Role of irrigation water, inorganic and organic fertilizers in soil and crop contamination by potentially hazardous elements in intensive farming systems: Case study from Moghan agro-industry, Iran

There is interconnection between soil quality, water quality, and food safety that is necessary to evaluate pollution levels in these components. Soil contamination by potentially hazardous elements may pose direct and indirect threats as negative impacts on the plant growth and yield, entering the human food chain with potentially negative effects on human health. Intensive agriculture (industrial agriculture) in agro-industry could have resulted in an enrichment of potentially hazardous elements in soils and accumulation in crops because of excess use of fertilizers and amendments. Unfortunately, despite these conditions, there were few or no investigations of potentially hazardous elements in farming areas of agro-industry sectors. This research was undertaken in agricultural lands of Moghan agro-industry complex located in the Moghan's plain (as one of the main poles of agriculture) in the north of Ardebil province and west of the Caspian Sea. The present study was designed to investigate the concentrations of Cd and Pb in agricultural soils, irrigation water, Alfalfa and commonly used fertilizers in the agricultural lands of Moghan agro-industry. The results showed that the average concentrations of the Cd and Pb in agricultural soils of Moghan agro-industry complex were 0.55 and 163.60 mg·kg− 1, respectively. Moreover, the mean concentrations of Cd and Pb were 0.61, and 0.07 μg·l− 1 in irrigation water samples, respectively, 0.45, and 0.009 mg·kg− 1 in Alfalfa samples, 0.62 and 51.87 mg·kg− 1 in superphosphate fertilizer samples, 0.67 and 51.87 mg·kg− 1 in animal manure samples and 0.001 and 3.66 mg·kg− 1 in urea fertilizer samples. Superphosphate fertilizer showed higher content of Cd and Pb than urea fertilizer, indicating the importance of phosphate fertilizer on the accumulation of potentially hazardous elements in soils. Based on the results of this research and values of Transfer Factor (TF), it was found that the Alfalfa (Medicago scutellata) had high ability to accumulate cadmium from contaminated soils, but the accumulation rate of Pb was much lower than Cd. Phosphate fertilizer and/or animal manure may be the main sources of contribution by Cd and Pb in the agricultural soils of the study area, but irrigation water had no significant effect on the potentially hazardous elements accumulation in soil.