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

The residual effects of biochar doses on Entisols after five years application have not received attention. However, there is an assumption that the positive can last longer in soil. Therefore, field experiments were carried out polybags to assess impact applying fifth year and addition urea fertilizer growth red spinach (Amaranthus tricolor) Entisol. growing media used this study was a medium previously for containing Entisols. This 2-factor randomized block design consisting (3 levels) (2 levels). There no interaction between N fertilizer. Application at dose 500 g/polybag gave better follow-up effect than 250 year. Chlorophyll content increased with fertilization. Applying fertilization positively impacted Spinach yield 30% remaining 52% Within years, using higher adding will result