Preprints
https://doi.org/10.5194/bg-2021-215
https://doi.org/10.5194/bg-2021-215

  01 Sep 2021

01 Sep 2021

Review status: this preprint is currently under review for the journal BG.

The role of cover crops for cropland soil carbon, nitrogen leaching, and agricultural yields – A global simulation study with LPJmL (V. 5.0-tillage-cc)

Vera Porwollik1,2, Susanne Rolinski1, Jens Heinke1, Werner von Bloh1, Sibyll Schaphoff1, and Christoph Müller1 Vera Porwollik et al.
  • 1Potsdam Institute for Climate Impact Research, Member of the Leibniz Association, P.O. Box 60 12 03, 14412 Potsdam, Germany
  • 2Department of Agricultural Economics, Humboldt-University of Berlin, Unter den Linden 6, 10099 Berlin, Germany

Abstract. Land management practices can reduce the environmental impact of agricultural land use and production, improve productivity, and transform cropland into carbon sinks. We applied the global vegetation model LPJmL5.0-tillage-cc with a modified representation of cover crop practices. We assessed simulated responses to cover crop practices on agroecosystem components in comparison to bare soil fallow between two consecutive primary crops’ growing seasons on global cropland for a simulation period of 50 years. With cover crops and tillage, we obtained annual global median soil carbon sequestration rates of 0.52 and 0.48 t C ha−1 yr−1 for the first and last decades of the entire simulation period, respectively. We found that cover crops with tillage reduced annual nitrogen leaching rates from cropland soils by a median of 39 % and 54 % but also the productivity of the following main crop by average of 1.6 % and 2 % for the two analyzed decades. Largest reduction of productivity were found for rice, modestly lowered for maize and wheat, whereas soybean yield revealed an almost homogenous positive response to cover crop practices during fallow periods.

Further, the results suggest that no-tillage is a suitable complementary practice to cover crops, enhancing their environmental benefits and reducing potential trade-offs with the main crop productivity due to their impacts on soil nitrogen and water dynamics. For cover crops applied in conjunction with no-tillage across the mapped Conservation Agriculture cropland area for the period 1974–2010, we estimated a cumulative soil carbon net-accumulation of 1.4 PgC, an annual median reduction of soil nitrogen leaching by 57 %, as well as mostly enhanced yields of the following main crop.

The spatial heterogeneity of simulated impacts of cover crops on the variables assessed here was related to the time period since the introduction of the management practice as well as to environmental and agronomic conditions of the cropland. This study supports findings of other studies, highlighting the substantial potential contribution of cover crop practices to the sustainable development of arable production.

Vera Porwollik et al.

Status: open (until 14 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2021-215', Anonymous Referee #1, 12 Sep 2021 reply

Vera Porwollik et al.

Model code and software

LPJmL5.0-tillage-cc model source code, management simulation outputs, and R script for post-processing data (1.0.1) V. Porwollik, S. Rolinski, J. Heinke, W. von Bloh, S. Schaphoff, T. Herzfeld, C. Müller https://zenodo.org/record/5178070

Vera Porwollik et al.

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Short summary
The study assesses the impacts of cover crop practices on soil carbon, nitrogen leaching, and crop yields in comparison to a control management scenario with bare soil fallowing by applying the global vegetation model LPJml (V.5.0-tillage-cc). The potential and determinants of environmental and agronomic benefits of the practice vary with respect to management duration, type of tillage, mineral fertilizer application rate, and environmental conditions of the cropland.
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