Rapid detection method for improving effect of soil conditioner on water retention of loess

Abstract

The application provides a rapid detection method for the water retention improvement effect of soil improver on loess, which comprises the following steps: preparing a test soil sample and an improver; preparing a standardized soil column; setting water saturation and initial moisture content; dynamically monitoring in a simulated evaporation environment; data processing and evaluation index calculation; collecting volume moisture content data at each time point, drawing a water evaporation dynamic curve, calculating multi-dimensional evaluation indexes, comparing the evaluation indexes of each treatment group and a control group, and judging the water retention efficiency of the soil improver and the optimal addition ratio.

Description

Technical Field

[0001] This invention relates to the field of soil and water conservation and soil improvement technology, specifically to a rapid detection method for improving the water retention capacity of loess using soil conditioners. Background Technology

[0002] During the construction of infrastructure projects such as power transmission and transformation projects, large-scale land disturbance further exacerbates the risks of soil erosion and ecological degradation. In order to restore vegetation and stabilize slopes, soil conditioners are often added to improve the physical structure of loess, enhance its water retention capacity and erosion resistance.

[0003] Currently, the methods for evaluating the effect of soil amendments on improving the water retention capacity of loess typically rely on long-term field trials or indoor pot experiments, using methods such as periodic weighing and measurement of water content changes. While these traditional methods yield relatively reliable results, they generally suffer from problems such as long experimental cycles, cumbersome operations, significant susceptibility to environmental factors, and poor repeatability, making it difficult to meet the needs of engineering practice for rapid, efficient, and standardized evaluation of amendment effects.

[0004] Existing methods for evaluating the water retention capacity of soil conditioners have the following main shortcomings:

[0005] 1. Long cycle and poor timeliness: Traditional methods are mostly based on long-term planting experiments or water evaporation monitoring under natural conditions, which usually takes several weeks or even months to obtain effective data, and cannot provide timely support for material selection and rapid decision-making on the engineering site.

[0006] 2. Complex operation and high cost: Existing methods require continuous manual recording, periodic sampling and weighing, which is cumbersome and has high requirements for test site and environmental conditions, making it difficult to achieve parallel testing of batch samples.

[0007] 3. Limited evaluation indicators: Most methods only focus on changes in total soil moisture content, lacking in-depth analysis of key parameters such as the dynamic changes in soil moisture after improvement, water retention rate, and available water content, making it difficult to fully reflect the mechanism of action of soil amendments.

[0008] 4. Significant environmental interference and poor reproducibility: Field experiments are significantly affected by natural factors such as weather, temperature, and evaporation, resulting in poor comparability of results from different batches of experiments; although indoor experiments can control some conditions, traditional methods are still difficult to accurately simulate extreme environments such as drought and high temperature, and there is a lack of standardized operating procedures.

[0009] Therefore, there is an urgent need to develop a rapid detection method for improving the water retention capacity of loess using soil conditioners. This method can solve the problems of existing evaluation methods, such as long evaluation cycles, complex operations, significant environmental interference, and single evaluation indicators. It can enable rapid, accurate, and standardized quantitative evaluation of the water retention performance of different soil conditioners and their ratios, providing technical support for the screening and application of soil conditioner materials in power transmission and transformation projects and other construction projects. Summary of the Invention

[0010] This invention aims to address the technical deficiencies of existing technologies by providing a rapid detection method for improving the water retention capacity of loess using soil amendments. By constructing a standardized simulated evaporation environment and employing a soil moisture sensor for real-time continuous monitoring, the method uses data analysis to comprehensively evaluate the water retention efficiency of soil amendments from multiple dimensions. This enables a rapid, accurate, and standardized quantitative evaluation of the water retention efficiency of different soil amendments and their ratios, providing technical support for the selection and application of soil amendment materials in power transmission and transformation projects and other construction projects.

[0011] This invention provides the following technical solution: a rapid detection method for improving the water retention capacity of loess using soil conditioners. This method involves constructing a standardized simulated evaporation environment and using a soil moisture sensor for real-time continuous monitoring. Data analysis is then used to comprehensively evaluate the water retention efficiency of the soil conditioner from multiple dimensions. The method includes the following steps:

[0012] Step 1: Preparation of test soil samples and amendments;

[0013] Representative loess samples from the project area to be evaluated were collected, air-dried, sieved, and their basic physicochemical properties, including initial bulk density, moisture content, and organic matter content, were determined.

[0014] Soil conditioners to be evaluated were selected, and soil conditioners with different addition ratios were set as treatment groups. At least three parallel replicates were set for each soil conditioner ratio. Pure loess was set as the control group.

[0015] Step 2, Preparation of standardized soil columns;

[0016] The treatment group and the control group were filled into the soil column tube in layers according to the preset unit weight, and the height of the soil column was kept consistent after filling.

[0017] Step 3, setting moisture saturation and initial moisture content;

[0018] Water is injected into the soil column to saturate the soil. Soil moisture sensors are inserted at the center of each soil column, with the probe located at 1 / 2 of the soil column depth. The initial volumetric water content is continuously monitored and recorded as an evaluation benchmark.

[0019] Step 4: Dynamic monitoring under simulated evaporation conditions;

[0020] The soil column was transferred to a controlled environment simulation device to simulate the natural evaporation process. The soil moisture sensor was connected to the data acquisition device, and the sampling interval and monitoring cycle were set to monitor the dynamic changes of soil volumetric water content in real time.

[0021] Step 5: Data processing and evaluation index calculation;

[0022] Volumetric water content data were collected at each time point, dynamic curves of water evaporation were plotted, multidimensional evaluation indicators were calculated, and the evaluation indicators of each treatment group and the control group were compared to determine the water retention efficiency of the soil conditioner and its optimal addition ratio.

[0023] Preferably, the soil column pipes used in the treatment group and the control group have the same inner diameter and height, with a permeable layer laid at the bottom. The inner diameter is 8-15cm, the height is 15-25cm, and the ratio of inner diameter to height is 1:1.5-1:2.5.

[0024] Preferably, in step 2, the treatment group and the control group are filled into the soil column tube in layers according to a preset bulk density, wherein the thickness of each layer does not exceed 5cm, and the layers are roughened.

[0025] Preferably, in step 3, water is injected into the soil column to saturate the soil. Water is slowly injected from the bottom of the soil column to fully saturate the soil column from bottom to top until water accumulates on the surface of the soil column. The soil is left to stand for 12-24 hours to reach saturation. The drainage outlet at the bottom of the soil column is then opened to allow natural drainage until gravity water no longer seeps in. At this point, the soil moisture content is the field capacity.

[0026] Preferably, in step 4, the natural evaporation process is simulated, and the temperature, relative humidity, and wind speed parameters of the simulated target climate conditions are set, with the top of each soil column tube kept open.

[0027] The temperature control accuracy of the controllable environment simulation equipment is ±0.5℃, the relative humidity control accuracy is ±5%, and the wind speed control range is 0-2m / s.

[0028] Preferably, the evaluation index in step 5 includes the initial volumetric water content. Final volumetric water content Average evaporation rate Water retention enhancement index , where the moisture decay model parameter k ; In the formula Let be the volumetric water content of the treatment group at time t. The volumetric water content of the control group at time t is .

[0029] Preferably, the water decay model parameter k is fitted to the water evaporation dynamic curve using an exponential decay model, and the model expression is:

[0030] ;in, Residual moisture content refers to the moisture content when the evaporation of water tends to stabilize.

[0031] Preferably, the sampling interval is set to 0.5-2 hours, and the monitoring period is determined according to the soil moisture evaporation rate until the soil moisture content tends to stabilize or reaches the preset termination condition.

[0032] Preferably, the monitoring period is 48-96 hours, and the preset termination condition is that the soil moisture content drops below 5%.

[0033] Preferably, the controllable environment simulation equipment is a constant temperature and humidity chamber or an artificial climate chamber.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. Fast and efficient: By constructing a standardized simulated evaporation environment and using soil moisture sensors for real-time continuous monitoring, the water retention performance of soil conditioners can be accurately evaluated within a few days, significantly shortening the testing cycle;

[0036] 2. Simple operation and high repeatability: Standardized soil column or soil box device is used, with uniform filling density and initial moisture content. Combined with an automatic data acquisition system, batch and standardized testing can be achieved, and the results have high reproducibility.

[0037] 3. Comprehensive evaluation indicators: It not only monitors the decay process of total soil moisture content, but also obtains multiple dynamic indicators such as water evaporation rate, effective water retention time, and residual moisture content through data analysis, so as to comprehensively evaluate the water retention efficiency of the soil amendment from multiple dimensions.

[0038] 4. Controllable simulation conditions: The simulation device can precisely control the ambient temperature, humidity and wind speed to simulate the water evaporation process under different climatic conditions, making the evaluation results more targeted and scientific.

[0039] 5. Provide direct guidance for engineering applications: By quickly screening out soil conditioners with excellent water retention properties and their optimal ratios, they can be directly applied to soil improvement and vegetation restoration practices in areas such as the slopes of power transmission and transformation tower foundations and spoil heaps, significantly improving the efficiency and success rate of ecological restoration. Attached Figure Description

[0040] Figure 1 This is the dynamic curve of water evaporation;

[0041] Figure 2 Demonstration diagram for preparing a soil column. Detailed Implementation

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0043] like Figures 1-2 As shown, it illustrates a specific embodiment of the present invention:

[0044] Example 1:

[0045] 1. Experimental Materials and Equipment: The soil samples were taken from typical loess along a power transmission and transformation project in northern Shaanxi Province. The sampling depth was 0-20 cm, and the soil was air-dried and then sieved through a 2 mm sieve for later use. Its basic physicochemical properties were: bulk density 1.32 g / cm³, organic matter content 0.85%, and pH value 8.2.

[0046] Soil conditioner: Municipal sewage sludge compost (organic matter content ≥45%, moisture content ≤30%) was selected as the tested conditioner, and pure loess without any conditioner was set as the control group (CK). Based on previous experiments, two treatment groups were set up: T1 (loess + 5% sewage sludge compost, mass ratio) and T2 (loess + 10% sewage sludge compost, mass ratio).

[0047] Experimental setup: A PVC soil column with a height of 20 cm and an inner diameter of 10 cm was used. Filter paper and fine mesh were laid at the bottom of the soil column to ensure water permeability but not soil leakage. Three parallel replicates were set up for each treatment group.

[0048] Monitoring equipment: Soil moisture sensor (model: HydraProbe, which can monitor volumetric water content in real time with an accuracy of ±0.01%), data logger, and constant temperature and humidity chamber (which can precisely control temperature and humidity).

[0049] 2. Test Methods

[0050] Soil column filling: Thoroughly mix the air-dried and sieved loess with different proportions of soil conditioner. Fill the soil column into layers (5cm apart) according to the target bulk density of 1.30g / cm³, roughening the layers to ensure uniform filling. After filling, the total height of the soil column is 15cm.

[0051] Water saturation and initial moisture content setting: Water is slowly injected from the bottom of the soil column until the soil reaches saturation. After standing for 24 hours, water is drained through the bottom opening until gravity water no longer seeps in. At this point, the initial volumetric water content of each soil column is measured using a soil moisture sensor as a baseline.

[0052] Evaporation Simulation and Monitoring: All soil columns were transferred to a constant temperature and humidity chamber. To simulate typical summer evaporation conditions on the Loess Plateau, the chamber temperature was set to 35℃, relative humidity to 40%, and a windless environment (wind speed 0 m / s). A soil moisture sensor was vertically inserted into the center of the top of each soil column, with the sensor probe positioned 7-8 cm deep at the center of the column. The data logger was set to automatically record volumetric water content data every hour.

[0053] Test period: Continuous monitoring for 96 hours. Record the moisture content at each time point and calculate the cumulative evaporation (the difference between the initial moisture content and the current moisture content).

[0054] 3. Data Processing and Indicator Calculation

[0055] The following methods were used to calculate each evaluation index:

[0056] (1) Initial volumetric water content : Monitor the volumetric water content at the start time (t=0h).

[0057] (2) Final volumetric water content Volumetric water content at the end of monitoring (t=96h).

[0058] (3) Average evaporation rate (% / h)

[0059] (4) Water retention improvement index The formula for evaluating the relative improvement effect of soil amendment on soil water retention capacity is as follows:

[0060]

[0061] in, To improve the volumetric water content of the treatment group at time t, This represents the volumetric water content of the control group at the same time. The larger the positive value of this index, the more significant the water retention improvement effect of the amendment.

[0062] (5) Parameters of the moisture decay model: The dynamic curve of moisture evaporation is fitted by nonlinear regression using an exponential decay model. The model expression is as follows:

[0063]

[0064] in, The volumetric water content at time t (%). Initial volumetric water content (%) Residual moisture content (%), which is the moisture content when the evaporation of water tends to stabilize; The rate constant of water decay (h) -1The value of k reflects the rate of moisture loss; the smaller the k value, the longer the moisture is retained.

[0065] 4. Results and Analysis

[0066] The experimental data (average of 3 replicates per group) are shown in Table 1, and the dynamic curve of water evaporation is shown in Table 1. Figure 1 As shown.

[0067] Table 1. Changes in soil moisture content over time under different treatments (volume moisture content, %)

[0068]

[0069] The three curves in the graph represent CK, T1, and T2, respectively. The curves generally show a downward trend, with the CK curve decreasing the steepest and reaching its lowest value, the T2 curve decreasing the most gently and reaching its highest value, and the T1 curve in the middle. This graph visually demonstrates that the soil moisture evaporation rate is significantly reduced after adding the soil amendment, and that the higher the amount of amendment added, the better the water retention effect.

[0070] Table 2 Calculation results of evaluation indicators for each treatment group

[0071]

[0072] Table 2 shows that after adding sludge compost, the initial saturated water content of the soil increased from 38.5% in pure loess to 42.1% (T1) and 45.8% (T2), respectively, representing increases of 9.4% and 19.0%. This indicates that sludge compost itself has a strong water-holding capacity and can improve the pore structure of loess, increasing the total porosity and effective water-holding pores of the soil.

[0073] At the end of the 96-hour monitoring period, the moisture content of the CK group had dropped to 1.4%, essentially approaching a dry state; while the T1 and T2 groups still retained moisture contents of 6.7% and 12.4%, respectively. Calculations showed that the water retention improvement indices for T1 and T2 were 378.6% and 785.7%, respectively, meaning that the water retention capacity of the T2 treatment group was nearly nine times that of the CK group. This index directly reflects the significant improvement effect of the soil amendment on the water retention performance of loess, and the improvement rate is positively correlated with the amount of amendment added.

[0074] The water evaporation process of each treatment group was fitted using an exponential decay model, and the goodness of fit R was measured. 2 All values ​​were greater than 0.99, indicating that the model can well describe the soil moisture decay process. Residual water content The residual water content of the CK group was only 0.5%, while that of the T1 and T2 groups reached 4.8% and 10.2%, respectively. This indicates that after adding the soil conditioner, the soil can retain more available water, providing the necessary water supply for plant growth even under prolonged drought conditions. (Water decay rate constant) The k value for group CK is 0.072h. -1 This means that approximately 7.2% of the initial water content is lost per hour; the k value for group T1 is 0.051h. -1 The rate decreased by approximately 29.2%; the k value for group T2 was 0.038h. -1 The k value decreased by approximately 47.2%. A smaller k value indicates a slower rate of water evaporation and a longer retention time of moisture. The significantly lower k value in group T2 demonstrates that adding 10% sludge compost can effectively slow down the evaporation process of soil moisture.

[0075] This rapid detection method successfully quantified the effect of different ratios of sludge compost on improving the water retention capacity of loess. The results showed that adding 10% sludge compost (T2) had the best improvement effect, significantly enhancing the soil's water holding and retention capacity, making it suitable for subsequent vegetation restoration experiments or engineering applications. The water decay model parameters (residual water content and decay rate constant) can reveal the mechanism of action of the amendment more deeply, providing a more scientific and comprehensive quantitative basis for evaluating water retention performance. This rapid detection method can complete the entire process from sample preparation to result analysis within 96 hours, significantly improving efficiency compared to traditional field trials (which take several months).

[0076] To further verify the reliability of this method, the rapid detection results were compared with those of a traditional 90-day pot experiment. The pot experiment used the same soil sample and amendment ratio, planted alfalfa as an indicator plant, and regularly measured soil moisture content and plant growth indicators. The results showed that the water retention enhancement index obtained by the rapid detection was significantly positively correlated with the soil moisture retention rate after 90 days in the pot experiment. This verifies the reliability of the evaluation results and their engineering guidance value.

[0077] In summary, this invention, through standardized soil column preparation, controllable simulation of evaporation environment, continuous automatic monitoring, and comprehensive evaluation combining the water retention enhancement index and water decay model parameters, successfully achieves rapid, accurate, and quantitative evaluation of the water retention performance of loess improved by sludge composting. This method can complete the test within 96 hours, and the evaluation results highly agree with long-term pot experiment results, providing reliable technical support for the rapid screening and engineering application of soil amendment materials in power transmission and transformation projects and other construction projects.

[0078] Example 2:

[0079] 1. Experimental materials and equipment

[0080] Soil samples were taken from loess in a typical disturbed area along a power transmission and transformation project in northern Shaanxi Province. The sampling depth was 0-20 cm, and the samples were air-dried and sieved through a 2 mm sieve for later use. The basic physicochemical properties were: bulk density 1.35 g / cm³, organic matter content 0.72%, and pH value 8.1.

[0081] Soil amendment: Apple tree biochar (prepared by pyrolysis at 500℃ and sieved through a 0.5mm sieve) was selected as the tested amendment. Biochar has abundant oxygen-containing functional groups and negatively charged surfaces, exhibiting strong hydrophilicity. A control group (CK) of pure loess without any amendments was also included. Based on the results of preliminary experiments, two treatment groups with different ratios were established: T1 (loess + 3% biochar, by mass) and T2 (loess + 6% biochar, by mass).

[0082] Experimental setup: A 25cm high, 12cm inner diameter acrylic glass soil column was used, with a permeable layer (filter paper + 2cm thick quartz sand layer) at the bottom to ensure water permeability but no soil leakage. Each treatment group was configured with 3 parallel replicates.

[0083] Monitoring equipment: Soil moisture sensor (FDR type, accuracy ±0.01%), data logger, constant temperature and humidity chamber (temperature control accuracy ±0.5℃, relative humidity control accuracy ±5%).

[0084] 2. Test Methods

[0085] Soil column filling: Thoroughly mix air-dried and sieved loess with biochar in different proportions. Fill the soil column tube in layers (5cm each) according to the target bulk density of 1.30g / cm³, roughening the layers to ensure good contact. After filling, the total height of the soil column is 18cm.

[0086] Water saturation and initial moisture content setting: Water is slowly injected from the bottom of the soil column to fully saturate the soil from bottom to top until water accumulates on the surface of the soil column. After standing for 24 hours, the bottom drainage outlet is opened to allow natural drainage until gravity water no longer seeps in (approximately 4 hours). At this point, the initial volumetric water content of each soil column is measured using a soil moisture sensor as a baseline.

[0087] Evaporation Simulation and Monitoring: All soil columns were transferred to a constant temperature and humidity chamber. The chamber temperature was set to 30℃ (daytime) / 18℃ (nighttime) with a 12-hour day-night cycle and a relative humidity of 45% to simulate typical evaporation conditions in the Loess Plateau during autumn. The sensor probe was located 9cm deep at the center of the soil column, and the data logger was set to automatically record the volumetric water content data every 1.5 hours.

[0088] Test cycle: 96 hours of continuous monitoring.

[0089] 3. Data Processing and Indicator Calculation

[0090] The following methods were used to calculate each evaluation index:

[0091] (1) Initial volumetric water content : Monitor the volumetric water content at the start time (t=0h).

[0092] (2) Final volumetric water content Volumetric water content at the end of monitoring (t=96h).

[0093] (3) Average evaporation rate (% / h)

[0094] (4) Water Retention Enhancement Index (IWR): This evaluates the relative improvement effect of the soil amendment on the soil's water retention capacity. The calculation formula is as follows:

[0095]

[0096] (5) Parameters of the moisture decay model: The exponential decay model was used for nonlinear regression fitting:

[0097]

[0098] Where θ(t) is the volumetric water content (%) at time t. The residual moisture content is % (%), and k is the moisture decay rate constant (h). -1 ).

[0099] 4. Results and Analysis

[0100] The experimental data (the average of three replicates in each group) are shown in Table 3.

[0101] Table 3. Changes in soil moisture content over time under different treatments (volume moisture content, %)

[0102]

[0103] Table 4. Calculation results of evaluation indicators for each treatment group

[0104]

[0105] As shown in Tables 3 and 4, after adding biochar, the initial saturated water content of the soil increased from 36.8% in pure loess to 40.3% (T1) and 43.7% (T2), respectively, representing increases of 9.5% and 18.8%. This is attributed to the fact that the rich microporous structure and oxygen-containing functional groups on the surface of biochar enhance the soil's hydrophilicity and water retention capacity.

[0106] At the end of the 96-hour monitoring period, the moisture content of the CK group dropped to 1.0%, close to an air-dried state; the T1 and T2 groups retained moisture contents of 5.0% and 9.8%, respectively. The water retention improvement indices of T1 and T2 were 400.0% and 880.0%, respectively, indicating that the higher the biochar addition, the more significant the improvement in water retention performance.

[0107] An exponential decay model was used for fitting, and the goodness of fit R² was greater than 0.99 for all values. Residual water content θ resThe moisture decay rate was only 0.3% in the CK group, while it reached 3.8% and 7.9% in the T1 and T2 groups, respectively. The moisture decay rate constant k was 0.079 h⁻¹ for the CK group. -1 Group T1 is 0.055h. -1 The decrease was approximately 30.4% in group T1 and 0.040h in group T2. -1 The rate of water loss decreased by approximately 49.4%, indicating that adding 6% biochar can significantly slow down the rate of soil moisture evaporation and improve water retention.

[0108] This rapid detection method successfully quantified the effect of different biochar ratios on improving the water retention capacity of loess. The results showed that the addition of 6% apple tree biochar (T2) had the best improvement effect, and its high hydrophilicity and porous structure significantly enhanced the soil's water holding and retention capacity.

[0109] To further verify the reliability of this method, the rapid detection results were compared with those of a traditional 90-day pot experiment. The pot experiment used the same soil sample and amendment ratio, with alfalfa planted as an indicator plant. Soil moisture content and plant growth indicators were measured periodically. The results showed that the water retention enhancement index obtained by the rapid detection was significantly positively correlated with the soil moisture retention rate after 90 days in the pot experiment (R²=0.94), verifying the reliability of the evaluation results and its engineering guidance value.

[0110] Example 3

[0111] 1. Experimental materials and equipment

[0112] The tested soil was disturbed loess from the tower foundation area of ​​a power transmission and transformation project in northern Shaanxi Province. The sampling depth was 0-30 cm, and the soil was air-dried and sieved through a 2 mm sieve for later use. Its basic physicochemical properties were: bulk density 1.40 g / cm³, organic matter content 0.58%, pH value 8.3, indicating that the soil was relatively infertile and loosely structured.

[0113] Soil conditioner: A polyacrylamide-potassium polyacrylate copolymer polymeric water-retaining agent (SAP, water absorption ratio ≥300g / g) was selected as the tested conditioner. The polymeric water-retaining agent has a three-dimensional network structure, enabling rapid water absorption and slow water release. A control group (CK) of pure loess without any conditioner was also included. Based on the typical application effects of the water-retaining agent in loess slope restoration, two treatment groups were set up: T1 (loess + 0.2% water-retaining agent, mass ratio) and T2 (loess + 0.5% water-retaining agent, mass ratio). The water-retaining agent was thoroughly mixed with the soil before being applied.

[0114] Experimental setup: A PVC soil column pipe with a height of 20cm and an inner diameter of 10cm was used, with a permeable layer (filter paper + fine mesh) laid at the bottom to ensure water permeability but no soil leakage. Each treatment was set up with 3 replicates.

[0115] Monitoring equipment: Soil moisture sensor (TDR type, accuracy ±0.01%), data logger, artificial climate chamber (capable of precise control of temperature, humidity and wind speed).

[0116] 2. Test Methods

[0117] Soil column filling: Thoroughly mix air-dried and sieved loess with water-retaining agents in different proportions. Fill the soil column into layers (5cm each) according to the target bulk density of 1.35g / cm³, roughening the layers to ensure uniform filling. After filling, the total height of the soil column is 15cm.

[0118] Water saturation and initial moisture content setting: Water is slowly injected from the bottom of the soil column until the soil reaches saturation. After standing for 24 hours, water is drained through the bottom opening until gravity water no longer seeps in (approximately 3 hours). At this point, the initial volumetric water content of each soil column is measured using a soil moisture sensor as a baseline.

[0119] Evaporation Simulation and Monitoring: All soil columns were transferred to an artificial climate chamber. To simulate the hot and dry conditions of the Loess Plateau in summer, the temperature inside the climate chamber was set at 38℃ (daytime) / 22℃ (nighttime), with a 12-hour diurnal cycle, relative humidity of 35%, and wind speed of 0.5 m / s (simulating a natural breeze). A soil moisture sensor was vertically inserted into the center of the top of each soil column, with the sensor probe located 7-8 cm deep at the center of the column. The data logger was set to automatically record volumetric water content data every 0.5 hours to capture the rapid moisture decay process of the water-retaining agent-modified soil under hot and dry conditions.

[0120] Test cycle: Continuous monitoring for 72 hours (the rate of water evaporation is faster under dry and hot conditions, and a stable state can be reached in 72 hours).

[0121] 3. Data Processing and Indicator Calculation

[0122] The same evaluation metrics and calculation methods were used in Examples 1 and 2:

[0123] (1) Initial volumetric water content

[0124] (2) Final volumetric water content θt (t=72h)

[0125] (3) Average evaporation rate (% / h)

[0126] (4) Water retention enhancement index (IWR)

[0127] (5) Parameters of the moisture decay model

[0128] 4. Results and Analysis

[0129] The experimental data (the average of three parallel replicates in each group) are shown in Table 5.

[0130] Table 5. Changes in soil moisture content over time under different treatments (volume moisture content, %)

[0131]

[0132] Table 6. Calculation results of evaluation indicators for each treatment group

[0133]

[0134] As shown in Tables 5 and 6, after adding the polymeric water-retaining agent, the initial saturated water content of the soil increased significantly from 39.2% in pure loess to 48.6% (T1) and 56.3% (T2), representing increases of 24.0% and 43.6%, respectively. This is attributed to the three-dimensional network structure of the water-retaining agent, which has an extremely strong water absorption capacity, capable of absorbing hundreds of times its own weight in water.

[0135] At the end of the 72-hour monitoring period, the moisture content of the CK group had dropped to 0.6%, indicating complete air drying; while the T1 and T2 groups still retained moisture contents of 9.2% and 18.7%, respectively. The water retention enhancement indices of T1 and T2 were as high as 1433.3% and 3016.7%, respectively, meaning that the water retention capacity of the T2 treatment group was more than 30 times that of the CK group, fully demonstrating the excellent water retention performance of the polymer water-retaining agent under dry heat conditions.

[0136] An exponential decay model was used for fitting, and the goodness of fit R² was greater than 0.99 for all results. Residual water content The moisture decay rate was only 0.2% in the CK group, while it reached 6.8% and 15.3% in the T1 and T2 groups, respectively. The moisture decay rate constant k was 0.095 h⁻¹ for the CK group. -1 Group T1 was 0.042h. -1 The decrease was approximately 55.8% in group T1 and 0.028h in group T2. -1 The value of k decreased by approximately 70.5%. This significant decrease in the k value indicates that the polymer water-retaining agent can extremely effectively slow down the evaporation loss of soil moisture, and can still retain a large amount of effective water for plant absorption and utilization even under harsh evaporation conditions such as high temperature, low humidity, and wind.

[0137] It is worth noting that in this embodiment, the water retention improvement index and the reduction in k value of group T2 (0.5% water-retaining agent) are better than those of group T2 (10% sludge compost) in Example 1 and group T2 (6% biochar) in Example 2. This shows that the polymeric water-retaining agent can achieve excellent water retention effect at a very low addition amount (0.5%), and has good economy and operability in engineering applications.

[0138] This rapid detection method successfully quantified the effect of different ratios of polymeric water-retaining agents on improving the water retention capacity of loess. The results showed that the addition of 0.5% polyacrylamide-potassium polyacrylate copolymer water-retaining agent (T2) had the best improvement effect, which could significantly enhance the water holding and retention capacity of the soil under extreme evaporation conditions. It is suitable for soil improvement and vegetation restoration in areas with poor moisture conditions, such as the slope of the tower foundation area of ​​power transmission and transformation projects and spoil heaps.

[0139] To further verify the reliability of this method, the rapid detection results were compared with those of a traditional 90-day pot experiment. The pot experiment used the same soil sample and amendment ratio, planting *Caragana korshinskii* as an indicator plant (*Caragana korshinskii* is a typical stress-resistant shrub of the Loess Plateau, showing excellent performance in slope restoration). Soil moisture content and plant survival rate were measured periodically. The results showed that the water retention enhancement index obtained by the rapid detection was significantly positively correlated with the soil moisture retention rate after 90 days in the pot experiment (R²=0.96), and the survival rate of *Caragana korshinskii* in the T2 treatment group reached 92%, further verifying the reliability and engineering guidance value of the evaluation results of this method.

[0140] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. These changes involve related technologies well known to those skilled in the art, and all of them fall within the protection scope of the present invention.

[0141] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A rapid detection method for the effect of soil conditioner on improving the water retention capacity of loess, characterized in that, By constructing a standardized simulated evaporation environment and using soil moisture sensors for real-time continuous monitoring, the water retention efficiency of soil conditioners is comprehensively evaluated from multiple dimensions through data analysis. This includes the following steps: Step 1: Preparation of test soil samples and amendments; Representative loess samples from the project area to be evaluated were collected, air-dried, sieved, and their basic physicochemical properties, including initial bulk density, moisture content, and organic matter content, were determined. Soil conditioners to be evaluated were selected, and soil conditioners with different addition ratios were set as treatment groups. At least three parallel replicates were set for each soil conditioner ratio. Pure loess was set as the control group. Step 2, Preparation of standardized soil columns; The treatment group and the control group were filled into the soil column tube in layers according to the preset unit weight, and the height of the soil column was kept consistent after filling. Step 3, setting water saturation and initial moisture content; Water is injected into the soil column to saturate the soil. Soil moisture sensors are inserted at the center of each soil column, with the probe located at 1 / 2 of the soil column depth. The initial volumetric water content is continuously monitored and recorded as an evaluation benchmark. Step 4: Dynamic monitoring under simulated evaporation conditions; The soil column was transferred to a controlled environment simulation device to simulate the natural evaporation process. The soil moisture sensor was connected to the data acquisition device, and the sampling interval and monitoring cycle were set to monitor the dynamic changes of soil volumetric water content in real time. Step 5: Data processing and evaluation index calculation; Volumetric water content data were collected at each time point, dynamic curves of water evaporation were plotted, multidimensional evaluation indicators were calculated, and the evaluation indicators of each treatment group and the control group were compared to determine the water retention efficiency of the soil conditioner and its optimal addition ratio.

2. The rapid detection method for improving the water retention capacity of loess using soil conditioners according to claim 1, characterized in that, The treatment group and the control group used soil column pipes with the same inner diameter and height, with a permeable layer laid at the bottom. The inner diameter was 8-15cm and the height was 15-25cm, with an inner diameter to height ratio of 1:1.5-1:2.

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3. The rapid detection method for improving the water retention capacity of loess using soil conditioners according to claim 1, characterized in that, In step 2, the treatment group and the control group are filled into the soil column tube in layers according to the preset bulk density, wherein the thickness of each layer does not exceed 5cm, and the layers are roughened.

4. The rapid detection method for improving the water retention capacity of loess using soil conditioners according to claim 1, characterized in that, In step 3, water is injected into the soil column to saturate the soil. Water is slowly injected from the bottom of the soil column so that the water can fully saturate the soil column from bottom to top until water accumulates on the surface of the soil column. The soil is left to stand for 12-24 hours to reach saturation. Open the drainage outlet at the bottom of the soil column pipe and allow natural drainage until gravity water no longer seeps in. At this point, the soil moisture content is the field capacity.

5. The rapid detection method for improving the water retention capacity of loess using soil conditioners according to any one of claims 1-4, characterized in that, In step 4, the natural evaporation process is simulated, and the temperature, relative humidity and wind speed parameters of the simulated target climate conditions are set, with the top of each soil column tube kept open. The temperature control accuracy of the controllable environment simulation equipment is ±0.5℃, the relative humidity control accuracy is ±5%, and the wind speed control range is 0-2m / s.

6. The rapid detection method for improving the water retention capacity of loess using soil conditioners according to claim 5, characterized in that, The evaluation indicators in step 5 include initial volumetric water content. Final volumetric water content Average evaporation rate Water retention enhancement index , where the moisture decay model parameter k ; In the formula Let be the volumetric water content of the treatment group at time t. The volumetric water content of the control group at time t is .

7. The rapid detection method for improving the water retention capacity of loess using soil conditioners according to claim 6, characterized in that, The parameter k of the moisture decay model is fitted to the dynamic curve of moisture evaporation using a nonlinear regression model with an exponential decay model. The model expression is as follows: ;in, Residual moisture content refers to the moisture content when the evaporation of water tends to stabilize.

8. The rapid detection method for improving the water retention capacity of loess using soil conditioners according to claim 6, characterized in that, The sampling interval is set to 0.5-2 hours, and the monitoring period is determined according to the soil moisture evaporation rate until the soil moisture content tends to stabilize or reaches the preset termination condition.

9. The rapid detection method for improving the water retention capacity of loess using soil conditioners according to claim 8, characterized in that, The monitoring period is 48-96 hours, and the preset termination condition is that the soil moisture content drops below 5%.

10. The rapid detection method for improving the water retention capacity of loess using soil conditioners according to claim 1, characterized in that, The controllable environment simulation equipment is a constant temperature and humidity chamber or an artificial climate chamber.

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