Nutrient distribution on soil and aboveground biomass of Macaranga gigantea five years after planting

Abstract

Abstract. Susanto D, Kusuma R, Amirta R. 2018. Nutrient distribution on soil and aboveground biomass of Macaranga gigantea five years after planting. Asian J For 2: 12-19. Despite the high potentials of Macaranga gigantea to be developed as biofuel plantation, there is limited understanding of the growth of this species especially when it is planted as uniform stand and treated with silvicultural application. This research aimed to investigate the growth and accumulation of aboveground biomass of M. gigantea in varying fertilization treatments five years after planting, and to evaluate the distribution of nutrients in soil and aboveground biomass. Five treatments at randomized design were established with each treatment having three blocks, and each block contained 20 plants, making 300 plants in total. The five treatments of M. gigantea were the application of NPK fertilizer at five measures, i.e.: P0: 0 g, P1: 40 g, P2: 80 g, P3: 120 g and P4: 160 g. Aboveground biomass and nutrient contents of N, P, K, Ca and Mg accumulated the plants were measured across the treatments, while soil sampling was conducted to analyze the nutrients accumulated in the soil. The research findings revealed that treatment P4 had the best growth performance with accumulation of  N, P, K, Ca and Mg in wood, bark, branches, and leaves twice as higher than those in treatment P0. The most distributed nutrients in the soil were magnesium, nitrogen, calcium, and phosphorus. Whereas the most accumulated nutrient in plant was potassium. The relative portion of K stored in the soil is quite small (44.18%) while K accumulated in plant was 55.82%. These findings imply that if M. gigantea plantation is harvested at five years rotation, it needs to give attention to the availability of potassium nutrients for the next planting cycles.