Abstract

Black soybean production can be increased by increasing the planting area like idle fields or deployed land. Such land generally has limitations such as low water availability or low soil fertility. Soil fertility can be improved through organic matter input such as compost. Compost application can improve soil fertility but has a relatively short effect; therefore another effort is needed to support sustainable agriculture programs. Another alternative is the use of biochar. Several studies have been shown that biocharhas a long-term effect on improving soil fertility.The study was conducted in Sukamakmur Village, District of Binjai, Regency of Langkat, which is a rainfed rice field. The soil type isAndisol. The study used a factorial randomized block design (RBD) with 3 replications. The first factor is palm oil solid waste compost (K) which consists of 4 levels and the second factor is biochar which consists of 4 levels. Optimization was carried out using the Response Surface Method to get the optimal soybean production response. The response design was carried out through the Minitab 14 program to determine fixed and independent variables. The fixed variable is black soybeans production, while the independent variable is Solid waste compost as factor 1 (X1) and Palm oil Shell Biochar as factor 2 (X2).The optimum production of black soybeans on rainfed land was obtained at doses of 2-6 tons/ha biochar combined with 6 tons/ha of compost. Increased production of black soybeans through the application of biochar and compost is due to improvements in soil fertility.