Nitric and Nitrous Oxide Emissions and Soil Nitrate Distribution in a Center-Pivot-Irrigated Cornfield
- W. D. Guenzi,
- G. L. Hutchinson * and
- W. E. Beard
Research on soil N loss mechanisms remains a high priority not only because of the need to increase agricultural N use efficiency, but also because of environmental concernsuch as NO−3 contamination of groundwater and increasing N oxide concentrations in the atmosphere. We measured NO and N2O emissions and downward movement of NO−3 in an eastern Colorado corn (Zea mays L.) field irrigated with a modified center-pivot system that applied water to alternate furrows. One hour after infiltration of the irrigation water, emission rates measured by an enclosure method ranged from 0 to 6 g N ha−1 d−1 for NO and 0 to 26 g N ha−1 d−1 for N2O. The emission rates were largest after the first irrigation and much smaller following subsequent irrigations. Greater N oxide evolution from nonirrigated furrows than adjacent irrigated furrows probably resulted from lateral transport of gases produced in the wet soil. Analyses of soil cores taken after planting and after harvest provided no evidence that NO−3 moved below the root zone during the growing season, despite the presence of substantially more inorganic N than required for maximum corn yield. These data suggest that when the size and frequency of irrigations are efficiently managed, use of a low energy precision application (LEPA) irrigation system results in no N loss to groundwater and no economically significant gaseous N oxide loss to the atmosphere.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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