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Nitrogen requirements of first‐year small grains after alfalfa
Author(s) -
Yost Matt A.,
Pound Collin A.,
Creech J. Earl,
Cardon Grant E.,
Pace Michael G.,
Kitchen Boyd,
Nelson Mark,
Russell Kathleen
Publication year - 2021
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.1002/saj2.20269
Subject(s) - agronomy , fertilizer , yield (engineering) , medicago sativa , irrigation , test weight , spring (device) , nitrogen , nitrate , zoology , grain yield , environmental science , biology , chemistry , ecology , materials science , organic chemistry , mechanical engineering , metallurgy , engineering
Small grains are commonly grown in rotation following alfalfa ( Medicago sativa L.) in Utah and the Intermountain West, especially during drought years, as they require less irrigation than corn ( Zea mays L.). Several studies have shown that corn following alfalfa rarely needs N fertilizer, yet few have evaluated the N needs of small grains. Objectives of this research were to determine whether N fertilizer is needed to economically optimize the yield and quality of first‐year soft white winter wheat ( Triticum aestivum L.) following alfalfa and whether the response could be predicted. Fertilizer trials (four replications of up to 13 N rates) were conducted on 12 first‐year wheat sites in Utah during 2018–2019. Three sites in 2018 with spring soil nitrate concentrations ≥17 mg kg –1 required no N to improve yield. The remaining nine sites in 2019 with soil nitrate ≤13 mg kg –1 all had yield, test weight, and protein responses to fertilizer N. Economic optimum N rates for optimal yield, protein, and test weight across the nine sites in 2019 were 22 kg N ha –1 (18%) greater for split applications (fall and spring) compared with single spring N across various wheat/N price ratios. Delaying N applications until flag leaf decreased yield in 2019 provided no economic protein or test weight advantages. Results indicate that 96–147 kg N ha –1 (depending on price ratio) should be applied as a single application in the spring to first‐year soft white winter wheat following alfalfa only when spring soil nitrate is <17 mg kg –1 .