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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOP AND IMPROVE STRATEGIES FOR MANAGEMENT OF IRRIGATED AGRICULTURAL CROPS AND SOILS

Location: Northwest Irrigation and Soils Research

Title: Nitrogen Response and Economics for Irrigated Corn in Nebraska

Authors
item Dobermann, A -
item Wortmann, C -
item Ferguson, R -
item Hergert, C -
item Shapiro, D -
item Tarkalson, David
item Walters, D -

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 13, 2010
Publication Date: January 1, 2011
Citation: Dobermann, A., Wortmann, C.S., Ferguson, R.B., Hergert, C.A., Shapiro, D.D., Tarkalson, D.D., Walters, D.T. 2011. Nitrogen Response and Economics for Irrigated Corn in Nebraska. Agronomy Journal. 103(1):67-75.

Interpretive Summary: Nitrogen management recommendations may change as yield levels and efficiency of crop production increase. A 32 site study was conducted in Nebraska to quantify the yield response and economics of corn to nitrogen at high yield levels. The mean yield with adequate nutrient availability was 14.8 Mg per hectare. The mean economically optimal nitrogen rates for irrigated corn varied with the fertilizer nitrogen to grain price ratio. At a fertilizer nitrogen to corn price ratio of 7, the economically optimal nitrogen rate was 171, 122, and 93 kg per hectare, respectively, for cropping systems with corn following corn, soybean, and drybean. At this price ratio the present University of Nebraska recommendation procedure gave mean nitrogen recommendations that were 17.2, 0.3, and 68.1 kg per hectare higher than the mean economically optimal nitrogen rate determined in this study for corn following corn, soybean, and drybean, respectively. The University of Nebraska algorithm, adjusted for mean cropping system economically optimal nitrogen rate gave more accurate prediction of site-year economically optimal nitrogen rate than alternative nitrogen rate predictions for corn following corn and drybean with returns to applied nitrogen of -$22 and -$13 per hectare compared with measured site-year economically optimal nitrogen rate. Prediction of site-year economically optimal nitrogen rate using mean economically optimal nitrogen rate adjusted for soil organic matter was more accurate for corn following soybean than other methods with an return to applied nitrogen of -$6 per hectare compared with measured site-year economically optimal nitrogen rate. Further research is needed to extend the results to: lower yield situations, alternatives to split application of nitrogen, and adjustment of economically optimal nitrogen rates to protect against inadequate nitrogen in atypical seasons or for environmental protection.

Technical Abstract: Nitrogen management recommendations may change as yield levels and efficiency of crop production increase. The mean yield with adequate nutrient availability in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska to evaluate crop response to split-applied N was 14.8 Mg per ha. The mean economically optimal N rates (EONR) for irrigated corn varied with the fertilizer N to grain price ratio. At a fertilizer N:corn price ratio of 7, the EONR was 171, 122, and 93 kg per hectare, respectively, for cropping systems with corn following corn (CC), soybean (Glycine max L.) (CS), and drybean (Phaseolus vulgaris L.) (CD). At this price ratio the present University of Nebraska (UNL) recommendation procedure gave mean N recommendations that were 17.2, 0.3, and 68.1 kg per hectare higher than the mean EONR determined in this study for CC, CS, and CD, respectively. The UNL algorithm, adjusted for mean cropping system EONR gave more accurate prediction of site-year EONR than alternative N rate predictions for CC and CD with returns to applied N (RTN) of -$22 and -$13 per hectare compared with measured site-year EONR. Prediction of site-year EONR using mean EONR adjusted for soil organic matter was more accurate for CS than other methods with an RTN of -$6 per hectare compared with measured site-year EONR. Further research is needed to extend the results to: lower yield situations, alternatives to split application of N, and adjustment of EONR to protect against inadequate N in atypical seasons or for environmental protection.

Last Modified: 7/31/2014
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