This study quantitatively assesses the input-output relationship, resource productivity and allocative efficiency of farm inputs under different systems of irrigation through profit function approach using farm level primary cross-section data with respect to sugarcane and wheat of 120 farms from the Meerut district of Western Uttar Pradesh. The study reveals that improvement in water management on private tubewell farms caused a structural break in production relations and shifted the crop production function upwards. The absolute income of all the factors of production by and large was found to be higher under private tubewells as compared to other systems of irrigation. Better water management .in terms of assured, timely and adequate water supply led to an improvement in the productivity of land and fertilizer on private tubewell farms as compared to state tubewell and canal irrigated farms for sugarcane and wheat crops. The reallocation of variable inputs had a very limited scope for increasing the yields and returns under all the irrigation systems. However, the horizontal expansion of irrigation especially through private tubewell, will enhance agricultural production and the net income of the farmers at a rapid rate.