427-21 Field-Specific Fertilizer Nitrogen Requirements for Second-Year Corn Following Alfalfa.

Poster Number 1208

See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Nitrogen Science & Management Posters

Wednesday, November 18, 2015
Minneapolis Convention Center, Exhibit Hall BC

Matt A. Yost, Utah State University, Logan, UT, Michael P. Russelle, University of Minnesota, St. Paul, MN, Jeffrey A. Coulter, Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN, Thomas F. Morris, 1376 Storrs Rd.; Unit U-4067, University of Connecticut, Storrs, CT, Joseph G. Lauer, 1575 Linden Drive, University of Wisconsin-Madison, Madison, WI and Antonio P. Mallarino, 716 Farm House Lane, Iowa State University, Ames, IA
Abstract:
The most extreme cases of excessive N fertilization in corn (Zea mays L.) occur when it is grown as the first and second crop following alfalfa (Medicago sativa L.). Past research suggests that second-year corn following alfalfa requires fertilizer N only one-half of the time to economically optimize yield, yet surveys indicate that many growers still hesitate to reduce fertilizer N applications. This may be due to the inability to identify which fields will require additional N. A meta-analysis was conducted using plot-level data from 212 site-years of research mainly in Iowa, Minnesota, and Wisconsin to identify: 1) which site-years of second-year corn responded to fertilizer N; 2) the economically optimum N rate at various fertilizer N/corn grain price ratios for responsive site-years; and 3) combinations of variables(soil texture, alfalfa termination timing, alfalfa stand age, and weather conditions) that predict corn response to fertilizer N. Only 32% of the 212 site-years responded to fertilizer N. Of those that responded, EONRs ranged widely from 48 to ≥269 kg N ha-1 at the price ratio of 5.6 (US$ kg N-1/US$ Mg-1; 0.10 lb-1 N/$ bu-1). Preliminary regressions appear to correctly identify which fields will respond to N about two-thirds of the time when using combinations of alfalfa stand age and monthly precipitation and air temperature prior to the beginning of second-year corn (October – May). Refinement and addition of soil, crop, and weather variables should further improve predictions and allow for a more field- or site-specific approach to N management for corn following alfalfa.

See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Nitrogen Science & Management Posters