Fertilizer nitrogen recovery of irrigated spring malt barley

Abstract

AbstractWell‐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.