Abstract: Abstract: Background It is of great significance for gully remediation to protect farmland and ensure national grain security and ecological security in the Northeast China black. The farmland protected by gully remediation (FPGR) is the key for evaluating the effectiveness of gully erosion prevention and management. To clarify the differences in the area of FPGR by erosion ditch management across different regions. MethodsIn Heilongjiang Province, erosion gullies that had already been treated and managed between 2020 and 2024 were selected. Using an unequal-probability systematic sampling approach, 2175 gullies were sampled as the study objects. An integrated methodology combining remote-sensing interpretation, hydrological model–based identification, and field investigations was employed, delineate the extents of FPGR, direct FPGR, and indirect FPGR. A comparative analysis was conducted on the of FPGR across various regions and gully types. Results The results show that the average area of FPGR is 0.32 km² . Significant regional differences were also observed, the Rolling Hills Soil Conservation Section and the Sanjiang middle and downstream ecological protection and Farmland Protection Section exhibited higher FPGR. According to gully type, FPGR areas followed the order: large gully > medium gully > small gully. the average FPGR areas of large and medium gullies are 20.8 and 4.3 times bigger than that of small gullies, respectively. Conclusions The results showed that the area of FPGR was positively correlated with the length of erosion ditch and the area of ditch margin. These findings and methodologies provide valuable insights for evaluating the effectiveness of gully remediation and protecting farmland in the black soil region.