Optimizing corn production and reducing nitrate losses with water table control-subirrigation.
Drury C.F. | Tan C.S. | Gaynor J.D. | Oloya T.O. | Van Wesenbeeck I.J. | McKenney D.J.
Water table control-subirrigation (WTC) systems have increased crop production and improved water quality; however, the relationship between N management, water table depths, and corn production has not been well defined. We hypothesized that optimizing water depth depth would increase corn (Zea mays L.) growth, improve N fertilizer efficiency, and reduce NO3(-) losses. A greenhouse incubation study with three water table depths (30, 60, and 80 cm) and four N rates (0, 0.7, 1.4, and 2.1 g N plant-1) was conducted using undisturbed soil columns (Fox sandy loam, Typic Hapludalf) planted to corn. The 30-cm WTC treatment had the greatest NO3(-) loss through tile drainage (715 microgram N column-1). The 60-cm WTC treatment reduced these losses by 54%. Nitrate losses through tile drainage were proportional to drainage volume, which followed the order 30 cm > 60 cm > 80 cm WTC. The 60-cm WTC treatment increased crop yields (95 g plant-1) compared with the 30-cm (68 g plant-1) and 80-cm WTC (18 g plant-1) treatments at the optimal N rate of 1.4 g N plant-1. After the first simulated rainfall event, N2O production was increased by 12.7 times with the 30-cm WTC treatment (825 microgram N column-1 d-1) compared with the 60- and 80-cm WTC treatments. Water stress imposed by the 80-cm WTC treatment limited crop growth, N uptake, leaching, and N2O emissions. However, up to 28% of added N (664 mg N column-1) remained in the soil after corn was harvested from the 80-cm WTC treatment, which would be susceptible to leaching between cropping seasons.
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