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Title: NITROGEN FERTILIZATION OF IRRIGATED CORN IN A HIGH RESIDUAL SOIL N ENVIRONMENT IN THE ARKANSAS RIVER VALLEY.

Author
item Halvorson, Ardell
item SCHWEISSING, FRANK - AVRC, ROCKY FORD, CO
item Reule, Curtis

Submitted to: Proceedings of Great Plains Soil Fertility Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/15/2002
Publication Date: 3/5/2002
Citation: Halvorson, A.D., Schweissing, F., Reule, C.A. 2002. Nitrogen fertilization of irrigated corn in a high residual soil n environment in the arkansas river valley. Proceedings of Great Plains Soil Fertility Conference. Kansas State University, Manhattan and Potash and Phospate Institue, Brookings, SD. 9:138-142.

Interpretive Summary: High levels of NO3-N are present in the soils and groundwater in the Arkansas River Valley where melons and other vegetable crops are produced. The amount of N fertilizer required to optimize the yield potential of crops, such as corn, following vegetables needs to evaluated to reduce NO3- ching. This study evaluated the effects of N fertilizer rate (0, 50, 100, 150, 200, and 250 lb N/a) and N source (urea and Polyon) on corn yields following 5 years of alfalfa and then one year of watermelon production. Corn grain yields were not increased by N fertilization in 2000 and were not influenced by N source. Corn plant stands were reduced by urea broadcast, incorporated application rates above 150 lb N/a in 2000, but were maintained when Polyon was used. Silage yields increased with increasing N rate up to about 150 lb N/a, then decreased with increasing N rate. Soil residual NO3-N levels increased with increasing N rate in 2000. In 2001, corn grain and silage yields did not increase with increasing residual soil NO3-N levels (no N fertilizer applied). Based on this study, it appears that a minimal amount (<50 lb N/a) of N fertilizer needs to be applied to corn to maintain grain and silage yields in the Valley in rotations with a vegetable crop like watermelon. Fertilizer N appears to be moving out of the root zone with downward movement of irrigation water. Valley farmers are encouraged to soil test for residual soil NO3-N before applying N fertilizer to corn and vegetable crops. Minimizing N fertilizer application will reduce the amount of residual NO3-N available for leaching and groundwater contamination.

Technical Abstract: High levels of residual soil NO3-N are present in the soils in the Arkansas River Valley where melons and other vegetable crops are produced. The amoun of N fertilizer required to optimize the yield potential of crops, such as corn, following vegetables needs to evaluated to reduce NO3-N leaching potential in the Valley where high NO3-N levels have been reported in the ground water. This study evaluated the effects of N fertilizer rate (0, 50 100, 150, 200, and 250 lb N/a) and N source (urea and Polyon3) on corn yiel following 5 years of alfalfa and one year of watermelon production. Corn gr yields were not increased by N fertilization in 2000 and were not influence by N source. Corn plant stands were reduced by urea broadcast, incorporated application rates above 150 lb N/a in 2000, but were maintained when Polyon was used. Silage yields increased with increasing N rate up to about 150 lb N/a, then decreased with increasing N rate. Soil residual NO3-N levels increased with increasing N rate in 2000. In 2001, corn grain and silage yields did not increase with increasing residual soil NO3-N levels (no N fertilizer applied). Based on this study, it appears that a minimal amount (<50 lb N/a) of N fertilizer needs to be applied to corn to maintain grain silage yields in the Valley in rotations with a vegetable crop like watermelon. Fertilizer N appears to be moving out of the root zone with downward movement of irrigation water.