Maize-Pigeonpea Intercropping Outperforms Monocultures Under Drought

Abstract

There is an urgent need to develop resilient agroecosystems capable of helping smallholder farmers adapt to climate change, particularly drought. In East Africa, diversification of maize-based cropping systems by intercropping with grain and tree legumes may foster productivity and resilience to adverse weather conditions. We tested whether intercropping enhances drought resistance and crop and whole-system yields by imposing drought in monocultures and additive intercrops along a crop diversity gradient—sole maize (Zea mays), sole pigeonpea (Cajanus cajan), maize-pigeonpea, maize-gliricidia (Gliricidia sepium, a woody perennial), and maize-pigeonpea-gliricidia—with and without fertilizer application. We developed and tested a novel low-cost, above-canopy rainout shelter design for drought experiments made with locally-sourced materials that successfully reduced soil moisture without creating sizeable artifacts for the crop microenvironment. Drought reduced maize grain yield under fertilized conditions in some cropping systems but did not impact pigeonpea grain yield. Whole-system grain yield and theoretical caloric and protein yields in two intercropping systems, maize-pigeonpea and maize-gliricidia, were similar to the standard sole maize system. Maize-pigeonepea performed most strongly compared to other systems in terms of protein yield. Maize-pigeonpea was the only intercrop that consistently required less land than its corresponding monocultures to produce the same yield (Land Equivalent Ratio >1), particularly under drought. Despite intercropping systems having greater planting density than sole maize and theoretically greater competition for water, they were not more prone to yield loss with drought. Our results show that maize-pigeonpea intercropping provides opportunities to produce the same food on less land under drought and non-drought conditions, without compromising drought resistance of low-input smallholder maize systems.

Narrow and Brittle or Broad and Nimble? Comparing Adaptive Capacity in Simplifying and Diversifying Farming Systems

“…Increasing crop diversity at multiple scales, from intercropping to whole farms to regional scales, can also reduce drought risk in ways other than changes to soil (Lin, 2011;Renwick et al, 2020). Increasing the diversity of crops grown at the farm-scale to include ones that differ in their water use, drought tolerance, or phenology helps reduce risks to farm-level yield and income through a "portfolio effect" (Helmers et al, 2001, Isbell et al, 2017.…”

Integrating evidence of potential impacts of climate-smart agriculture in Tanzania.

“…Productivity gains were often highly site specific. For example, a study by Renwick et al (2020) found that whole-system crop yield was consistent with that of the control for maize-pigeonpea intercropping and negatively impacted by maize-pigeonpea-gliricidia intercropping, except under drought conditions, where maize-pigeonpea-gliricidia intercropping increased maize yield. Compared to monoculture controls, Renwick et al (2020) consistently found that intercropping with maize and pigeonpea produced the same yield on less land, or a land equivalent ratio (LER) greater than 1, suggesting positive mitigation outcomes as a result of increased agronomic efficiency.…”

“…For example, a study by Renwick et al (2020) found that whole-system crop yield was consistent with that of the control for maize-pigeonpea intercropping and negatively impacted by maize-pigeonpea-gliricidia intercropping, except under drought conditions, where maize-pigeonpea-gliricidia intercropping increased maize yield. Compared to monoculture controls, Renwick et al (2020) consistently found that intercropping with maize and pigeonpea produced the same yield on less land, or a land equivalent ratio (LER) greater than 1, suggesting positive mitigation outcomes as a result of increased agronomic efficiency. In the same study, findings showed that, while intercropping with a leguminous crop (pigeonpea) consistently produced an LER greater than 1, introducing an agroforestry species (gliricidia) only had positive mitigation outcomes under certain conditions (unfertilized ambient conditions and fertilized drought conditions).…”

“…This positive trend in productivity was noted in both crop-based and livestock-based production systems. Two studies found that specific practices, including maize-pigeon-pea intercropping, improved animal genomics and reduced stocking rates, maintained yield levels consistent with conventional practices (Renwick et al 2020;Paul, Groot, et al, 2020). Yet negative impacts to productivity were also found in intercropping with maize and pigeonpea and/or glircidia (a forage crop).…”

Allometric equations for estimating on-farm fuel production of Gliricidia sepium (Gliricidia) shrubs and Cajanus cajan (pigeon pea) plants in semi-arid Tanzania

“…Therefore, fuelwood production should not impair food production. Studies from the same research site showed that the integration of Gliricidia and pigeon pea in cropping plans does not lead to crop yield loss but bears the potential to yield more using less area (sustainable intensification) [51,52]. The introduction of agroforestry systems needs to consider the whole crop/tree value chain, including the availability of seeds, the availability of seedlings, the growth rates, the local interests, as well as the marketability of the product [8].…”