The objective of the research was to determine the best N nutrient management for isoflavone content in three soybean cultivars under dry land conditions. Two experiments were experiment I (June to September 2012 growing season) and Experiment II (October to December 2012 growing season). Experimental design was a randomized block design with 2 factors and 3 replications. The first factor was soybean cultivars (Anjasmoro, Wilis, Sinabung). The second factor was N source, with Urea (50 kg/ha), Bradyrhizobium sp., farmyard manure (10 ton/ha), a combination of Bradyrhizobium sp. + farmyard manure (5 ton/ha) and a control with no N. A combined analysis of variance was done to evaluate the production and the content of isoflavone in the two different growing seasons as affected by N source and cultivar. The parameters observed were the content of genistein, daidzein, glycitein and total isoflavone content. Results showed that the October to December growing season had higher genistein, daidzein, glycitein and total of isoflavones than the June to September growing season. The treatment cultivar Wilis plus Bradyrhizobium sp. grown at October to December growing season increased total isoflavone content more than other treatments. Keywords: isoflavone, nitrogen, soybean