The potential benefits and trade-offs of using sub-surface water retention technology on coarse-textured soils: Impacts of water and nutrient saving on maize production and soil carbon sequestration uri icon

abstract

  • In Sub-Saharan Africa (SSA), many smallholder communities continuously grapple with soil-based poverty as the coarse-textured (sandy) soils, on which they eke out a living, have low water and nutrient retention capacities. The new sub-surface water retention technology (SWRT), which is based on the subsurface installation of impermeable water-retaining membranes of linear and low-density polyethylene, reduces the amount of water and nutrients lost through deep percolation especially on coarse-textured soils. In this study, we used stochastic simulations on the diffusion of SWRT on coarse-textured soils in eight different Eastern and Southern African countries. Using results from previous research on SWRT we estimated increases in maize grain yields and biomass accumulation. Results from the most promising diffusion scenarios suggested that with 20 years of widespread adoption of SWRT regional maize production could increase by 15 and 50 million tons per season. Carbon sequestration could reach 15 tons around 22 years after implementation (YAI) for the best diffusion scenario because of increased biomass production following SWRT adoption. The increased grain yield and carbon sequestration are limited by the initial state of SWRT adoption, which we expect will be based on the extent of awareness and promotional campaigns conducted by governments and development practitioners. While our results suggest synergistic reductions in the rate of water and nutrient loss from crop root zones, SWRT is characterized by high initial financial and labor investment costs, which without effective financial support, would be prohibitive to uptake by the generally resource-limited smallholder farmers working on sandy soils. Moreover, as SWRT is new, there is a need for more dissemination efforts to increase awareness on the technologies amongst extension workers, decision-makers, and agricultural investors that can promote and incentivize the adoption of this technology in areas where agricultural productivity is constrained by coarse-textured soils.

publication date

  • 2019
  • 2019