Optimizing Application of Biochar Amendment for Nitrogen use Efficiency in Upland Rice under Melaleuca cajuputi Stands

Background: The main problem in nitrogen fertilization for crop cultivated is the very low efficiency due to the leaching process. The purpose of this study was to the determination of the optimum levels of biochar amendment made from Melaleuca cajuputi biochar (MCB) and urea fertilizer (UF) for nitrogen use efficiency in upland rice under M. cajuputi stands. Methods: The study was conducted during dry season within March to June 2019 in Menggoran Forest Resort, Playen Forest Section, Yogyakarta Forest Management District, Indonesia. The experimental design was laid out in a randomized complete block design factorial with three replications as the response surface methodology (RSM). The treatments consisted of MCB levels (0, 5, 10, 15 tons ha−1) and UF levels (0, 100, 200, 300 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). The data was analyzed using RSM approach and ridge regression. Result: The optimizing applications of 11.14 tons ha−1 of MCB and 281.13 kg ha−1 of UF resulted in NUE and SY by 2.14 kg grain kg Nfertilizer−1 and 5.83 tons ha−1 or increased by 19.07% and 13.02%, compared to a single application of UF by 300 kg ha−1. © 2021. All Rights Reserved.