Mapping crop rotation by satellite-based data fusion in Southern Brazil

Abstract

Crop monitoring is a key process for agricultural management and policy making linked to food security and sustainability. The spatio-temporal assessment of crop-specific management is essential for mapping crop rotation at field-scale. The aims of this study were to generate a satellite-based data fusion approach for mapping crop rotation at field-scale and generating analyses of crop rotation patterns among different mesoregions, examining the impact of environmental factors on crop yields, within the Rio Grande do Sul, southern Brazil. Within this geographical region, soybeans (Glycine max (L.) Merr.), corn (Zea mays L.), and rice (Oryza sativa L.) are the major grain crops of the state. We have utilized a satellite-based data fusion crop type classification and mapping to extract spatial crop features during four growing seasons (2017–2021), associated to field boundary delineation to generate the crop rotation database. This database showed current crop rotation practices within the study region, highlighting continuous soybean (monocrop), and three soybeans with one corn year rotation as the most frequent in the state. Midwestern and Northwest mesoregions presented the highest mean municipality values of continuous crop with 76% and 61%, respectively. Crop rotation patterns in Porto Alegre metropolitan, Southwest, and Southern mesoregions showed soybean-rice rotation, but with a trend of increases in soybean area in detriment to rice in lowlands. Crop rotation effects on yield for soybeans varied from 20 up to 65% depending on the regions and years of crop rotation. Other crop rotation effects in the crop yields were not significant at the municipality level. Crop rotation showed more significant benefits for soybean yields in warm and wet climate, with higher bulk density and lower soil organic carbon. Lastly, this study presents the first crop rotation map layer for the entire state of Rio Grande do Sul, southern Brazil, serving as a foundation for the creation of similar database for other states in the country and around the globe.