Background: Wastewater irrigation is widely utilized to address water scarcity and enrich soil fertility, yet its impacts on soil carbon-nutrient cycling and environmental sustainability remain complex and multifaceted.
Methods: In this systematic review of 89 peer-reviewed studies published between 2000 and 2025, we synthesized data on soil organic carbon (SOC), nitrogen dynamics, crop yields, and greenhouse‑gas (GHG) emissions (CO₂, N₂O, and CH₄) under various wastewater irrigation regimes.
Results: The findings indicated that wastewater irrigation can boost SOC by up to 164% and increase soil nitrogen content by up to 152%, driving short-term crop‑yield gains of up to 56% through enhanced nutrient availability. However, prolonged application frequently leads to soil salinization, heavy‑metal accumulation, and elevated CO₂ and N₂O emissions, with several studies reporting eventual declines in yield over time.
Conclusion: These results reveal a dual effect: immediate agronomic benefits counterbalanced by long-term environmental risks. Sustainable implementation requires advanced wastewater treatment, continuous soil monitoring, and optimized irrigation practices to mitigate negative impacts while preserving soil health and carbon sequestration potential. Future research should prioritize strategies that minimize GHG emissions and maximize nutrient retention to ensure long-term agricultural and environmental sustainability.