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Title: Does K affect N response of corn after alfalfa?

item YOST, MATT - University Of Minnesota
item Russelle, Michael
item COULTER, JEFFREY - University Of Minnesota
item SHEAFFER, CRAIG - University Of Minnesota
item KAISER, DANIEL - University Of Minnesota

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/2011
Publication Date: 7/22/2011
Citation: Yost, M.A., Russelle, M.P., Coulter, J., Sheaffer, C.C., Kaiser, D.E. 2011. Does K affect N response of corn after alfalfa [abstract]? ASA-CSSA-SSSA 2011 International Annual Meeting, October 16-19, 2011, San Antonio, Texas. Abstract No. 66693. Available:

Interpretive Summary:

Technical Abstract: Rising potassium (K) fertilizer prices in recent years have made it imperative for farmers to apply optimum K rates for alfalfa-corn rotations. However, little is understood about the effect of excess K applied to alfalfa on the subsequent corn crop's grain and silage yield. Furthermore, relatively few studies have investigated the effects of applied K on the N-credit from alfalfa to corn. On-farm research was conducted at 10 fields in 2008 to 2010 on medium-K-testing soils to determine optimal rates of K for last-year alfalfa and optimal rates of N for first-year corn. Topdressed K applications to the corn did increase corn grain and silage yield across all alfalfa K rates, which suggests that carryover K was less available than newly-applied K. There was no response to N across all previous K rates suggesting K has no effect on N credit when soils are medium-K-testing at the beginning of the corn year.