The five-year project will focus on microbial ecology and hydrology of shrub-crop ecosystems within the Sahel -- a long, narrow strip of land located just south of the Sahara Desert and spanning West Africa from the Atlantic Ocean to Sudan. This agriculturally dependent region is threatened with desertification and soil degradation that reduce crop productivity and negatively impact local communities.
Ohio State’s collaborators in the project include the Institut Sénégalais de Recherches Agricoles (Senegal’s Agricultural Research Institute); France’s Research Institute for Development (IRD); the IRD’s Laboratory of Tropical Microbial Ecology, Senegal; the University of California-Merced; the University of Thies, Senegal; and Central State University, Wilberforce, Ohio.
“In the Sahel, unlike in other semi-arid regions where fields are cleared for agriculture, there are woody shrubs that co-exist with crops because of the lack of mechanized tillage,” said Richard Dick, project director and a professor of soil microbial ecology in CFAES’s School of Environment and Natural Resources. “As a result of our previous NSF-funded research in the region, we have discovered that these shrubs play a key agro-ecological role through hydraulic lifting (transporting water from deep below to the soil surface), which in turn maintains a more diverse and potentially beneficial microbial community and may aid crops during periods of drought.”
The NSF grant will allow in-depth studies on the unique root-soil habitat that occurs because of hydraulic lift by these resilient shrubs (Guiera senegalensis and Piliostigma reticulatum), whose roots can reach up to 30 feet into the wet subsurface. Such water-distribution function allows for biogeochemical processes to continue even during the Sahel’s long nine-month dry season.
Specifically, these studies will profile the shrub rhizosphere (the small region of soil that is directly influenced by plant root secretions and associated soil microorganisms) for its ability to harbor beneficial microorganisms, plant-growth promoters, nutrient inputs and release, drought and disease resistance, which impact adjacent crops. An intriguing investigation, Dick said, will be on the role of mycorrhizal (root) fungi to “connect” shrub and crop roots in order to provide water and nutrients. Other potential benefits to be studied include the shrubs’ role in assisting crops through drought periods and sequestering carbon in the soil.
The project’s fieldwork will be done along a rainfall and ecosystem gradient typical of the Sahel with a multidisciplinary approach that includes microbiology, plant and landscape ecology, soil physics, and hydrology. The research will be accomplished at labs in Senegal, at Ohio State and at the University of California-Merced. Advanced molecular and cellular techniques, such as massive genome sequencing to identify microbial members, will be used to study microorganisms with plant growth-promoting abilities. Among other techniques, the team will employ micrometeorology and soil moisture instrumentation to determine the fate of hydraulically lifted water in soils, crop roots and mycorrhizal fungi.
“If we can understand the hydrology and microbial ecology of these shrub-crop rhizosphere interactions of Sahelian agro-ecosystems, this will provide the foundation to develop optimized cropping systems that can boost agricultural productivity and sustainability,” said Dick, who has more than a decade of experience working in Senegal, on the Sahel’s northwestern edge. “Besides applications for agriculture in other dry environments, we also expect this research could lead to a new way to remediate polluted soils by taking advantage of hydraulic lift to drive microbial degradation of contaminants -- particularly hydrocarbons that are ubiquitous in semi-arid regions such as the Middle East and Texas.”
Another important aspect of the project, Dick said, is the rare and unique opportunity for collaborative state-of-the art research between African and American scientists and students, leading to extremely valuable cross-cultural and educational exchanges. As part of the grant, 20 U.S. early-career scientists will receive advanced training in tropical microbial ecology along with four Ph.D. students and six U.S. undergraduate interns who will be involved in various facets of the research. Central State University, Ohio’s only historically black college, will lead the undergraduate internship research program.
This NSF-funded project adds to CFAES’s recent involvement in the Sahel region. Last year, Dick and collaborators from Senegal’s Université Gaston Berger received a $1.1 million grant from the U.S. Agency for International Development (USAID) and Higher Education for Development (HED) to enhance that country’s agricultural research and outreach capabilities (http://go.osu.edu/CRW).
CFAES has vast experience managing international development, research and outreach projects in many other sub-Saharan nations, including Ethiopia, Ghana, Kenya, Malawi, Mali, Mozambique, Nigeria, Swaziland, South Africa, Tanzania, Uganda and Zambia. This past February, the college received a $24 million USAID grant to boost agriculture and food security in Tanzania (http://go.osu.edu/tanzania).