Narrow Row Corn Production with Subsurface Drip Irrigation

In the southeastern U.S. Coastal Plains, supplemental irrigation is required to reduce the impact of short‐term droughts and yield‐reducing plant water stress that can occur at least biennially. Sprinkler irrigation is commonly used to water agronomic crops in the region. Microirrigation is typically used for high value fruit and vegetable crops. In recent years and at some locations, microirrigaiton combined with conservation tillage has been implemented for agronomic crop production to help conserve soil moisture. In this research, we investigated the feasibility of planting corn (Zea Mays L) in narrow rows over subsurface drip irrigation (SDI). Our specific objectives were to 1) compare narrow‐row corn yields using surface and subsurface drip irrigation with laterals spaced at 1 and 2 m; 2) compare the effects of pulsed SDI applications to move irrigation water farther away from the laterals on narrow‐row corn yields; and 3) evaluate the impact of corn row distance from SDI laterals on plant biomass, nitrogen, and yield components. Corn was planted in 0.38‐m rows on an existing subsurface drip irrigation system with laterals installed 0.30 m below the soil surface and spaced at 1 and 2 m apart. Surface drip irrigation was installed at both lateral spacings to compare with the SDI treatments. Irrigation was applied weekly as required to meet the crop water demands. All nutrients were applied through the subsurface drip irrigation system. Corn yields for 2003 ranged from 4301 to 5420 kg/ha, while in 2004 the yields were greater and ranged from 4452 to 6329 kg/ha. No significant differences were observed between the SDI and surface drip irrigated treatments. Corn yields from the pulsed SDI treatments were not significantly different from non‐pulsed treatments. Early season whole plant biomass was significantly higher for the 2‐m SDI lateral spacing, but there were no significant biomass differences at later growth stages. Corresponding whole plant N concentrations were significantly higher for the 1‐m SDI lateral spacing in 2004. Grain N, ear length, and ear weight were not significantly different at harvest for SDI lateral spacing. We found that the distance of the corn rows from the SDI lateral greatly influenced the crop growth and grain yield. Plant biomass, whole plant N, ear length, and grain weight all decreased significantly with distance from the SDI laterals. These results show a great deal of variability among rows when corn is grown in 0.38‐m spacing over SDI laterals for wider row crops. Higher plant populations placed closer to the laterals may increase productivity.