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Title: Crop Yield and Nitrate Losses from Sidedressing N at Canopy Closure

item Jaynes, Dan

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/2009
Publication Date: 11/5/2009
Citation: Jaynes, D.B. 2009. Crop Yield and Nitrate Losses from Sidedressing N at Canopy Closure [abstract]. ASA-CSSA-SSSA Annual Meeting, Nov. 1-5, 2009l, Pittsburgh, PA.

Interpretive Summary:

Technical Abstract: There is growing interest in applying N to corn in response to remotely sensed plant N status. Remote sensing of N status appears to be most successful after canopy closure (V10), but needs to be before reproduction starts (R1) for optimal N use and lowest NO3 leaching under natural rainfall (Jaynes and Colvin, 2006). While the yield benefits of sidedressing N at V10 are well documented, little information is available on the impacts to water quality. We compared grain yields and NO3 losses in drainage water as a result of applying N either once after plant emergence or equally split between just after emergence (V1) and early crop growth (V6 or V10). Nitrogen treatments consisted of 138 kg ha-1 applied post-emergence (V1), and 69 kg ha-1 applied post-emergence and again at either V6 or V10. Grain yield for corn and soybean, grown in a 2-yr rotation, and drainage water NO3 concentrations were measured on replicated tile-drained plots in a producer’s field from 2006 through 2009.