biochar (statistically 5% probability level). With increasing incubation and levels of poultry manure and natural biochar, the adsorbent concentration of zinc and soil cadmium decreased significantly (P <0.05), which decreased in treatments containing poultry manure for zinc and cadmium, respectively, 19.9 and 29.5 percent, and in treatments containing natural biochar, zinc and cadmium were measured as 28.4 percent and 22.7 percent, respectively. In poultry manure treatments, the lowest zinc and cadmium concentrations extracted with DTPA extract in the fourth month and the consumption level of 8% were 304.7 and 10.9 mg/kg, respectively, and the highest amount was observed in the first month. Witness treatment (zero percent level) was observed to be 380.2 and 20.0 mg/kg, respectively. In treatments containing natural biochar, the lowest amount of zinc and cadmium extracted with DTPA extract in the fourth month and 10% consumption level were 272.4 and 12.9 mg / kg, respectively, and the highest amount was treated in the first month. The control (zero percent level) was observed to be 380.3 and 20.7 mg/kg, respectively.
Conclusion: According to the results of this study, the use of biochar and manure fertilizer caused a decrease in the concentration of absorbable heavy metals studied in the soil. Although treatments containing biochar and manure reduced the adsorption concentration of metals in the soil, the concentration of adsorbent metals in the soil decreased further with increasing levels of poultry manure and biochar and the incubation of the soil. In general, it can be stated that the application of poultry manure and natural biochar in the soil is an effective method to reduce the toxicity and absorbable concentration of heavy metals in the soil and also increase the yield and quality of agricultural products.