|MOTAVALLI, P - UNIV OF MO
|NELSON, K - UNIV OF MO
|ANDERSON, S - UNIV OF MO
|SCHARF, P - UNIV OF MO
|TRACY, P - MFA INC., MO
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/10/2005
Publication Date: 11/6/2005
Citation: Motavalli, P., Nelson, K., Kitchen, N.R., Anderson, S., Scharf, P., Tracy, P. 2005. Variable source N fertilizer applications to optimize crop N use efficiency [abstract]. ASA-CSSA-SSSA Annual Meeting. Paper No. 92-1413.
Technical Abstract: Spatial variation in soil water content and drainage due to differences in soil physical properties may lead to higher soil N loss, primarily through leaching and gaseous losses, and lower N fertilizer use efficiency. This research investigated the concept of variable source N fertilizer application in which slow-release N fertilizer was applied to areas in a field which have higher probability of N loss and conventional N fertilizer was applied to areas with a low risk of N loss. The objectives of this study were to determine methods to delineate and map areas in fields which are more vulnerable to N loss due to wet conditions and to examine the use of a variable-source strategy to optimize crop N fertilizer use efficiency. Two claypan soil field experiments planted to corn were initiated in 2005, one in north-east and one in north-central Missouri. For the north-east Missouri field treatments consisted of application of 168 kg N ha-1 as broadcast pre-plant urea, polymer-coated urea, a 50% blend of urea and polymer-coated urea, or injected anhydrous ammonia. For the north-central Missouri field treatments consisted of 168 kg N/ha as broadcast pre-plant urea or polymer-coated urea. All N fertilizer treatments were applied on strips over 365 meters in length that included spatial variation in elevation and depth to the claypan layer. Assessment of environmental N loss and fertilizer N efficiency included measurement of soil nitrous oxide flux and crop N recovery. Based on initial results, this presentation will discuss whether variable-source N fertilizer application is an effective management practice to improve crop performance while reducing environmental N losses.