Effects of oil palm midrib compost and humic acid on the growth and water use of immature oil palm (Elaeis guineensis)

Immature oil palm requires adequate supply of nutrients and water to support their growth and development. Nutrient supply is provided by fertilization, in this case is utilization of oil palm midrib compost as a nutrient source and at the same time is expected to hold water in the planting media. Decomposition process of oil palm midrib compost is assisted with the application of humic acid as a bio-activator. This study was conducted during 2019 at Ciparanje Experimental Farm, Faculty of Agriculture, Padjadjaran University, Sumedang Regency, Indonesia to study and determine the effect of oil palm midrib compost applied with humic acid in providing nutrients and water for the growth of immature oil palms (using 19 months old oil palm trees). This study comprising nine treatments: inorganic fertilizer NPK (16:16:16) 86.4 kg/ha (A), oil palm midrib compost 457.6 kg/ha (B), oil palm midrib compost 457.6 kg/ha + 4.3 L/ha humic acid (C), oil palm midrib compost 457.6 kg/ha + 8.58 L/ha humic acid (D), oil palm midrib compost 457.6 kg/ha + 12.9 L/ha humic acid (E), oil palm midrib compost 915.2 kg/ha (F), oil palm midrib compost 915.2 kg/ha + 4.3 L/ha humic acid (G), oil palm midrib compost 915.2 kg/ha + 8.58 L/ha humic acid (H), oil palm midrib compost 915.2 kg/ha + 12.9 L/ha humic acid (I). The results showed that application of oil palm compost 915.2 kg/ha with humic acid 4.3 L/ha (treatment G) giving 588.875 cm² leaf area growth and addition of 3, 4.83, and 6.5 of leaf midrib number at 2, 4, and 6 months after treatment respectively and altogether with evapotranspiration value around 0.24 mm/day or water loss suppression by 59%.