RADARSAT-2 Polarimetric SAR Response to Crop Biomass for Agricultural Production Monitoring

Agricultural production monitoring plays a key role in a variety of economic and environmental practices including crop yield forecasting, identifying risk of disease and application of chemicals. Remote sensing has the potential to provide accurate crop condition information across large areas and has the ability to deliver information products in a timely within-season manner. Synthetic aperture radar (SAR) frequencies are unaffected by most atmospheric conditions, making use of this technology of interest to crop monitoring. In this study, RADARSAT-2 polarimetric SAR responses of 21 parameters are compared with dry biomass of canola, corn, soybean, and spring wheat crops over a 6-week period for a site in western Canada. Dry biomass was targeted as this variable is a strong predictor of crop productivity. During the period of biomass accumulation, significant correlations with dry biomass were observed for most SAR parameters, for corn, canola, and soybeans. These findings are of interest as they could be used to target fungicide applications (canola) and to determine silage yields and resistance to disease (corn). For spring wheat, linear cross polarization and circular cross polarization backscatter, volume scattering and pedestal height were able to detect when wheat entered the milking stage which could prove useful as an indicator for the timing of spring wheat harvest. This study demonstrates that polarimetric SAR responds to accumulation of dry biomass, but as well that several radar parameters can uniquely identify changes in crop structure and phenology.