The objective of this study was to evaluate the effects of cattle barnyard compost (CBC) and nitrogen (N) fertilizer on soil and on yield and quality of maize (MZ) and italian ryegrass (IR) in double cropping system. The experiment used 4 rates of CBC and N fertilizer, respectively, i.e. CBC at rate of 0, 3, 6, 9 ton/10a and N fertilizer at rate of 0, 18, 36, 54 kg N/10a for MZ and 0, 10, 20, 30 kg N/10a for IR. Cattle barnyard compost increased organic matter and total N in soil. There was no significant difference in dry matter yield (DMY) of MZ among CBC treatments. Whereas the DMY increased as rise of N fertilizer applications from 0 to 18 kg/10a, thereafter, it was declined. Crude ash, crude protein and crude fiber (CF) concentrations of MZ increased with CBC application of 3 and 6 ton/10a and thereafter, the concentration declined. Total DMY and CF of IR increased as rise of CBC applications from 0 to 6 ton/10a, thereafter, declined. As for MZ, P and K concentrations were tended to increase as increased of CBC application. Rate applications of N fertilizer did not significantly effect on yield and chemical composition of IR, except for fraction of ether extract concentration.