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United States Department of Agriculture

Agricultural Research Service

Research Project: Enhanced Alfalfa Germplasm and Genomic Resources for Yield, Quality, and Environmental Protection

Location: Plant Science Research

Title: The alfalfa N credit: field-specific recommendations may be coming

Authors
item Russelle, Michael
item Yost, Matt -
item Coulter, Jeffrey -

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 2, 2014
Publication Date: N/A

Technical Abstract: Alfalfa can provide all the nitrogen (N) needed for two years of corn. This may sound surprising, but research reports support this statement for about one-half of all trials that have been conducted in the US. However, in other research trials, the need for fertilizer N varied widely and ranged up to the rate recommended for continuous corn. Current fertilizer N guidelines do not account for this wide disparity in fertilizer N requirements for corn grown after alfalfa and surveys indicate that many farmers do not follow the N guidelines. In an effort to better understand what affects the N supply from alfalfa to corn, we collected published and unpublished data from more than 450 site-years of first-year corn response to fertilizer N after alfalfa, removed reports with missing or low grain yield, missing data on alfalfa management, or other known problems. Using statistical approaches with the remaining dataset of 259 site-years, we learned that simple mixtures of weather (from October of the last year of alfalfa through March or May of the first year of corn), alfalfa stand age, soil texture, and termination time (fall or spring), we could identify 1) which fields required fertilizer N, and 2) the economically optimum N rate for those fields. We are extending this type of analysis to second-year corn after alfalfa. These results are remarkable, and if validated with independent field experiments, they could provide the first site-specific N recommendation system for this rotation.

Last Modified: 10/24/2014
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