The use of synthetic aperture radar technology for crop biomass monitoring: A systematic review
Mikka Parag, Romano Lottering, Kabir Peerbhay, Naeem Agjee, Nitesh Poona
Abstract
In agriculture, crop biomass is a vital indicator of the overall health of an ecosystem. Recent developments in synthetic aperture radar (SAR) technologies have promoted the application of SAR remote sensing for agricultural monitoring. SAR imaging systems are unaffected by atmospheric conditions yet are sensitive to the structural properties of vegetation; considering these capabilities, SAR observations may offer immense potential for crop biomass monitoring. In this context, a systematic review was undertaken to examine the development patterns, emerging themes and research opportunities in crop biomass monitoring using SAR. An extensive literature search was conducted, and 100 scientific publications were deemed eligible for further analysis and synthesis. Through bibliometric and trend analysis, the results of this review show that the application of SAR imagery for crop biomass monitoring has gained momentum over the last decade. Research has predominantly been conducted in Asia, whilst only a few studies have been conducted in Africa and South America. Numerous crops were monitored using SAR technology, with wheat crops observed most frequently. Whilst various radar remote sensors have been utilised for crop biomass monitoring, RADARSAT-2 and, more recently, Sentinel-1 were favoured by researchers. The C-band sensor configuration was the most widely used frequency range for crop biomass monitoring. Finally, the dual-polarimetric polarisation sensor configuration had the highest utilisation frequency in the literature reviewed. The findings of this study indicate that the use of SAR for crop biomass monitoring applications is still in its infancy; as such, numerous research gaps still need to be explored. However, despite this, the potential of SAR for crop biomass monitoring applications is evident.