IMPROVING ALFALFA AND OTHER FORAGE CROPS FOR BIOENERGY, LIVESTOCK PRODUCTION, AND ENVIRONMENTAL PROTECTION
Location: Plant Science Research
Title: Corn response to nitrogen after alfalfa as affected by tillage and regrowth
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 2011
Publication Date: July 22, 2011
Citation: Coulter, J.A., Yost, M.A., Russelle, M.P., Sheaffer, C.C., Kaiser, D.E. 2011. Corn response to nitrogen after alfalfa as affected by tillage and regrowth [abstract]. ASA-CSSA-SSSA 2011 International Annual Meeting, October 16-19, 2011, San Antonio, Texas. Abstract No. 65019. Available: http://a-c-s.confex.com/crops/2011am/webprogram/Paper65019.html.
Current N guidelines for corn following alfalfa in Minnesota suggest that when compared to corn following corn, N rates for first-year corn after alfalfa can be reduced by 168 kg N/ha when greater than or equal to 43 alfalfa plants/square meter are present at termination. Two unanswered questions regarding N availability to first-year corn after alfalfa relate to the timing of primary tillage for alfalfa termination and the amount of alfalfa regrowth incorporated. In 2010, experiments were conducted in first-year corn after alfalfa on six farms in southern and central Minnesota with medium- to fine-textured soils and greater than or equal to 43 alfalfa plants/square meter at termination. The response of grain and silage yields to N fertilizer was evaluated within four combinations of alfalfa regrowth management (regrowth after early September left in place or harvested after the first freeze) and tillage timing for alfalfa termination (disc-chiseling in the fall vs. spring) on each farm. Corn grain and silage yields were not affected by regrowth management or tillage timing on any farm. There was above-normal potential for N loss at these farms, as precipitation from 1 Oct. 2009 to 31 Sep. 2010 was 20 to 57% above the 30-yr average. Corn grain yield ranged from 11.3 to 14.5 Mg/ha among farms, and grain and silage yields responded to N fertilizer on just one of six farms. At this farm, net return to N fertilizer within $2.50/ha of the maximum for grain yield occurred with 76 to 90 kg N/ha, and silage yield was increased by 13% with 110 kg N/ha. These results demonstrated that on farms with greater than or equal to 43 alfalfa plants/square meter at termination and high yield potential, little to no N fertilizer was needed for first-year corn and this response was not affected by alfalfa regrowth management or tillage timing for alfalfa termination.