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Urea and Urea Additives as Fertilizer Sources for Corn Production in Minnesota

Start Date: 2016
Principal Investigator: Fabian Fernandez
Organization: University of Minnesota, Department of Soil, Water, and Climate
Status: Ongoing

Background Info

Urea is increasingly an important nitrogen (N) source in Minnesota. Approximately 43% of our farmers use urea as their major N source. In the southwestern, south-central and west-central areas approximately 45% of the N is applied in the fall, 50% is applied in the spring, and 5% is applied at side dress. While most of those that use urea as the major N source apply it in the spring, approximately 4% do the major application with urea in the fall and there are others that apply some of their N as urea in the fall as this application is part of the listed Best Management Practices. However, in recent years, due in part to wet spring conditions, fall urea applications have resulted in yield reduction. We will evaluate fall and spring applications of urea to determine their feasibility and calculate the economic optimum N rate for fall and spring applications when corn follows corn and corn follows soybean. Further, we will investigate the role of placement (band vs. broadcast and incorporated) and of a nitrification inhibitor to improve management of this important source. A robust 15 site-years database will be generated to provide guidelines on urea management in Minnesota.

Objectives

Generate the needed data to calculate the economic optimum N rate for fall and spring applications of urea for corn following corn (CC) and for corn following soybean (CSb)

Investigate the role of placement (band vs. broadcast and incorporated) and of a nitrification inhibitor (Instinct II) to improve management of this important N source

Determine the usefulness of in-season N soil testing and canopy sensing as management tool

Key Findings

N-NH4+ was low regardless of N rate indicating that N transform rapidly to N-NO3-. Early in the growing season (V4 development stage) N-No3– increased with N rate. At post-harvest, however, there was very little residual N regardless of N rate. The N sources and placement treatments show small and inconsistent differences at the V4 development stage.

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