|Bartalo, Michael - CSU/ROCKY FORD, CO|
|Schweissing, Frank - CSU/ROCKY FORD, CO|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 5, 2000
Publication Date: November 5, 2000
Citation: Halvorson, A.D., Follett, R.F., Bartalo, M., Schweissing, F. 2000. Nitrogen fertilizer use efficiency by onion and corn in rotation. Agronomy Abstracts. 92:353. Technical Abstract: Onion production, with high rates of N fertilizer, may be contributing nitrate-N to irrigation and ground waters in Colorado. Frequent irrigation early in the onion growing season when consumptive water use is low, increases N leaching potential. This study determined the growth and N uptake patterns of onion grown on a silty clay soil. Onions were sampled bi-weekly from May to September 1998 from plots receiving 0 and 224 kg N/ha. Labeled 15N fertilizer was band applied in split applications of 112 kg N/ha each on 18 May and 25 June. A randomized complete block design with four replications was used. Onion dry matter accumulation was slow from planting to about day 110, followed by a rapid increase in biomass production. Because soil N was high at planting, only a small increase in bulb yield was observed due to N fertilization. Greatest demand for N by onion occurred during bulb development. Fertilizer N uptake by onion was 11 and 19% for early and late N applications. The fertilizer N remained i the upper 60 cm of soil profile near the center of the onion bed at harvest, with small amounts detected at 180 cm. The 1999 corn crop, with no additional N fertilization, recovered 13 to 17% of fertilizer N applied to the onions. Results suggest that onion growers should delay most of the N fertilizer application until bulbing begins to improve N fertilizer use efficiency.