Effect of Tea Waste on Some Chemical Properties of an Alkaline Soil with Clay Loam Texture

Background and Objectives
The rising consumption of chemical fertilizers and pesticides has introduced significant challenges to agricultural production, including soil degradation, reduced water retention, and the proliferation of pests and diseases. Consequently, the agricultural community is exploring sustainable solutions, such as the use of organic fertilizers, which can help maintain soil health and enhance fertility. Tea, recognized as a valuable global commodity, generates substantial waste during its production and processing stages. If effectively managed, these wastes can not only reduce environmental pollution but also create additional income opportunities through the conversion of waste into value-added products. Tea cultivation holds considerable socio-economic importance, particularly in developing countries, with global consumption reaching approximately 5 million tons in 2013. Over recent decades, the global tea industry has experienced rapid growth, with production increasing by about 19 million tons from 1992 to 2022. The growing demand for tea has resulted in the generation of significant amounts of waste, including pruned stems, buds, leaves, and residues from processing. These wastes are often burned or improperly disposed of, leading to potential soil, water, and air pollution. Proper management of tea waste can transform it into valuable resources. Sustainable and effective utilization of this waste is critical for managing tea production by-products. Tea waste generally contains the same components as the primary tea, offering similar biological activities. Due to their accessibility and high potential, tea wastes can serve as a rich source of organic matter to enhance soil fertility. With nutrient deficiencies prevalent in many soils and the high cost of chemical fertilizers, recycling agricultural waste is seen as an important solution. This process can supply essential nutrients for plants and improve overall soil fertility. Additionally, the use of organic wastes mitigates environmental issues and pollution, while the recycling and repurposing of these wastes can enhance soil organic matter. Thus, the recycling of agricultural and other organic wastes is vital for maintaining soil health, increasing food security, and generating additional income, positioning it as an effective strategy for sustainable crop production that can enhance both environmental and agricultural conditions.
Materials and Methods
In this study, soil samples with a clay loam texture were collected from a depth of 0-25 cm at the Research Farm of the Faculty of Agriculture, University of Tehran, Karaj, Iran. The physical and chemical properties of the soil were evaluated using standard laboratory methods. The tea waste, including leaves, stems, and wood, was obtained from Lahijan and characterized. The tea waste was sieved through a 4 mm mesh and added to soil columns at weight ratios of 0%, 1%, 2%, and 4%. Statistical analyses and mean comparisons were conducted using SAS software. The experiment included 24 columns, divided into two sets of 12 for chemical assessments before and after incubation. Treatments involved three replicates and four levels of tea waste mixed with 3 kg of soil.
Results
The variance analysis indicated that the addition of tea waste significantly influenced soil chemical properties. Specifically, soil pH levels decreased with increasing percentages of tea waste, with the 4% treatment showing the most substantial increase in acidity. Electrical conductivity also demonstrated significant changes, particularly before and after the incubation period. The addition of tea waste led to a notable increase in organic matter and nitrogen content, enhancing the nutrient status of the soil. Additionally, the levels of potassium and phosphorus in the soil increased significantly with the incorporation of tea waste, indicating improved these nutrients availability. These findings are consistent with previous studies, reinforcing the notion that tea waste can effectively improve soil quality and promote sustainable agricultural practices. The results illustrate that tea waste can serve as a sustainable solution for improving soil properties and providing essential nutrients, thereby contributing to enhanced agricultural productivity.
Conclusion
This study showed that adding tea waste to soil can significantly improve its quality. Key improvements include increased levels of organic matter, nitrogen, phosphorus, and potassium in the soil. These enhancements contribute to better soil health and fertility, making tea waste a valuable organic resource for sustainable farming. Using tea waste as a natural soil amendment helps reduce reliance on chemical fertilizers and supports environmental sustainability in agricultural practices.
Author Contributions
Conceptualization, M.S. and A.A.; methodology, M.S., A.A. and M.M.; software, M.S., A.A. and M.M.; validation, M.S.; formal analysis, M.S. and A.A.; investigation, M.S., S.A., and M.M.; resources, A.A.; data curation, M.S. and A.A.; writing-original draft preparation, A.A.; writing–review and editing, M.S. and A.A.; visualization, A.A.; supervision, M.S..; project administration, A.A. and M.S.; funding acquisition, M.S. All authors have read and agreed to the published version of the manuscript.
Data Availability Statement
Data is available on reasonable request from the authors.
Acknowledgements
This paper is published as a part of a Master's thesis supported by the Vice Chancellor for Research and Technology of the University of Tehran, Iran. The authors are thankful to the University of Tehran for financial supports.
Conflict of interest
The authors declare no conflict of interest.
Ethical considerations
The authors avoided data fabrication, falsification, plagiarism, and misconduct.