Date of Graduation

12-2022

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Roberts, Trenton L.

Committee Member

Miller, David M.

Second Committee Member

Kelley, Jason P.

Third Committee Member

Bateman, Nicholas R.

Keywords

Fertilizer Nitrogen Recovery Efficiency; Furrow Irrigated Corn; Late Season Nitrogen Applications; Mid-south; Nitrogen Use Efficiency; Nutrient Accumulation

Abstract

Corn (Zea mays L.) production continues to be a critical component of row-crop production systems within Arkansas and is seeing a resurgence in recent years. Nitrogen (N) is critical for corn growth and is often one of the single largest input costs associated with corn production. Research objectives for this study were to determine the nitrogen use efficiency (NUE) of late season N applications as influenced by sidedress N rate and timing of pretassel application and to quantify the nutrient uptake and partitioning in modern era corn hybrids within a furrow-irrigated production system. Research was conducted at the Milo J. Shult Agriculture Research & Extension Center (SAREC) near Fayetteville, AR and the Pine Tree Research Station (PTRS) near Colt, AR during the 2018 and 2019 growing season. Eight different N treatments were implemented as a combination of sidedress rate and pretassel N application timing. At the sidedress application timing near the V6-V8 growth stage, either 90 or 112 kg N ha-1 was surface broadcast as urea. At the pretassel growth stage, treatments received either 0 or 50 kg N ha-1 surface broadcast as 15N-labeled urea and were compared across two different application timings; early tassel (VT) or at late reproductive stage 1 (R1). To assess N-fertilizer use, whole plant samples were collected at R2, R4, and R6 and analyzed for total N uptake and atom% 15N to assess Fertilizer Nitrogen Recovery Efficiency (FNRE). Results indicate that N uptake from pretassel N applications were more efficient at the early tassel stage (79% FNRE) compared to late R1 (50% FNRE) applications (P <.0001). A significant sidedress rate by growth stage interaction (P=0.0146) was identified and indicated that FNRE was maximized at R4 sampling time (79% NUE) when the 112 kg N ha-1 sidedress rate was used. This data indicates that earlier applied pretassel N applications near the VT growth stage are preferred and improve NUE in Arkansas corn production and that optimal rates of sidedress N can result in high NUE of pretassel N applications under furrow-irrigated corn production. Total aboveground biomass reported in this study was higher than what has been previously reported in the literature and may be attributed to irrigation and enhanced fertilizer management (split applications). Total nutrient accumulation was 326.6 kg N, 62.0 kg P, 437.2 kg K, 30.7 kg Mg, 28.0 kg S, and 686.4 g Zn ha-1, respectively. The average grain yield produced was 15.2 Mg ha-1. The general nutrient uptake patterns could be described as sigmoidal, consisting of a curved shape, a peak accumulation period followed by a transition of nutrient remobilization. These results help to identify the season total nutrient demand for modern era corn hybrids produced in a furrow-irrigated production system and will help guide future soil fertility and nutrient management decisions to ensure maximal corn yield and producer profitability are achieved.

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