Conservation agriculture reduces climate change impact of a popcorn and wheat crop rotation

RESEARCH ARTICLE Conservation agriculture reduces climate change impact of a popcorn and wheat crop rotation Maria Vittoria Guidoboni1, Annie Duparque2, Joachim Boissy2, Jean-Christophe Mouny2, Julie AubergerID1, Hayo MG van der WerfID1* 1 UMR SAS, INRAE, Institut Agro, Rennes, France, 2 Agro-Transfert Ressources et Territoires, Estre´es- Mons, France * hayo.van-der-werf@inrae.fr Abstract Urgent action is needed to ensure humanity’s future under climate change. Agriculture faces major challenges as it is both influenced by and contributes to climate change. Con- servation agriculture sequesters carbon (C) in the soil due to practices such as reduced till- age and planting of cover crops. This study assessed effects of an innovative conservation agriculture popcorn (Zea mays) and wheat (Triticum aestivum) crop rotation in south-west- ern France on soil C sequestration, GHG emissions and several environmental impacts. Two complementary approaches were used: i) a comparison based on field data and expert judgement to assess short-term effects and ii) modelling of three scenarios to quantify long- term outcomes. In both approaches Life cycle assessment (LCA) was used to compare pop- corn and wheat rotations. The conventional rotation used ploughing, and its soil was bare between wheat harvest and popcorn sowing. Conservation agriculture used reduced tillage, cover crops, and compost of green waste. Impacts of compost production were allocated mainly to its waste treatment function, based on waste treatment cost and compost price.

Simulation modelling of soil C was used to estimate the amount of C sequestered by the conservation and conventional crop rotations. LCA was combined with soil C modelling over 100 years to assess the long-term climate change impact of three scenarios for the popcorn and wheat rotation. These scenarios were 1) Conventional agriculture, 2) Conservation agri- culture with cover crops only, 3) Conservation agriculture with cover crops + compost. Mean annual C sequestration and net climate change impact were -0.24 t/ha and 3867 kg CO2- eq./ha, respectively, for the conventional rotation and 0.91 t/ha and 434 kg CO2-eq./ha, respectively, for the conservation rotation. The climate change impact of the conservation rotation depended strongly on the allocation of composting impacts between the waste treatment and compost production functions. Compared to the conventional rotation, the conservation rotation had a lower marine eutrophication impact (-7%) but higher impacts for terrestrial acidification (+9%), land competition (+3%), and cumulative energy demand (+2%). Modelling over 100 years revealed that, at near soil C equilibrium, a conventional scenario lost 9% of soil C, whereas conservation agriculture scenarios gained 14% (only PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0285586 May 23, 2023 1 / 18 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Guidoboni MV, Duparque A, Boissy J, Mouny J-C, Auberger J, van der Werf HMG (2023) Conservation agriculture reduces climate change impact of a popcorn and wheat crop rotation. PLoS

ONE 18(5): e0285586. https://doi.org/10.1371/ journal.pone.0285586 Editor: Farhan Hafeez, COMSATS University Islamabad Abbottabad Campus, PAKISTAN Received: November 25, 2022 Accepted: April 27, 2023 Published: May 23, 2023 Copyright: © 2023 Guidoboni et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting information files. Funding: Hayo van der Werf received funding from the Carbon Farming research and innovation project (www.climate-kic.org/innovation-spotlight/ carbon-farming-is-innovating-land-use/) under grant agreement no. TCL 210065, this funding paid the salary of Maria Vittoria Guidoboni. The other authors did not receive specific funding for the project. The funders encouraged publication of the