The decline in lowland soil fertility is a major constraint to improving rice productivity and fertilizer use efficiency at the farm level, primarily caused by unbalanced fertilization, low organic matter application, and inappropriate timing and methods of fertilizer application. This community service activity aimed to implement the Participatory Soil Fertility Management (PSFM) approach as a farmer empowerment strategy for participatory soil fertility diagnosis. The activity was conducted in the Ngudi Makmur Farmer Group, Sragen Regency, through a Farmer Field School approach integrated with Participatory Rural Appraisal (PRA). The activity stages included initial condition identification, soil fertility training, the use of a rice field diagnostic card, group discussions, and the implementation and evaluation of soil management strategies. The results showed that soil fertility management practices were still dominated by the use of urea as the main fertilizer (98%), the absence of balanced fertilization with N, P, and K (76%), and low organic matter application (60%). In addition, most farmers did not apply fertilizers in stages or according to crop growth phases, leading to low nutrient use efficiency. Participatory diagnosis indicated that the main soil fertility constraints were low organic matter (score 5.8), nitrogen inefficiency (5.2), and potassium deficiency (4.9). The implementation of PSFM significantly improved farmers’ capacity to understand soil conditions, perform independent soil fertility diagnosis, and adopt more appropriate and balanced fertilization practices. Furthermore, the approach encouraged behavioral changes toward more efficient and sustainable farming practices, contributing to improved productivity and long-term sustainability of lowland rice farming systems.