Lead (Pb) is a hazardous heavy metal that can contaminate the environment and inhibit the growth of rubber seedlings. This study evaluated the effects of combining organic (tankos) and inorganic (NPK) fertilizers on Pb accumulation and the growth of GT1 and PB260 rubber seedlings. The method used was a factorial Split-Plot Design (SPD) with two factors: Clone as the main plot and fertilizer combination (0%, 25%, 50%, 75% tankos + NPK) as the subplot, repeated three times. The results showed that the application of NPK and tankos affected soil chemical properties, increasing K-dd, but had no significant effect on P-Bray I, organic C, and total N. No Pb contamination was found in the seedlings, indicating that fertilization remained within safe limits. This study serves as a guide for environmentally friendly fertilizer management, supports the growth of healthy rubber seedlings, and enhances future rubber tree productivity.
Eva Yanti Manihuruk1, Yayuk Purwaningrum2*, Muhammad Rizwan2 (Mon,) studied this question.