The goal of this research was to determine the effects of different irrigation levels applied via drip irrigation on the dry matter yield (DMY) and silage quality of maize grown on clay loam soil in the sub-humid environmental conditions of Turkey. Six irrigation treatments were studied: full irrigation (FI) in which irrigation water was applied at 100% crop evapotranspiration (ETc) at 7-day intervals during the entire growing season; deficit irrigation (DI) in which 0%, 25%, 50% and 75% of FI irrigation water was applied; and excessive irrigation (EI) in which 125% of FI irrigation water was applied. The DMY, pH, dry matter ratio (DMR), crude protein (CP), acid detergent fibre (ADF), neutral detergent fibre (NDF) and water soluble carbohydrate (WSC) contents of maize silage were measured in 2007 and 2008. Increasing the irrigation rate increased DMY; the highest values obtained were from the EI treatment in 2007, 2008 and in the two years combined. Deficit irrigation improved irrigation water use efficiency in relation to dry matter yield. Increasing the drip irrigation levels decreased the CP and WSC content of silage but did not affect the dry matter rate, pH, ADF and NDF content of silage. With respect to dry matter yield, irrigation water productivity and the silage quality of maize, 100% ETc and 75% ETc irrigation strategies can be considered optimal.