TWN Info Service on Sustainable Agriculture
26 October 2021
Third World Network
www.twn.my
Dear Friends and Colleagues
Push-Pull Intercropping System Improves Soil Microbiome and Plant Productivity
Smallholder farmers across southern and eastern Africa use the ‘push-pull’ system to manage stem-borers and fall armyworm attacks on cereal crops particularly maize and sorghum, thus increasing yield. The technology exploits the chemical ecology of a leguminous intercrop belonging to the genus Desmodium, which ‘pushes’ stem-boring insects from the main crop through its volatile compounds that signal an unfavourable egg-laying environment. At the same time, a grass trap crop, such as napier grass, is planted as border vegetation to ‘pull’ the insects towards itself without supporting their development.
Additional ecosystem functions gradually emerged to include combating parasitic weeds of cereals (such as Striga spp.), increasing soil nitrogen and carbon, and even reducing incidence of human pathogenic fungal toxins in maize kernels. In addition, both Desmodium and the trap crops are a reliable source of animal fodder. The overall impact is increased cereal yield with minimum chemical inputs.
This study compared the diversity of soil microorganisms between long-term maize-Desmodium and maize monoculture plots. It found that long-term maize–Desmodium intercropping causes a complex shift in the composition of the soil microbiome compared to maize monoculture. Maize–Desmodium intercropping diversifies fungal microbiomes and favors taxa associated with important ecosystem functions including plant health, productivity and food safety.
With best wishes,
Third World Network
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LONG-TERM MAIZE-DESMODIUM INTERCROPPING SHIFTS STRUCTURE AND COMPOSITION OF SOIL MICROBIOME WITH STRONGER IMPACT ON FUNGAL COMMUNITIES
Mwakilili, A.D., Mwaikono, K.S., Herrera, S.L. et al.
Plant Soil
14 Aug 2021
https://doi.org/10.1007/s11104-021-05082-w
https://link.springer.com/article/10.1007/s11104-021-05082-w#citeas
ABSTRACT
Purpose
Push–pull is an intercropping technology that is rapidly spreading among smallholder farmers in Sub-Saharan Africa. The technology intercrops cereals with Desmodium to fight off stem borers, eliminate parasitic weeds, and improve soil fertility and yields of cereals. The above-ground components of push–pull cropping have been well investigated. However, the impact of the technology on the soil microbiome and the subsequent role of the microbiome on diverse ecosystem benefits are unknown. Here we describe the soil microbiome associated with maize—Desmodium intercropping in push–pull farming in comparison to long-term maize monoculture.
Methods
Soil samples were collected from long-term maize–Desmodium intercropping and maize monoculture plots at the international centre for insect physiology and ecology (ICIPE), Mbita, Kenya. Total DNA was extracted before16S rDNA and ITS sequencing and subsequent analysis on QIIME2 and R.
Results
Maize–Desmodium intercropping caused a strong divergence in the fungal microbiome, which was more diverse and species rich than monoculture plots. Fungal groups enriched in intercropping plots are linked to important ecosystem services, belonging to functional groups such as mycorrhiza, endophytes, saprophytes, decomposers and bioprotective fungi. Fewer fungal genera were enriched in monoculture plots, some of which were associated with plant pathogenesis and opportunistic infection in humans. In contrast, the impact of intercropping on soil bacterial communities was weak with few differences between intercropping and monoculture.
Conclusion
Maize–Desmodium intercropping diversifies fungal microbiomes and favors taxa associated with important ecosystem services including plant health, productivity and food safety.