Nitrogen Management and Nitrification Inhibitor Effects on Nitrogen-15 Urea: I. Yield and Fertilizer Use Efficiency
1990
Walters, D. T. | Malzer, G. L.
Nitrification inhibitors (NI) are sometimes recommended for use with ammoniacal fertilizers in corn (Zea mays L.) production to improve fertilizer N use efficiency (FUE). The objectives of this experiment were to evaluate the effects of the NI nitrapyrin [2-chloro-6-(trichloromethyl) pyridine] application on yield and FUE of irrigated corn, and to monitor the fate of a single application of ¹⁵N-enriched urea during a multiyear period in both soil and plant. Treatments included a factorial combination of two N rates (90 or 180 kg urea-N ha⁻¹ yr⁻¹) applied during a 3-yr period, with or without a NI and with or without incorporation, plus a zero-N control. Twenty-seven nonweighing lysimeters were used to quantify leaching load. Treatment effects on yield and FUE differed each year due to interactions of climate and N-management variables. Nonincorporated urea + NI reduced grain yield when leaching load was low and increased yield at the 90 kg ha⁻¹ N rate when leaching load was high. Maximum FUE occurred at the 90 kg ha⁻¹ N rate when leaching load was low. The NI increased FUE only at the 90 kg ha⁻¹ N rate when leaching load was high. Incorporation of urea + NI reduced plant recovery of fertilizer-derived N (FDN) in the year of application, but resulted in increased uptake of residual FDN in subsequent years. Incorporation of NI with moderate N rates coupled with conservative irrigation management should reduce the risk of yield loss and minimize NO₃ movement to groundwater.
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