CP4: N2O emissions from NOcsPS stands: Influence of crop type and greenhouse gas mitigation strategies (nitrification inhibitor and deep placement) on N fertilization

In a nutshell

What?

Our research group focus on the assessment of greenhouse gas emissions of NOcsPS cropping systems and the potential savings through different depth placement of N-fertilizers and the use of nitrification inhibitors.

Why?

Especially nitrous oxide (N2O) emissions from the cultivation of agricultural crops contribute to a high proportion of greenhouse gas emissions due to their high specific global warming potential. This means that N2O emissions at field level play a key role in assessing the climate impact of cropping systems.

How?

In addition to assessing the greenhouse impact by determining crop-specific fertilizer-induced emission factors (EF) of NOcsPS cropping systems, the measurements will focus on identifying strategies to reduce these N2O emissions. In this context, the use of nitrification inhibitors (NI) will be discussed and quantified.  

Another focus will be on the potential N2O reduction through deep placement of N fertilizers.

Dep. Fertilization and Soil Matter Dynamics (340i)

Fruwirthstraße 20
70599 Stuttgart

in planning stage

Subproject Team

Prof. Dr. Torsten Müller
Subproject Leader

Prof. Dr. Torsten Müller

Dr. Reiner Ruser
Postdoc

Dr. Reiner Ruser

State of the Art and Problem Assessment

Nitrous oxide emissions can account for up to 80% of total greenhouse gas emissions in crop production. N2O release generally increases with increasing availability of substrates (mineral N) for microbial N2O formation in soils. Therefore, fertilized soils show higher N2O emissions than unfertilized soils. Due to different fertilization times and application rates of the NOcsPS crop types, it is to be expected that the annual N2O emissions and the emission factors (EF) derived from the NOcsPS crops also vary depending on the crop type. Previous measurements in the first NOcsPS phase resulted in a lower EF in NOcsPS wheat compared to standard emission factors (e.g. according to IPCC: 1.0%). However, these measurements were conducted in a very dry year with very low N2O emissions and the EF of the conventional treatment was also lower than the IPCC factor.

For more accurate calculations of life-cycle analyses, better data is needed to calculate adequate EFs for the NOcsPS cropping systems.

The N2O reduction efficiency of a NI can vary depending on the location and inhibitor. A reduction potential of approx. 35% appears realistic (Ruser & Schulz, 2015).There is further potential for N2O mitigation in connection with different placement depths of N-fertilizers.

Objectives and Research Hypotheses of Research Proposal

One aim of the project is to determine EFs for selected types of crops from the NOcsPS crop rotation and to implement these into the calculation of the atmospheric impact by NOcsPS systems. A further aim is to identify N2O reduction strategies. The use of a NI or deep placement of the N fertilizer will be evaluated.

Description of Work Program and Expected Results

In a plot experiment, the N2O fluxes are determined on a weekly basis using the closed chamber method. These are supplemented by event-related measurements (e.g. after fertilization). The emission factors from WP1 and WP2 derived from the measurements are passed on to VP 13, 14 and 15 for further analysis and modeling.

WP1: Determination of crop-specific emission factors of selected NOcsPS crops

  • Repetition of measurements in winter wheat 2026
  • Measurements in potatoes, maize and vegetables in 2026 and 2027

WP2: Evaluation of N2O mitigation strategies

  • Testing the effect of a NI in winter wheat and vegetables and the deep placement of N fertilizers in maize and potatoes 2026 and 2027
  • Quantification of possible greenhouse gas reductions from the results.