Utilization of biochar and NPK fertilizer for soybean planting (Glycine max (L.) Merrill) in Ultisol media

This study aimed to obtain the growth and yield of soybean plants on ultisol medium after being treated with biochar and NPK fertilizer. The research was carried out in the experimental garden of the Faculty of Agriculture, Riau University, from November 2020 to February 2021. The research was carried out experimentally in a 3 x 3 factorial form, arranged using a Completely Randomized Design. Factor I, biochar doses (0, 10, and 20 ton.ha -1 were equivalent to 0, 100, and 200 g per plant). Factor II, NPK doses (175, 350, and 525 kg.ha -1 equivalent to 1.75; 3.5; and 5.25 g per plant). Of the two factors, 9 combinations were obtained, and each combination was repeated 3 times to obtain 27 experimental units. Each experimental unit contained 7 plants in 7 polybags observed. Observed parameters; plant height, number of primary branches , number of effective root nodules, plant growth rate, number of pods per plant, number of pithy pods per plant, number of seeds per plant, seed weight per plant. The results showed that the combination of biochar 20 ton.ha -1 and NPK 350 kg.ha -1 gave good results for plant growth (number of effective root nodules and plant growth rate) and soybean yield (number of pods and seed weight per plant). The application of biochar 20 ton.ha -1 significantly increased plant growth (number of effective root nodules and plant growth rate) and soybean yield (number of pods, number of pithy pods, number of seeds, and seed weight per plant), but administration of NPK did not significantly increase growth and yield of soybeans.