Ridging, double-film-mulching, temperature-accumulating, cold-resistant, soil moisture-preserving, growth-period-prolonging and high-yield ecological cultivation method for rehmannia

Abstract

The invention belongs to the technical field of crop cultivation, and particularly relates to a rehmannia root ridging double-film-mulching temperature accumulation cold-resistant soil moisture preservation growth period prolonging high-yield ecological cultivation method which comprises the following steps: (1) applying a compound base fertilizer to a land parcel, and uniformly mixing the compound base fertilizer with soil; (2) ridging according to the line spacing of 55-65 cm, the ridge height of 25-30 cm, the ridge top width of 40-45 cm and the ridge side slope of 35-40 degrees to form a continuous ridge body, laying a phase change energy storage material layer with the thickness of 5-8 mm on the arc-shaped surface of the top of the ridge body, and covering the surface of the phase change energy storage layer with a breathable polypropylene non-woven fabric; (3) construction of a double-film-covering system: laying a heat preservation film on the surface of the polypropylene non-woven fabric, laying an anti-ultraviolet film on the outer side of the heat preservation film, and embedding the edges of the two layers of films into film pressing grooves dug in the two sides of the ridge body to be compacted and sealed to form a closed heat preservation space; temperature measuring holes with the diameter of 10-12 mm are reserved in the anti-ultraviolet film every 2-3 m, and the hole openings are covered with elastic rubber plugs. The invention provides a rehmannia cultivation method which can synchronously solve the problems of insufficient accumulated temperature, weak cold resistance, poor soil moisture conservation, short growth period and poor ecological property.

Description

Technical Field

[0001] This invention belongs to the field of crop cultivation technology, specifically relating to a high-yield ecological cultivation method for Rehmannia glutinosa using a raised bed with double mulching to accumulate heat, resist cold, retain moisture, extend the growing season. Background Technology

[0002] Rehmannia glutinosa is a traditional and precious Chinese medicinal herb listed in the Chinese Pharmacopoeia. Its tuberous roots contain active ingredients such as catalpol and rehmannia polysaccharides, which have the effects of nourishing yin and blood, and replenishing essence and marrow. It is widely used in the fields of medicine and health products.

[0003] Rehmannia glutinosa is a temperate plant with an optimal growth temperature of 15-28℃. It has strict requirements for soil temperature and humidity and is not cold-resistant (growth stops below 10℃ and tubers are easily damaged by frost below 0℃). Insufficient moisture retention will lead to malformed tuber development. The length of the growth period directly affects the accumulation of active ingredients.

[0004] The current cultivation of Rehmannia glutinosa mostly adopts the traditional model of "single film covering + ridging", which has the following unavoidable technical defects: single film covering can only increase the temperature under the film by 3-5℃. When raising seedlings in early spring in the north or planting in low-temperature areas, the accumulated soil temperature cannot meet the needs of Rehmannia glutinosa germination and seedling growth, resulting in low germination rate, weak seedlings, and poor resistance to adverse conditions in the later stage; in winter or during late spring frost, single film covering has no effective cold protection measures, which can lead to complete crop failure in severe cases, and the frost-damaged tubers are prone to rotting and cannot be used for medicinal purposes; single film covering has poor sealing, resulting in a high soil moisture evaporation rate, requiring frequent irrigation, which wastes water resources and easily leads to soil compaction, affecting the root penetration; In existing improvement schemes, some technologies attempt to add a straw covering layer, but there are problems such as separation of "film-straw", poor sealing, and low accumulated temperature utilization. Therefore, there is an urgent need for a low-cost, easy-to-operate method for cultivating Rehmannia glutinosa that can simultaneously solve the problems of insufficient accumulated temperature, weak cold resistance, poor moisture retention, short growing season, and poor ecological performance, so as to improve the survival rate, yield and quality of Rehmannia glutinosa. Summary of the Invention

[0005] To address the aforementioned shortcomings in the existing technology, this invention provides a high-yield ecological cultivation method for Rehmannia glutinosa using raised beds with double mulching to accumulate heat, resist cold, retain moisture, extend the growing season, and solve the problems mentioned in the background technology.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for high-yield, ecological cultivation of Rehmannia glutinosa using raised beds with double mulching to accumulate heat, resist cold, retain moisture, extend the growing season, and includes the following steps: (1) Apply compound base fertilizer to the plot and mix the compound base fertilizer evenly with the soil; (2) Make ridges with a row spacing of 55-65cm, a ridge height of 25-30cm, a ridge top width of 40-45cm, and a ridge side slope of 35°-40° to form a continuous ridge. Lay a 5-8mm thick phase change energy storage material layer on the arc-shaped surface of the top of the ridge, and cover the surface of the phase change energy storage layer with breathable polypropylene non-woven fabric. (3) Construction of double-film system: a heat insulation film is laid on the surface of polypropylene nonwoven fabric, and an anti-ultraviolet film is laid on the outside of the heat insulation film. The edges of the two films are embedded in the film pressing grooves dug on both sides of the ridge and compacted to form a closed heat insulation space. Temperature measuring holes with a diameter of 10-12mm are reserved every 2-3m in the anti-ultraviolet film, and the holes are covered with elastic rubber plugs. (4) Monitor the soil temperature at a depth of 10-15cm in the temperature measuring hole every day. When the temperature is <11℃, send hot air into the closed insulation space to assist in heating. Before the arrival of the low temperature season, cover the surface of the UV-resistant film with a composite insulation layer of 5-8cm thick decomposed wheat straw + 3-5mm thick insulation cotton. (5) Monitor soil moisture content regularly. When the moisture content is <20%, turn on the drip irrigation tape and irrigate for 30-45 minutes. After irrigation, apply sodium polyacrylate water-retaining agent around the drip irrigation tape. (6) Extended management during the growing season: 15-20 days in advance, lay the double film system described in step (3) to maintain the soil temperature at 15-20℃; apply nitrogen, phosphorus and potassium compound fertilizer during the tuber formation period and supplement light for 3-4 hours a day; apply potassium sulfate fertilizer during the tuber enlargement period and extend the supplementary light time to 4-5 hours a day; remove the double film 10-15 days before harvest.

[0007] Furthermore, the compound base fertilizer is applied at a rate of 2000-2500 kg per mu. The compound base fertilizer is composed of well-rotted farmyard manure, corn straw-based biochar, and superphosphate, wherein the mass ratio of well-rotted farmyard manure, corn straw-based biochar, and superphosphate is 18:1:0.3.

[0008] Furthermore, the decomposed farmyard manure is a mixture of cow and sheep manure that has been fermented for more than 60 days.

[0009] Furthermore, the phase change energy storage material layer includes a polyethylene film and a composite phase change core material encapsulated within the polyethylene film.

[0010] Furthermore, the composite phase change core material comprises the following components in parts by weight: 70-85 parts paraffin wax, 5-15 parts thermal conductivity enhancer, and 5-15 parts shaping agent.

[0011] Furthermore, the thermal conductivity enhancer is selected from either expanded graphite or graphene microsheets.

[0012] Furthermore, the setting agent is selected from either high-density polyethylene or polypropylene.

[0013] Furthermore, the heat-insulating film is selected from EVA material, and the UV-resistant film is selected from PP film containing UV-resistant additives.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. To address the issues of "low temperature sensitivity and difficulty in seedling emergence," lay double-layer film coverings and a phase change energy storage layer 15-20 days in advance to maintain a stable soil temperature of 15-20℃. Apply compound fertilizer during the tuber formation period to promote leaf growth, induce root development, and control excessive growth. Combine this with 3-4 hours of full-spectrum supplemental lighting daily to make up for the lack of sunlight in northern regions during May and June. Apply high-purity potassium sulfate fertilizer during the tuber enlargement period to extend the supplemental lighting to 4-5 hours and increase light intensity. Remove the film 10-15 days before harvest to allow the tubers to gradually adapt to the external temperature and humidity, thus preventing diseases and epidermal cracking.

[0015] 2. The combination of double-layer film covering, phase change energy storage layer (daytime heat storage, nighttime heat release), and fuel-fired hot air blower (emergency heating) forms a "basic insulation + dynamic temperature regulation" system to ensure stable temperature throughout the entire cycle. Compound base fertilizer (early base application), staged topdressing (compound fertilizer → potassium sulfate fertilizer), and water-retaining agent (reducing nutrient loss) achieve "long-term supply + precise replenishment". The double-layer film covering can be reused for 1-2 seasons, the phase change energy storage layer can be recycled and preserved, and the straw can be returned to the field after harvest, taking into account both cultivation effect and ecological environmental protection, and reducing resource waste. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below with reference to embodiments.

[0017] In the existing cultivation techniques for Rehmannia glutinosa, the traditional "single mulch + ridging" model is mostly used, which has the following unavoidable technical defects: Single mulch can only increase the temperature under the mulch by 3-5℃. When raising seedlings in early spring in northern regions or planting in low-temperature areas, the accumulated soil temperature cannot meet the needs of Rehmannia glutinosa germination and seedling growth, resulting in low germination rate, weak seedlings, and poor resistance to adverse conditions in the later stages; In winter or during late spring frosts, single mulch has no effective cold protection measures, which can lead to complete crop failure in severe cases, and the frost-damaged tubers are prone to rotting and cannot be used for medicinal purposes; Single mulch has poor sealing, resulting in a high soil moisture evaporation rate, requiring frequent irrigation, which wastes water resources and easily leads to soil compaction, affecting the root development; Some techniques have attempted to add a straw mulch layer, but there are problems such as separation of "mulch-straw", poor sealing, and low accumulated temperature utilization.

[0018] This invention provides a high-yield ecological cultivation method for Rehmannia glutinosa with ridge-forming double-film mulching, heat accumulation, cold resistance, moisture retention, and extended growth period to solve the problems in the above-mentioned background technology. The method specifically includes the following steps: (1) applying compound base fertilizer to the plot and mixing the compound base fertilizer with the soil evenly; (2) Make ridges with a row spacing of 55-65cm, a ridge height of 25-30cm, a ridge top width of 40-45cm, and a ridge side slope of 35°-40° to form a continuous ridge. Lay a 5-8mm thick phase change energy storage material layer on the arc-shaped surface of the top of the ridge, and cover the surface of the phase change energy storage layer with breathable polypropylene non-woven fabric. Rehmannia glutinosa is a fibrous root crop, mainly distributed in the 10-20cm shallow soil layer. A row spacing of 55-65cm ensures that the roots of adjacent ridges do not compete for nutrients (two rows of seedlings are planted per ridge, with a plant spacing of 25-30cm). Sufficient field access is also provided for manual inspection, drip irrigation maintenance, and harvesting operations, preventing soil compaction caused by trampling during handling. Rehmannia glutinosa is susceptible to waterlogging; the incidence of root rot increases dramatically with increasing soil moisture content. A ridge height of 25-30cm reduces the soil moisture content at the top of the ridge compared to flat ground, decreasing the risk of root rot. Simultaneously, higher ridges increase the surface area exposed to sunlight. Combined with subsequent phase change layer and mulching, this rapidly increases the ridge temperature. The soil temperature 10cm below the mulch is 5-7℃ higher than on flat ground, meeting the accumulated temperature requirement of "≥15℃ for 5 consecutive days" during the germination period of Rehmannia glutinosa. The width of the ridge top should be 40-45cm: The width of the ridge top should simultaneously meet the requirements of "laying the phase change energy storage material layer" and "the space for tuber expansion": After the 5-8mm thick phase change layer is laid, the remaining space on the ridge top can accommodate the lateral expansion of the tubers of two rows of seedlings. The diameter of the tubers of Rehmannia glutinosa can reach 5-8cm, and each plant needs 15-20cm of lateral space to avoid the tubers becoming deformed due to insufficient space; at the same time, the width of 40-45cm can ensure that the curved surface of the ridge top is smooth, and the subsequent film covering can be tightly attached, reducing the air gap under the film and avoiding heat loss. A ridge slope of 35°-40° represents the optimal balance between ridge stability and mulch adhesion. A slope that is too steep (>40°) can easily lead to ridge collapse, especially when the soil is moist after irrigation. A slope that is too gentle (<35°) can cause the mulch to wrinkle and form air pockets, which accelerate heat loss and reduce insulation. This slope allows the outer UV-resistant film to naturally adhere to the ridge side, ensuring a seamless seal when subsequently embedded in the pressing groove, preventing air leakage at the film edge. The core function of the non-woven fabric is to isolate the phase change layer from the insulation film: on one hand, its "breathable but waterproof" properties prevent condensation under the film (condensation easily occurs due to day-night temperature differences after mulching; direct contact with the phase change layer will damage the sealing film, leading to leakage of the phase change material); on the other hand, it buffers friction during the laying of the insulation film (preventing damage caused by direct friction between the insulation film and the phase change layer sealing film), while not hindering heat transfer (solar heat can penetrate to the phase change layer, and the heat released by the phase change layer at night can also penetrate to the soil).

[0019] (3) Construction of double-film system: a heat insulation film is laid on the surface of polypropylene nonwoven fabric, and an anti-ultraviolet film is laid on the outside of the heat insulation film. The edges of the two films are embedded in the film pressing grooves dug on both sides of the ridge and compacted to form a closed heat insulation space. Temperature measuring holes with a diameter of 10-12mm are reserved every 2-3m in the anti-ultraviolet film, and the holes are covered with elastic rubber plugs. (4) Monitor the soil temperature at a depth of 10-15cm in the temperature measuring hole every day. When the temperature is <11℃, send hot air into the closed insulation space to assist in heating. Before the arrival of the low temperature season, cover the surface of the UV-resistant film with a composite insulation layer of 5-8cm thick decomposed wheat straw + 3-5mm thick insulation cotton. (5) Monitor soil moisture content regularly. When the moisture content is <20%, turn on the drip irrigation tape and irrigate for 30-45 minutes. After irrigation, apply sodium polyacrylate water-retaining agent around the drip irrigation tape. (6) Extended management during the growing season: 15-20 days in advance, lay the double film system described in step (3) to maintain the soil temperature at 15-20℃; apply nitrogen, phosphorus and potassium compound fertilizer during the tuber formation period and supplement light for 3-4 hours a day; apply potassium sulfate fertilizer during the tuber enlargement period and extend the supplementary light time to 4-5 hours a day; remove the double film 10-15 days before harvest.

[0020] Specifically, some preparatory work needs to be done before fertilization, including but not limited to removing weeds and gravel from the plot, deep plowing (25-35cm) the land, leveling the surface of the plot, ensuring that there are no obvious protrusions or depressions (slope ≤3°), and avoiding the concentration of nutrients in low-lying areas when fertilizing; at the same time, the premixed compound base fertilizer (weighed at 2000-2500kg / mu) is evenly divided into two portions, one for "broadcasting across the entire plot" and the other for "strip application in the ridge area".

[0021] Then, apply fertilizer in stages. The first stage is to spread fertilizer evenly across the entire plot (accounting for 60% of the total amount). In actual operation, a self-propelled fertilizer spreader can be used to spread the compound base fertilizer evenly on the surface of the plot at a uniform speed along the longitudinal direction of the plot. The second stage is to apply fertilizer in strips in the ridge area (accounting for 40% of the total amount). Mark the center line of the ridge on the plot according to the preset ridge spacing (55-65cm). Dig shallow trenches with a depth of 8-10cm and a width of 15-20cm along the center line using a furrow opener. Fill the remaining 40% of the compound base fertilizer evenly into the trenches to avoid the base fertilizer from accumulating in the trenches.

[0022] Finally, a medium-sized rotary tiller was used for mixing. The tillage depth was the same as the previous deep tillage depth (25-35cm) to ensure that the compound base fertilizer was in complete contact with the topsoil and that there was no stratification between the "base fertilizer layer" and the "soil layer". After tilling once longitudinally along the plot, it was tilled once transversely (cross-tillage) to break up the base fertilizer clumps. Uniformity check: After tillage, 5 sampling points were randomly selected (1 per hectare). A 20cm deep soil sample was taken from each point. No obvious aggregation of base fertilizer particles was observed by the naked eye. The coefficient of variation of total nitrogen and total phosphorus content in the laboratory test was ≤8%, which was considered to indicate that the mixture was uniform.

[0023] In this embodiment, the amount of compound base fertilizer applied is 2000-2500 kg per mu. The compound base fertilizer is composed of well-rotted farmyard manure, corn straw-based biochar, and superphosphate, wherein the mass ratio of well-rotted farmyard manure, corn straw-based biochar, and superphosphate is 18:1:0.3. The well-rotted farmyard manure is a mixture of cow and sheep manure fermented for more than 60 days.

[0024] It is worth noting that the corn straw-based biochar (porous structure) and well-rotted farmyard manure (organic matter) in the compound base fertilizer are evenly mixed to fill soil pores and break up the compacted layer, thereby increasing soil porosity and significantly enhancing aeration and water permeability. This directly solves the problem of "obstructed respiration and difficulty in root development" in Rehmannia glutinosa roots, providing a loose environment for root development in the seedling stage (the main root can reach a depth of over 30cm). Traditional single-strip application can easily lead to excessively high local concentrations of superphosphate, causing root burn in seedlings. By using "broadcasting + strip application + cross-rotary tillage," the effective phosphorus concentration in the soil is stabilized at 0.12-0.15%, and the nitrogen concentration is stabilized at 0.15-0.2%, perfectly matching the nutrient tolerance threshold of Rehmannia glutinosa seedlings. Broadcasting throughout the entire plot ensures that non-ridged areas (such as between ridges) also have basic nutrients, avoiding nutrient deficiency when the roots extend to the between ridges during the later tuber enlargement stage, eliminating nutrient blind spots, improving nutrient utilization, and reducing nutrient loss.

[0025] The adsorption properties of corn straw-based biochar need to be fully utilized through "uniform mixing": increasing the contact area between biochar and superphosphate prevents phosphorus from being fixed by soil calcium ions; at the same time, the organic matter of well-rotted farmyard manure combines with soil particles to form a "nutrient slow-release reservoir," extending the nitrogen release cycle and covering the nutrient needs of Rehmannia glutinosa seedlings to tuber formation. The uniformly mixed compound base fertilizer layer can improve the soil's thermal conductivity, forming a synergy with the subsequent "phase change energy storage layer + double mulch": accelerating the absorption of solar energy during the day and conducting it to the deep soil, and releasing heat at night in conjunction with the phase change layer; at the same time, organic matter improves the soil's water retention capacity, increasing the soil's field water holding capacity, reducing irrigation frequency, and forming a moisture-preserving closed loop with rainwater harvesting and drip irrigation systems.

[0026] From the seedling stage to the tuber enlargement stage, Rehmannia glutinosa needs to continuously obtain organic matter, phosphorus and trace elements: well decomposed farmyard manure provides long-lasting organic matter, which can meet the soil organic matter consumption throughout the entire growth period and avoid nutrient deficiency in the later stage; Superphosphate provides readily available phosphorus. A dosage of 51.2-64.0 kg / mu can ensure the phosphorus requirements for seedling root development (phosphorus promotes root hair formation) and early tuber differentiation, without the need for additional phosphorus supplementation. A dosage of 102.6-128.2 kg / mu of corn straw-based biochar can both adsorb nutrients through its porous structure (reducing phosphorus leaching loss) and improve soil porosity, thus avoiding soil compaction caused by insufficient application.

[0027] In some feasible plans, where the cultivation plots are sandy loam or loam, the amount of compound base fertilizer applied needs to be adjusted according to the soil's nutrient retention capacity: specifically, Sandy loam soil (with poor fertilizer retention): Select 2300-2500 kg / mu, and use a higher amount to make up for nutrient leaching loss and ensure stable nutrient concentration in the root distribution layer (10-20cm); For loamy soil (with strong fertilizer retention): choose 2000-2200 kg / mu (close to the lower limit) to avoid excessive application leading to soil nutrient enrichment (such as excessive phosphorus inhibiting zinc absorption) and reducing the risk of seedling yellowing.

[0028] In this invention, the phase change energy storage material layer comprises a polyethylene film and a composite phase change core material encapsulated within the polyethylene film. The composite phase change core material comprises the following components in parts by weight: 70-85 parts paraffin wax, 5-15 parts thermal conductivity enhancer, and 5-15 parts shaping agent. The thermal conductivity enhancer is selected from either expanded graphite or graphene microflakes. The shaping agent is selected from either high-density polyethylene or polypropylene.

[0029] In this embodiment, the composite phase change core material uses paraffin as the basic phase change carrier, combined with a thermal conductivity enhancer and a shaping agent, to form a three-in-one functional system of "energy storage-thermal conduction-shaping". The specific components and their functions are as follows: Basic phase change component: paraffin wax, selected from industrial-grade fully refined paraffin wax (carbon chain length C). 20 -C 30 The phase change temperature range is 15-25℃ (matching the suitable soil temperature for Rehmannia glutinosa growth), and the latent heat value is 180-220J / g (meeting the nighttime heat release requirements of the ridge). It absorbs solar energy during the day and converts it into latent heat for storage. When the temperature drops at night, it releases latent heat to maintain a stable soil temperature under the film.

[0030] Functional enhancement component 1: Thermal conductivity enhancer, selected from expanded graphite (particle size 50-100 mesh, porosity ≥90%) or graphene micro flakes (thickness 1-5nm, flake diameter 5-10μm); it solves the defect of low thermal conductivity of pure paraffin (only 0.2W / (m・K)), improves the thermal conductivity efficiency of the core material, ensures rapid heat storage during the day and uniform heat release at night, and avoids local temperature imbalance.

[0031] Functional enhancement component 2: The sizing agent is selected from high-density polyethylene (HDPE, melting point 120-130℃) or polypropylene (PP, melting point 160-170℃); it prevents leakage during the phase change of paraffin (solid-liquid conversion), fixes the paraffin through the polymer network, ensures that the core material maintains a stable shape in the encapsulation film, and is suitable for the laying requirements of the curved surface of the ridge.

[0032] It should be noted that if paraffin content is less than 70%, the latent heat value will drop below 160 J / g, resulting in insufficient heat release at night and an inability to maintain the critical growth temperature of Rehmannia glutinosa above 11℃, leading to the failure of accumulated temperature control. If the thermal conductivity enhancer content is greater than 15%, it will increase the hardness of the core material (making it prone to brittleness at room temperature), making it difficult to fit the curved surface of the ridge, and significantly increasing the cost (expanded graphite is 5-8 times more expensive than paraffin). If the sizing agent content is greater than 15%, it will reduce the paraffin content and increase the phase transition temperature of the core material (polymers will increase the crystallization temperature of paraffin), which may exceed the target range of 15-25℃ and fail to meet the growth requirements of Rehmannia glutinosa.

[0033] In this embodiment, the specific steps for constructing the double-film system include: laying an insulation film on the surface of a polypropylene nonwoven fabric, laying an anti-ultraviolet film on the outside of the insulation film, and embedding the edges of the two films into the pressing grooves excavated on both sides of the ridge to compact and seal them, forming a closed insulation space; the anti-ultraviolet film reserves temperature measuring holes with a diameter of 10-12mm every 2-3m, and the hole openings are covered with elastic rubber plugs; the insulation film is selected from EVA material, and the anti-ultraviolet film is selected from PP film containing anti-ultraviolet additives.

[0034] The double-layer membrane system is key to "locking in heat and resisting external interference." It forms a closed space through "inner insulation + outer protection + sealing and heat locking," solving the defects of traditional single-layer membranes such as "poor heat insulation, easy aging, and weak sealing." The inner insulation membrane is made of EVA (ethylene-vinyl acetate copolymer) material (thickness 0.08-0.12mm, light transmittance ≥90%). On the one hand, the high light transmittance ensures that sunlight penetrates to the phase change layer and the surface of the ridge (providing energy for heat storage in the phase change layer and photosynthesis of Rehmannia glutinosa, improving photosynthetic efficiency). On the other hand, the heat insulation properties of EVA material (thermal conductivity ≤0.04W / (m・K)) can reduce the loss of heat from under the membrane to the outside, keeping the temperature fluctuation range in the closed space within ±2℃ and maintaining stable accumulated temperature.

[0035] Outer UV-resistant film: PP film (0.12-0.15mm thick) containing UV-resistant additives is selected. Its core function is to resist external environmental interference: ① Prevent ultraviolet rays in sunlight from causing the inner EVA film to age and crack; ② Prevent wind and rain from damaging the film structure and prevent rainwater from seeping into the pressing groove and causing soil loss; ③ Reduce the impact of low temperature outside the film on the enclosed space in winter, and raise the minimum temperature under the film by 2-3℃.

[0036] Dig 8-10cm deep film-pressing trenches on both sides of the ridge, embed the edges of the two layers of film, and compact them with fine soil to form a closed space that is "air-free and water-free": The closed space ensures that the heat released by the phase change layer is retained at a rate of ≥90%, and the soil temperature 10cm below the film is stabilized at 15-28℃ (the optimal growth temperature for Rehmannia glutinosa), improving the utilization rate of accumulated temperature compared to unsealed areas; ② Moisture retention: The closed space reduces soil moisture evaporation, and with the help of rainwater collection ditches, the irrigation interval can be extended from 5-7 days to 12-15 days; ③ Prevent weeds from growing from the edges of the film (weeds compete for nutrients and block sunlight), reducing the cost of manual weeding.

[0037] The ridging, phase change layer + non-woven fabric, and double-film covering system are not independent structures, but rather form a synergistic system of "basic carrier → energy regulation → sealing and efficiency preservation": ridging provides stable support for the phase change layer and film covering; the phase change layer solves the problems of large diurnal temperature differences and insufficient accumulated temperature; the non-woven fabric protects the phase change layer and prevents moisture; and the double film covering maximizes the heat storage effect of the phase change layer and soil moisture through "heat preservation + anti-aging + sealing," achieving a cultivation environment of "stable temperature under the film, soil that is neither waterlogged nor drought-prone, and convenient operation," thereby improving the germination rate and reducing the rate of root frost damage.

[0038] In this embodiment, temperature measuring holes with a diameter of 10-12 mm are reserved every 2-3 m in the UV-resistant film, and the openings are covered with elastic rubber plugs. The soil temperature at a depth of 10-15 cm in the ridge is monitored daily. When the temperature is <11℃, hot air is delivered to the enclosed heat-insulating space to assist in warming. Before the arrival of the low-temperature season, a composite heat-insulating layer of 5-8 cm thick decomposed wheat straw + 3-5 mm thick heat-insulating cotton is covered on the surface of the UV-resistant film.

[0039] Rehmannia glutinosa is sensitive to soil temperature, requiring a suitable temperature above 11℃ (growth stagnates below 11℃, and tubers are easily damaged by frost below 5℃). However, if the "closed, insulated space" formed by the double-layer film is completely sealed, it is impossible to monitor the internal temperature in real time, easily leading to problems such as "undetected low temperatures" or "uncontrolled high temperatures." Therefore, the design of the temperature measuring hole must simultaneously meet the requirements of "accurate temperature monitoring" and "not compromising the sealed insulation." Specific details are as follows: Spacing of 2-3m: If the spacing is too small (e.g., <1m), it will increase the mulch damage rate (each hole is a potential hot spot) and make field operations redundant; if the spacing is too large (e.g., >3m), it will lead to insufficient representativeness of monitoring data (the temperature difference between the edge and center of the plot may reach 2-3℃). A spacing of 2-3m can achieve "single hole covering 20-25m² of ridge", balancing monitoring accuracy and sealing, and ensuring uniform and reliable temperature data throughout the plot.

[0040] 10-12mm diameter: This size is just right to match the insertion requirements of commonly used agricultural mercury thermometers (about 8-10mm in diameter) or electronic temperature probes. It avoids the problem of "the orifice being too small to insert the temperature measuring tool" and also prevents "the orifice being too large (such as >15mm) from causing rapid heat loss". Actual tests show that when the 10-12mm orifice is sealed with a rubber stopper, the daily temperature loss under the membrane is only 0.5-1℃, which is much lower than the 3-4℃ without a rubber stopper.

[0041] The key function of the elastic rubber stopper is to resolve the core contradiction between "monitoring needs and sealing"—during non-monitoring periods, the rubber stopper completely seals the aperture, maintaining the integrity of the sealed and insulated space (preventing the intrusion of cold air from the outside and the dissipation of internal heat); during monitoring periods, the rubber stopper only needs to be removed to insert the temperature measuring tool, which is convenient to operate and does not damage the membrane, achieving "monitoring on demand and sealing under normal conditions".

[0042] Temperature measurement holes are a prerequisite for subsequent "hot air heating" and "composite insulation layer laying" - by monitoring twice a day, from 9:00 to 10:00 (critical period of daytime warming) and from 15:00 to 16:00 (before nighttime cooling), the soil temperature at a depth of 10-15cm in the ridge can be monitored in real time (this depth is the concentrated distribution area of ​​Rehmannia glutinosa roots, and the temperature directly affects the root absorption function), avoiding "blindly increasing the temperature" or "missing the risk of low temperature", and ensuring precise and efficient temperature control.

[0043] The basic insulation system of double-layer membrane + phase change energy storage layer can maintain the temperature through the phase change material's "daytime heat storage and nighttime heat release," but when encountering extreme weather such as late spring cold snaps or continuous rain, the heat released by the phase change material may not be sufficient to meet the demand (e.g., after three consecutive cloudy days, the phase change layer's heat storage is insufficient, and the temperature under the membrane may drop to 8-10℃), requiring additional emergency heating. Hot air (temperature 30-35℃, wind speed 0.8-1.2m / s) is delivered to the enclosed insulation space through flexible hoses and can be evenly diffused along the length of the ridge. The hot air heating can raise the temperature under the membrane from 10℃ to 15℃ within 30 minutes, with a temperature distribution deviation of ≤1℃.

[0044] Specifically, air can be supplied by a fuel-fired hot air blower. The hot air blower can cover a 20-25m long ridge by "setting up at both ends of the ridge and distributing it with a hose". There is no need to set up equipment for each ridge, which is highly efficient.

[0045] When the soil temperature is below 11℃, the root absorption function of Rehmannia glutinosa decreases by more than 50%. If this continues for 24 hours, it will lead to a 10%-15% increase in seedling yellowing rate and a 3-5 day delay in tuber differentiation. Hot air-assisted warming can quickly bring the temperature back to the suitable range, forming a dual guarantee of "basic heat storage + emergency warming" with the phase change energy storage layer, ensuring that the growth rhythm of Rehmannia glutinosa is not interrupted and accumulating sufficient biomass for the subsequent tuber enlargement period.

[0046] During the low-temperature season (daily average temperature ≤5℃, such as November to February of the following year in northern regions), double-layer film covering + phase change layer alone is insufficient to withstand extreme low temperatures below -2℃ (easily leading to root frost damage exceeding 30%). An additional "outer insulation barrier" needs to be constructed. A composite structure of "decomposed wheat straw + insulation cotton" is selected, specifically as follows: 5-8cm of decomposed wheat straw is used as the inner layer, with a porosity of 60%-70%, which can trap air to form an "air insulation layer." At the same time, a small amount of heat is slowly released during the decomposition process to supplement the heat under the film. Moreover, straw is agricultural waste, which is low in cost and easy to obtain, in line with the concept of ecological cultivation.

[0047] A 3-5mm thick insulating cotton (centrifugal glass wool, thermal conductivity ≤0.035W / (m・K)) serves as the outer layer. Its high-density fiber structure blocks the intrusion of cold air, preventing heat loss due to excessive pores in the straw. This composite insulation layer can raise the temperature under the film by 4-6℃ compared to single straw covering. The composite insulation layer is fixed to the surface of the UV-resistant film with polypropylene pressing ropes (1.5-2m spacing). Laying and removing it (after spring temperature rise) does not require damaging the film, and the straw can be subsequently crushed and returned to the field, achieving a resource cycle of "insulation-returning to the field" and avoiding waste pollution. This ensures the safety of tubers during overwintering / low-temperature seasons, extends the growing season, and ensures normal germination the following spring. It also advances the seedling cycle; the insulation layer can be removed 15-20 days earlier in spring, allowing the temperature under the film to quickly rise above 15℃, enabling earlier seedling cultivation than traditional methods. This indirectly extends the growth period of Rehmannia glutinosa (adding 20-30 days to tuber enlargement), laying the foundation for increased yield.

[0048] In this embodiment, the soil moisture content is monitored regularly. When the moisture content is <20%, the drip irrigation tape is turned on for 30-45 minutes. After irrigation, sodium polyacrylate water-retaining agent is sprinkled around the drip irrigation tape.

[0049] Specifically, a high-precision insertion soil moisture meter can be used, with monitoring every 3 days. Each time, select 3 representative monitoring points within the plot (the edge, middle, and random locations on the ridge) to avoid single-point data deviation. Insert the moisture meter probe vertically into the ridge to a depth of 15-20cm (coinciding with the dense area of ​​the Rehmannia glutinosa root system), leave it for 30 seconds until the data stabilizes. If the average moisture content of the 3 monitoring points is <20%, trigger irrigation; if the moisture content is ≥20%, maintain the current state and no additional water is needed.

[0050] The drip irrigation tape is automatically controlled by a timer (set irrigation time to 30-45 minutes), with the working pressure stabilized at 0.1-0.15MPa (ensuring uniform dripper flow rate of 2.0-2.5L / h). The drip irrigation tape is laid between the inner insulation film and the polypropylene non-woven fabric, with a dripper spacing of 25-30cm (matching the planting spacing of Rehmannia glutinosa). The water flow directly penetrates to a depth of 10-15cm into the surface of the ridge, avoiding deep leakage. 30 minutes after irrigation, the moisture content is monitored again with a hygrometer to ensure it reaches 22%-25% (the suitable moisture content range for Rehmannia glutinosa growth). If it does not meet the standard, irrigate for another 10-15 minutes. If it exceeds the standard, shorten the next irrigation time by 5-10 minutes. Select granular sodium polyacrylate water-retaining agent with a particle size of 0.5-1mm (water absorption ratio of 300-500 times, meeting agricultural-grade safety standards), and weigh it in rows at a dosage of 3-5kg / acre; manually spread it evenly within 5cm on both sides of the drip irrigation tape (overlapping with the water flow penetration range) along the drip irrigation tape, avoiding spreading it too far, which would cause a disconnect between water retention and replenishment; after spreading, use a small rake to lightly rake the surface layer of the ridge to a depth of 5-8cm (without damaging the double-film sealed structure) to ensure that the water-retaining agent is in full contact with the moist soil and accelerate subsequent water absorption and expansion.

[0051] Rehmannia glutinosa is a fibrous root crop with shallow roots (mainly distributed in the 15-25cm soil layer). It is not drought tolerant but is susceptible to waterlogging: water shortage in the seedling stage will cause yellowing of leaves, and water shortage in the tuber formation stage will reduce the number of tubers by 2-3 per plant. If watering is excessive (moisture content > 30%), "water accumulation under the film" is likely to form in the double-covered closed environment, which will lead to root hypoxia and rot (the incidence of root rot will increase to more than 20%).

[0052] While double-film mulching systems can reduce soil moisture evaporation, they also present a contradiction: water is easily retained / lost after replenishment. If flood irrigation is used, water flow under the closed film cannot penetrate quickly and is easily lost along the slope of the ridge. If irrigation is not timely, the film will exacerbate the "lock-in effect" of soil moisture, preventing the roots from absorbing deep water. The design of "drip irrigation tape for targeted replenishment + timed monitoring" avoids the waste of flood irrigation and prevents hidden drought under the film through high-frequency monitoring, adapting to the water control logic of the closed environment. Sodium polyacrylate water-retaining agent is introduced (which forms a gel after absorbing water and slowly releases water) to form a combination of "short-term replenishment + long-term retention" with drip irrigation replenishment, solving the problems of "poor timeliness and low efficiency" of traditional water retention.

[0053] In this embodiment, the double film covering system described in step (3) is laid 15-20 days in advance during the seedling stage to maintain the soil temperature at 15-20℃; nitrogen, phosphorus and potassium compound fertilizer is applied during the tuber formation stage, and supplemental light is provided for 3-4 hours per day; potassium sulfate fertilizer is applied during the tuber enlargement stage, and the supplemental light duration is extended to 4-5 hours per day; the double film covering is removed 10-15 days before harvest.

[0054] The specific operating steps include Seedling stage: Lay the double-film mulching system 15-20 days in advance to maintain soil temperature at 15-20℃. Start the operation 15-20 days after sowing Rehmannia glutinosa seeds / before transplanting tuber seedlings (usually mid-March in northern regions, corresponding to the early spring low temperature period); ensure that the plot has completed "ridge making + phase change energy storage layer laying + polypropylene non-woven fabric covering", and check the double-film mulching system (inner layer EVA insulation film, outer layer UV-resistant PP film) in advance to ensure it is undamaged; first, lay the inner layer EVA insulation film flat on the surface of the non-woven fabric, ensuring that the film surface adheres to the curved surface of the top of the ridge (without wrinkles); then cover the outside of the EVA film with the outer layer UV-resistant PP film, and simultaneously embed the edges of the two films into the pre-set U-shaped film pressing grooves (8-10cm deep, 5-7cm wide) on both sides of the ridge, and fill them with fine soil with a moisture content of 20%-25%. Compact the layers (each layer 3-4cm thick) to prevent air leakage under the film. After covering, monitor the soil temperature at a depth of 10-15cm in the ridges by inserting a mercury thermometer (accuracy ±0.1℃) through the temperature measuring holes in the outer PP film (one every 2-3m) between 9:00-10:00 and 15:00-16:00 daily. If the temperature is <15℃, turn on the fuel-fired hot air blowers at both ends of the ridges (hot air temperature 30-35℃, wind speed 0.8-1.2m / s) to deliver hot air to the enclosed insulation space through hoses (lasting 1-1.5 hours each time) until the temperature stabilizes at 15-20℃. If the temperature is >20℃, open the elastic rubber plugs of the temperature measuring holes to ventilate and cool down, avoiding scorching of the seedlings by high temperature.

[0055] During tuber formation: Apply NPK compound fertilizer and supplement with 3-4 hours of light daily. When the local yellow seedlings reach the 4-6 leaf stage (tuberous differentiation begins, usually in mid-to-late May), first dig shallow trenches 5-6 cm deep on both sides of the ridge, 5-8 cm from the edge (avoid damaging the surface roots); evenly spread NPK compound fertilizer (N:P2O5:K2O=1:1.2:1.5) at a rate of 15-20 kg / mu into the shallow trenches, then cover and compact with fine soil (3-4 cm thick) to prevent fertilizer loss; 1-2 days before topdressing, erect supplemental lighting supports—erect them 1.2-1.8 cm high around the perimeter of the plot (at both ends along the length of the ridge). A galvanized steel pipe support frame is constructed, with steel wire ropes strung between the supports. Full-spectrum LED plant grow lights (400-700nm, 30-50W / lamp) are fixed to the steel wire ropes, with a lamp spacing of 1.5-2m (ensuring each lamp covers a 1.5-2m wide ridge). Supplemental lighting is turned on daily from 17:00 to 20:00 (or adjusted according to local sunshine duration, ensuring a total duration of natural light + supplemental lighting ≥ 12 hours), with each session lasting 3-4 hours and the light intensity controlled at 200-300μmol / m²・s (adjusted via the lamp's dimming knob).

[0056] During the tuber enlargement stage: Apply potassium sulfate fertilizer and extend supplemental lighting to 4-5 hours. When the diameter of the local yellow rhizome tubers reaches 3cm or more (entering the critical period of enlargement, usually July-August), dig trenches 8-10cm deep on both sides of the ridge, 8-10cm from the edge (deeper than during the tuber formation stage, to meet the needs of potassium fertilizer transport to deeper roots); apply potassium sulfate fertilizer (K2O content ≥50%, granular) at a rate of 25-30kg / mu into the trenches, cover with fine soil and lightly compact (avoid fertilizer particles being exposed); extend the supplemental lighting time from 3-4 hours to 4-5 hours, adjusting the supplemental lighting period to 16:30-21:30 (supplemental lighting can maximize the accumulation of photosynthetic products), and increase the light intensity to 300-400μmol / m²・s; during this period, regularly check the working status of LED lights, and replace any damaged lights within 24 hours to avoid insufficient supplemental lighting in some areas of the ridge.

[0057] 10-15 days before harvest: Remove the double-film system when the leaves of the locust trees begin to turn yellow and the wilting rate reaches 60%-70% (10-15 days before harvest, usually in mid-to-late October). First, remove the outer UV-resistant PP film—untie the fine soil from the film-pressing groove at one end of the ridge and slowly roll the PP film towards the other end (avoid tearing and damage; after rolling, fold and store in a cool, dry place; it can be reused for 1-2 seasons). Then, remove the inner EVA insulation film in the same way, and simultaneously recover the phase change energy storage layer (rinse the surface soil with clean water, dry, and seal for storage). After removing the film, retain the polypropylene non-woven fabric to prevent the surface soil of the ridge from compacting.

[0058] Early mulching during the seedling stage: Rehmannia glutinosa seedlings (from emergence to the 3-leaf stage) are extremely sensitive to temperature—when soil temperature is <15℃, seed germination rate drops below 60%, and seedling root growth stagnates (root length is only 50% of that at suitable temperature). Traditional cultivation without early mulching relies on natural accumulated temperature, resulting in a 7-10 day delay in emergence and uneven seedling growth. Laying a double-mulching system 15-20 days in advance utilizes the high heat retention of the EVA film (temperature under the film is 7-10℃ higher than the outside) and the phase change energy storage layer's "daytime heat storage - nighttime heat release" function to stably maintain a suitable temperature environment of 15-20℃, meeting the physiological needs of seedlings for "temperature-driven growth." Applying compound fertilizer and supplemental lighting during the tuber formation period: This matches the needs of "nutrients for differentiation + light for photosynthesis." The tuber formation period is a critical period for Rehmannia glutinosa to transition from "vegetative growth" to "reproductive growth (tuber development)." Nitrogen can promote leaf photosynthesis (increasing chlorophyll content by 20%), providing organic nutrients for tuber differentiation; phosphorus can induce root differentiation and increase the number of tuber primordia; potassium can inhibit excessive stem and leaf growth and avoid nutrient waste. Therefore, a compound fertilizer with N:P2O5:K2O=1:1.2:1.5 is chosen to precisely match the needs of "promoting leaves, inducing roots, and controlling excessive growth." In northern regions, the average daily sunshine duration in May and June is only 8-10 hours, which is lower than the critical value of 12 hours required for photosynthesis in Rehmannia glutinosa, resulting in insufficient accumulation of photosynthetic products. Supplemental lighting for 3-4 hours can make up for the light gap and provide sufficient carbohydrates for tuber differentiation. Applying potassium fertilizer and extending supplemental lighting during the tuber enlargement stage focuses on "nutrient accumulation and product transport." Potassium is a key coenzyme in the synthesis of active components such as starch and polysaccharides in Rehmannia glutinosa tubers. It can promote the transport of photosynthetic products from leaves to tubers, while also enhancing the toughness of tuber cell walls and reducing deformities. High-purity potassium sulfate fertilizer (K2O≥50%) should be selected to avoid the impact of chlorine on the quality of Rehmannia glutinosa (chlorine will reduce the content of catalpol). At this time, the daily photosynthetic product consumption of tubers is twice that of the formation period, and only 3-4 hours of supplemental lighting cannot meet the demand. Extending supplemental lighting to 4-5 hours can increase the daily accumulation of photosynthetic products by 25%-30%, directly supporting the increase in tuber weight. Remove the film before harvest: This avoids the risks of "high humidity under the film + sudden environmental changes." Although the double-film system can retain heat and moisture, long-term sealing can lead to air humidity under the film reaching over 85%. If the film is not removed before harvest, the tubers are susceptible to pathogen infection. At the same time, the stable temperature and humidity environment under the film makes the tuber epidermis delicate. Direct exposure to the low outside temperature after harvest (average daily temperature of 5-8℃ in northern regions in mid-to-late October) can easily cause epidermal cracking. Removing the film 10-15 days in advance allows the tubers to gradually adapt to the outside temperature and humidity, enhances epidermal toughness, and reduces the risk of disease and cracking.

[0059] The above are merely embodiments of the present invention. The circuits, electronic components, and modules involved are all prior art, fully achievable by those skilled in the art, and require no further explanation. The scope of protection in this application does not involve improvements to the software and methods. Commonly known structures and characteristics in the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all prior art in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the application.

Claims

1. A method for high-yield, ecological cultivation of Rehmannia glutinosa using raised beds with double mulching to accumulate heat, resist cold, retain moisture, extend the growing season, and promote longevity, characterized by: Includes the following steps: (1) Apply compound base fertilizer to the plot and mix the compound base fertilizer evenly with the soil; (2) Make ridges with a row spacing of 55-65cm, a ridge height of 25-30cm, a ridge top width of 40-45cm, and a ridge side slope of 35°-40° to form a continuous ridge. Lay a 5-8mm thick phase change energy storage material layer on the arc-shaped surface of the top of the ridge, and cover the surface of the phase change energy storage layer with breathable polypropylene non-woven fabric. (3) Construction of double-film system: a heat insulation film is laid on the surface of polypropylene nonwoven fabric, and an anti-ultraviolet film is laid on the outside of the heat insulation film. The edges of the two films are embedded in the film pressing grooves dug on both sides of the ridge and compacted to form a closed heat insulation space. Temperature measuring holes with a diameter of 10-12mm are reserved every 2-3m in the anti-ultraviolet film, and the holes are covered with elastic rubber plugs. (4) Monitor the soil temperature at a depth of 10-15cm in the temperature measuring hole every day. When the temperature is <11℃, send hot air into the closed insulation space to assist in heating. Before the arrival of the low temperature season, cover the surface of the UV-resistant film with a composite insulation layer of 5-8cm thick decomposed wheat straw + 3-5mm thick insulation cotton. (5) Monitor soil moisture content regularly. When the moisture content is <20%, turn on the drip irrigation tape and irrigate for 30-45 minutes. After irrigation, apply sodium polyacrylate water-retaining agent around the drip irrigation tape. (6) Extended growing season management: Lay the double film covering system described in step (3) 15-20 days in advance during the seedling stage to maintain the soil temperature at 15-20℃; Apply nitrogen, phosphorus, and potassium compound fertilizer during the tuber formation period and supplement with light for 3-4 hours daily; apply potassium sulfate fertilizer during the tuber enlargement period and extend the supplemental lighting time to 4-5 hours daily; remove the double mulch 10-15 days before harvest.

2. The method for high-yield ecological cultivation of Rehmannia glutinosa using raised beds with double mulching as described in claim 1, characterized in that: The compound base fertilizer is applied at a rate of 2000-2500 kg per mu. The compound base fertilizer is composed of well-rotted farmyard manure, corn straw biochar, and superphosphate, wherein the mass ratio of well-rotted farmyard manure, corn straw biochar, and superphosphate is 18:1:0.

3.

3. The method for high-yield ecological cultivation of Rehmannia glutinosa using raised beds with double mulching as described in claim 2, characterized in that: The decomposed farmyard manure is a mixture of cow and sheep manure that has been fermented for more than 60 days.

4. The method for high-yield ecological cultivation of Rehmannia glutinosa using raised beds with double mulching as described in claim 1, characterized in that: The phase change energy storage material layer includes a polyethylene film and a composite phase change core material encapsulated within the polyethylene film.

5. The method for high-yield ecological cultivation of Rehmannia glutinosa using raised beds with double mulching as described in claim 4, characterized in that: The composite phase change core material comprises the following components in parts by weight: 70-85 parts paraffin wax, 5-15 parts thermal conductivity enhancer, and 5-15 parts shaping agent.

6. The method for high-yield ecological cultivation of Rehmannia glutinosa using raised beds with double mulching as described in claim 5, characterized in that: The thermal conductivity enhancer is selected from either expanded graphite or graphene microflakes.

7. The method for high-yield ecological cultivation of Rehmannia glutinosa using raised beds with double mulching as described in claim 5, characterized in that: The sizing agent is selected from either high-density polyethylene or polypropylene.

8. The method for high-yield ecological cultivation of Rehmannia glutinosa using raised beds with double mulching as described in claim 1, characterized in that: The heat-insulating film is made of EVA material, and the UV-resistant film is made of PP film containing UV-resistant additives.