Biochar and organic fertiliser effectivity on 3irst harvest production of four <i>Pennisetum purpureum</i> cultivars in nickel post-mining soil

Abstract Nickel is currently one of the most popular and important commodities in the world, and its production continues to increase. The nickel mining process using the open mining method causes damage to post-mining soil, requiring efforts to repair it. Current reclamation programmes focus on restoring damaged ecosystems by planting trees as forests. This has been found to be ineffective, resulting in many failures. A comprehensive solution is needed, utilizing soil amendment agents such as biochar and organic fertilizers, which according to numerous studies, have the ability to enhance crop productivity and soil quality. By utilising soil amendment agents (SAA) and superior forage grasses as reclamation subjects, it is hoped that the reclamation programme will be effective. This research purposed to evaluate the effectiveness of biochar (BC) and organic fertiliser (OF) on the productivity of several cultivar elephant grasses ( Pennisetum purpureum ) planted on postmining-nickel soil. Four levels of BC and OF were used: (negative control - without BC without OF; positive control - without BC + 20 tonnes ha -1 OF; 5 tonnes ha -1 BC + 20 tonnes ha -1 OF and 10 tonnes ha -1 BC + 20 tonnes ha -1 OF) as the Oirst factor and four elephant grass cultivars ( Pennisetum purpureum, Pennisetum purpureum Cv. GU, Pennisetum purpureum Cv. Mott and Pennisetum purpureum Cv. Thailand) as the another factor. The results showed no interaction between the use of SAA and elephant grass cultivar on agronomic and productivity parameters. The difference in SAA used was able to increase stem height (188.65 to 228.94 – 248.81 cm), number of tillers (4.38 to 6.89 – 7.69 tillers), dry matter content (22.29 to 18.44 to 19.20%) and dry matter production (4.08 to 7.89 – 1.16 tonnes ha -1 ), but resulted in decrease of dry matter content (22.29 to 18.44 – 19.20%) and leaf/stem ratio (2.20 to 1.32 – 1.51). P. purpureum Cv. Mott was the cultivar that had the highest number of tillers (9.38), leaf/stem ratio (3.28) and dry matter content (21.58%) as high as P. purpureum Cv. GU (20.20%).