Monitoring Macronutrients for Eutrophication Control Using the Internet of Things: A Systematic Reviews

Excessive macronutrients—particularly nitrogen (N), phosphorus (P), and carbon (C)—contribute to eutrophication, algal blooms, and water quality degradation in both aquatic and agricultural ecosystems. Traditional nutrient monitoring methods are time-intensive and often lack real-time responsiveness. The Internet of Things (IoT) presents a transformative opportunity for continuous, precise macronutrient monitoring. This systematic review evaluates the global application of IoT technologies in macronutrient monitoring systems, identifying technological trends, challenges, and opportunities for eutrophication control and sustainable nutrient management. The review followed the PRISMA 2020 guidelines and analyzed studies published between 2015 and 2025 across Scopus, Web of Science, and Google Scholar. Inclusion criteria focused on peer-reviewed English-language studies involving real-time IoT-based monitoring of nitrogen, phosphorus, or carbon in agricultural or aquatic settings. A total of 20,251 records were screened, with 82 studies meeting all eligibility criteria. IoT-based macronutrient monitoring research has grown steadily, with statistical modeling used in 43.90% of studies. Thematic emphasis centered on nutrient pollution/removal (52.38%), algal blooms and eutrophication (25.00%), and water quality modeling (11.90%). China (31.70%) and the United States (18.30%) led in research contributions. Despite promising accuracies (up to 98.67%), major gaps remain in reporting hardware specifications, cloud infrastructure, and connectivity protocols, affecting reproducibility. IoT technologies offer substantial potential for enhancing nutrient tracking, precision agriculture, and water quality management. However, adoption is hindered by technical, infrastructural, and reporting barriers, particularly in developing regions. Greater standardization, improved training, and policy integration are needed to realize the full potential of IoT-enabled nutrient monitoring systems.