Open AccessDMPP reduced nitrification, but not annual N 2 O emissions from mineral fertilizer applied to oilseed rape on a sandy loam soil
Author(s) -
Thers Henrik,
Petersen Søren O.,
Elsgaard Lars
Publication year - 2019
Publication title -
gcb bioenergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.378
H-Index - 63
eISSN - 1757-1707
pISSN - 1757-1693
DOI - 10.1111/gcbb.12642
Subject(s) - fertilizer , nitrification , loam , nitrous oxide , agronomy , chemistry , human fertilization , ammonium , nitrate , ammonium sulfate , denitrification , zoology , soil water , brassica , phosphate , environmental science , nitrogen , soil science , biology , organic chemistry , chromatography
Direct field emissions of nitrous oxide (N 2 O) may determine whether biodiesel from oilseed rape ( Brassica napus L.) fulfills the EU requirement of at least 50% reduction of greenhouse gas emissions as compared to fossil diesel. However, only few studies have documented fertilizer N emission factors (EF) and mitigation options for N 2 O emissions from oilseed rape cropping systems. We conducted a field experiment with three N levels (0, 171, and 217 kg/ha), where the N fertilizer was applied as ammonium sulfate nitrate with or without the nitrification inhibitor 3,4‐dimethylpyrazole phosphate (DMPP). N 2 O fluxes were measured using static chambers technique and soil samples were analyzed for water and mineral N content during a monitoring period of 368 days. The DMPP treatments showed a significantly increased level of ammonium ( NH 4 + ) for up to 18 weeks after spring fertilization as compared to the treatments without DMPP. However, this difference did not result in a corresponding decrease in NO 3 - soil content, and no differences in cumulative N 2 O emissions were found between any fertilized treatments with or without DMPP (mean, 1.26 kg N 2 O‐N ha −1 year −1 ). More field experiments are needed to clarify whether DMPP‐coated mineral fertilizers could mitigate N 2 O emissions under different weather conditions, for example, under conditions where fertilization events concurred with rainfall events increasing water‐filled pore space to the assumed 60% threshold for denitrification. Emission factors for mineral N fertilizer were 0.28%–0.36% with a mean of 0.32% across the fertilized treatments. These data concur with recent European studies suggesting that the EF for mineral N fertilizers in oilseed rape cropping systems may typically be lower than the default IPCC value of 1%. Further studies are needed to consolidate an EF for oilseed rape under temperate conditions, which will be determining for the sustainability of Northern European oilseed rape cultivation for biodiesel.