EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Influence of N inhibitors on carbon losses/sequestration in Maize cropping

Oscar Monzon1, Danica Antonijevic1, Barbara Vergara N1, Gernot Verch2, Matthias Lück1, Jürgen Augustin1, and Mathias Hoffmann1
Oscar Monzon et al.
  • 1Leibniz-Zentrum für Agrarlandschaftsforschung (ZALF), Isotope Biochemistry and Gas Fluxes, Müncheberg, Germany
  • 2​​​Leibniz Centre for Agricultural Landscape Research (ZALF) Research Station Dedelow, Prenzlau, Germany

As a result of globally strongly intensified N fertilization, agriculture is an important source not only for greenhouse gas (GHG) and especially gaseous N emissions but also N pollution through leaching. To increase nitrogen use efficiency and reduce gaseous N emissions and leaching, N inhibitors can be used. The use of N inhibitors, however, might directly affect crop growth and alter yield, which influences CO2 exchange and might potentially change C sequestration. While the applicability of N inhibitors to reduce especially NH3 and N2O emissions is well recognized, to date, the influence of these inhibiters on CO2 emissions and C sequestration is rather unclear.

We investigated the influence of urease (UI) and nitrification inhibitors (NI) when used with mineral fertilizer on GHG emissions and C sequestration for maize cropping in an on-farm, strip-field trial in NE Germany (Uckermark Region, “53°18'54.2"N, 13°40'15.2"E”). The on-farm field trial consists of four treatments, each implemented on a strip of 15m by 100m: non-fertilized (NF), fertilized (Urea Ammonium Sulfate (AS-HS)), with one (AS-HS + UI) and with two (AS-HS + UI + NI) inhibitors. On each treatment 5 PVC frames (0.5625 m2) for manual closed chamber measurements of GHG emissions were installed. Out of these 5 repetitive plots, one frame per treatment was kept clear of maize crops to obtain soil respiration (Rs). N2O (and CH4) emissions were measured using opaque chambers, evacuated glass bottles for sampling and subsequent GC analyses (Shimadzu GC-14B with ECD and FID detectors), while CO2 exchange (Reco, Rs (opaque chamber) and NEE (transparent chamber)) were determined on-site by connecting the chambers with an infrared gas analyzer (LI-850, LI-COR Biosciences, Lincoln, USA). Crop growth was monitored through weekly measurements of plant height, NDVI and RVI as well as biomass samples. To obtain heterotrophic respiration (Rh), complementary to in-situ measurements, laboratory incubation experiment was conducted, using a fully automated incubation system (Rillig et al. 2021) and soil samples collected at distinct periods of maize cropping period and under different temperatures, to determine soil respiration. C sequestration was determined through calculating the net ecosystem C balance (NECB = NEE + Cimport - Cexport) as well as through repeated soil inventories.

The use of N inhibitors did reduce GHG emissions through reducing N2O emissions, but also reduced maize biomass production (dry matter (t/ha): 18.2, 24.1, 19.9 and 19.5 for NF, AS-HS, AS-HS + UI, and AS-HS + UI + NI respectively). Consequently, Reco and gross primary productivity (GPP) were lower for the treatments with N inhibitors compared to the fertilized field without N inhibitors but higher than the non-fertilized treatment. No significant effect on NEE was found, while the C losses seemed to be slightly higher for the treatment without N inhibitor use.

How to cite: Monzon, O., Antonijevic, D., Vergara N, B., Verch, G., Lück, M., Augustin, J., and Hoffmann, M.: Influence of N inhibitors on carbon losses/sequestration in Maize cropping, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4627,, 2022.