Enhancing sugarcane field management in a tropical island: A comparative analysis of mapping gaps in sugarcane fields using drone and satellite imageries

Mauritius, a tropical island where sugarcane has been cultivated for the past 300 years, plays a vital role as an economic cornerstone. The sustainability of the sugar industry in Mauritius is under threat due to various challenges. Key obstacles include the high costs of inputs, a shortage of labor, an ageing workforce and declining sugar prices on global markets. Another critical factor is the presence of gaps in fields that often go undetected in a timely manner for replantation, leading to the inefficient use of cultivable land, thus posing a threat to the industry's sustainability. To address the challenge of field gaps, remote sensing emerges as a viable solution. Leveraging high-resolution drone imagery from open sources, such as Google Earth Pro, proves to be effective in mapping gaps in sugarcane fields. The first part of the study focused on mapping gap lengths in each cane row using very high-resolution drone imagery, achieving an accuracy of 99 % when compared to conventional ground truthing. Further mapping the area devoid of sugarcane plantation and comparing the results with the total length of gaps, produced an accuracy of 98 %. Recognizing that drone surveys cannot cover the entire island, the study further evaluates the effectiveness of mapping areas of gaps using open-source satellite imagery, revealing a notable 94 % accuracy when comparing drone imagery. The research concludes that open-source imagery proves to be a reliable source for mapping gap areas, enhancing the management of sugarcane fields and mitigating the impact of gaps on overall productivity.