Real-time nitrogen monitoring and management to augment N use efficiency and ecosystem sustainability–A review

Agriculture faces the pressing challenge of feeding a growing population while preserving the environment and natural resources. Nitrogen (N) is an essential nutrient for plant growth, and its availability in soil is a key indicator of fertility. However, the indiscriminate use of N fertilizers can lead to nutrient imbalances and soil degradation, underscoring the need for accurate and efficient soil N management. Traditional sampling and analysis methods are time-consuming and prone to error, making real-time soil N assessments crucial for effective management. Moreover, precise estimation of soil N is vital for monitoring losses, developing targeted fertilizer strategies, and enhancing crop productivity and N use efficiency. Real-time N management, which involves applying N as needed during critical growth stages, can significantly improve its usage efficiency. To achieve this, the leaf color chart offers a simple, inexpensive, and user-friendly solution for assessing N needs based on leaf color, facilitating real-time management. Furthermore, sensors and the Internet of Things (IoT) play a key role in sustainable soil management and crop productivity, contributing to the development of resilient food systems and reducing uncertainty in global food markets. Accurate, rapid, cost-effective methods for assessing soil N levels are essential to achieve these sustainable goals. This review delves into the current status, limitations, and future of N-sensing in precision agriculture, highlighting cutting-edge technologies such as real-time monitoring using remote and proximal sensors, ground-based canopy sensors, drones, and Unmanned Aerial Vehicle (UAV) equipped with high-resolution cameras or multispectral/hyperspectral sensors, Geographic Information Systems (GIS)- Global Positioning Systems (GPS) integration (GIS-GPS), data analysis, Variable Rate Technology (VRT) and crop models for precise N management. By harnessing these innovations, we can revolutionize agriculture, benefiting plant health and promoting a more sustainable future.