Effectiveness of Melaleuca cajuputi biochar as a leaching loss for nitrogen fertilizer and intercropping in maize

Background: Biochar has a function for soil amendment and leaching loss for nitrogen fertilizer. The objectives of this study was to evaluate the effectiveness of Melaleuca cajuputi biochar as a leaching loss for nitrogen fertilizer and intercropping in maize. Methods: The study was conducted from February to June 2019 in Menggoran Forest Resort, Playen District, Gunungkidul Regency, Special Province of Yogyakarta, Indonesia. The experimental design was a randomized complete block design (RCBD) factorial with three replications as the response surface methodology (RSM). The treatments consisted of biochar levels made from Melaleuca cajuputi waste (0, 5, 10, 15 tons ha⁻¹) and nitrogen fertilizer levels sourced from urea (0, 150, 300 kg ha⁻¹) as independent variables. The observation parameters were nitrate reductase activity (NRA), total chlorophyll (TC), net photosynthesis (NP), nitrogen loss (NL), nitrogen use efficiency (NUE) and seed yield per hectare (SY). Result: The RSM revealed that the optimum value of 13.290 tons ha⁻¹ of Melaleuca cajuputi biochar (MCB) and 245.350 kg ha⁻¹ of nitrogen fertilizer (NF) can reduced urea by 18.22%. This recommendation increased NRA, TC, NP, NL, NUE and SY by 35.28%, 19.55%, 18.09%, -46.81%, 27.96% and 61.78%, respectively, in compare to the single application of urea.