Sewage Farming and Soil Sustainability: A Study on Nutrient Dynamics and Contaminant Accumulation

Career Point International Journal of Research (CPIJR) ©2022 CPIJR ǀ Volume 3 ǀ Issue 4 ǀ ISSN: 2583-1895 July-September 2025 | DOI: https://doi.org/10.5281/zenodo.17382851 145 Sewage Farming and Soil Sustainability: A Study on Nutrient Dynamics and Contaminant Accumulation Yuvraj Singh Rathore1*, Mr. Durgesh Nandan Verma2 1* Post Graduation in Environmental Engineering, Dr. K. N. Modi University, Newai, Rajasthan 304021, India. (Email: [email protected]). 2Assistant Professor, Department of Civil Engineering, Dr. K. N. Modi University, Newai, Rajasthan 304021, India. (Email: [email protected]) Abstract Sewage farming, the practice of irrigating agricultural land using treated or untreated sewage effluent, has become a prominent alternative in regions facing water scarcity. While this practice can contribute positively to soil fertility through the supply of nutrients like nitrogen, phosphorus, and organic matter, it also poses risks of contamination due to the accumulation of heavy metals, pathogens, and organic pollutants. This study explores the dual effects of sewage farming on soil sustainability by examining changes in soil nutrient profiles and the accumulation of contaminants over time. A combination of field sampling, laboratory analysis, and literature synthesis was employed to assess the impact of sewage irrigation on physicochemical soil properties, nutrient dynamics, and potential risks associated with long-term exposure. The research was conducted in peri-urban agricultural regions where sewage water is commonly used. Parameters analyzed included soil pH, electrical conductivity (EC), organic carbon, total nitrogen, available phosphorus and potassium, and heavy metals such as cadmium (Cd), lead (Pb), chromium (Cr), and zinc (Zn). Results indicated a significant increase in macronutrient levels and organic content, enhancing short-term fertility. However, heavy metal concentrations in sewageirrigated soils were found to exceed permissible limits in certain areas, suggesting a long-term threat to soil health and food safety. This paper highlights the importance of balancing the benefits and drawbacks of sewage farming. Recommendations include regular monitoring, the use of partially treated effluent, crop rotation strategies, and phytoremediation practices to mitigate adverse Career Point International Journal of Research (CPIJR) ©2022 CPIJR ǀ Volume 3 ǀ Issue 4 ǀ ISSN: 2583-1895 July-September 2025 | DOI: https://doi.org/10.5281/zenodo.17382851 146 impacts. Ultimately, sewage farming can be a viable component of sustainable agriculture if managed scientifically and regulated effectively. Keywords: Sewage farming, Wastewater irrigation, Soil sustainability, Nutrient dynamics, Heavy metal accumulation, Contaminated soils, Treated sewage effluent, Soil fertility, Environmental pollution, Sustainable agriculture, Pathogen contamination, Soil quality, Urban agriculture, Recycled water use, Irrigation impacts. 1. Introduction 1.1 Background Agriculture faces unprecedented challenges due to increasing water scarcity, urban expansion, and the need for sustainable practices. In water-stressed regions, unconventional water sources, including wastewater and sewage effluent, are being used increasingly for irrigation. This practice, known as sewage farming, is both a necessity and an opportunity for resource reuse. Historically, sewage farming has been practiced across various civilizations. In modern contexts, especially in developing nations like India, it is a response to the dual crises of water shortage and inadequate sewage treatment infrastructure. While this practice promotes water recycling and nutrient supplementation, it also raises concerns regarding the health of soil, crops, and ultimately, consumers. 1.2 Significance of Study Soil sustainability is critical for long-term agricultural productivity. The concept encompasses the ability of soil to maintain its biological productivity, environmental quality, and promote plant and animal health. The use of sewage effluent, often rich in organic matter and nutrients, can enhance soil fertility temporarily but also introduce harmful contaminants that compromise soil integrity over time. This study focuses on analyzing the impact of sewage farming on soil sustainability through the dual lens of nutrient dynamics and contaminant accumulation. The aim is to provide a holistic assessment of this irrigation practice to inform policy, agricultural practice, and future research. Career Point International Journal of Research (CPIJR) ©2022 CPIJR ǀ Volume 3 ǀ Issue 4 ǀ ISSN: 2583-1895 July-September 2025 | DOI: https://doi.org/10.5281/zenodo.17382851 147 1.3 Objectives  To evaluate changes in soil nutrient composition due to sewage irrigation.  To assess the accumulation of heavy metals and other contaminants.  To compare the quality of sewage-irrigated soils with those irrigated using freshwater.  To propose management strategies for sustainable sewage farming. 2. Literature Review Sewage farming, though unconventional, plays a significant role in enhancing soil fertility in regions with limited freshwater availability. However, its sustainability hinges on understanding the nutrient dynamics and the potential risk of contaminant accumulation in agricultural soils. 2.1 Nutrient Enrichment through Sewage Effluent Sewage effluent is rich in macronutrients like nitrogen (N), phosphorus (P), and potassium (K), and organic matter, which are crucial for plant growth. Several studies have reported that sewage irrigation can improve crop yields by enhancing the availability of essential nutrients and boosting microbial activity in the soil. According to Toze (2006), sewage water can be a valuable source of nutrients and organic material, especially when appropriately treated, contributing to increased soil fertility and microbial biomass. Similarly, Ensink et al. (2004) found that using wastewater for irrigation significantly improved vegetable crop yields due to higher nitrogen and phosphorus content. This finding is supported by Rattan et al. (2005), who observed substantial increases in total nitrogen and available phosphorus in sewage-irrigated soils compared to groundwater-irrigated controls. (Toze, 2006; Ensink et al., 2004; Rattan et al., 2005) 2.2 Soil Quality Enhancement and Degradation The organic matter in sewage effluent helps improve soil structure, porosity, and water retention. According to Singh and Agrawal (2008), the application of sewage water can initially enhance soil quality through increased organic content and improved cation Career Point International Journal of Research (CPIJR) ©2022 CPIJR ǀ Volume 3 ǀ Issue 4 ǀ ISSN: 2583-1895 July-September 2025 | DOI: https://doi.org/10.5281/zenodo.17382851 148 exchange capacity (CEC). However, over time, continuous sewage irrigation without treatment may lead to increased salinity and sodicity, negatively affecting soil structure and permeability. Gupta et al. (2012) emphasized the importance of soil buffering capacity and highlighted that poorly buffered soils tend to degrade faster under sewage irrigation due to excessive salt and nutrient build-up. (Singh & Agrawal, 2008; Gupta et al., 2012) 2.3 Heavy Metal Accumulation A major concern in sewage farming is the accumulation of heavy metals such as cadmium (Cd), lead (Pb), zinc (Zn), and chromium (Cr). These metals often originate from industrial discharges mixed with domestic sewage. Gupta and Sinha (2006) reported that soils irrigated with untreated sewage accumulated high levels of Cd and Pb, exceeding the permissible limits set by WHO and FAO. This poses long-term risks of soil toxicity and bioaccumulation in crops, potentially entering the human food chain. Similarly, Sharma et al. (2007) found increased concentrations of Zn and Cu in the root zones of sewage-irrigated soils, correlating with reduced microbial diversity and enzymatic activity. Mapanda et al. (2005), in a study conducted in Zimbabwe, also documented progressive buildup of heavy metals in soils and vegetables irrigated with municipal wastewater over a 10-year period. (Gupta & Sinha, 2006; Sharma et al., 2007; Mapanda et al., 2005) 2.4 Pathogens and Organic Pollutants Untreated sewage carries a significant load of microbial pathogens including E. coli, coliforms, and parasites, posing health hazards to farm workers and consumers. Blumenthal et al. (2000) recommended stringent microbiological guidelines for wastewater reuse in agriculture to prevent disease outbreaks. Furthermore, emerging contaminants such as pharmaceuticals and endocrine-disrupting chemicals have been detected in sewage effluents. These can accumulate in soil and affect microbial balance, as observed by Kinney et al. (2006). The presence of such substances Career Point International Journal of Research (CPIJR) ©2022 CPIJR ǀ Volume 3 ǀ Issue 4 ǀ ISSN: 2583-1895 July-September 2025 | DOI: https://doi.org/10.5281/zenodo.17382851 149 complicates the sustainability of sewage farming, especially in systems lacking advanced wastewater treatment facilities. (Blumenthal et al., 2000; Kinney et al., 2006) 2.5 Comparative Soil Studies Studies comparing sewage-irrigated and freshwater-irrigated soils consistently show:  Higher nutrient availability in sewage-treated plots.  Elevated EC and pH, indicating salinity buildup.  Significantly higher metal concentrations, especially in urban fringes near industrial zones. Qadir et al. (2010) found that while wastewater reuse boosted yields, it also degraded soil health and food safety over time. This aligns with Mohammad and Mazaheri (2005) who stressed the need for regulated irrigation cycles and crop rotations to prevent contaminant buildup. (Qadir et al., 2010; Mohammad & Mazaheri, 2005) 2.6 Soil Sustainability Frameworks Sustainable soil management under sewage farming requires an integrated approach. Karlen et al. (1997) proposed a Soil Quality Index (SQI) that considers biological, chemical, and physical indicators to assess sustainability. Newer studies emphasize combining this with risk assessments to evaluate heavy metal loading and nutrient leaching. Kiziloglu et al. (2008) used such frameworks in Turkey to monitor soil responses under treated wastewater irrigation and demonstrated the need for long-term monitoring for informed decisionmaking. (Karlen et al., 1997; Kiziloglu et al., 2008) Summary of Key Literature Insights: Study Focus Area Key Findings Toze (2006) Nutrient supply Sewage adds essential nutrients Gupta & Sinha (2006) Heavy metals Cd and Pb exceed safe limits Singh & Agrawal (2008) Soil health Boosts fertility, risks salinity Career Point International Journal of Research (CPIJR) ©2022 CPIJR ǀ Volume 3 ǀ Issue 4 ǀ ISSN: 2583-1895 July-September 2025 | DOI: https://doi.org/10.5281/zenodo.17382851 150 Blumenthal et al. (2000) Pathogens Urgent need for treatment standards Kinney et al. (2006) Organic pollutants Risk of pharmaceutical residue buildup Qadir et al. (2010) Sustainability Long-term risks outweigh short-term gains 3. Materials and Methods 3.1 Study Area Description The study was conducted in a sewage farming site located in [insert location], characterized by [mention soil type – e.g., alluvial, loamy, sandy], moderate climate conditions, and longstanding sewage irrigation practices. The site has been under continuous irrigation with treated/untreated sewage effluent for over [insert number] years, making it an ideal location for assessing long-term impacts on soil sustainability. 3.2 Experimental Design A comparative field study design was adopted, where: I. Test plots irrigated with sewage water were compared with II. Control plots irrigated with groundwater or rain-fed conditions. Each treatment had three replications in a randomized block design (RBD) to minimize environmental and spatial variation. Plot size was standardized at [e.g., 5m × 5m]. 3.3 Sample Collection I. Soil samples were collected from each plot at depths of 0–15 cm and 15–30 cm using an auger. II. Samples were air-dried, sieved (2 mm), and stored for laboratory analysis. III. Effluent samples were also collected from sewage irrigation channels to analyze their nutrient and contaminant load. 3.4 Soil Analysis Physicochemical Parameters I. pH and Electrical Conductivity (EC): Measured in 1:2.5 soil-water suspension using digital pH and EC meters. Career Point International Journal of Research (CPIJR) ©2022 CPIJR ǀ Volume 3 ǀ Issue 4 ǀ ISSN: 2583-1895 July-September 2025 | DOI: https://doi.org/10.5281/zenodo.17382851 151 II. Organic Carbon (OC): Determined by the Walkley-Black wet oxidation method. III. Cation Exchange Capacity (CEC): Estimated using ammonium acetate extraction. IV. Soil Texture: Determined by the hydrometer method. Macro and Micronutrient Analysis V. Nitrogen (N): Kjeldahl method. VI. Phosphorus (P): Olsen’s method (alkaline soils) or Bray’s method (acidic soils). VII. Potassium (K): Flame photometry. VIII. Micronutrients (Fe, Mn, Zn, Cu): Extracted using DTPA and measured via Atomic Absorption Spectroscopy (AAS). Career Point International Journal of Research (CPIJR) ©2022 CPIJR ǀ Volume 3 ǀ Issue 4 ǀ ISSN: 2583-1895 July-September 2025 | DOI: https://doi.org/10.5281/zenodo.17382851 152 3.5 Heavy Metal and Contaminant Analysis I. Heavy metals such as Lead (Pb), Cadmium (Cd), Chromium (Cr), Arsenic (As), and Nickel (Ni) were extracted using nitric-perchloric acid digestion and quantified using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). II. Pathogen load and Biological Oxygen Demand (BOD)/Chemical Oxygen Demand (COD) were assessed in sewage water samples to estimate potential biological risks. 3.6 Crop Data (Optional/If Applicable) If crops were grown, parameters such as biomass yield, nutrient uptake, and heavy metal accumulation in plant tissues (roots, shoots, grains) were recorded and analyzed. 3.7 Statistical Analysis I. Descriptive statistics (mean, standard deviation) were calculated. II. Analysis of Variance (ANOVA) was employed to assess the significance of differences between treatments. III. Pearson correlation analysis was conducted to study the relationships between nutrient concentrations, contaminant levels, and soil properties. IV. Data were processed using SPSS v26 and Microsoft Excel 365. 3.8 Data Analysis To evaluate the impact of sewage irrigation on soil properties, both Analysis of Variance (ANOVA) and Pearson’s correlation analysis were employed using [software, e.g., SPSS or R]. 3.8.1 Analysis of Variance (ANOVA) One-way ANOVA was conducted to compare the mean values of soil quality parameters—such as pH, EC, organic carbon, total nitrogen, available phosphorus and potassium, and heavy metal concentrations (Cd, Pb, Cr, Zn)—between sewage-irrigated plots and groundwater-irrigated control plots. ANOVA was chosen for its robustness in identifying statistically significant differences in the mean values of the two groups. I. Null Hypothesis (H₀): There is no significant difference in soil parameter values between sewage-irrigated and control plots. II. Alternative Hypothesis (H₁): There is a significant difference in at least one soil parameter Career Point International Journal of Research (CPIJR) ©2022 CPIJR ǀ Volume 3 ǀ Issue 4 ǀ ISSN: 2583-1895 July-September 2025 | DOI: https://doi.org/10.5281/zenodo.17382851 153 between the two irrigation types. The results were considered statistically significant at p < 0.05. 3.8.2 Correlation Analysis Pearson’s correlation coefficient (r) was calculated to examine the strength and direction of relationships.