Fertilizer nitrogen recovery of irrigated spring malt barley.

Well-defined nitrogen (N) management in irrigated two-row malting barley (Hordeum vulgare L.) is critical for yield and quality and to minimize environmental impacts. Data on fertilizer N recovery efficiency (FNRE) and the fate of fertilizer-N in the soil are lacking. The study objective was to determine uptake and partitioning of 15N-labeled urea in the plant and soil. Urea was either surface applied or incorporated at a total N rate (inorganic-N + applied N) of 214 kg N ha^-1 at planting. Three malt cultivars were grown, and samples were collected four times during the growing season (Feekes growth stages 4/5, 10.0, 11.2, and 11.4). Barley plants at Feekes 11.2 and 11.4 were separated into vegetative tissue and spikes. Plant N accumulation was lowest at Feekes 4/5 and reached a maximum at Feekes 11.2, whereas FNRE was greatest at Feekes 10.0. Nitrogen was redistributed from vegetative tissue to the spike from Feekes 11.2 to 11.4. Plant FNRE averaged 43% at Feekes 11.4. Total plant--soil FNRE for the surface application was 66%, which was less than the incorporated FNRE of 77%. Results provide evidence of the increased plant--soil system FNRE of incorporated applications in high-input barley production systems compared with surface applications despite no yield difference. Similar FNRE as compared to previous work with lower yields was measured, and modern cultivars out-yielded an older cultivar with no reduction in FNRE. Results of the study indicate that a relatively high plant--soil system FNRE of irrigated malting barley was achieved under high-input, irrigated conditions common in southern Idaho. [ABSTRACT FROM AUTHOR]