PEMBERIAN BIOCHAR PLUS KOMPOS TERHADAP PERBAIKAN KIMIA ULTISOL DAN PERTUMBUHAN BIBIT KELAPA SAWIT (Elaeis guineensis Jacq) PADA TAHAP MAIN NURSERY

This study was aimed to determine the effect of rice husk biochar and compost (oil palm leaves plus tithonia) to improve the chemical properties of Ultisol and the growth of oil palm (Elaeis guineensis Jacq) seedlings. This research was conducted in Experiment Station, Faculty of Agriculture, Andalas University, Padang. Soil and crop analysis was conducted at Soil Laboratory, Faculty of Agriculture, Andalas University, Padang and in the Laboratory of Molecular Chemistry, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Japan from January 2017 until January 2018. This experiment used a completely randomized design (CRD) consisting of 6 treatments ( controls; 100% compost; 75% compost + 25% biochar; 50% compost + 50% biochar; 25% compost + 75% biochar; 100% biochar) with 3 replications. The results showed that the treatment 25% compost + 75% biochar was found to be the best treatment to improve the chemical properties of Ultisol by increasing 0.36 unit pH; 0.18 % N; 3.13% organic C; 21.31 ppm P; and 12.0 cmol kg-1 CEC. Furthermore, crop growth also improved, especially plant height increased by 13.32 cm; number of leaves by 2; stem diameter by 8.42 mm, N uptake by 4.54 g/plant; P by 0.71 g/plant; K by 2.28 g/plant, as well as dry matter weights by 2.80 g/plant, if it was compared to controls. Keywords: biochar, oil palm, compost, ultiso