SUBSTITUTION OF SYNTHETIC NITROGEN FERTILIZER WITH BOKASHI ON UPLAND RICE GROWTH AND YIELD. Thesis: Annisa Nur Rahmawati (H0720018). Advisor: Prof. Dr. Ir. Supriyono, M.S., Dr. Ir. Puji Harsono, M.P., and Prof. Dr. Ir. Djoko Purnomo, M.P. Department of Agrotechnology, Faculty of Agriculture, Sebelas Maret University. Upland rice is one food commodities that has potential to be developed on drylands. Indonesia has a total dryland area of 144.47 million ha with a potential dryland area of 99.65 million ha. As the demand for rice continues to increase, it is necessary to expand the planting area by utilizing potential drylands. Growth and productivity of upland rice is determined by several factors, including nutrients in the soil, especially nitrogen. This element is generally obtained from urea fertilizer, but the continuous use of urea fertilizer can be detrimental both in terms of the environment and production. The negative impact needs to be overcome by reducing the dosage of urea fertilizer and replacing it with organic fertilizers that are environmentally friendly, affordable, and contain complex nutrients. The research through this experiment was carried out in the laboratory greenhouse Faculty of Agriculture, Sebelas Maret University in October 2023 - January 2024, 148 meters above sea level at coordinates 07° 37' 831'' south latitude and 110° 56' 905'' east longitude. Experiment used a single factor Randomized Complete Group Design (RCGD), the dose of synthetic nitrogen fertilizer replacement in form urea with bokashi nitrogen fertilizer. Treatments consisted of 5 types: synthetic nitrogen 200 kg/ha, synthetic nitrogen 150 kg/ha + bokashi nitrogen 50 kg/ha, synthetic nitrogen 100 kg/ha + bokashi nitrogen 100 kg/ha, synthetic nitrogen 50 kg/ha + bokashi nitrogen 150 kg/ha, and bokashi nitrogen 200 kg/ha. Each treatment was repeated 5 times so there were 25 experimental units. This experiment aims to obtain the dose bokashi nitrogen to replace synthetic nitrogen and the balance the minimum dose synthetic nitrogen and bokashi nitrogen on the growth and yield of upland rice. Data analysis was carried out using Analysis of Variance (ANOVA). If the results obtained have significantly different results, the Duncan Multiple Range Test (DMRT) is carried out with level of trust 95%. Results of the experiment showed that dose 50 - 100 kg/ha bokashi nitrogen can replace same dose synthetic nitrogen on upland rice growth and yield, and the balance minimum dose synthetic nitrogen obtained is the use of 50 kg/ha synthetic nitrogen fertilizer with 150 kg/ha bokashi nitrogen resulting in seed weight of 17.28 g/polybag.