Nitrogen Leaching as Influenced by Nitrogen Management and Supplemental Irrigation Level
1981
Timmons, D. R. | Dylla, A. S.
Corn (Zea mays L.) management systems involving two nitrogen (N) fertilization methods and two supplemental irrigation levels were evaluated for soil water percolation and N leaching losses in west central Minnesota. Nonweighing lysimeters were used to collect soil water and the accompanying nutrients that moved below the root zone of the droughty Estherville sandy loam soil studied. Nitrogen was applied either as granules broadcast and disked in before planting or in liquid form through the irrigation system four times during the growing season. Supplemental irrigation was applied as either a partial replenishment (2.5 cm) or full replenishment (5 cm) irrigation each time the available soil water decreased to about 5 cm (50% depletion). Annual soil water percolation from spring thaw to fall freezeup averaged about 7.1, 11.2, and 18.0 cm for nonirrigated corn, 2.5-cm irrigated corn, and 5-cm irrigated corn, respectively, during the 5-year period studied. Average annual NO₃-N leaching losses ranged from about 29 (for nonfertilized, nonirrigated corn) to 112 kg ha⁻¹, and the combination of variable rainfall, soil NO₃-N content, and low soil water-holding capacity caused great variation within and among years. Compared with values for fertilized nonirrigated corn, annual NO₃-N leaching losses increased an average of 17 and 53%, respectively, for the partial and full replenishment irrigations. The periodic application of liquid N through the irrigation system reduced average annual NO₃-N leaching loss by about 12 kg ha⁻¹ at the 5-cm irrigation level, but no difference resulting from N management was observed at the 2.5-cm level.
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