Sustainable intensification of sorghum-based cropping systems in semi-arid sub-Saharan Africa: The role of improved varieties, mineral fertilizer, and legume integration

Traoré Amadou, Falconnier Gatien, Couedel Antoine, Sultan Benjamin, Chimonyo Vimbayi G.P., Adam Myriam, Affholder François. 2023. Sustainable intensification of sorghum-based cropping systems in semi-arid sub-Saharan Africa: The role of improved varieties, mineral fertilizer, and legume integration. Field Crops Research, 304:109180, 10 p.

Résumé : Problem: Sustainable intensification of cereal cropping systems can contribute to reducing food insecurity while mitigating biodiversity losses thanks to land sparing. Yet, intensifying crop production with more nutrient inputs often increases sensitivity to climate hazards and yields inter-annual variability. How different options for sustainable intensification interact and how they could help achieve greater and less variable yields is not well known for key cereal cropping systems of sub-Saharan Africa. Objective: Here, we aim to assess the impact on productivity and its interannual variation of three contrasted strategies of crop intensification, namely i) the integration of cowpea intercropped with sorghum or as sole crop, ii) improved varieties with high harvest index and greater nitrogen use efficiency, and iii) the use of more mineral fertilizer. Methods: We did this assessment using a calibrated soil-crop model for a case study of sorghum-based cropping systems of semi-arid southern Mali, using a historical weather series from 1980 to 2010. Results: We found that the incremental combinations of two or three strategies helped increase productivity in terms of energy and protein. However, greater productivity went hand in hand with greater inter-annual variability. Intercropping sorghum with cowpea helped to reduce the inter-annual variability of productivity, but only when mineral fertilizer was not added. With mineral fertilizer input, sorghum contributed the largest share of the intercrop productivity, and sorghum yield was more variable from a year to another than cowpea yield. The overall productivity of intercropping sorghum with cowpea was always greater than having the two sole crops on separate plots. This was possible thanks to the facilitation of light, water and N acquisition by the two crops in the intercropping, regardless of the specificities of the growing season with regard to water and nitrogen stress. However, the variability of productivity was smaller for the cultivation of the two sole crops on separate plots, regardless of fertilizer input. Conclusion: The often-claimed benefit of intercropping on reducing the inter-annual variability of production does not hold when the three strategies are combined.

Mots-clés Agrovoc : variété indigène, système de culture, culture intercalaire, rendement des cultures, intensification, niébé, accident climatique, plante céréalière, engrais minéral, engrais azoté, fertilisation, biodiversité

Mots-clés géographiques Agrovoc : Mali, Afrique au sud du Sahara, Afrique

Mots-clés libres : Stics, Intercropping, Fertilizer, Yield variability, Sorghum, Cowpea

Classification Agris : F08 - Systèmes et modes de culture

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Auteurs et affiliations

• Traoré Amadou, IER (MLI)
• Falconnier Gatien, CIRAD-PERSYST-UPR AIDA (ZWE) ORCID: 0000-0003-3291-650X - auteur correspondant
• Couedel Antoine, CIRAD-PERSYST-UPR AIDA (FRA)
• Sultan Benjamin, IRD (FRA)
• Chimonyo Vimbayi G.P., CIMMYT (ZWE)
• Adam Myriam, CIRAD-BIOS-UMR AGAP (KHM) ORCID: 0000-0002-8873-6762
• Affholder François, CIRAD-PERSYST-UPR AIDA (MOZ) ORCID: 0000-0002-3919-4805

Source : Cirad-Agritrop (https://agritrop.cirad.fr/606965/)

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