This study aimed to determine the appropriate concentrationABSTRACTand frequency of bio organic fertilizer (POH) on ultisol soil to the growth and yield of bok Choy plants in the second cultivation. This study was conducted for 3 (three) months from April to June 2018, at Green House of Agro-technology Study Program Faculty of Agriculture, Universitas Muhammadiyah Purwokerto with altitude of + 80 meters above sea level. This study was carried out through non factorial completely randomized design (CRD). The treatment was the provision of bio organic fertilizer (POH) and its frequency with 13 treatments, those were P0: Control (without treatment of POH), P1: provision of POH 20 ml / Liter of water at planting, P2: provision of POH 20 ml / Liter of water when planting and 10 days after planting, P3: the provision of POH 20 ml / Liter of water at planting, 10 days and 20 days after planting, P4: The treatment of POH 20 ml / Liter of water at planting, 10 days, 20 days and 30 hours, P5: 30 ml of POH per Liter of water during planting, P6: provision of POH 30 ml / Liter of water at planting and 10 days after planting, P7: provision of POH 30 ml / Liter of water at planting, 10 days and 20 days, P8: provision of POH 30 ml / Liter of water when planting, 10 days, 20 days and 30 hours, P9: provision of POH 40 ml / liter of water during planting, P10: provision of POH 40 ml / liter of water at planting and 10 days after planting, P11: provision of POH 40 ml / liter of water at planting, 10 days and 20 days after planting, P12: 40 ml / Liter of POH given during planting, 10 days, 20 days and 30 days after each treatment was repeated 3 (three) times.
The results of this study indicated that the concentration and frequency of bio organic fertilizer had a significant effect on the observation variables of leaf area, root fresh weight, and root dry weight. The concentration and frequency of biological organic fertilizer that had the best effect on the growth and yield of bok choy plants were in the treatment of P4: the concentration of 20 ml / liter of water is given at planting, 10 days, 20 days and 30 days.