Maintaining and enhancing soil stability for electrical pylon installation is very vital to provide an uninterrupted energy supply. Conventionally, the stability of soil is maintained using the chemical stabilization technique, which has its limitations, is not environmentally friendly, may not provide a stable soil condition in the longer term, is and prone to disruption. Therefore, in this work, a more sustainable approach is suggested where a biomediated technique where microbes from biological degradations of vegetables are used to integrate with polyethylene terephthalate (PET) plastic waste as a soil stabilizer. The findings of the triaxial shear test showed that the treated soil enhanced the soil's resistance to shearing forces by 33% due to the bridging effect and soil interlocking. The combination of 20% of fermented vegetables grout liquid and 1% of PET has improved the soil's cohesion significantly. The slope stability test also proved that the PET additions could improve the factor of safety (FOS) up to 81.47% and exceed the minimum requirement of a stable design slope as compared to the untreated slope. The results proved the influence of the bio-mediated technique with different variations of PET addition is an effective method to improve the engineering properties of the slope.

The processes involved in deformation, internal strength and stability of soils with long-term application of fertilizers (organic and inorganic sources) remain poorly investigated and hence understood, particularly in agricultural systems under subtropical climatic conditions. We investigated how long-term fertilizer management with organic and inorganic amendments in no-till crops affects the microstructural stability of a sandy Alfisol under oscillatory shear. The study was conducted in southern Brazil on a 17-year completely randomized block experiment with five fertilizer treatments: pig slurry (PS), cattle slurry (CS), pig deep litter (PDL), mineral fertilizer (MF) and control, i.e. unfertilized (CL). Soil samples were collected from two layers (0-5 and 5-15 cm) for physical and chemical analyses and evaluation of soil rheological properties under oscillatory shear at two matric potentials (0 and -10 kPa). Organic matter accumulation in soil provided by the PDL and CS fertilizers resulted in higher soil stability and elasticity under oscillatory shear, especially in the 0-5 cm layer. Conversely, MF and PS enhanced the soil susceptibility towards deformation under transient stresses, mainly in the 0-5 cm layer under saturated conditions. The PDL significantly increased soil shear resistance under low-shear strain conditions. Significant differences ceased under high-shear strain conditions, though PS and MF yielded at significantly lower strains. Hence, under subtropical conditions, long-term application of organic fertilizers with fibrous components promoted soil microstructure strengthening, reducing soil susceptibility to erosive processes and compaction.