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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #192815
Title: VARIABLE SOURCE N FERTILIZER APPLICATIONS TO OPTIMIZE CROP N USE EFFICIENCY

Author
item MOTAVALLI, PETER - UNIVERSITY OF MISSOURI
item NELSON, KELLY - UNIVERSITY OF MISSOURI
item Kitchen, Newell
item ANDERSON, STEVE - UNIVERSITY OF MISSOURI
item SCHARF, PETER - UNIVERSITY OF MISSOURI

Submitted to: Missouri Soil Fertility and Fertilizers Research Update
Publication Type: Other
Publication Acceptance Date: 3/1/2006
Publication Date: 3/15/2006
Citation: Motavalli, P., Nelson, K., Kitchen, N.R., Anderson, S., Scharf, P. 2006. Variable source N fertilizer applications to optimize crop N use efficiency. Missouri Soil Fertility and Fertilizers Research Update. Available: http://aes.missouri.edu/pfcs/research/prop405.pdf

Interpretive Summary:

Technical Abstract: Research was initiated in 2005 to determine methods to delineate and map areas in fields which are more vulnerable to N loss due to wet conditions, to examine the use of a variable-source strategy to optimize crop N fertilizer use efficiency and, to calculate the cost-effectiveness of using this variable-source strategy compared to uniform applications of conventional or other N fertilizer sources. Two field trials were initiated in 2005, one at the University of Missouri Greenley Experiment Station and one in a farmer’s field near Centralia, MO. Both sites were mapped for elevation and apparent electrical conductivity using a Geonics EM-38 sensor. At the Greenley site, N fertilizer treatments included a control and 150 lb N/acre of either urea, polymer-coated urea (ESN, Agrium, Inc.), a 50% urea/50% polymer-coated urea mixture, or anhydrous ammonia, injected or broadcast applied. At the Centralia site, N fertilizer treatments of 150 lb N/acre of either urea or polymer-coated urea were broadcast surface-applied in 15 by 1470 ft strips across landscape positions representing shallow and deep areas. Rainfall during the 2005 cropping year was relatively low during the growing season at both field sites with a long period of drought after the middle of July. Both polymer-coated urea and anhydrous ammonia had higher grain yields compared to urea in the low-lying area at Greenley. However, there were no differences among these fertilizer sources at the other landscape positions, which suggest that response to N fertilizer source may vary across fields depending on landscape position. Yield response at Centralia was apparently due to relative differences in soil water storage between soils with different depths to the claypan layer, and not due to applied N sources. Surface application of the N sources at Centralia versus incorporation of N sources at Greenley may also have been a factor. This first year of research indicates that the concept of variable source application may have some validity for N fertilizer management. However, further research is required under wetter climatic conditions when risk of N loss is higher.