The potential of crop genotype selection to enhance soil health and sustainable cycling of SOM

Dr Lumbani Mwafulirwa1, Dr Eric Paterson2, Prof Tim Daniell3, Dr Jill Cairns4, Dr Christian Thierfelder4, Prof Liz Baggs1

1University of Edinburgh, Edinburgh, United Kingdom, 2The James Hutton Institute, Aberdeen, United Kingdom, 3The University of Sheffield, Sheffield, United Kingdom, 4CIMMYT Zimbabwe, Harare, Zimbabwe

Rhizosphere microbiomes can enhance the contribution of soil organic matter (SOM) to soil fertility and resilience to drought. Thus, exploiting plant-associated microbiomes is a likely route to sustainable agricultural production contributing to sustainable development goals (SDGs), especially SDG 2 (zero hunger), SDG 1 (no poverty) and SDG 3 (good health and well-being). In particular, understanding how plant influence on rhizosphere microbiome relates to nutrient and water use efficiency and SOM stocks can help inform selection of plant species and cultivars for desired function. To this end, we are investigating plant impacts on C and N cycling in maize-based cropping systems in southern Africa to help ensure sustainable food production. In stage one, we characterized six field trial sites in Zimbabwe for soil physical-chemical and microbial properties. In stage two, we applied ¹³CO₂ labelling to 105 maize genotypes to assess the impacts of cultivars on SOM mineralization. This informed selection of 7 cultivars that we are using for in-depth functional characterization in stage three, where ¹⁴NH₄¹⁵NO₃ labelling and molecular techniques were applied to investigate nitrification potential and the soil microbial groups undertaking this process, respectively. Characterization of field sites showed strong variation in soil properties, such as organic matter content, microbial biomass C, pH and cation exchange capacity, by site and management such as conservation agriculture practices. Soil respiration measurements revealed cultivar-specific effects on SOM derived-C respired as CO₂, indicating a strong control of maize genotype on SOM mineralization. This work could benefit nutrient use efficiency through cultivar selection and SOM management, and help ensure maize yield stability, resilience to low nutrient availability and drought and, in turn, improve food security in southern Africa, where maize is the main staple food crop and its productivity remains low.


Lumbani Mwafulirwa works in the Global Academy of Agriculture and Food Security at the University of Edinburgh as a Research Fellow studying soil microbial populations and the processes they undertake to gain in-depth understanding of root-soil interactions underpinning soil health and sustainable crop production, working closely with project partners at the James Hutton Institute, University of Sheffield and CIMMYT Zimbabwe. He obtained a PhD in Soil Science from the University of Aberdeen in 2017. He previously worked at the International Institute of Tropical Agriculture (IITA) in Malawi as a research associate.

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