Correlation Analysis of Vegetation Index Impact on Rice Paddy Productivity Estimation using Landsat-8 and Sentinel-2A Images (Case Study: Blitar District)

Rice is consumed by most of the population in Indonesia. The generative phase, the final stage of rice growth cycle, produces raw grains that are processed into rice, forming the basis of rice production. To estimate rice paddy productivity in March 2023, vegetation indices such as the Normalized Difference Vegetation Index (NDVI) and the Optimized Soil-Adjusted Vegetation Index (OSAVI) are used. These indices are crucial as they correlate with rice paddy areas in the generative phase. Sentinel-2A imagery calculations have shown strong correlations, with NDVI at R = 0.61 and OSAVI at R = 0.75. The OSAVI index from Sentinel-2A yielded an average productivity estimate of 31.35 ton/ha with an RMSE of 5.7041, while NDVI gave an average of 63.63 ton/ha with an RMSE of 12.3224. In comparison, Landsat-8 imagery estimates using NDVI showed a moderate correlation (R = 0.54), with an average productivity of 20.75 ton/ha and an RMSE of 3.2321. The OSAVI index with Landsat-8 provided an average estimate of 64.27 ton/ha with an RMSE of 12.3338 and a moderate correlation (R = 0.41). The correlation coefficients from Sentinel-2A are higher than those from Landsat-8, indicating that the choice of imagery significantly affects rice productivity estimates.