The limitation in open-field systems in Qatar is mainly due to harsh pedo-climatic conditions including prolonged hot season, limited rainfall, and poor soils. In this regard, irrigation and fertilization are necessary to maintain cropping activities. The dairy and gas-to-liquid (GTL) industries in Qatar both generate respectively cow manure and GTL sludge that can be recycled as sustainable organic amendments for soil quality enhancement. In this field study, we compared the performance of soil treatments with GTL sludge to the more conventional cow manure compost and chemical fertilizers for the cultivation of cotton under hyperarid conditions. After a complete growing season, GTL sludge application resulted in the enhancement of soil properties and plant growth compared to conventional inputs. As such, there was a significant dose-dependent increase of soil organic matter (4.01% and 4.54%), phosphorus (534 and 1090 mg kg-1), and cumulative lint yield (4.68 and 5.67 t ha-1) for GTL sludge application rates of 1.5% and 3%, respectively. The application of cow manure compost resulted in the least cotton yield owing to lower intrinsic organic matter and macronutrient contents. On the other hand, the adverse effects generally related to industrial sludge reuse were not significant and did not affect the designed agro-environmental system. Accordingly, plants grown on GTL sludge-amended soils showed lower antioxidant activity despite significant salinity increase. In addition, the concentrations of detected heavy metals in soil were within the standards’ limits, which did not pose environmental issues under the described experimental conditions. Leachate analysis revealed no risks for groundwater contamination with phytotoxic metals, which were mostly retained by the soil matrix. Therefore, recycling GTL sludge as an organic amendment can be a sustainable solution to improve soil quality and lower carbon footprint.
Biography
Dr. Helmi Hamdi is currently a Research Associate Professor at the Center for Sustainable Development. He obtained a MS degree in Agricultural Engineering from the National Institute of Agronomy, Tunisia (2000), and a PhD in Environmental Science and Resource Management from Okayama University, Japan (2006). He also holds a Habilitation degree in Crop Production, Soil and Environment. Prior to joining Qatar University in Fall 2018, Dr. Helmi Hamdi held successively the positions of senior research engineer, assistant professor then associate professor at the Water Research and Technology Center in Tunisia. He has been carrying out research in the field of Agro-Environmental Sciences for more than 20 years. Dr. Helmi Hamdi has been awarded several international fellowships for PhD, postdoc and visiting researchers from the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), the Japanese Society for the Promotion of Science (JSPS), the Fulbright Visiting Scholar Program (USA), and the German Academic Exchange Service (DAAD). As of October 2023, He has published two books, three book chapters and more than 60 peer-reviewed papers, conference papers, and research reports in the fields of sustainable crop production, reuse of alternative inputs in agriculture, soil quality monitoring, and nanotechnology applications in agriculture.
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