Water Table Depth Interaction with Nitrogen Rates on Subirrigated Corn
1984
Woodruff, J. R. | Ligon, J. T. | Smith, B. R.
Water table control for both drainage and subirrigation holds potential benefit to crop production on many soils with imperfect drainage. Losses of soil NO⁻₃-N may occur through denitrification under partial anaerobic conditions such as would be encountered near a water table. In this 3-year field study, four N rates were superimposed over three water table depths to test the effect of water table depth on corn (Zea mays L.) response to N in a Chewacla silt loam (fine-loamy, mixed, thermic Fluvaquentic Dystrochrepts). Water table depths were 0.35,0.70, and 1.00 m and N rates were 0,112,224, and 336 kg ha⁻¹. The effects of N fertilization depended on the water table depth. For the 3-year means, quadratic regressions described the relationship between N rate and ear yield or leaf N for each water table depth except 1.00 m ear yield for which no response to N fertilizer was obtained. The N rate required for maximum ear yield or leaf N increased with decreasing water table depth. There were positive linear regressions of stover yields and soil NO⁻₃-N on N rate for each water table depth. With the 1.00 m water table, the N response slope was less for stover yield and greater for soil NO⁻₃-N than over the shallower water table depths. The lowest ear and stover yields were associated with deficient leaf N concentrations (< 27.5 g kg⁻¹) where no N was added over the 0.35 and 0.70 m wafer table depths. The results suggest that soils with water tables within 0.70 m depth require more N fertilization to reach maximum corn yields than soils with deeper water tables.
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