Climatic effect of no-tillage and mulch due to albedo change differs with soil type: a field study in Zimbabwe

Diop Souleymane, Cardinael Rémi, Lauerwald Ronny, Ferlicoq Morgan, Thierfelder Christian, Chikowo Régis, Corbeels Marc, Ceschia Eric. 2023. Climatic effect of no-tillage and mulch due to albedo change differs with soil type: a field study in Zimbabwe. . AAB. Rothamsted : AAB, Résumé, 2 p. Long Term Experiments: Meeting Future Challenges, Rothamsted, Royaume-Uni, 20 Juin 2023/22 Juin 2023.

Résumé : Biogeochemical effects of conservation agriculture (CA), i.e. soil organic carbon storage and greenhouse gas emissions have been investigated in numerous studies. Recent ones suggest that management practices also have significant biogeophysical impacts on local and global climate through changes in surface albedo and energy partitioning. For Africa, relevant studies are scarce. In this study, we assessed the biogeophysical effects of CA in maize fields over the 2021/22 and 2022/23 seasons at two sites established in 2013 in Zimbabwe on an abruptic Lixisol at Domboshawa Training Center (DTC) and on a xanthic Ferralsol at the University of Zimbabwe Farm (UZF). We hypothesised that CA would have different effects on albedo dynamics and radiative forcing (RF) depending on 1) the presence/absence of crop residues at soil surface, 2) soil type/colour. We monitored dynamics of albedo, longwave radiation, LAI, soil moisture/temperature under three different treatments: conventional tillage (CT), no-tillage (NT) and no-tillage with mulch (NTM). Our results showed that NT and NTM induced a RF cooling effect (higher albedo compared to CT) in the clayey soil at UZF but the mean annual RF of NT was higher than that under NTM with -0.83 W.m-2 and -0.43 W.m-2 respectively. In sandy soil (at DTC), we observed a warming effect due to the soil darkening effect induced by mulching. The mean annual RF of NT was -3.4 W.m-2 (cooling effect compare to CT treatment) against 1.2 W.m-2 for NTM (warming effect). Next step is to compare the albedo induced RF induced by NT and NTM with the other biogeophysical effects and the biogeochemical effects on climate of those treatments. These results suggest that application of mulch or crop residues on sandy soils might not be relevant for a climate change mitigation perspective, even if it provides benefits for soil health and adaptation to climate change.

Mots-clés libres : Conservation agriculture, Climate change mitigation, Albedo

Auteurs et affiliations

• Diop Souleymane, CIRAD-PERSYST-UPR AIDA (FRA)
• Cardinael Rémi, CIRAD-PERSYST-UPR AIDA (ZWE) ORCID: 0000-0002-9924-3269
• Lauerwald Ronny, Université Paris-Saclay (FRA)
• Ferlicoq Morgan, Université Toulouse III Paul Sabatier (FRA)
• Thierfelder Christian, CIMMYT (ZWE)
• Chikowo Régis, University of Zimbabwe (ZWE)
• Corbeels Marc, CIRAD-PERSYST-UPR AIDA (KEN)
• Ceschia Eric, INRAE (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/605167/)

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