Journal of Tropical Crop Science Vol. 7 No. 8, February 2021 www.j-tropical-crops.com 16 R.A. Diana Widyastuti, Kus Hendarto, Ali Rahmat, Hayane Adeline Warganegara, Indah Listiana The Combination of Biofertilizer and Organic Fertilizer to Improve Shallot (Allium ascalonicum L.) Production R.A. Diana Widyastuti* A , Kus Hendarto A , Ali Rahmat D , Hayane Adeline Warganegara B , Indah Listiana C , Sandi Asmara E A Department of Agrotechnology, Faculty of Agriculture, University of Lampung, Indonesia B Department of Agronomy and Horticulture, Faculty of Agriculture, University of Lampung, Indonesia C Department of Agribusiness, Faculty of Agriculture, University of Lampung, Indonesia D Indonesian Institute of Science, Indonesia E Department of Agriculture Engineering, Faculty of Agriculture, University of Lampung *Corresponding author; email: radianawidyastuti@yahoo.co.id Abstract Shallot is one of important horticultural crops in Indonesia; shallot consumption per capita is estimated to be 4.6 kg per year. The objective of this study was to evaluate the efect of combining biofertilizer and organic fertilizer on the production of shallot in Sukabanjar village, Pesawaran, Lampung, Indonesia. The study was set up using a randomized completely block design with two factors, biofertilizers and various organic fertilizers, i.e. cow manure, chicken manure, rice straw compost, oyster mushroom baglog. Our study demonstrated that combining biofertilizer and organic fertilizer signifcantly increased the number, diameter, and fresh and dry weight of tubers of “Bima Brebes” shallot. Shallots treated with biofertilizer combined with oyster mushroom baglog produced the highest tuber yield of 1788 g compared to 282 g in the control. Keywords: chicken manure, cow manure, oyster mushroom baglog, rice straw compost, shallot tuber Introduction Shallot is one of the important horticulture commodities in Indonesia and worldwide. The major use of shallot is for spice, but it is also used as a component of traditional medicine (Sun et al., 2019). Shallot contains benefcial nutrients such as protein, fat, calcium, phosphorus and vitamin C (Rahayu and Berlian, 2006). Among several shallot varieties known, the “Bima Brebes” (Allium ascalonicum L. var “Bima Brebes”), which was produced in 1984, is now widely adopted in Brebes, Indonesia. Brebes is one of the largest shallot production centers in Indonesia (Basuki et al., 2017). “Bima Brebes” is known to have a good yield potential when grown in favorable environment (Gardner et al., 2013). “Bima Brebes” yield could be up to 10 ton.ha -1 with a relatively short growing season; it is ready to harvest at 55–60 days after planting (DAP) compared to the other shallot cultivars, i.e. 60–90 DAP (Sumarno, 2019). “Bima Brebes” is also well adapted to rainy season; the tubers have medium to large tuber size, and pink to red maroon tuber color, making them highly sought in the market (Basuki et al., 2017). The low productivity of shallots could be related to the low organic matter in its agro-ecosystem (Direktorat Pangan dan Pertanian, 2017), therefore it is important to maintain the level of organic matter in the soil. Excessive use of inorganic fertilizer for a long period can reduce the soil fertility, as indicated by the hardening of soil structure, reduction of soil aggregates and soil viability (Blanco-Canqui and Alan, 2013). The higher biological activities in soil, the higher soil fertility, the better the plant growth (Kemas, 2005). There is a need to compensate the negative efect of chemical fertilizer, and the use of biofertilizer and organic fertilizer are good candidates to minimize the negative impact of inorganic fertilizers. Biofertilizers contain active microorganisms that can be benefcial for plant growth (Damanik et al., 2011). A previous study also showed that organic fertilizers also improve soil health and fertility (Lin et al., 2020). This study aimed to evaluate the efect of combining biofertilizer and organic fertilizer on the production of “Bima Brebes” shallot. Materials and Methods The study was carried out in the village of Sukabanjar, subdistrict of Gedong Tataan, Pesawaran district,