RII Track-4: NSF: Bio-inspired Solutions to Prevent Soil Erosion in Farmland and Scouring in Fluvial Regions

Soil erosion has affected the fertility of the land, agricultural productivity, and crop health in many regions of the USA, and climate change is expected to worsen this issue. Traditionally, weak soils have been stabilized by cement or lime; however, such measures are not environmentally friendly and may not be suitable for all types of soils, such as sulfate-rich soils.

Therefore, the biostabilization of soils using biofilms has been proposed to sustainably address these problems. Biofilms are naturally occurring microbial communities enclosed in a protective layer. Biofilm-treated soils are anticipated to bind soil particles together, enhancing strength and reducing soil erosion and scouring.

In this study, problematic soils were treated with biofilms like dental biofilm and sulfate-reducing bacteria (SRB) to increase their strength. These novel biofilms represent the first attempts to enhance soil properties. The higher organic content in biofilms will increase soil fertility and agricultural productivity, allowing for carbon storage in soils, which helps address climate change.

There is significant potential for dental biofilm and SRB to be beneficial in other disciplines, such as developing drought-resistant crops, self-healing concrete, mitigating coastal dune migration, enhancing slope stability, reforestation after wildfires, and more.

This Research Infrastructure Improvement Track-4 EPSCoR Research Fellows (RII Track-4) project will provide a fellowship to an Assistant professor and training for a graduate student at South Dakota State University. This work will be conducted in collaboration with researchers at Arizona State University. The objective of the project is to investigate the feasibility of using dental biofilms and SRB to enhance the strength of soils, thereby mitigating soil erosion and scouring, and improving agricultural productivity and the resilience of civil infrastructure such as embankments and bridges.

The inspiration for this project stems from the observation that dental plaque or biofilms, once hardened, require specialized tools to dislodge them from teeth. If such a process can be replicated to bind soil particles together using dental biofilms, it will result in stronger soils that are resistant to erosion, potentially mitigating scouring near bridge foundations.

SRB is anticipated to remove available sulfate from the soil before the application of lime, which is needed for better crop growth. The absence of sulfate ions in the soil will prevent the formation of highly expansive mineral ettringite, thereby mitigating sulfate-induced heave. A series of strength-based and volume change tests, along with freeze-thaw tests, have been planned to study the feasibility of inoculating these biofilms in soils.

Preliminary studies will be conducted to investigate the increase in soil fertility and the mitigation of scouring using dental biofilms and SRB. The success of these techniques has the potential to be revolutionary and may aid in carbon sequestration. The project will contribute to enhancing our knowledge of soil-biofilm interactions under different climatic conditions by better understanding the rate of growth and optimal conditions required for the attachment and growth of such biofilms, as well as the rate of increase in the strength and moisture retention capacity of bio-stabilized soils.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.