# Estimating Double Cropping Plantations in the Brazilian Cerrado through PlanetScope Monthly Mosaics
## 3 Results
### Spectral Signatures and Indices  
Figure 5 shows the spectral signatures of forestlands, cultivated pastures, single cropping, and double cropping found in the municipality of Goiatuba over the 2021/2022 crop growing season. The spectral signature of forestlands was derived based on averaging 36 sampling points that were visited during the field campaign of October 2021. A varying number of pixels was extracted from each sampling point, ranging from 418 to 555 pixels, with a total of 4300 pixels. In the same way, the spectral signature of cultivated pastures was obtained based on 46 sampling points (range: 254-646 pixels; total: 22,496 pixels). The spectral signature of double cropping was obtained considering the 49 field sampling points recorded as bare soil in October 2021 and as maize or sorghum in April 2022 (range: 402-604 pixels; total: 21,891 pixels). Finally, the spectral signature of single cropping was obtained through six sampling points recorded as bare soil in October 2021 and sugarcane in April 2022 (range: 418-552 pixels; total: 4300 pixels). The typical spectral signature of sugarcane (older than one year) is not shown in this paper because of varying plant growing conditions found in the study area.  
The forestlands presented spectral signatures that are typical of those from green leaves, that is, low reflectance in the red band due to the absorption of electromagnetic radiation related to the photosynthetic activities and high reflectance in the NIR band due to the high reflection of solar incident radiation controlled by the internal structure of leaves during the entire time series. Similar signatures were also found for shrubland and reforestation (not show in this figure).  
In October, cultivated pastures did not show strong absorption in the red band or strong reflection in the NIR band, indicating that the pastures were mostly dry. The main difference between the temporal signatures of areas with single cropping and double cropping is in the red and NIR spectral bands from December and January. Most of the double cropping areas are in the peak of growing season in December and early January, while the harvesting  
Figure 5: Multitemporal surface reflectance of forestlands (**A**), cultivated pasturelands (**B**), single croplands (**C**), and double croplands (**D**) from the municipality of Goiatuba, Goiás State, Brazil (2020/2021 crop growing season). The bands 1, 2, 3, and 4 represent the spectral bands of PlanetScope satellite in the blue, green, red, and near-infrared ranges, respectively.  
season is in early February. The single crop spectral signature from December does not show the typical reflectance of green vegetation because most of these areas were recently planted with sugarcane, which presents a much longer crop growing season.  
The most stable EVI values during the 2021/2022 crop growing season were found in the forestlands (typical range: 0.40-0.65) (Figure 6). Although we found some sites with deciduous forest, most of the forestlands in the study area were composed by gallery forests and semideciduous forests. As expected, the cultivated pastures were driest in October (lowest EVI values, typically around 0.25) and greenest in January, the peak of rainy season in the study area. The most impressive aspect is the difference in EVI values between single cropping and double cropping from February. EVI from double cropping showed much lower EVI values (average: 0.19) than those from single cropping (average: 0.37). The variance of EVI values for single cropping was also much higher than that from double cropping for this period.