Fertilizer Placement Affects Corn and Nitrogen Use Efficiency in a Claypan Soil

Abstract

Agronomic efficiency (AE) and apparent N recovery efficiency (RE) can be improved by developing more effective N fertilizer placement strategies; however, minimal research has focused on poorly‐drained claypan soils which are prone to saturated conditions and gaseous N loss. The objective of this 2‐yr study was to determine the effectiveness of different N fertilizer placement methods on corn (Zea mays L.) grain yield, grain quality, silage yield, N uptake, AE, RE, and spatial soil N distribution over time. Nitrogen placement treatments included deep‐banded urea (DB) or urea plus nitrapyrin (DB+NI) at a depth of 20 cm compared to urea broadcast applied (BC) or BC incorporated to a depth of 8 cm (BCI). The DB and DB+NI treatments generally resulted in higher grain and silage yields than the non‐treated control (NC), BCI, and BC treatments. The DB+NI increased silage yield 4.14 to 4.77 Mg ha−1 over the BC and DB treatments in 2016. Additionally, DB+NI resulted in 21 and 27% greater N uptake and RE than other N placement treatments. Deep‐banded treatments with and without NI had the highest AE (10.3–13.3 kg kg N−1) compared to other treatments. Deep‐banded urea had significantly higher soil NO3–N concentrations in deep soil layers compared to DB+NI when sampled in July. Results indicated DB+NI increased N availability for a longer period during the growing season and was a reliable strategy for increasing corn yields and improving AE and RE on a poorly‐drained claypan soil. Core Ideas Yield response to urea was ranked DB+NI = DB > BCI > BC. Apparent N recovery efficiency was greatest (76.5%) with DB+NI. Highest agronomic efficiency (10.3 to 13.3 kg kgN−1) was observed for DB and DB+NI. Distribution of pHs, NO3‐N, and NH4‐N in the soil was affected by urea placement.

Urea Nitrapyrin Placement Effects on Soil Nitrous Oxide Emissions in Claypan Soil

“…In addition to drying and wetting cycles, soil pH also had an important role in regulating urea hydrolysis, nitrification, and denitrification, which can affect N 2 O emissions (Cabrera et al, 1991; Dancer et al, 1973; Van den Heuvel et al, 2011). Soil pH of the study site in 2017 varied between 6.7 and 5.3 for depths of 0 to 61 cm among treatments (Steusloff et al, 2019). Van den Heuvel et al (2011) reported that NO 3 − production in low pH soils was reduced and resulted in buildup of N 2 O in soil that contributed to higher emissions of N 2 O at soil pH of 5.…”

“…Soil samples to a depth of 61 cm from all treatments were collected on 10 July 2017 (data not shown). The DB+NI treatment had 7 to 10 mg kg −1 greater NO 3 –N in soil at the 15‐cm depth compared with all other treatments, which could explain higher N 2 O losses later in the season (Steusloff et al, 2019). Additionally, higher N 2 O loss from IA and SA early in the growing season was probably due to greater NO 3 − substrate left in the soil for IA and SA, which might have been reduced in concentrations which resulted in lower N 2 O fluxes later in the season from these treatments (Steusloff et al, 2019).…”

“…The DB+NI treatment had 7 to 10 mg kg −1 greater NO 3 –N in soil at the 15‐cm depth compared with all other treatments, which could explain higher N 2 O losses later in the season (Steusloff et al, 2019). Additionally, higher N 2 O loss from IA and SA early in the growing season was probably due to greater NO 3 − substrate left in the soil for IA and SA, which might have been reduced in concentrations which resulted in lower N 2 O fluxes later in the season from these treatments (Steusloff et al, 2019). The seasonal pattern of soil N 2 O emissions observed in our study is consistent with previous research in the midwestern US Corn Belt region (Fernández et al, 2015; Nash et al, 2012; Parkin and Hatfield, 2014).…”

“…The lower yield scaled N 2 O emissions with DB and DB+NI were observed due to higher grain yields observed in these treatments. Corn grain yields in 2016 were generally lower than in 2017 (Steusloff et al, 2019). Not only was this due to greater gaseous N loss, but it could also be due to below average rainfall in June 2016 during the late vegetative growth stages of corn (Abendroth et al, 2011), which may have had the greatest impact on corn grain yields (Rhoads and Bennett, 1990; Shaw, 1988).…”

Enhanced Efficiency Liquid Nitrogen Fertilizer Management for Corn Production

“…In addition to N application timing, fertilizer N placement strategies may improve crop yields and N use efficiency in claypan soils. Many studies have shown lower grain yields and N uptake with a surface broadcast N application compared to incorporated band N placement [6,[15][16][17]. Other studies did not observe any advantages of subsurface band placement of urea ammonium nitrate (UAN) over surface broadcast placement [8,18].…”