Gaseous Nitrogen Losses from a Cambisol Cropped to Spring Wheat with Urea Sizes and Placement Depths

Abstract

Globally identifying mitigation options for the emission of reactive N gases from agricultural soils is a research priority. We investigated the effect of urea size and placement depth on sources and emissions of N gases from a Cambisol cropped to spring wheat (Triticum aestivum L.). In Exp. 1, wheat received either prilled urea (PU) mixed within the soil, urea super granule (USG; diam. 10.1 mm) point‐placed at a soil‐depth of 7.5 cm, or no N fertilizer. In Exp. 2, wheat received either USG (diam. 10.2 mm) point‐placed at 2.5‐, 5.0‐, and 7.5‐cm soil depths, or no N fertilizer. In both experiments, maximum peaks for nitrous oxide (N2O) fluxes and nitrification were delayed by 2 to 3 wk in the USG compared with the PU treatment. The added 15N‐urea lost as 15N‐N2O over 116 d was only 0.01% for both PU and USG treatments in Exp. 1. This loss for USGs was higher in Exp. 2 (0.02–0.15%) measured over 70 d, mainly related to higher moisture‐induced denitrification. Temporal N2O fluxes were significantly related to changes in soil NO3−–N, water‐filled pore space and NH4+–N (R2 = 0.50, P < 0.05). However, the previous predictive model of Khalil et al. (2006) could best estimate its cumulative fluxes over time. The relative losses of ammonia (0.07–1.17%) and nitrogen oxides (0.19–1.54%) measured in Exp. 2 over 43 d decreased with increasing depths of USG placement. The USG point‐placed at the 5.0‐ and 7.5‐cm depths decreased the pooled gaseous N losses by 35 and 77%, respectively, over the shallower placement. The 15N results imply that soil N could be the major source of N2O emissions (79–97%). Field studies are suggested to validate our findings that the deeper placement of USG can decrease N emissions under arable cropping.

Deep placement of nitrogen fertilizers reduces ammonia volatilization and increases nitrogen utilization efficiency in no-tillage paddy fields in central China

“…But, we also found that nitrogen deep placement significantly decreased cumulative NH 3 losses during the rice growing seasons ( Table 2). The reduction under nitrogen deep placement was also reported in other studies of crop fields (Drury et al, 2006;Liu et al, 2006;Khalil et al, 2009). After basal nitrogen was deep placed, lower soil urease activity was observed under nitrogen deep placement treatments than under S treatment (Table 3), which may lead to less NH 4 + in the soils and floodwater from hydrolyzed nitrogen fertilizers under nitrogen deep placement treatments (Fig.…”

Physical and Chemical Manipulation of Urea Fertilizer To Limit the Emission of Reactive Nitrogen Species

“…However, the USG overall retained more mineral N compared with the sPAT and UNI treatments. The findings signify that both the USG and urea amended with inhibitors (DCD/TZ and UNI) could effectively limit nitrification from 5-7 weeks, which is in accordance with laboratory (28,29) and field experiments (24). (29)).…”

“…Khalil et al (28) examined the impact of USG point-placed at 2.5, 5 cm and 7.5 cm applied at 91.74 kg N ha -1 in a loess soil cropped to spring wheat on NO x emission. The maximum NO x emission peaked at 31 days after fertilization and thereby started to increase when NH 3 volatilization was declining (Fig.…”

Emissies naar lucht uit de landbouw in 2015 : Berekeningen met het model NEMA

“…De toedieningsmethode is niet alleen bij vloeibare ureummeststoffen relevant maar ook bij korrels. Bij een toediening van ureumkorrels op een diepte van 2,5-, 5,0-, en 7,7-cm diep daalde de NH3 emissie 35 en 77% ten opzichte van de meest ondiepe plaatsing in een veldexperiment (Khalil et al, 2009 Basfoliar 36 extra,NTS 27 + 3 SO3,NTS 27 + 7,5 SO3,Plantacote start (ureaform npk),Plantosan (ureaform npk), Ureaform 38 N,Urean 28 N,Urean 30 N,Ureum 40% vlb,FertiFlow Plus,Powerstart Feed,Powerbasic Groei,Fertiflow Blue,Fertiflow Zomer 4 • De emissiefactor voor kalkloze landbouwgronden is 0%.…”