Enhancing the mechanical and hydraulic properties of coarse quartz sand using a water‐soluble hydrogel based on bacterial alginate for novel application in agricultural contexts

Abstract

Climate change is generating severe changes in the physical behavior of soils (i.e., soil structure, mechanical resistance, and water conductivity), causing negative impacts on different agricultural systems and, therefore, threatening food security. To cope with this situation, hydrogels based on biopolymers have been proposed to modify the mechanical and hydraulic behavior of complex porous materials such as soils, yet most of them are nonsoluble, making their application at field level laborious. In this study, we investigated the effect of a water‐soluble hydrogel based on bacterial alginate on the mechanical and hydraulic behavior of coarse quartz sand. The results from unconfined uniaxial compression test showed that the strength of the sand treated with hydrogel increased by 94.5%, whereas hydraulic conductivity decreased 33%. Interestingly, we observed that bacterial alginate and hydrogel shifted the mechanics of the fluid phase toward a Darcy regime. The aggregate stability tests showed that coarse quartz sand treated with hydrogel displays larger mean weight diameter, reaching 1.5 mm compared with 0.12 mm of the control (i.e., coarse quartz sand). Finally, transmission light microscopy imaging of the hydrogel treatment revealed a new three‐dimensional matrix between the quartz sand particles, changing the microaggregates and macroaggregates and providing a modified structure of the sand material. Our findings suggest that the use of the water‐soluble hydrogel improves the mechanical and hydraulic behavior of coarse quartz sand, allowing better soil conservation against climate change‐related phenomena, and is also potentially applicable in agricultural systems facing water scarcity.

Development of a Xanthan Gum Based Superabsorbent and Water Retaining Composites for Agricultural and Forestry Applications

“…This means that the mixing process was performed efficiently with an effective dispersion of the polymer and the fibers in the water solution. It can be hypothesized that the network of cellulose fibers within the hydrogel structure may lead to a reinforcing and stabilizing effect of the material, when it is applied in the soil [ 64 , 65 ].…”

Biomechanics and hydraulics of Opuntia ficus-indica roots exposed to extreme drought

“…Sampled roots were selected, and each root end were attached to the mini tensile grips using Parafilm® M film (Bemis Company Inc., USA), then inserted into 200 µl micropipette tips and glued with superglue (La Gotita®, FENEDUR S.A., Uruguay) to improve grip. The texture analyzer software was set as follows: pre-test = 0.01 mm s -1 , speed-test = 0.2 mm s -1 , post-test = 0.05 mm s -1 , force = 0.05 N (Barrientos-Sanhueza et al, 2021; Barrientos-Sanhueza et al, 2022). Trigger force were set in force, and the tensile force was recorded in Newton (N) at a yield force of 5 N to record with accuracy the mechanical behavior of treated roots (Barrientos-Sanhueza et al, 2022).…”

“…Toluidine blue O and Sudan Red 7B stained sections were mounted on slides with diH 2 O and glycerol under the microscope, respectively (Cuneo et al, 2016; Cuneo et al, 2020). Finally, stained mounted root sections images were observed and captured with a Leica MC170HD digital camera attached to a Leica DMIL LED inverted microscope (Leica Microsystems, Wetzlar, Germany) (Barrientos-Sanhueza et al, 2022; Barrientos-Sanhueza et al, 2021).…”

Bacterial Alginate-Based Hydrogel Reduces Hydro-Mechanical Soil-Related Problems in Agriculture Facing Climate Change

“…However, soil physical properties can be lost by (1) slaking, (2) dispersion, (3) mechanical disturbance and (4) compaction [ 4 ]. Slaking is the breakdown of aggregates at macroscopic level into small fragments [ 5 ], and soil aggregate resistance to slaking depends on the internal configuration of soil particles matrix, organic matter and cementation (e.g., bacterial EPS, hyphae, active humus and recently, biopolymers) [ 4 , 6 , 7 ]. While slaking is a macroscopic breakdown, dispersion is the total breakdown of aggregates into primary particles (i.e., clay, silt, sand and organic materials) [ 4 , 7 ].…”

“…This type of material has been used in different human activities such as construction, biomedical engineering, the food industry and agriculture [ 10 , 11 , 19 , 20 , 22 ]. In our previous study, we used calcium as the covalent crosslinking agent to improve the ionic gel strength, and as a result the mechanical and hydraulic properties or coarse-quartz sand were greatly improved by adding the Ca-alginate hydrogel [ 7 ]. However, it is unclear whether these results could be expanded to different textured soils subjected to different conditions of water content and temperature.…”