Article ID: D26-033
Crop residue trials were conducted to evaluate sprayed pesticide residue levels in the parts of rice whole-crop silage (RWCS) above ground. This study evaluated the validity of 15-hill composite sampling across different rice varieties (Koshihikari and Tachisuzuka) and years. Despite substantial unit-to-unit heterogeneity (coefficient of variation [CV] up to 116%), the analytical results of 15-hill composite samples were largely within the theoretically estimated residue level ranges, confirming the validity of this sampling approach for the entire field. Furthermore, no substantial differences in residue levels were observed between the two varieties under identical experimental designs, and the residue levels of the 15-hill composite samples were in good agreement with the mean values of the 20 individual hills (R2=0.963). These results suggest that the current 15-hill composite sampling procedure is a practical and valid method for obtaining reliable residue data in RWCS, regardless of variety.
