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Alfalfa Nitrogen Credit to First-Year Corn: Potassium, Regrowth, and Tillage Timing Effects

Permanent URL:
http://handle.nal.usda.gov/10113/54148
File:
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Abstract:
Compared with corn (Zea mays L.) following corn, N guidelines for first-year corn following alfalfa (Medicago sativa L.) in the U.S. Corn Belt suggest that N rates can be reduced by about 168 kg N ha−1 when ≥43 or 53 alfalfa plants m−2 are present at termination. These guidelines have been questioned by practitioners, however, as corn grain yields have increased. We conducted experiments at 16 locations in Minnesota to address questions regarding N availability to first-year corn after alfalfa relating to the effect of carryover fertilizer K from alfalfa and the amount and timing of alfalfa regrowth incorporation. Corn grain yield, silage yield, and fertilizer N uptake were not affected by carryover K or amount or timing of regrowth incorporation. Maximum corn grain yield ranged from 12.0 to 16.1 Mg ha−1 among locations but responded to fertilizer N at only one. At that location, which had inadequate soil drainage, the economically optimum N rate (EONR) was 85 kg N ha−1, assuming prices of US$0.87 kg−1 N and US$132 Mg−1 grain. The EONR for silage yield across 6 of 15 locations where it was measured was 40 kg N ha−1, assuming US$39 Mg−1 silage. These results demonstrate that on highly productive medium- to fine-textured soils in the Upper Midwest with ≥43 alfalfa plants m−2 at termination, first-year corn grain yield is often maximized without fertilizer N, regardless of alfalfa regrowth management or timing of incorporation, but that small N applications may be needed to optimize silage yield.
Author(s):
Yost, Matt A. , Coulter, Jeffrey A. , Russelle, Michael P. , Sheaffer, Craig C. , Kaiser, Daniel E.
Subject(s):
Medicago sativa , Zea mays , alfalfa , corn , fertilizer rates , fertilizer use reduction , fine-textured soils , grain yield , nitrogen , nitrogen fertilizers , plants , potassium , prices , regrowth , silage , tillage , United States
Note:
Includes references
Source:
Agronomy journal 2012 July, v. 104, no. 4
Language:
English
Year:
2012
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.