Koreh, A. A., Widowati, & Julianto, R. P. D. (2023). Long-term residual effects of biochar from tobacco scraps on red spinach (Amaranthus tricolor) growth in Entisols: a five-year field experiment with urea fertilizer addition. Jurnal Ilmiah Pertanian, 20(2), 153-164. https://doi.org/10.31849/jip.v20i2.13451