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Title: Corn Response to Nitrogen Following Onion in Rotation

Author
item Halvorson, Ardell
item BARTOLO, MICHAEL - CO ST U, ROCKY FORD, C
item Reule, Curtis
item BERRADA, ABDEL - CO ST U, ROCKY FORD, C

Submitted to: Agricultural Experiment Station Publication
Publication Type: Experiment Station
Publication Acceptance Date: 10/15/2007
Publication Date: 12/15/2008
Citation: Halvorson, A.D., Bartolo, M., Reule, C.A., Berrada, A. 2008. Corn Response to Nitrogen Following Onion in Rotation. Agricultural Experiment Station Technical Report TR08-16, Colorado State University, Fort Colins, CO. p. 10-14.

Interpretive Summary: High N rates applied to onion often result in high levels of residual soil NO3-N. The effect of residual soil N level plus applied N fertilizer (6 N rates) on corn grain yields and corn N uptake following an onion crop was evaluated. Residual soil N levels in the 0- to 6-ft soil profile at corn planting ranged from 86 to 189 lb N/a where furrow irrigation was used to produce onions and 106 to 398 lb N/a where drip irrigation was used. Corn grain yields increased from 202 bu/a with no N applied to 267 bu/a with 80 lb N/a applied, then leveled off at higher N rates near 270 bu/a when corn followed the drip irrigated onions. Corn yields following furrow irrigated onions ranged from 166 bu/a with no N applied to a maximum yield of 262 bu/a with the application of 120 lb N/a. Corn yields responded to the higher level of residual soil N present in the drip irrigated onion plots. Residual soil NO3-N levels were relatively low (generally less than 50 lb N/a in 0-6 ft soil profile) in the 2005 furrow irrigated onion plots after corn harvest in Sept. 2006 compared to >200 lb N/a present in the 0- to 6-ft soil profile at the highest N rate where drip irrigation was used in 2005. Corn was effective in utilizing soil residual N from the root zone but considerable residual soil N remained in the higher rate N plots of the 2005 drip irrigated onions plots. Using corn to recover residual fertilizer N applied to a previous onion crop will help reduce the potential of NO3-N contamination of the groundwater in the lower Arkansas River Valley in Colorado and improve N use efficiency.

Technical Abstract: In 2006, we evaluated the effects of residual soil N level plus applied N fertilizer (6 N rates) on corn grain yields and corn N uptake following the 2005 onion crop. Residual soil N levels in the 0- to 6-ft soil profile at corn planting ranged from 86 to 189 lb N/a where furrow irrigation was used in 2005 and 106 to 398 lb N/a where drip irrigation was used in 2005. Corn grain yields increased from 202 bu/a with no N applied to 267 bu/a with 80 lb N/a applied, then leveled off at higher N rates near 270 bu/a when corn followed the drip irrigated onions. Corn yields following furrow irrigated onions ranged from 166 bu/a with no N applied to a maximum yield of 262 bu/a with the application of 120 lb N/a. Thus, the corn responded to the higher level of residual soil N present in the drip irrigated onion plots. Residual soil NO3-N levels were relatively low (generally less than 50 lb N/a in 0-6 ft soil profile) in the 2005 furrow irrigated onion plots after corn harvest in Sept. 2006 compared to >200 lb N/a present in the 0- to 6-ft soil profile at the highest N rate where drip irrigation was used in 2005. Corn was effective in utilizing soil residual N from the root zone but considerable residual soil N remained in the higher rate N plots of the 2005 drip irrigated onions plots. Therefore, corn will be grown on these same plots in 2007 to recover additional residual soil N. Using corn to recover residual fertilizer N applied to a previous onion crop will help reduce the potential of NO3-N contamination of the groundwater in the lower Arkansas River Valley in Colorado and improve N use efficiency.