Precision Nitrogen Management in Rice Using NDVI and SPAD: A Systematic Review of Current Applications and Limitations

Abstract

The management of nitrogen is necessary to maximize the productivity of rice and enhance the nitrogen use efficiency. Vegetation Index and other remote sensing tools have been extensively employed to determine the nitrogen status of crops, but they can be affected by environmental fluctuation. The study aimed to evaluate the effectiveness of Vegetation Index in determining nitrogen status and predicting yield performance in rice systems. Scopus, ScienceDirect, and Web of Science were used to search the articles published between 2015 and 2025 by search query: (paddy OR rice) AND (NDVI OR Vegetation Index) AND (nitrogen). The methodology used was a four-step screening system, which left 13 applicable studies to be examined in detail. Results showed that Vegetation Index is highly correlated with nitrogen content and yield components, especially in late vegetative and reproductive periods. Diagnostic accuracy was further improved with SPAD chlorophyll meter and UAV-based images. Nevertheless, the diurnal variability of light, sensitivity to growth stages, and cultivar variability are a few of the challenges that decrease the uniformity of its implementation. Altogether, Vegetation Index is a useful non-destructive means of precision rice management if measurements are made under optimal conditions. Future research should focus on the integration of light quality and canopy structure parameters integration to enhance monitoring protocols and robust decision-making in sustainable rice production.