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

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Relation http://oar.icrisat.org/11889/
https://doi.org/10.1111/jac.12552
doi:10.1111/jac.12552
 
Title Can intercropping be an adaptation to drought? A model‐based analysis for pearl millet–cowpea
 
Creator Nelson, W C D
Hoffmann, M P
Vadez, V
Rötter, R P
Koch, M
Whitbread, A M
 
Subject Drought Tolerance
Pearl Millet
Cowpea
 
Description 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.
 
Publisher Wiley
 
Date 2021-08
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
Identifier http://oar.icrisat.org/11889/1/Nelson_etal_Intercrop_drought_PearlMillet_cowpea_JAg%26CS_2021.pdf
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