Succour may be in the offing for smallholder farmers in sub-Saharan Africa facing the challenges of poor soil, thanks to a new technology that can enrich fields without massive investments in irrigation and fertiliser.
Modelled for eight African countries, and currently being tested in Zimbabwe, the technology shows potential for substantially improving harvests through increased water retention and accumulation of organic material to make soils more fertile.
Farmers across sub-Saharan Africa are wont to coax crops out of sandy soils that seem not ideal for holding water and nutrients, leading in most cases to poor harvests. A traditional approach would have them apply more fertilisers and use irrigation, but both options require access to resources and infrastructure that many of them do not have.
But the relatively new, somewhat simple and cost-effective technology consists of long strips of polyethylene membranes installed in a U-shape below and near the root zones of crops. Known as subsurface water retention technology (SWRT), these membranes are said to have been used in different soils in other regions of the world, according to the International Centre for Tropical Agriculture (CIAT).
Projected results showed that the SWRT could increase maize yields in the eight African countries in the study by close to 50 percent and capture some 15 million tons of carbon in 20 years.
“With this new technology, sandy soil has the potential to lead a new green revolution,” said George Nyamadzawo, a professor at Bindura University in Zimbabwe.
The researchers said the technology, if deployed and adopted at scale, could address major issues facing sub-Saharan African farmers, including food security and erratic rainfall patterns, while also helping countries meet climate change mitigation targets.
The study was published in Frontiers in September 2019.
For the study, SWRT was modelled for the sandy soils of eight countries in Southern Africa and Eastern Africa: Angola, Botswana, Kenya, Namibia, Mozambique, South Africa, Tanzania, and Zimbabwe.
The main objective of the study was to model scenarios of adoption of SWRT and estimate increases in maize yields, crop biomass, and soil carbon sequestration.
Co-authors include scientists at the Swedish University of Agricultural Sciences (SLU), in Sweden; Jomo Kenyatta University of Agriculture and Technology, in Kenya; Cape Peninsula University of Technology, in South Africa; Bindura University of Science Education, in Zimbabwe; and Michigan State University (MSU), in the United States.
“Potential benefits are obvious with new technologies such as SWRT, but there is a need to overcome non-technical barriers; this requires support from decision-makers who can put in place the necessary policies and financial mechanisms to support farmer adoption,” said Libère Nkurunziza, the lead author and researcher at SLU. “Similar technologies should be tested and adapted to smallholder farmer conditions to solve productivity challenges on sandy soils.”
Using data collected in other regions where SWRT has been tested, the authors made their projections for Africa. The technology is now being tested in Zimbabwe, through a new Swedish Research Council-funded project, called Productive Sands, that is being led by SLU.
“The new innovative, long-term SWRT will lead the way for modifying soils that best assist plant resilience to changing climates and associated weather patterns, enabling smallholder farmers of sandy soils to establish reasonable nutritious food supplies and annual income across all nations,” said Alvin Smucker, a co-author from MSU and one of the pioneers of the technology.
“This fabulous contribution constitutes another great example of the need for increasing public and private investments in applied research on new agronomic practices and particularly those focusing on the management of soil fertility as an effective and efficient way of securing food production as well as sequestering carbon,” said Ruben Echeverría, the Director General of CIAT. “Congratulations to the authors for the research results and for building a great research partnership.”