This study evaluated the effect of organic fertilizer on the yield of sesame and the movement of nitrogen and carbon in soil under mulching cultivation. The seven fertilizer treatments investigated are as follows: 1) 8-4-9 kg N-P2O5-K2O 10a-1-control, 2) 80% of control treatment N from mixed expeller cake (MEC)-MEC 80%, 3) 100% of control treatment N from MEC-MEC 100%, 4) 80% of control treatment N from mixed organic fertilizer (MOF)MOF 80%, 5) 100% of control treatment N from MOF-MOF 100%, 6) 80% of control treatment N from latex coated urea complex fertilizer (LCU)-LCU 80%, and 7) no nitrogen. The soil mineral N available in the applied organic MEC and MOF fertilizers was less than the available N in the applied urea fertilizer during the early growth stage of sesame but the amount was observed to increase with time. The concentration of nitrate-N in leached solution 35 days after application was highest at 75 mg l-1 in the control, followed in descending order by MEC 100%, MOF 100%, LCU 80%, MOF 80% and MEC 80%. The concentration of nitrate-N in the leachate in all treatments was observed to rapidly decrease 45 days after fertilizer application and recorded at less than 20 mg l-1 65 days after application. The concentration of dissolved organic carbon in the leached solution and organic carbon in the soil of the organic fertilizer plots was higher than in the urea- and LCU-fertilized plots during the whole growing period. The yields of sesame applied with MEC and MOF organic fertilizers were 2 to 7% higher than those fertilized with urea. The amount of retained mineral N or organic carbon in the soil is higher in the LCU and organic fertilizer plots than in the urea-fertilized treatments, which resulted in the reduction of nitrate leaching, increasing N efficiency and sesame yield.