Soil Improvement Techniques Research Articles

Stiffness Characteristics of Pile Models for Cement Improving Sandy Soil by Low-Pressure Injection Laboratory Setup

Soil improvement has developed as a realistic solution for enhancing soil properties so that structures can be constructed to meet project engineering requirements due to the limited availability of construction land in urban centers. The jet grouting method for soil improvement is a novel geotechnical alternative for problematic soils for which conventional foundation designs cannot provide acceptable and lasting solutions. The paper's methodology was based on constructing pile models using a low-pressure injection laboratory setup built and made locally to simulate the operation of field equipment. The setup design was based on previous research that systematically conducted unconfined compression testing (U.C.Ts.). The soil improvement techniques were investigated by injecting a low-pressure mixture of water and ordinary Portland cement (O.P.C.) with (0.8, 1, and 1.3) W/C ratios. The study revealed the relationship between pile model samples (U.C.Ts.) and W/C ratios. It also showed that the pile model samples' (U.C.Ts.) result decreased from 14 to 12 to 10 MPa, respectively, with an increase in W/C ratios from 0.8 to 1 and 1.3, respectively. Furthermore, the stiffness characteristics of a jet grouting column were calculated based on Mohr's Circles theory, and numerous theoretical approaches obtained the consequences of tensile strength.

Comparison between cement and chemically improved sandy soil by column models using low-pressure injection laboratory setup

Abstract The jet grouting method for soil improvement represents an innovative geotechnical alternative for problematic soils when the classic foundations’ designs cannot be appropriate, sustainable solutions for these soils. This study’s methodology was based on producing column models using a low-pressure injection laboratory setup designed and locally manufactured to approximate the field-equipment operation. The setup design was inspired by the works of previous researchers, where its functioning was validated by systematically performing unconfined compression tests (UCTs). Two soil improvement techniques were investigated, one by low-pressure injection of a mixture of water and ordinary Portland cement (OPC) with 0.8, 1, and 1.3 W/C ratios. The other type uses silica fume (SF) as a chemical additive with 10% of the cement weight added to the water and cement mix with 1, 1.3, and 1.6 W/C ratios. The study revealed that the UCT results of SF column model samples were higher than those of OPC with an equal W/C ratio. For each binder type, the UCT sample results increase with a decrease in the W/C ratio.

Numerical investigation of the performance of the 3-sided impact roller

Rolling dynamic compaction (RDC) is a soil improvement technique, which involves towing heavy (6–15 t), non-circular (3-, 4-, and 5-sided) modules behind a tractor to achieve soil compaction. Both potential and kinetic energies are imparted to the underlying soil as the modules fall and impact the ground. This paper presents a combined, three-dimensional finite element method (FEM)-discrete element method (DEM) model to investigate the behaviour of the 1:13 scale, 3-sided roller. Numerical results are compared against results from a field study using the corresponding full-size, 3-sided roller in two aspects namely, ground settlements and induced peak pressures. It is demonstrated that the numerical results are in very good agreement with the field observations. This paper examines the influence of the twin modules of the 3-sided roller with respect to ground improvement and the results suggest that the soil beneath a single module is improved solely by the module above it. Therefore, the current practice of using the total weight of the 3-sided roller to predict the energy imparted to the ground and the depth of influence should be avoided. The validated numerical model is also used to predict the energy delivered to the soil and the depth of influence of the roller. The energy imparted to the ground is approximately 22.5 ± 3 kJ per impact with 95% confidence, and the depth of influence is approximately 1.5 m for each of the twin modules of the 13-t, 3-sided roller operating at 11 km/h on granular soils investigated in this study.

Soil bio-cementation treatment strategies: state-of-the-art review

Bio-cementation is a new sustainable approach that has gained popularity due to its low energy and carbon dioxide footprint compared with those of existing technologies for geotechnical and geoenvironmental engineering applications. Bio-cementation is a soil improvement technique that involves binding the pore space of soil particles with calcium carbonate minerals by microbially induced carbonate precipitation (MICP) and filling the soil pore space. The purpose of this paper is to present the current state of the art and a comprehensive discussion on the development of bio-cementation for soil improvement/reinforcement. Premixing, injection, immersing and surface percolation are identified as four distinct bio-cementation treatment techniques. Furthermore, scholars have reported employing ureolytic bacteria such as Sporosarcina pasteurii, Bacillus sphaericus and Lysinibacillus sphaericus isolated from corals, limestone caves, soils, waste materials, seawater and other sources to accomplish effective bio-cementation. Some of the major issues (bacterial cultivation costs and ammonium production) that impede its industrial potential and promising remedial techniques are also discussed. This state-of-the-art review also discusses the benefits and drawbacks of bio-cementation compared with traditional approaches. The significance of enzyme-induced carbonate precipitation as a soil bio-cementation alternative to MICP is also highlighted. Finally, the sustainable procedure, bio-cementation principles and future implications are discussed.

Compressibility characteristics of bio-cemented calcareous sand treated through the bio-stimulation approach

Calcareous sand is widely present in coastal areas around the world and is usually considered as a weak and unstable material due to its high compressibility and low strength. Microbial-induced calcium carbonate precipitation (MICP) is a promising technique for soil improvement. However, the commonly adopted bio-augmented MICP approach is in general less compatible with the natural soil environment. Thus, this study focuses on the bio-stimulated MICP approach, which is likely to enhance the dominance of ureolytic bacteria for longer period and thus is deemed more efficient. The main objective of this paper is to investigate the compressibility of calcareous sand treated by bio-stimulated MICP approach. In the current study, a series of one-dimension compression tests was conducted on bio-cemented sand prepared via bio-stimulation with different initial relative densities ( D r ). Based on the obtained compression curves and particle size distribution (PSD) curves, the parameters including cementation content, the coefficient of compressibility ( a v ), PSD, relative breakage ( B r ), and relative agglomeration ( A r ) were discussed. The results showed that a v decreased with the increasing cementation content. The bio-cemented sand prepared with higher initial D r had smaller (approximately 20%–70%) a v values than that with lower initial D r . The specimen with higher initial D r and higher cementation content resulted in smaller B r but larger A r . Finally, a conceptual framework featuring multiple contact and damage modes was proposed.

Implementation of eggshell extracted calcium acetate in biocementation via soybean urease

Biocementaion, a promising soil improvement technique, mostly utilizes calcium chloride (CaCl2) as its calcium source. However, using CaCl2 poses a critical environmental problem of producing ammonium chloride as a by-product. Alternatively, when calcium acetate (Ca(CH3COO)2) is used as the calcium source, the production of ammonium chloride during biocementation can be reduced. Ca(CH3COO)2 can be easily derived from waste eggshells. Nevertheless, such research has been conducted only with Microbial Induced Carbonate Precipitation (MICP) to date. This paper aims to study the implementation of eggshell Ca(CH3COO)2 in the more effective biocementation approach: Enzyme Induced Carbonate Precipitation (EICP) via soybean urease. For this study, EICP solutions of varying molar ratios and concentrations were studied for their precipitation efficiency and reinforcement effect on poorly graded sandy soil. The findings showed that the EICP solution composition of 1:1 molar ratio between Ca(CH3COO)2 and urea, added with 50 g/L soybean solution reached the maximum precipitation efficiency. It also produced the highest 7-day UCS of 371 kPa at a calcium carbonate content of 0.40%. Furthermore, the eggshell-soybean EICP produced 8.5% higher UCS than CaCl2-soybean EICP despite having similar calcium carbonate content.

ANALISIS PERBAIKAN TANAH LEMPUNG LUNAK MENGGUNAKAN GEOTEXTILE (STUDY KASUS PEMBANGUNAN JALAN LINGKAR TUBAN STA 9+050 – 9+075)

Soil is a material that has a significant influence on the performance of building construction. Soil improvement techniques are soil stabilization measures by improving the characteristics of the original soil, to meet the technical requirements required by the construction, such as increasing the bearing capacity and shear strength of the soil, reducing soil compressibility, increasing or decreasing soil permeability, and so on. In the Tuban Ring Road Development Project, there are soft clay soils at STA 9+050 – 9+075, where the subsidence was seen after placing selected embankments 30 cm thick. The analysis used in this study uses the geotextile method as an alternative to reinforcement at STA 9+050 – 9+075 in the Tuban Ring Road Development project. From the data obtained it is known that the soil appears to be soft soil. The type of geotextile used is UW-250 with a strength capacity of 5.20 t/m which serves as a separator for the reinforcement of the Tuban Ring Road Development Project at STA 9+050 – 9+075. Based on the data analysis performed, it can be concluded that the amount of settlement that occurs due to loads on soft soil at STA 9+050 – 9+075 is 57.35 cm and the consolidation time obtained is 190.311 years. The length of the geotextile (L) planted at STA 9+050 – 9+075 in the Tuban Ring Road Development project is 9.884 m installed in 1 layer. The value of Safety Factor (SF) on soil with selected embankments and geotextile reinforcement at STA 9+050 – 9+075 is 2.7, so it is known that the use of geotextile as an alternative to soft soil improvement at STA 9+050 – 9+075 in development projects Tuban Ring Road.

Compressibility Characteristics of an Organic Soil Treated with Fly Ash and Fly Ash-Based Geopolymer

Organic soils are problematic soil for various engineering applications due to their high compressibility and low shear strength which need to be improved. For many soil improvement techniques, using waste materials, such as fly ash (FA), is a practical and sustainable process. In this research, FA and geopolymer were used e used to reduce organic soil's compressibility. A one-dimensional consolidation test was performed to evaluate the organic soil's consolidation and compressibility properties. The geopolymer was prepared using 20% FA and of sodium hydroxide ratio and sodium silicate alkali solutions. The geopolymer specimens were first cured for 2 hours at 45 and 65 oC, then cured for further 28 days at room temperature. The consolidation test results showed that FA-based geopolymer is effective in stabilizing organic soils due to the observed improvement in the compressibility, consolidation, and permeability characteristics. The compression index decreased by 98.16%, and the permeability decreased by 95%.

Effects of initial static shear stress on cyclic behaviour of sand stabilised with colloidal silica

Colloidal silica (CS) grouting is a soil improvement technique introduced as an innovative remedial measure against seismic liquefaction. It consists of injecting soils with a time-hardening, nanosilica-based solution forming a silica gel among soil particles. This paper presents the results of an experimental study on the effects of an initial static shear stress on the behaviour of a cyclically loaded clean sand stabilised with 5% CS. Undrained cyclic triaxial tests were performed to analyse the cyclic response of loose untreated and stabilised sand specimens, isotropically or anisotropically consolidated at the same initial mean effective stress. The consolidation stage was used to provide insight on the compressibility of stabilised soil. Stress–strain behaviour, pore water pressure response and cyclic shear resistance were investigated. The results showed that: (i) stabilised sand exhibits higher compressibility than the untreated one during isotropic consolidation; (ii) cyclic strength is higher for stabilised sand than for the untreated one, increasing as the degree of anisotropic initial stress increases; and (iii) extra pore water pressure development does not depend on the degree of initial anisotropy for stabilised sand, while the same does not hold for untreated sand. Simplified relationships are proposed to describe the consolidation process and the residual extra pore water pressure build-up process.

3D DEM modeling of biocemented sand with fines as cementing agents

AbstractMicrobially induced calcium carbonate precipitation (MICP) has attracted much attention as a promising green technique for soil improvement. Despite the significance of precipitation pattern in mind, constitutive relations or numerical models considering the finite‐strain mechanical effects of the various precipitation patterns are rarely developed. In this paper, we propose a novel 3D DEM modeling scheme by using coarse particles to represent sand grains and fines as cementing agents, to reproduce the various precipitation patterns in MICP‐treated sand. Based on the topological relations with adjacent particles and the contribution to the mechanical improvement, the cementing fines are classified into effective, partially effective, surface coating, and pore filling ones. The microstructural characteristics and their evolution upon external loading are investigated quantitatively after a careful calibration and validation. The microstructural variation in experiments can be well reproduced, pinpointing this variation as a possible cause for the fluctuation in experimental data. Massive coating fines are produced accompanying the microstructural degradation, which is initiated by the breakage of effective bonds. The breakage of partially effective bonds may become dominating later in the medium to strong cemented specimens. One weakly cemented specimen shows diffuse failure with simultaneous bond‐breakage and friction. In contrast, the medium to strong cemented specimens show localized failure with the dominating mechanism transiting from bond‐breakage to friction producing notable pore filling fines. We propose a relation between unconfined compressive strength and the equivalent effective volume fraction of cementing agents normalized by the pretreatment porosity, which reveals the coupling effects of the initial configuration and the precipitation pattern on the mechanical improvement.

Application of technical grade reagent in soybean-crude urease calcite precipitation (SCU-CP) method for soil improvement technique

Soybean crude urease-calcite precipitation (SCU-CP) is a potential method as a sustainable and economical soil improvement technique. This method begins with developing the bio-cementation method that has successfully increased soil strength. The use of laboratory-grade material is high-cost for large-scale. The applicability of original soybean material combined with technical grade reagent in SCU-CP was discussed, considering its relevance for a larger scale treatment. The hydrolysis rate, test-tube experiment, and X-Ray Diffraction (XRD) test were conducted to evaluate the entire material's potential for the calcite precipitation method considered for precipitation materials. This study shows that low-cost soybean material and technical-grade reagents have a good level of effectiveness for calcite production. The low-cost material of soybean 20 g/L produced the highest hydrolysis rate of 331.701 u/g. Technical-grade reagent with a concentration of 1 mol/L was proven effective compared to laboratory-grade with a precipitation ratio of 114.44%. XRD results showed that the highest calcite formation was in technical-grade samples using soybean Gasol with a crystallinity of 40.25%. Unconfined compressive strength (UCS) results showed that the original soybean has a higher value than other solutions, which is 66.18 kPa in 14 days. Therefore, technical-grade materials are more economical with 100% cheaper than laboratory-grade. The result of this study elucidated that SCU-CP has a high potential to be an economical, sustainable and effective soil improvement technique.

Improving Very High Plastic Clays with the Combined Effect of Sand, Lime, and Polypropylene Fibers

Improving the mechanical properties of low-strength soils (e.g., high plasticity clays) is one of the main branches of geotechnical engineering. The adoption of stabilization techniques for ensuring that structures will be founded on an adequately strong soil base is a common practice. Stabilization techniques for clay soils may include inert materials (cohesionless soils), chemical substances (cement, lime, or industrial additives), or the use of randomly distributed fibers. While all of these additives are added to low-strength soils by mixing, the question remains whether an optimal combination of stabilization techniques can be achieved for maximizing soil strength. Besides, each one of these additives contributes to an increase in soil strength in a different manner (soil replacement, chemical bonding of soil particles, and soil reinforcement respectively), while, according to the literature, each technique has its limitations. The latter refers to a limited effect on strength improvement and a maximum possible percentage, beyond which an additive has an adverse effect on strength; it also refers to other factors, such as brittleness failure, material availability, overall cost, and environment-related issues. Hence, in the present study, the efficiency of improving the basic geotechnical properties of a very high plasticity clay (liquid limit ωl = 86%) with a coupled effect between dune sand, lime, and polypropylene (PP) fibers has been investigated. The samples prepared by combining the three aforementioned soil improvement techniques were compared in terms of plasticity, compaction characteristics, unconfined compressive strength (UCS), and California Bearing Ratio (CBR) index. The experimental results show that the combination of these additives may lead to a considerable improvement in the strength and ductility of soils, even with a small amount of lime additive. Also, it was observed that 20% of sand, 3.4% of lime and 0.9% of fibers (by wt%) offers the best performance in terms of strength improvement for the clay tested (i.e., 12.75 times improvement compared to the untreated clay).

A Systematic Framework for Evaluating the Effectiveness of Dynamic Compaction (DC) Technology for Soil Improvement Projects Using Cone Penetration Test Data

Despite recent innovations in soil improvement techniques, it remains difficult for project managers to select the most appropriate technique for soil improvement projects due to the lack of a reliable and systemic framework that may support the decision-making process. Therefore, the aim of this paper is to introduce a new systematic assessment framework that establishes reliable criteria for the selection of dynamic compaction (DC) technology, evaluates its effectiveness using Cone Penetration Test (CPT) data, and predicts the expected improvement in soil bearing capacity (Qc). The proposed framework uses zone-based soil categorization in conjunction with soil behavior type index (Ic) and CPT data to predict the expected improvement in soil bearing capacity after the implementation of the DC technique. In addition, a case study is used to highlight the applicability and the effectiveness of the proposed framework in evaluating the suitability of the DC technique and in predicting the expected improvement in the bearing capacity of soil. The results show that the DC technique is appropriate when the soil has a behavior type index of Ic ≤ 1.31, 1.31 < Ic ≤ 2.05, 2.05 < Ic ≤ 2.6, 2.6 < Ic ≤ 2.95 and Ic > 2.95, and the expected improvement in soil bearing-capacity (Qc) is within the range of [+20, +∞], [15–20], [5–15], [1–5] and [0–1] MPa, respectively.

Electricity-reaction–diffusion system for microbially induced carbonate precipitation

Microbially induced carbonate precipitation (MICP) has attracted attention as a novel soil-improvement technique. The precipitation and growth of calcium carbonate on the surface of sand and in its pores can be simulated using the recently proposed numerical simulation techniques. However, these simulations have not incorporated certain parameters, such as electrical properties and adsorption. The current study proposes a novel coupling system that considers the adsorption of microorganisms and dissolved ions due to the weak electrostatic field generated on the surface of sand. Additionally, the Michaelis–Menten model was introduced into the system for the enzymatic reaction of ureolytic bacteria, the Monod model for bacterial growth, and a chemotaxis model. To validate the proposed simulation model, previously reported experimental and computational results were compared with the suggested simulation results. Consequently, the calcium carbonate precipitation obtained with the simulation model was 0.335 μmol/mm3 at 10.3 h, which is close to that obtained by the experiment of 0.315 μmol/mm3. Moreover, the spatial distribution of calcium carbonate was consistent with the precipitation pattern of the active bonding structure obtained by the traditional experiment.

Mitigating the risks of climate variability and change on mango seedlings in Ghana: Evidence from mango seedlings producers in the Yilo Krobo Municipality

While adaptation interventions offer a window of opportunity to mitigate the susceptibility of mango seedlings to adverse impact of climate variability and change, there is a scarcity of information on how mango seedlings producers respond to climate variability and change in Ghana. Using a qualitative case study with 20 mango seedlings producers selected through purposive and snowball sampling techniques, this study investigates participants’ knowledge and experience of climate variability and change, the effects of the observed changes on mango seedlings and the adaptation strategies employed to counter the risks associated with climate variability and change in a mango production zone of Ghana. Results indicate that floods, droughts, rising temperature, erratic rainfall and windstorm have been observed among the participants, which negatively affect the survival, growth, establishment and quality of mango seedlings. Adaptation strategies, such as creating gutters, applying agrochemicals, grafting and improved seed varieties, planting of trees as shades, irrigation and soil improvement techniques including mulching, have been implemented by the participants to mitigate climate variability and change effects. The practical and policy implications of the results are discussed and recommendations provided.

Field experiment of cement-modified loess

The construction of a compacted and stabilized layer with local soil from the excavation, mixed with Portland cement, is a soil improvement technique widely applied in foundation works in collapsible loess ground in Bulgaria. Commonly, the role of that cement-modified layer is to replace a part of the collapsible ground, to increase the bearing capacity of the soil base, and/or to be an engineering barrier against migration of harmful substances in the geoenvironment. A multi-barrier near-surface short-lived low- and intermediate-level radioactive waste repository is under construction in Bulgaria. A cement-modified soil layer beneath the disposal cells is going to be built by in-situ compacted mixture of local loess and Portland cement. The cement-modified layer (indicated as loess-cement cushion) is not a continuation of the foundation, but it is a part of the soil base and performs two main functions: to be an engineering barrier against eventual migration of radionuclides in the geoenvironment and to increase the bearing capacity to restrict deferential settlement of the soil base. The present paper describes a field experiment aiming to verify the strength and deformation characteristics of a selected optimum loess–cement mixture by implementation of in-situ cement-modified loess ground. After 28-day curing at in-situ conditions, the loess-cement did not exhibit any fissuring or other disturbances. The allowable bearing capacity qa of the cement-modified loess ground exceeded 900 kN/m2, and it possessed the following strength and deformation characteristics: deformation (plate) modulus EPLT = 500 MPa; coefficient of sub-grade reaction ks = 2158 МPa/m, and unconfined compressive strength qu = 2.00 MPa.

The Effect Of Microbially Induced Calcite Precipitation (MICP) On Shear Strength Of Coal Contaminated Soil

Microbially induced calcite precipitation (MICP) is a soil improvement technique using microorganisms that can change and improve mechanical properties. This technology has been explored and is promising with potential in a variety of applications. Bacillus subtilis bacteria as much as 6% were added to soil contaminated with 5%, 10%, and 15% coal. The bacteria used were cultured for 3 days in growth medium. In this study, a direct shear test was used to determine the effect of calcite deposition on the behavior of the shear strength of coal contaminated soil. The results showed that there was an increase in the value of cohesion and internal friction angle as parameters of shear strength after the curing period. MICP stabilization in soil contaminated with 5% coal resulted in an increase in shear strength of three times, while in soil contaminated with 10% and 15% coal there was an increase in shear strength of seven times and fifteen times, compared to the untreated soil

Study on Strength and Swell Behavioral Change and Properties of the Clay–Fiber Mixtures

Clayey soils are spread over large areas of the world. This soil type has numerous problems due to its low strength, high compressibility, and high level of volumetric changes. To overcome these difficulties, many researchers have concentrated their studies on soil improvement techniques. Recently, soil reinforcement has been considered an effective and reliable technique for improving the strength and stability of these soils by using different types of reinforcing materials. This paper aims to investigate the feasibility of using polypropylene fiber as a low-cost and environmentally friendly reinforcing material for high plasticity clay, and assess the strength and swelling behavioral change with fiber content to determine the optimum fiber content that meets the effective improvement rate. A series of laboratory experiments such as a direct shear test, swell test, and unconfined compressive strength (UCS) test were carried out to evaluate the fiber content effect on the strength and swell behavior of composite clay (clay mixed with fiber). The fiber content varied from 0% to 1.5% (by dry weight of the soil). The results show that the inclusion of fiber affects the shear strength (an average increase of 184% at 1.5% fibers), and unconfined compressive strength (an increase of 86% at 1.5% fibers). Likewise, the increase in fiber content causes an increase in the strength properties, cohesion, and friction angle (257% and 62% at 1.5% fibers, respectively). Also, the increase of fiber content causes a decrease in both swelling potential and swell stress (a decrease of 24% and 46% at 1.5% fibers, respectively) in the studied clayey soil.

Numerical analysis of drained compression behavior of fiber-reinforced sand based on a soil skeleton structure concept

Reinforcing soils with tension resisting elements is an alternative soil improvement technique confirmed by a series of experimental studies. Fiber reinforcement has advantages in increasing the soil strength and improving the stability of geo-structures. In order to describe and assess the effect of fiber inclusions in soils a suitable constitutive equation is necessary with considering different testing conditions (drainage characteristics, density, applied stress, etc.). In this study, the super/subloading yield surface Cam-clay model (SYS Cam-clay) was used to reproduce the experimental results of drained triaxial compression tests performed under different confining pressures with varying initial relative densities of both unreinforced and fiber-reinforced sand. The reproduced results were in good agreement with experimental results. Both simulated and experimental results showed that an increase in fiber content led to decrease in initial stiffness and increase in initial volumetric compression. This was attributed to the lower initial anisotropy of reinforced sand due to the fiber inclusions. Furthermore, the simulation results indicated that the fiber inclusions inhibited the development of anisotropy compared to unreinforced sand. Consequently, a higher peak and post-peak stresses with increased critical state parameter M, and less volumetric expansion at higher strain rates observed in fiber-reinforced sand.

Soil Element Assessment in Organic Paddy Fields in the Thung Kula Ronghai Zone, Thailand

Organic rice production (ORP) has been promoted as a means of sustaining both farmers and the ecology of paddy fields, so this research aims to evaluate soil properties and soil elements in the ORP and general rice production (GRP) systems in the Thung Kula Ronghai (TKR) zone in Thailand. Soil samples were collected in Roi-et province from fields classified as ORP (5 fields) or GRP (4 fields), and interviews were also conducted with the field owner about rice yield and rice production. Data from the ORP and GRP groups were compared by t-test, and soil enhancement practices were measured by one-way analysis of variance (ANOVA) for variances. Results indicate there were 14 indicators of soil element control in the TKR. All indicators in the ORP and GRP systems were lower than the rate in soil that is suitable for rice production. The macroelement content in the TKR zone was total nitrogen > total potassium > phosphorus available at a ratio of 338: 3: 1, and the soil organic matter (SOM)/soil organic carbon (SOC) ratio is about 3.45. The soil improvement techniques used in the ORP systems—manure only and manure combined with green manure—have a higher pH value (p < 0.05) than the fertilizer only input but a lower TK value (p < 0.05) than the fertilizer only input. As a result, the ORP yield was higher than that of the GRP systems (p < 0.05), greatly affecting farmers’ practices.