Remotely sensed sugarcane phenological characteristics at Umfolozi South Africa

Abstract

The South African Sugar Association Experiment Station is investigating the use of satellite remote sensing for monitoring areas under sugarcane, assessing what proportion of the crop has been harvested and forecasting seasonal yields. In such applications, a good understanding of the spectral characteristics of the sugarcane crop over time is important for identification and stratification into different crop production classes. Preliminary results of a study undertaken to investigate reflectance characteristics of different sugarcane varieties for large-scale grower fields at Umfolozi, South Africa, are presented in this paper. Relationships between the spectral profiles of sugarcane varieties at different (thermal) ages were investigated. The spectral profiles were obtained from normalized multi-temporal Landsat 7 imagery. Preliminary results for sugarcane suggest that four classes in growth can be identified by remote sensing techniques, namely: pre-emergence, tillering, tiller senescence and tiller stabilization/crop maturation. While the four classes in sugarcane growth were significantly different, on-going research quantifies the errors for misclassifying the thermal ages of fields, given the overlapping distribution of the four thermal age groups. Comparisons of sugarcane varieties of similar thermal ages revealed no consistent differences in the spectral characteristics.