Nitrogen Fertilizer Use Efficiency of Furrow-Irrigated Onion and Corn
2002
Halvorson, Ardell D. | Follett, Ronald F. | Bartolo, Michael E. | Schweissing, Frank C.
Furrow-irrigated onion (Allium cepa L.) production, with high N fertilization rates, may be contributing NO₃–N to ground water in southeastern Colorado. This study determined the growth and N uptake patterns of onion grown on a silty clay soil, N fertilizer use efficiency (NFUE) of onion, and recovery of residual N fertilizer by corn (Zea mays L.) following onion in rotation. Onion was sampled biweekly from 18 May to 15 Sept. 1998 from plots receiving 0 and 224 kg N ha⁻¹ Nonlabeled N and labeled ¹⁵N fertilizer were band-applied near the onion row in split applications of 112 kg N ha⁻¹ each on 18 May and 25 June. Onion dry matter accumulation was slow from planting to about late May, followed by a rapid increase in biomass production and N uptake. Because residual soil NO₃–N was high, N fertilization resulted in only a small increase in bulb yield. Greatest demand for N by onion occurred during bulb development. Fertilizer N recovery by onion was 11 and 19% for May and June N applications (average 15%), respectively. Much of the fertilizer N remained in the upper 60-cm soil profile at harvest and had moved toward the onion bed center. Fertilizer ¹⁵N detected at 180-cm soil depth indicated leaching losses from the root zone. The unfertilized 1999 corn crop recovered 24% of fertilizer N applied to onion for a total fertilizer N uptake by the two crops of 39%. Delaying N fertilizer application until onion bulbing begins may improve NFUE. Planting corn directly on the previous onion bed may result in greater N fertilizer recovery by corn.
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