Effect of formulated biochar on nodule production, dry matter and grain yield of black soybean (Glycine max (L.) Merr) in Indonesia

Biochar is an important material for soil mineral supply and amendment. Root nodule formation in leguminous plants is also stimulated by biochar. Biochar contains carbon which can be used as an energy source by microbes and contains pores which are suitable for microbial habitat, and it temporarily increases activity of free-living nitrogen-fixing bacteria. Coconut shell biochar can be used as an ameliorant, but the use of single coconut shell biochar can cause a problem such as the use of high dose that will lead into high cost. One of the solutions to solve the problem is to improved coconut shell biochar into formulated biochar (FB) by managing the composition and enrich it with chemical fertilizer’s such as dolomite, organic fertilizer compost of sugarcane bagasse and guano. Mixture of formulated biochar (FB) gave better results than single biochar alone on black soybean. When this FB is applied in the field, it can make efficient use of an organic fertilizers in increasing grain yields. This research was conducted to determine the effect of Formulated Biochar (FB) on nodule production, dry matter and productivity of black soybean seeds. The study was conducted for one season in an experiment field in Winaya Mukti University, Sumedang-Indonesia at 850 m above sea level (m ASL). Detam I seed cultivar was used because it has a wide adaptability in Indonesia and has high nutrient composition and yield potential. The experiment was arranged in a randomized block design consisting of 5 treatment doses of FB (0, 0.5, 1.0, 1.5, 2.0 tons ha-1) and replicated 5 times. The responses observed were the number of effective nodules, growth characteristics, production components and productivity of black soybeans. The results showed that the application of FB had a significant effect on increasing the effectiveness of nodule production, dry matter, and productivity of black soybean seeds. The formulated biochar dose of 2.0 tons ha-1 increased the effectiveness of nodule production up to 100% and 44.87% of soybean productivity, while the formulated biochar dose of 1.5 tons ha-1 increased soybean productivity by 38.46% compared to the control. It is therefore concluded that formulated biochar as soil conditioner and soil booster could be used to improve the growth and grain yield of black soybean. Key words: Black soybean, coconut shell biochar, component yield, dry mater, formulated biochar, grain yield, growth, nodulation