Determination of heavy metal concentration in soils used for cultivation of Allium sativum L. (garlic) in East Gojjam Zone, Amhara Region, Ethiopia

Abstract

Garlic is the most widely used bulb crop next to onion in Ethiopia. It has been used in many local peoples of Ethiopia as a flavoring agent in food and medicinal value for different diseases. The concentrations of eight heavy metals (Fe, Zn, Mn, Cu, Co, Ni, Cd, and Pb) in soil samples used for cultivation of garlic in East Gojjam Zone (Debre Markos, Dejen, Bichena, and Debre Werk) in Ethiopia were determined. The results obtained revealed that the mean heavy metal concentrations for Fe, Zn, Mn, Cu, Co, Ni, Cd, and Pb were 23,866–32,262 mg/kg, 137.1–213.4 mg/kg, 401.8–583.7 mg/kg, 52.1–77.3 mg/kg, 106.6–177.6 mg/kg, 87.5–123.5 mg/kg, 2.3–2.5 mg/kg, and 13.8–23.2 mg/kg, respectively. In general, the levels of metals in soil collected from all the sampling sites was found to decreased in the order of: Fe > Mn > Zn > Co > Ni > Cu > Pb > Cd. In general, the results reveal that the level of contamination of the soils by the heavy metals is not high at present and the soil is not polluted by toxic heavy metals (Cd and Pb). Therefore, the soils studied were not harmful for cultivation of garlic and other agricultural purposes.

Keywords:

• soil
• heavy metals
• garlic
• wet digestion
• FAAS

Public Interest Statement

Garlic has been used throughout recorded history for both culinary and medicinal purposes. The soil condition is of great importance, because it is a universal medium for plant growth, which supplies essential nutrients to the plants. There is also a risk of contamination of soils with excess heavy metals because of atmospheric deposition, the use of pesticides and fertilizers that contain considerable amounts of metals. Therefore, it is the aim of this work to prove that the heavy metal content in the garlic growing soil has significant difference based on the soil type in East Gojjam Zone, Amhara Regional State, Ethiopia where garlic is growing abundantly. The results of this study reveal that the level of contamination of the soils by the heavy metals is not high at present and the soil is not polluted by toxic heavy metals. It is essential to asses the levels of heavy metals in soil used for agricultural activities to minimize the risk of contamination of food by heavy metals. Therefore, the soils studied were not harmful for cultivation of garlic and other agricultural purposes.

Competing Interests

The authors declare no competing interest.

Additional information

Notes on contributors

Wodaje Addis

Wodaje Addis, Alemayehu Abebaw have spent together as a member of a research group for couple of years mainly focusing on the determination of essential and non-essential metal concentration in garlic and soil sample using different analytical techniques. Our research group has equipped with the state-of-the-art analytical instruments which are capable of determining heavy metals in food and soil samples. Besides, the quality control, method development and statistical data analysis are also main components of our research. In addition, the authors have the experience with the analysis of environmental samples. In wider context, the research group has been working in the analysis of food, plant, soil, and water samples using analytical instruments available in their laboratory.