Interactions of Biochar Briquette with Ammonium Sulfate Fertilizer for Controlled Nitrogen Loss in Soybean Intercopping with Melaleuca cajuputi

Background:Nutrient briquette and biochar are used to reduce nitrogen loss and improve soil fertility. This study aimed to evaluate the interaction of biochar briquette with ammonium sulfate fertilizer for controlled nitrogen loss in soybean intercropping with Melaleuca cajuputi.Methods:The study was conducted in the wet season from November to February 2020 at Menggoran Forest Resort, Playen Forest Section, Yogyakarta Forest Management District, Indonesia. The experiment was using a randomized complete block design factorial with three blocks as the response surface methodology. The treatments included different levels of biochar briquette fromMelaleuca cajuputiwaste (0, 2 and 4 grain plant-1 or 0, 5 and 10 tons ha-1) and nitrogen fertilizer supplied by ammonium sulfate (0, 50 and 100 kg ha-1) as independent variables. The observation parameters were nitrate reductase activity (NRA), total chlorophyll (TC), leaf photosynthesis rate (LPR), nitrogen loss (NL), nitrogen use efficiency (NUE) and seed yield (SY).Result:The optimum values of 3.70 grain plant-1 or 9.25 tons ha-1 biochar briquette with 76.31 kg ha-1 ammonium sulfate fertilizer decreased NL by 38.25% and increased SY by 13.02% compared with single ammonium sulfate fertilizer.