As drought stress increasingly threatens corn production, subsurface drip irrigation (SDI) has emerged as a critical component of adaptive corn management. However, the cost-effectiveness and agronomic performance of varying dripline spacings remain uncertain, especially in sandy soils. This three-year field study (2022–2024) in the Eastern Coastal Plains of Virginia evaluated the agronomic and economic impacts of two SDI dripline spacings, narrow (0.91 m) and wide (1.82 m), on corn grain yield. This study was conducted on a long-term SDI system established in 2017 using a split–split plot design with irrigation as the whole plot, seeding rates as sub-plots, and nitrogen (N) rates as sub–sub-plots. Irrigation scheduling followed the checkbook method. The analysis of three years of data revealed significant yield advantages for narrow spacing (11,466 kg ha^-1) over wider spacing (10,688 kg ha^-1) and the non-irrigated control (7,359 kg ha^-1) (p < 0.001). Nitrogen application rates also significantly influenced yield, with 200, 267, and 333 kg N ha^-1outperforming the 133 kg N ha^-1 treatment (p = 0.008). Seeding rates of 74,100 and 88,920 seeds ha^-1 achieved the highest yields (9,984 and 10,132 kg ha^-1, respectively; p < 0.001). Notable interactions occurred between dripline spacing and N rates (p = 0.002), where narrow spacing with 333 kg N ha^-1 produced the highest yield (12,401 kg ha^-1). Overall, narrow dripline spacing proved more agronomically productive and potentially more cost-effective, despite the initial higher system cost (USD 6,175). These findings suggest that tighter dripline spacing in SDI systems may offer better yield stability and return on investment in sandy, drought-prone regions.