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Waste resulted from the distillation of kayu putih leaves is a problem in almost all kayu putih refineries throughout Indonesia due to its enormous availability and un-utilization. It has potential to be used as an organic fertilizer source due to its nutrient content (macro and micro) which is higher than organic fertilizer from animals. The use of kayu putih waste is useful to complement and increase the efficiency of nitrogen fertilizer in soybean intercropping with kayu putih. This study aimed to determine the optimum values of kayu putih waste and nitrogen fertilizer based on three scenarios: economic, environmental, and eco-environmental. A two-year experiment (2018-2019) was carried out in a central composite design (CCD) with two replications as the response surface methodology (RSM) at the Menggoran Forest Resort, Playen District, Yogyakarta Forest Management, Indonesia. The treatments consist of biochar and compost levels made from kayu putih waste (0, 2.5, and 5.0 t ha-1) and nitrogen fertilizer levels supplied by ammonium sulfate (0, 50, and 100 kg ha-1) as independent variables. The observations conducted on nitrate reductase activity (NRA), total chlorophyll (TC), leaf photosynthesis rate (LPR), nitrogen loss (NL), nitrogen use efficiency (NUE), and seed yield (SY). The response variables were fitted in a full quadratic polynomial model. The results showed that the resource-based on the eco-environmental scenarios was the most favorable cropping strategy for the soybean production intercropping with kayu putih with the optimum value of 2.890 t ha-1 of biochar, 2.27 t ha-1 of compost, and 67.85 kg ha-1 of ammonium sulfate. This recommendation can reduce the use of ammonium sulfate by 32.

Abstract. Suryanto P, Taryono, Supriyanta, Kastono D, Putra ETS, Widyawan MH, Alam T. 2020. Assessment of soil quality parameters and yield of rice cultivars in Melaleuca cajuputi agroforestry system. Biodiversitas 21: 3463-3470.  Interactions between rice cultivars and soil quality parameters rises problems in the attempt of increasing rice yield. The objective of this study was to assess soil quality parameters that affect the yield of 15 rice cultivars in an agroforestry system of ‘kayu putih’ (Melaleuca cajuputi) situated in Menggoran forest, Yogyakarta, Indonesia which have three soil types namely Lithic Haplusterts, Ustic Epiaquerts, and Vertic Haplustalfs. The observation was conducted on 21 soil quality parameters and yield of rice cultivars. The data were analyzed by using ANOVA, factor analysis, and stepwise regression. The highest yield of rice per hectare was attained by GM 28 in Ustic Epiaquerts with 6.493 tons ha-1, while Situ Patenggang and GM 28 in Vertic Haplustalfs as high as5.549 and 5.401 tons ha-1, respectively, and Situ Patenggang in Lithic Haplusterts as high as 4.893 tons ha-1. Soil quality parameters that had significant effect on the yield of rice cultivars were Clay, SMC, pH, SOC, N, Mg, Fe, Fg, and Bae. We suggested that rice cultivars recommendations for Lithic Haplusterts, Ustic Epiaquerts, and Vertic Haplustalfs are Situ Patenggang, Situ Patenggang or GM 28, and GM 28, respectively, in addition to fertilization based on limiting factors of each rice cultivars.

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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 from Melaleuca cajuputi waste (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.