Author(s)

Jonathan Alunge Metuge¹, Jean Rugandirababisha¹, Erneste Havugimana¹, Ernst Cebert², Umuraza Noella Rutayisire¹, Zachary Ngewoh Senwo^1*

¹Department of Natural Resources and Environmental Sciences, Alabama A & M University, Normal, AL, USA.
²Winfred Thomas Agricultural Research Station, Alabama A & M University, Normal, AL, USA.

Extracellular polymeric substances (EPS) derived from microorganisms have been shown to improve soil physical properties and used for soil erosion control. Due to their ability to enhance plant nutrient uptake, it was postulated that they could serve as a valuable natural resource to improve agricultural productivity. Black-eyed peas (BEPs) were planted in a field experiment on a Decatur silt loam soil amended with Rhizobium tropici-derived EPS, and their effects were evaluated on certain soil fertility indices, plant growth, and development potentials. The EPS increased soil CO₂ flux and microbial biomass compared to the control (unamended soil). Soil microbial population shifted towards Gram-negative bacteria at the initial stages of applications and plant growth, and subsequently towards Gram-positive bacteria in the amended soils. The active carbon, total soil N, soil nitrate, and available phosphorus were higher in soils amended with EPS compared to the control. The applied EPS increased several plant growth parameters, including stem height, branches per plant, leaf area index, root length, leaves per plant, and leaf chlorophyll content. Plants’ seed yields increased by 22% compared to the control, while the shoot biomass and root nodules counts per plant increased by 38.1% and 51.5%, respectively.

Extracellular Polymeric Substances (EPS), Black-Eyed Peas (BEPs), Rhizobium tropici, Plant Growth, Seed Yield, Microbial Biomass

Metuge, J.A., Rugandirababisha, J., Havugimana, E., Cebert, E., Rutayisire, U.N. and Senwo, Z.N. (2025) Field Evaluations of Rhizobium tropici Extracellular Polymeric Substances on Soil Fertility Indices, Plant Growth, and Development. Agricultural Sciences, 16, 609-628. doi: 10.4236/as.2025.167039.