Using of Oil Palm Empty Fruit Bunch Compost and Mycorrhizae Arbuscular for Improving the Fertility of Nickel Post-Mining Soil

The nickel post-mining soil with an open-pit mining system has poor soil chemical and physical properties. Thus, it requires appropriate site-specific management so that it can be optimized as a plant cultivation area. This study aimed to analyze the effectiveness of compost from oil palm empty fruit bunches (OPEFB) and mycorrhizal vesicular-arbuscular (MVA) in improving soil fertility of nickel post-mining soil. This study was conducted using a randomized block trial design with 2 factors. The first factor is compost with 3 treatments, consisting of 5 t•ha-1 (K1), 7.5 t•ha-1 (K2), 10 t•ha-1 (K3) and the second factor was mycorrhiza (M) in the fine-crushed brick carrier media with as many as 3 treatments consisting of 2 t•ha-1 (M1), 4 t•ha-1 (M2), 6 t•ha-1 (M3). A total of 9 treatment combinations were repeated 3 times, arranged in experimental pots at the Experimental Farm of Hasanuddin Uni- versity, South Sulawesi, Indonesia. The results showed that the compost and MVA treatments had a significant effect on increasing the average values of cation exchange capacity, organic carbon, available P2 O5 , calcium and magnesium exchangeable,as well as decreasing exchangeable aluminum and iron. The highest soil properties val- ues were found in the combination of compost 10 t•ha-1 (K3) and MVA 6 t•ha-1 (M3). The application of compost from OPEFB combined with MVA significantly improved soil fertility, which was indicated by improving soil chemical and biological properties. The application of MVA at various doses had a significant effect on the dry weight, root length of Calopogonium mucunoides and increase the number of MVA spores in the soil.