11 Caraka Tani: Journal of Sustainable Agriculture, 36(1), 11-19, 2021 URL: https://jurnal.uns.ac.id/carakatani/article/view/35682 DOI: http://dx.doi.org/10.20961/carakatani.v36i1.35682 ISSN 2613-9456 (Print) 2599-2570 (Online) Copyright © 2021 Universitas Sebelas Maret Growth and Yield of Soybean as a Response of the Fertilization of NPK Compound Produced with Spent and Deoiled Bleaching Earth Filler Radinal Arief Sinaga, Budiastuti Kurniasih and Eka Tarwaca Susila Putra  Department of Agronomy, Faculty of Agriculture, Universitas Gadjah Mada, Yogyakarta, Indonesia * Corresponding author: eka.tarwaca.s@ugm.ac.id Abstract Spent Bleaching Earth (SBE) is a by-product of the refining of Crude Palm Oil (CPO) into cooking oil which is classified as hazardous and toxic materials waste. SBE has the potential to be used as a filler in the production of NPK fertilizer. This study aims to compare the effect of SBE and Deoiled Bleaching Earth (DBE) as the replacement of clay mineral, which is expected to have the same effect as the control treatment in terms of the leaf area, total dry weight, plant height and yield of plant. This experiment used a one-factor Randomized Complete Block Design (RCBD) with three replicates. The treatments of filler in NPK fertilizer were 10% clay minerals, NPK with 5% clay mineral + 5% SBE filler and NPK with 5% clay mineral + 5% DBE filler. Fertilizer was given twice, ie when the plant was 14 days after planting (DAP) as much as 2 g polybag -1 and age 35 DAP as much as 3 g polybag -1 at each treatment. The results showed that the application of NPK fertilization with 5% clay mineral + 5% SBE filler and NPK fertilization with 5% clay mineral + 5% DBE filler had the same effect as NPK fertilization with 10% clay mineral filler on leaf area, total dry weight, plant height and yield of plant. SBE and DBE can be used as substituties for clay mineral in NPK fertilizer production. Keywords: deoiled bleaching earth; NPK; soybean; spent bleaching earth Cite this as: Sinaga, R. A., Kurniasih, B., & Putra, E. T. S. (2021). Growth and Yield of Soybean as a Response of the Fertilization of NPK Compound Produced with Spent and Deoiled Bleaching Earth Filler. Caraka Tani: Journal of Sustainable Agriculture, 36(1), 11-19. doi: http://dx.doi.org/10.20961/carakatani.v36i1.35682 INTRODUCTION Soybean is a popular food crop in Indonesia. According to PUSDATIN KEMENTAN (2018), soybean production in 2017 was 538,728 tons, then in 2018 increased to 982,598 tons. This is in line with the increase in the soybean harvest area, which was formerly 355,799 ha in 2017, increased to 680,373 ha in 2018. One of the intensive efforts to increase soybean production is to optimize the existing land area by using superior seeds, good soil tillage and the proper use of fertilizer. Plants need enough macro and micronutrients for their growing and developing. Fertilization must be applied to meet the needs of nutrients  Received for publication November 19, 2019 Accepted after corrections October 9, 2020 for plants, so they can grow, develop and produce well. Fertilizers contain nutrients needed by plants, both macro and micronutrients. Fertilizer can also provide the certain nutrients in the soil so that it meets the needs of plants for nutrients (Adileksana et al., 2020). Nutrients of N, P and K are essentially required by plants in large amounts. Nitrogen is needed for protein synthesis, leaf development and supports metabolic processes such as photosynthesis. Phosphorus plays a role in stimulating root growth and the formation of a good root system in young plants, as a constituent of cell nuclei (nucleic acids), fats and proteins. Potassium plays a role in helping the synthesis of proteins and carbohydrates, increasing plant resistance to pests