Background: Nutrient briquette technology and biochar are technologies to reduce nitrogen loss and improve soil fertility. The objective of this study was to evaluation of interaction between 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 Nopember-February 2020 in Menggoran Forest Resort, Playen Forest Section, Yogyakarta Forest Management District, Indonesia. The experimental design was a randomized complete block design (RCBD) factorial with three blocks as the response surface methodology (RSM). The treatments consisted of biochar briquette levels made from Melaleuca cajuputi waste (0, 2, 4 grain plant-1 or equivalent to 0, 5, 10 tons ha-1) and nitrogen fertilizer levels supplied by ammonium sulfate (0, 50, 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 equivalent to 9.25 tons ha-1 biochar briquette with 76.31 kg ha-1 of ammonium sulfate fertilizer decreased NL by 38.25% and increased SY by 13.02%, compared to the single ammonium sulfate fertilizer application.
