Can intercropping be an adaptation to drought? A model‐based analysis for pearl millet–cowpea

Nelson, W C D and Hoffmann, M P and Vadez, V and Rötter, R P and Koch, M and Whitbread, A M (2021) Can intercropping be an adaptation to drought? A model‐based analysis for pearl millet–cowpea. Journal of Agronomy and Crop Science (TSI). pp. 1-18. ISSN 0931-2250

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Cereal–legume intercropping is promoted within semi-arid regions as an adaptation strategy to water scarcity and drought for low-input systems. Our objectives were firstly to evaluate the crop model APSIM for pearl millet (Pennisetum glaucum (L.))—cowpea (Vigna unguiculata (L.) Walp) intercropping—and secondly to investigate the hypothesis that intercropping provides complimentary yield under drought conditions. The APSIM model was evaluated against data from a two year on station field experiment during the dry season of a semi-arid environment in Patancheru, India, with severe, partial and no water deficit stress (well-watered); densities of 17 and 33 plants per m−2, and intercrop and sole crop production of pearl millet and cowpea. Overall, APSIM captured the dynamics of grain yields, indicated by the Willmott Index of Agreement (IA: 1 optimal, 0 the worst) 0.91 from 36 data points (n), total biomass (IA: 0.90, n = 144), leaf area index (LAI, IA = 0.77, n = 66), plant height (IA 0.96, n = 104 pearl millet) and cowpea (IA 0.81, n = 102), as well as soil water (IA 0.73, n = 126). Model accuracy was reasonable in absolute terms (RMSE pearl millet 469 kg/ha and cowpea 322 kg/ha). However, due to low observed values (observed mean yield pearl millet 1,280 kg/ha and cowpea 555 kg/ha), the relative error was high, a known aspect for simulation accuracy in low-yielding environments. The simulation experiment compared the effect of intercropping pearl millet and cowpea versus sole cropping under different plant densities and water supplies. A key finding was that intercropping pearl millet and cowpea resulted in similar total yields to the sole pearl millet. Both sole and intercrop systems responded strongly to increasing water supply, except sole cropped cowpea, which performed relatively better under low water supply. High plant density had a consistent effect, leading to lower yields under low water supply. Higher yields were achieved under high density, but only when water supply was high: absolute highest total intercrop yields were 4,000 (high density) and 3,500 kg/ha (low density). This confirms the suitability of the common practice among farmers who use the low planting density under water scarce conditions. Overall, this study confirms that intercropping is no silver bullet, i.e. not per se a way to achieve high yield production or reduce risk under drought. It does, however, provide an opportunity to diversify food production by additionally integrating protein rich crops, such as cowpea.

Item Type: Article
Divisions: Global Research Program - Resilient Farm and Food Systems
CRP: CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS)
CGIAR Research Program on Grain Legumes and Dryland Cereals (GLDC)
Uncontrolled Keywords: Adaptation, Drought stress, Intercropping, Pennisetum glaucum (L.), Vigna unguiculata (L.) Walp
Subjects: Others > Drought Tolerance
Mandate crops > Millets > Pearl Millet
Others > Cowpea
Depositing User: Mr Arun S
Date Deposited: 08 Sep 2021 09:21
Last Modified: 08 Sep 2021 09:21
Official URL:
Acknowledgement: This study was conducted within the IMPAC3 (grant number 031A351A) funded by the German Ministry of Education and Research. RPR, MPH, and MK received support from the German Ministry of Education and Research via the ‘SALLnet’ project (grant number 01LL1802A) within the SPACES2 Program. VV acknowledges the CGIAR Research Programs Grain Legumes and Dryland Cereals (GLDC) for funding his time. AMW acknowledges salary from the CGIAR Research Program Climate Change, Agriculture and Food Security (CCAFS) carried out with support from the CGIAR Trust Fund rs/. The authors are grateful for the help of the field and laboratory staff from the Systems Analysis for Climate Smart Agriculture (SACSA) team at ICRISAT Hyderabad, India, for hosting the field trial on which this study is based.
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