Soybean was a legume high in protein and beneficial bioactive compounds. Soybean were sensitive to both drought and waterlogging, and Indonesia's climate often led to water stress that inhibited soybean growth. This research aimed to investigate the optimal watering frequency and organic fertilizer dosage to enhance soybean growth and yield, and to understand the interaction between these two treatments. The research was conducted at Field Laboratory Jumantono District, Karanganyar Regency from November 2024 to March 2025. The method was used Randomized Complete Block Design (RCBD) with a two-factor factorial, with two factors and three replications. The first factor was watering frequency, with four levels: every day, every 2 days, every 3 days, and every 4 days. The second factor was the organic fertilizer dosage using cow manure, with four levels: 0 g.polybag-1, 62.5 g.polybag-1, 125 g.polybag-1, and 187.5g.polybag-1. Observational parameters included initial soil analysis, growth, yield, tissue analysis, and nutrient uptake. Data analysis employed Analysis of Variances (ANOVA), Duncan's Multiple Range Test (DMRT) 5% significance level, regression, and correlation. The result showed that both watering frequency and organic fertilizer dosage significantly impacted soybean growth and yield, watering every 2 days was most effective for plant height and dry shoot weight, while watering every 4 days increased leaf number, leaf area, and pod and seed quantity. The application of cow manure at 10 tons/ha significantly boosted plant height, shoot weight, and pod and seed counts. A higher dosage of 20 tons/ha was optimal for leaf number, nodes, leaf area, flowering age, and seed weight per plant, with 30 tons/ha yielding the best 100-seed weight. An interaction between watering frequency and cow manure dosage was observed, with the best seed weight per plant resulting from daily watering combined with approximately 19.17 tons/ha of organic fertilizer.