Sugarcane Productivity Mapping through C-Band and L-Band SAR and Optical Satellite Imagery

Ramses Molijn,Ramon Hanssen,Jansle Vieira Rocha,Lorenzo Iannini

doi:10.3390/rs11091109

Abstract

Space-based remote sensing imagery can provide a valuable and cost-effective set of observations for mapping crop-productivity differences. The effectiveness of such signals is dependent on several conditions that are related to crop and sensor characteristics. In this paper, we present the dynamic behavior of signals from five Synthetic Aperture Radar (SAR) sensors and optical sensors with growing sugarcane, focusing on saturation effects and the influence of precipitation events. In addition, we analyzed the level of agreement within and between these spaceborne datasets over space and time. As a result, we produced a list of conditions during which the acquisition of satellite imagery is most effective for sugarcane productivity monitoring. For this, we analyzed remote sensing data from two C-band SAR (Sentinel-1 and Radarsat-2), one L-band SAR (ALOS-2), and two optical sensors (Landsat-8 and WorldView-2), in conjunction with detailed ground-reference data acquired over several sugarcane fields in the state of São Paulo, Brazil. We conclude that satellite imagery from L-band SAR and optical sensors is preferred for monitoring sugarcane biomass growth in time and space. Additionally, C-band SAR imagery offers the potential for mapping spatial variations during specific time windows and may be further exploited for its precipitation sensitivity.

Highlights

Sugarcane is the number one globally cultivated crop in terms of production quantity, more than the second and third crops, maize and rice, combined
For C-band HV the saturation point of the signal occurred at approximately 25 tons/ha (90 cm stalk height) for rain-affected signals and approximately 35 tons/ha (120 cm stalk height) for signals not affected by rain
The results presented the effects of sugarcane biomass growth, precipitation, and sensor characteristics on remote sensing signals, in particular from C-band Synthetic Aperture Radar (SAR), L-band SAR, and optical sensors

Summary

Introduction

Sugarcane is the number one globally cultivated crop in terms of production quantity, more than the second and third crops, maize and rice, combined. Brazil is the largest sugarcane producer, amounting to almost 40% of total global production [1], while São Paulo state hosts more than 60% of Brazil’s sugarcane acreage [2,3]. The main products are sugar and bioethanol; the latter allows Brazil to reduce the national automotive’s gasoline consumption by more than half [2]. This illustrates the importance of sugarcane production and research in São Paulo, which hosts the area of study. Sugarcane is a semiperennial crop; after each growth cycle, typically lasting for 12 to 18 months for Brazilian plantations [5], new ratoons emerge from the same root system. The sucrose content in the stem accumulates and senescence of the leaves occurs [5,6,7]

Methods

Results

Discussion

Conclusion