Regulation and control method of water-retaining agent in improved soil and application of regulation and control method

Abstract

The invention belongs to the technical field of ecological restoration, and particularly relates to a regulation and control method for water-retaining agent improved soil and application of the regulation and control method. Comprising the following steps: obtaining a water holding characteristic curve of a plant root system in improved soil, and obtaining suction force corresponding to a root system withering value; obtaining a water holding characteristic curve of the improved soil, and obtaining soil residual suction; if the residual suction force of the soil is higher than the suction force corresponding to the root system withering value, the risk of reverse water absorption exists, and at the moment, the water-retaining agent is not added into the improved soil; on the contrary, a water-retaining agent is added into the improved soil. Through water potential feature point fitting and overlapping region control, the problem of early withering or death of plants caused by water potential mismatching is effectively avoided, and the planting adaptability and the survival rate are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of ecological restoration, and particularly relates to a method for regulating and controlling a water-retaining agent in improved soil and application thereof. Background Art

[0002] Water-retaining agents (SUAs) are widely used in agricultural and forestry vegetation restoration and drought resistance and soil moisture conservation projects due to their high water absorption, high water retention, and slow water release properties. Studies have shown that appropriate amounts of SUAs can significantly increase soil moisture content, enhance plant drought resistance, and improve plant survival rates and yields.

[0003] Most current water-retaining agent (SAAs) formulations and application methods focus on their physical water-retention properties (e.g., yield and growth performance) while ignoring the water-holding characteristics of different plant roots. This results in incompatibility with some plants (especially water-loving plants with high water potential), and can even lead to "reverse water absorption" and premature wilting. Furthermore, multiple studies have shown that excessive SAAs, due to their high absorption capacity, can reversely absorb water from plant roots, causing plant death. Numerous experimental evidence also indicates that different plants respond significantly differently to SAAs levels. Some drought-tolerant plants, such as sea buckthorn and caragana, perform well in response to SAAs, while some water-loving plants, such as goosegrass and bermudagrass, experience early growth stunting or even death. These differences reflect that SAAs are not universally applicable, and their impact on plant physiological processes remains unclear. Therefore, accurately determining whether to add SAAs is crucial. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method for regulating and controlling a water-retaining agent in improved soil and its application.

[0005] A method for regulating and controlling a water-retaining agent in improved soil comprises the following steps: Obtain the water holding characteristic curve of plant roots in the improved soil and obtain the suction force corresponding to the root wilting value; Obtain the water holding characteristic curve of the improved soil with water retaining agent and obtain the soil residual suction; If the residual suction of the soil is higher than the suction corresponding to the root wilting value, there is a risk of reverse water absorption. At this time, water-retaining agent is not added to the improved soil; on the contrary, water-retaining agent is added to the improved soil.

[0006] Preferably, the suction force and moisture content of the improved soil to which the water-retaining agent is added and the plant roots in the improved soil are obtained by a filter paper method to obtain the water retention characteristic curve.

[0007] Preferably, the suction force and the moisture content are fitted using the Van Genuchten equation to obtain a water holding characteristic curve, and the Van Genuchten equation is as follows: Where: w represents the mass moisture content / %; w s Indicates saturated mass moisture content / %; w r represents the residual mass moisture content / %; ψ represents the matrix suction / kPa; a represents the fitting parameter of the air intake value, and n represents the fitting parameter of the slope of the inflection point. a and n are obtained by fitting the Van Genuchten equation, and m is 1-1 / n.

[0008] Preferably, the plant is Eleutherococcus or Hippophae rhamnoides.

[0009] Preferably, among the fitting parameters of the Goosegrass, a is 0.192, m is 0.123, and n is 10.685.

[0010] Preferably, among the fitting parameters of seabuckthorn, a is 8.539×10 -7 , m is 10.582, and n is 0.329.

[0011] Preferably, the improved soil is loess or sandy soil.

[0012] The application of the control method in drought ecological restoration.

[0013] Preferably, the drought ecological restoration refers to any one of slope management, degraded grassland restoration and plateau slope protection.

[0014] (1) Propose a "wilt potential protection mechanism" and use it in reverse water absorption avoidance design In this method, if the residual suction on the water-holding characteristic curve of the water-retaining agent-amended soil exceeds the suction corresponding to the target plant's wilting value, there is a risk of reverse water absorption. Based on this logic, the present invention clearly proposes the concept of a "wilt potential protection mechanism" for the first time and establishes boundary conditions for the improved soil design to avoid inappropriate usage scenarios.

[0015] (2) Water-retaining agent regulation method based on plant root water-holding characteristics For the first time, the water-holding characteristic curve parameters of the target plant's roots (specifically, the suction force corresponding to the root wilting value and the residual value of the improved soil) are used as quantitative input indicators. Based on this method, the addition ratio of the water-retaining agent can be adjusted based on the calculated results, achieving a coupled match between the water potential release performance of the improved soil and the water absorption capacity of the plant. This method breaks through the limitation of traditional selection criteria that solely relies on the water absorption rate of the water-retaining agent, and has broad adaptability and precise control capabilities.

[0016] (3) Water-retaining agent-soil composite improvement technology for adjustable water release platform By adjusting the dosage of water-retaining agent, the slope of the water-holding characteristic curve can be made gentle in the target water potential range, that is, a "slow-release platform section" is constructed, which can continuously supply water to plants and significantly improve the survival ability of plants during the drought period. This is a key technological innovation in the design of water-saving improved soil in ecological engineering.

[0017] (4) Practical zoning layout strategy for arid and semi-arid areas Based on the target plant classification, water potential requirements and soil type, the present invention forms a system method for water-retaining agent layout and material ratio based on plant-water potential requirements, which is suitable for scenarios such as slope management, degraded grassland restoration, and plateau slope protection, and has practical promotion prospects.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) Achieve "water potential adaptation" between plants and water-retaining agent-improved soil to avoid back-absorption and wilting Traditional water-retaining agent formulation methods often release excessively high water potential when used on water-loving plants, leading to a "water potential reversal" in the plant's roots, causing water to be absorbed back into the water-retaining agent. This invention, through water potential feature point fitting and overlap area control, effectively avoids the problem of premature plant wilting or death caused by water potential mismatch, significantly improving planting adaptability and survival rate.

[0019] (2) Propose a complete improvement strategy of “water potential regulation – plant adaptation – material customization” The present invention forms a ternary control framework of "plant physiological needs → water-retaining agent water-releasing characteristics → improved soil ratio", providing an integrated path for material design, dosage design and regional layout of future ecological restoration projects, thereby promoting efficient water utilization and precise plant selection.

[0020] (3) Construct a “water release control zone” based on water potential to optimize the slow-release performance of the water-retaining agent By adjusting the dosage and moisture content of the water-retaining agent and fitting the water-holding characteristic curve using the Van Genuchten equation, the improved soil can maintain a moderate water release rate within the suction range where plant roots most need water, achieving a "stable release and moisture control" regulatory effect and improving plant drought resistance and root activity sustainability.

[0021] (4) Highly versatile and suitable for a variety of arid areas and soil types The water-holding characteristic test, matching principle and layout method in the technology can be directly extended to different soil conditions such as sandy soil, silty soil and clay soil, and is suitable for typical drought-resistant shrubs such as sea buckthorn, caragana, and locust, as well as plants such as forage grass in plateau areas.

[0022] (5) Provide theoretical guidance and quantitative parameter support for ecological engineering The present invention provides a measurable, designable, and controllable improved soil preparation method and water potential evaluation framework, which bridges the technical gap between basic research and engineering implementation, provides theoretical support and process templates for ecological slope protection, artificial grass grids, and restoration of degraded farmland, and has promotion and transformation value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the water holding characteristic curve of pure water retaining agent.

[0024] Figure 2 This is the water holding characteristic curve of the root system of Goosegrass.

[0025] Figure 3 This is the water holding characteristic curve of seabuckthorn root system.

[0026] Figure 4 This is the water holding characteristic curve of pure loess.

[0027] Figure 5 The water holding characteristic curve of loess improved by water retaining agent.

[0028] Figure 6 This is the water holding characteristic curve of pure sand.

[0029] Figure 7 The water holding characteristic curve of sandy soil improved by water retaining agent.

[0030] Figure 8 These are the growth states of Gnaphalium wilfordii under different conditions, among which A contains no water retaining agent, B contains 2% water retaining agent, and C contains 5% water retaining agent. DETAILED DESCRIPTION

[0031] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0032] The pure water-retaining agent used in the present invention is KM3005 water-retaining agent produced by Jinyu Chemical Co., Ltd.

[0033] The present invention achieves: 1. Establish a regulation mechanism for the water potential matching relationship between “plants, soil and water retaining agent” The present invention forms a water potential-oriented water-retaining agent dosage control scheme by testing the water-retention characteristic curve parameters (air intake value, inflection point value, residual value) of the target plant root system and the water-retention characteristic curve of the improved soil, thereby ensuring the optimal growth performance of different plants in the improved soil.

[0034] 2. Propose a "wilting potential protection mechanism" to achieve plant water potential safety boundary design For the first time, the present invention takes the suction corresponding to the plant wilting value as one of the limiting conditions, avoiding the reverse suction phenomenon caused by the residual suction of the improved soil being higher than the suction corresponding to the plant wilting value, realizing the safety design principle with "plant extreme water potential" as the lower limit, and improving the survival rate of plants and the quality of ecological restoration in arid environments.

[0035] 3. Construct a platform section with improved soil water potential and adjustable water release to enhance drought resistance and stable water release capabilities Through the coordinated design of parameters such as water-retaining agent dosage, soil type, and initial moisture content, the slope of the water-retention characteristic curve is slowed down in the water requirement range of the target plants, thereby forming a controlled water release segment, enhancing the slow-release function of the soil during the drought resistance period, and realizing the plant's "stable absorption-slow release-long-term" water use process.

[0036] Follow these steps to achieve this: (1) Target plant root water potential characteristics test The water holding characteristic curve of plant roots was tested using pressure plate instrument and filter paper method to obtain the following parameters: Air intake value: the critical point at which the root system enters the unsaturated state from the saturated state; Inflection point value: the inflection point where the root water absorption rate drops sharply; Residual value: The suction force corresponding to the root withering value, which is the physiological limit of the plant.

[0037] (2) Preparation of water-retaining agent improved soil Take dry loess and sandy soil samples, pass them through a 2 mm sieve, and then dry them to obtain improved soil. Add a water-retaining agent and stir evenly to form water-retaining agent-improved soil. Add water and let it stand for 24 hours to allow it to fully absorb water. The mass ratio of improved soil to water-retaining agent is 1:50.

[0038] (3) Filter paper method and pressure plate instrument test water retention characteristic curve The suction and corresponding water content of seven materials were measured using the filter paper method or axis translation technique: pure water-retaining agent, Eleutherodactyl root system, Hippophae rhamnoides root system, pure loess, loess modified with water-retaining agent (loess + 2% water-retaining agent), pure sandy soil, and sandy soil modified with water-retaining agent (sandy soil + 2% water-retaining agent). Curve fitting was performed on the measured suction and water content to generate a water-holding characteristic curve.

[0039] The Van Genuchten equation is used for fitting: Where: w——mass moisture content / %; w s ——Saturated mass moisture content / %; w r ——residual mass moisture content / %; ψ——matrix suction / kPa; a, m and n——fitting parameters.

[0040] The fitting parameters of the seven materials are shown in Table 1: Table 1 Parameter values ​​of water retention curve fitting Results Figure 1 The residual suction of pure water-retaining agent is 1000.0kPa, the suction corresponding to the root withering value of Bermuda grass root system is 34.4kPa, the suction corresponding to the root withering value of sea buckthorn root system is 5500.0kPa, the soil residual suction of pure loess is 75000.0kPa, the soil residual suction of loess improved with water-retaining agent is 6500.0kPa, the soil residual suction of pure sandy soil is 2220.0kPa, and the soil residual suction of sandy soil improved with water-retaining agent is 250.5kPa.

[0041] Sandy soil in the present invention refers to soil with a high sand content in the soil particle composition, and sandy soil is defined as soil with a sand content of more than 50% in a particle size of 1-0.05 mm.

[0042] The loess in the present invention refers to porous yellow powdery soil with columnar joints formed under dry climatic conditions. Collapsible loess will produce large subsidence after being soaked in water.

[0043] Example 1 Preparation of loess improved with water-retaining agent suitable for goosegrass Obtain the water holding characteristic curve of the root system of Goosegrass and obtain the suction force corresponding to the root wilting value; Obtain the water holding characteristic curve of the improved soil with water retaining agent and obtain the soil residual suction; If the residual suction of the soil is higher than the suction corresponding to the root wilting value, there is a risk of reverse water absorption. At this time, water-retaining agent is not added to the improved soil; on the contrary, water-retaining agent is added to the improved soil.

[0044] 1. Composition and preparation The Loess Plateau Water Cycle and Geological Environment Field Observation Station of the Ministry of Education in Zhengning County, Gansu Province. The natural dry density is 1.33 g / cm³;

[0045] Add 2% by mass of water-retaining agent to loess and mix well to obtain water-retaining agent-improved loess. After adding water and stirring thoroughly, seal and let stand for 24 hours to make the moisture content of the water-retaining agent-improved loess 40.0%. Prepare ring knife samples with different moisture content gradients for filter paper method testing.

[0046] 2. Water potential adaptability test The water retention characteristic curve of loess improved by water retaining agent was fitted by Van Genuchten equation, and it was found that the water release suction range of loess improved by water retaining agent was mainly distributed in 4.0-6500.0 kPa. The inflection point suction of the Goosegrass root system is 7.0 kPa, and the suction corresponding to the wilting value of the Goosegrass root system is 34.4 kPa; After fitting analysis, the residual suction of loess improved with water-retaining agent was 6500.0 kPa, which was higher than the suction value corresponding to the wilting value of the Berberis root system. It could absorb water from the roots in reverse, which was not conducive to plant growth.

[0047] Example 2 Preparation of water-retaining agent-improved sandy soil suitable for seabuckthorn Obtain the water holding characteristic curve of the target plant's root system and obtain the suction force corresponding to the root wilting value; Obtain the water holding characteristic curve of the improved soil with water retaining agent and obtain the soil residual suction; If the residual suction of the soil is higher than the suction corresponding to the root wilting value, there is a risk of reverse water absorption. At this time, water-retaining agent is not added to the improved soil; on the contrary, water-retaining agent is added to the improved soil.

[0048] 1. Composition and preparation Add 2% by mass of water-retaining agent to sandy soil and mix well to obtain water-retaining agent-improved sandy soil. Add water to make the moisture content of the water-retaining agent-improved sandy soil 29.0%, and let it stand for 24 hours. Prepare samples with different moisture content gradients, test the water retention characteristic curve of the water-retaining agent-improved sandy soil by the filter paper method, and obtain the release water potential range of the water-retaining agent-improved sandy soil.

[0049] 2. Water potential response and adaptation judgment The water release range of the water-retaining agent-improved sandy soil covers 2.0 kPa~250.0 kPa; the suction corresponding to the sea buckthorn root wilting value is 5500.0 kPa, indicating that it has strong drought resistance; the residual suction of the water-retaining agent-improved sandy soil is 250.5 kPa, which is lower than the suction corresponding to the sea buckthorn root wilting value, indicating that the water-retaining agent-improved sandy soil can continuously supply water during most drought periods and avoid root water potential deficit.

[0050] Example verification The growth of the roots of Goosegrass in sandy soil is closely related to the content of water retaining agent. As the content of water retaining agent increases, the growth of the roots of Goosegrass deteriorates, which in turn accelerates its death. Figure 8 This is the growth status of goosegrass in the control group after one week. With the same amount of water, the plant without goosegrass showed the best growth. The plant pots with 2%, 5% or no water-retaining agent were placed outdoors in hot August. The plant pots with 2% water-retaining agent completely withered, while the plant pots with 5% water-retaining agent completely withered after just one day. The sea buckthorn root wilting value corresponds to a much higher suction force than that of other herbaceous plants, making it a suitable criterion for evaluating soil amendments containing other herbs.

[0051] This control method is suitable for planting projects of deep-rooted plants whose suction corresponding to the wilting value is higher than the residual suction of the soil, such as sea buckthorn and caragana.

[0052] It should be noted that when the claims of the present invention involve numerical ranges, it should be understood that the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. In order to avoid redundancy, the present invention describes preferred embodiments.

[0053] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0054] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for regulating and controlling water-retaining agents in improved soil, characterized in that: The following steps are involved: Obtain the water holding characteristic curve of plant roots in the improved soil and obtain the suction force corresponding to the root wilting value; Obtain the water holding characteristic curve of the improved soil with water retaining agent and obtain the soil residual suction; If the residual suction of the soil is higher than the suction corresponding to the root wilting value, there is a risk of reverse water absorption. In this case, no water retaining agent is added to the improved soil; On the contrary, water-retaining agents are added to the improved soil.

2. The control method according to claim 1, wherein The suction force and moisture content of the improved soil to which the water retaining agent is added and the plant roots in the improved soil are obtained by a filter paper method to obtain the water retention characteristic curve.

3. The control method according to claim 2, characterized in that The suction and the water content are fitted using the Van Genuchten equation to obtain a water holding characteristic curve. The Van Genuchten equation is as follows: Where: w represents the mass moisture content / %; w s Indicates saturated mass moisture content / %; w r represents the residual mass moisture content / %; ψ represents the matrix suction / kPa; a represents the fitting parameter of the air intake value, and n represents the fitting parameter of the slope of the inflection point. a and n are obtained by fitting the Van Genuchten equation, and m is 1-1 / n.

4. The control method according to claim 3, characterized in that The plant is goosegrass or sea buckthorn.

5. The control method according to claim 4, characterized in that: Among the fitting parameters of the Goosegrass, a is 0.192, m is 0.123, and n is 10.

685.

6. The control method according to claim 4, characterized in that: Among the fitting parameters of seabuckthorn, a is 8.539×10 -7 , m is 10.582, and n is 0.

329.

7. The control method according to claim 3, characterized in that: The improved soil is loess or sandy soil.

8. Application of the control method according to claim 1 in drought ecological restoration.

9. The use according to claim 8, characterized in that The drought ecological restoration refers to any one of slope management, degraded grassland restoration and plateau slope protection.

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