A three-layer substrate cultivation method for vegetables in a solar greenhouse

Abstract

This invention discloses a three-layer substrate cultivation method for vegetables in a solar greenhouse, belonging to the field of soilless cultivation technology in facility agriculture. The method includes: constructing a trapezoidal ridge group in the solar greenhouse, and laying a rock wool water-retaining layer, an organic substrate cultivation layer, and a washed river sand temperature-regulating layer in sequence from bottom to top on the ridge. After setting up a drip irrigation system, the moisture content of the sand layer is controlled in winter, and the high thermal conductivity of the wet sand is used to absorb solar radiation heat and release it at night to increase the temperature. In summer, the moisture content of the sand layer is reduced, and the low thermal conductivity of the dry sand is used to block the high temperature from being conducted to the root zone. This method solves the technical problems of difficult troughing in solar greenhouses, difficulty in water and fertilizer retention, large water and fertilizer evaporation, and uneven water and fertilizer supply affecting product quality.

Description

Technical Field

[0001] This invention belongs to the field of soilless cultivation technology in facility agriculture, specifically relating to a three-layer substrate cultivation method for vegetables in solar greenhouses, which is suitable for the efficient cultivation and production of vegetables such as eggplant, melons and cucurbits in solar greenhouses. Background Technology

[0002] The Gobi Desert region has abundant sunshine resources, but its ecosystem is fragile. The surface is mostly gravel, and the soil has extremely poor water and fertilizer retention capacity, severely limiting the development of traditional agriculture. Solar greenhouses are an important model for developing the vegetable industry on non-arable land, but they have long faced three core challenges:

[0003] First, the construction of cultivation foundations by trenching in the Gobi gravel substrate involves a large amount of work, high costs, and intensive labor.

[0004] Secondly, the sandy soil has a loose structure, extremely poor water and fertilizer retention capacity, and low efficiency in water and fertilizer input.

[0005] Third, the high temperature and dry environment leads to severe water and fertilizer evaporation losses and large supply fluctuations, which directly restricts the improvement of vegetable yield and quality.

[0006] Currently, the main cultivation methods used in Gobi greenhouses include traditional trough cultivation, rock wool cultivation, and sand cultivation. Traditional trough cultivation requires excavating a large amount of soil and backfilling with substrate, resulting in high substrate consumption per acre and severe water and fertilizer leakage and evaporation. Rock wool cultivation is usually a single substrate, which has good water retention but is costly and difficult to effectively insulate under high temperatures. Sand cultivation generally faces severe salt accumulation on the surface, which can easily burn the root system and cause salt damage. More importantly, existing technologies cannot simultaneously solve the comprehensive technical problem of winter heating, summer insulation, and year-round salt return prevention in a single cultivation structure.

[0007] Therefore, there is an urgent need for a cultivation method that is tailored to the characteristics of non-arable land in the Gobi Desert, can systematically integrate multiple functions such as water and fertilizer retention, temperature increase and heat insulation, and significantly reduce input and operating costs. Summary of the Invention

[0008] The purpose of this invention is to provide a three-layer substrate cultivation method for vegetables in a solar greenhouse, so as to solve the problems mentioned above.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A method for cultivating vegetables in a solar greenhouse using a three-layer substrate includes the following steps:

[0011] S1. Construct a three-layer composite trapezoidal cultivation ridge system:

[0012] On the ground inside the greenhouse, multiple parallel trapezoidal ridges are constructed along the east-west direction. For each trapezoidal ridge, a water-retaining layer, a cultivation layer, and a temperature-regulating layer are laid from bottom to top, forming a three-layer composite structure similar to a "sandwich".

[0013] The trapezoidal ridge has a stable structure that is wider at the bottom and narrower at the top. The bottom width is 0.5m, the top width is 0.3m, and the height is 0.3m. The spacing between adjacent trapezoidal ridges is 1.0-1.5m.

[0014] The water-retaining layer is made of rock wool with a thickness of 5-10cm, preferably 7cm. As a mineral material with high porosity and strong adsorption, rock wool has a dual function in this invention: during the cultivation period, it absorbs and temporarily stores the irrigation water, fertilizer and salt leached from top to bottom using its high water holding capacity, and isolates the salt below the root zone of the cultivation layer to maintain a low-salt environment in the cultivation layer; after each crop is harvested or before the next crop is planted, the salt accumulated in the rock wool layer can be washed out by a concentrated large volume of water leaching, restoring its water storage and salt holding capacity.

[0015] The cultivation layer is formed by laying an organic substrate on top of the water-retaining layer, with a thickness of 15-25cm, preferably 20cm. The organic substrate is made by mixing peat moss, mushroom residue and perlite in a volume ratio of 3:1:1 and fully fermenting and decomposing it. In this ratio, peat moss provides organic matter and water retention, mushroom residue provides nutrients and loose structure, and perlite enhances aeration and drainage. The three work together to create a "warm bed" environment for crop roots that has good structural stability, water and fertilizer buffering capacity, aeration and nutrient supply capacity.

[0016] The temperature-regulating layer is made of washed river sand and has a thickness of 3-5cm, preferably 3cm.

[0017] S2. Install the irrigation system:

[0018] Laying drip irrigation tape on the surface of the temperature-regulating layer can achieve uniform irrigation and further reduce water evaporation.

[0019] S3. Seasonal time-based water and temperature control and anti-salinity irrigation management:

[0020] The moisture content of the river sand in the temperature regulation layer is actively regulated by using a shallow TDR soil moisture sensor with a probe length of 1-3 cm, which is horizontally buried in the middle of the temperature regulation layer (about 1.5 cm from the top surface of the sand). After calibration with a special calibration curve for river sand, the moisture content is monitored in real time, and a gravimetric sample is taken every 3 days for calibration.

[0021] Winter warming mode: During sunny winter days (light intensity ≥ 200 lux in the greenhouse) The temperature-regulating layer is irrigated through the drip irrigation tape, so that the water content of the river sand in the temperature-regulating layer reaches 20%-30% after irrigation. The basis for determining this range is that the field water holding capacity of river sand is about 20%-25%. When the water content is in this range, the continuity of liquid water in the sand layer is high, and the thermal conductivity can reach 5-8 times that of dry sand. At the same time, a small number of air pores are retained to have a heat preservation effect. When the water content exceeds the field water holding capacity, the excess water is lost through gravity infiltration and no longer increases the water holding and thermal conductivity of the sand layer. Therefore, the water content range of 20%-30% is the optimal balance point to achieve the maximum effective thermal conductivity of the sand layer and the minimum ineffective water consumption.

[0022] The basic irrigation amount is calculated based on the sand layer volume and the target moisture content of 25%, and an additional 20% leaching amount is added. This allows the irrigation water to penetrate the sand layer, leach the cultivation layer, and then enter the rock wool water-retaining layer. After irrigation, the moisture content of the sand layer briefly rises to 25%-30%, and then drops back to 15%-20% within 2-3 hours due to gravity infiltration and crop transpiration. At night, the wet sand layer releases heat, and the root zone temperature is higher than that of traditional cultivation.

[0023] Summer heat insulation mode: During the high-temperature period in summer, irrigation is controlled to ensure that the moisture content of the river sand in the temperature-regulating layer is ≤5% (by mass). Simultaneously, deep leaching irrigation (8-10g) is carried out every 7-10 days on cloudy days or in the evening. The basis for determining this irrigation amount is: 8-10 Under the specified irrigation quota, the moisture content of the substrate in the cultivation layer increased from approximately 15% to 25%-30%. At this point, a significant water potential gradient was formed between the cultivation layer and the underlying rock wool water-retaining layer. The substrate suction on the dry side of the rock wool reached 10-30 kPa, driving the water in the cultivation layer to continuously move downwards in the form of an unsaturated flow. Dissolved salts entered the rock wool water-retaining layer with this water flow and were adsorbed and stored. Experimental results showed that within 48 hours after irrigation, the EC value of the substrate at the bottom 10 cm of the cultivation layer decreased by 15%-25% compared to before irrigation, while the corresponding EC value at the rock wool water-retaining layer increased by 0.5-1.2. mS / cm confirmed the effectiveness of directional salt migration driven by unsaturated flow. Simultaneously, the sand moisture content briefly increased to 15%-18% after irrigation, but decreased to ≤5% within 48 hours through downward drainage and natural evaporation, restoring the dry sand's insulation properties. If the scheduled rinsing day coincides with consecutive days of high temperatures (greenhouse temperature consistently ≥38℃), rinsing can be postponed by 1-3 days to prioritize maintaining the sand's insulation properties. Salt accumulation during the postponement period will be washed away during the next rinsing. Practice over multiple planting seasons has shown that 7-10 days... The rinsing cycle, within a flexible range of ±3 days, will not significantly affect the EC value of the cultivation layer. The principle is to utilize the extremely low thermal conductivity of dry river sand to form a thermal barrier layer from the top surface of the ridge, effectively reducing the heat conducted by the high-temperature air in the greenhouse through the top surface of the ridge to the cultivation layer and crop root zone. At the same time, combined with the trapezoidal air gaps formed between the ridges, the overall heat insulation effect is further enhanced, ensuring that the root layer is relatively cool. Furthermore, instantaneous spraying can be carried out during the peak temperature period of each day, using the evaporation of a small amount of surface moisture to remove latent heat and enhance the cooling effect.

[0024] Salt leaching: During irrigation, drip irrigation is carried out from top to bottom, forming a clean water flow pointing towards the water-retaining layer in the three-layer composite cultivation structure. The salt accumulated during cultivation is leached downwards and temporarily stored in the water-retaining layer or its interface. During irrigation intervals, the dry sand on the surface effectively inhibits evaporation and salt return, preventing salt from moving upwards. Through the alternating cycle of "irrigation leaching - dry sand blocking return", a low-salt microenvironment is maintained in the cultivation layer. During deep leaching in summer, the water flow carries the salt in the cultivation layer to the water-retaining layer for rapid infiltration and storage. Afterwards, during the dry period, the sand layer dries and blocks evaporation, preventing salt return.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. This invention significantly reduces the total amount of cultivation substrate by using a three-layer composite trapezoidal ridge design that allows for direct surface ridging without trenching. Although the root zone volume is reduced, the root vitality and health level are significantly better than traditional trench planting through precise control of rhizosphere temperature and directional leaching of salt, effectively compensating for the limitation of root zone space on yield.

[0027] 2. This invention utilizes a temperature-regulating layer of dry sand to suppress evaporation, combined with precise water supply through drip irrigation tape laid on the ground. This significantly reduces irrigation water consumption and pure nutrient input throughout the entire growth period. Salt is leached into the rock wool water-retaining layer for ex-situ storage, maintaining a low-salt microenvironment in the cultivation layer and further reducing ineffective irrigation for salt suppression.

[0028] 3. Thanks to the synergistic effect of rhizosphere temperature regulation and low-salt microenvironment, the yield of solanaceous vegetables is significantly increased compared with traditional trough planting, the soluble solids content and marketable fruit rate of the fruit are significantly improved, and the incidence of physiological diseases such as blossom-end rot is greatly reduced. Attached Figure Description

[0029] Figure 1 This is a schematic cross-sectional view of the three-layer composite trapezoidal cultivation ridge structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the ridge group structure formed by multiple trapezoidal ridges arranged in parallel according to the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and multiple embodiments. These embodiments are only used to explain the present invention and should not be construed as constituting any form of limitation on the scope of the present invention.

[0032] Example 1 (Preferred example: Overwintering tomato cultivation)

[0033] This experiment was conducted in Greenhouse No. 1 (80m long, 10m span) of Dongdong Gobi Agricultural Industrial Park, Suzhou District, Jiuquan City, Gansu Province. The experiment was conducted from August 2023 to June 2024, and the crop was tomato (variety: Jinpeng No. 1).

[0034] S1. Ridge Group Construction:

[0035] In July 2023, ridges were directly planned on the ground inside the greenhouse without the need for trenching. The ridges were raised in an east-west direction and arranged parallel to the span of the greenhouse to form multiple trapezoidal ridges with a ridge spacing of 1.5m. Each trapezoidal ridge had a base width of 0.5m, a top width of 0.3m, and a height of 0.3m.

[0036] First, lay a 7cm thick layer of rock wool (density 80) at the bottom. (as a water-retaining layer);

[0037] A 20cm thick organic substrate layer is laid on top. The organic substrate is made by fully mixing peat moss, mushroom residue and perlite in a volume ratio of 3:1:1 and fermenting for 60 days.

[0038] Finally, a 3cm thick layer of washed river sand is evenly spread on the top surface of the cultivation layer as a temperature-regulating layer. The sand particles are mainly 0.5-2mm in diameter and have a mud content of ≤3%.

[0039] S2. Irrigation system installation:

[0040] Drip irrigation tape is laid along the length of the ridge on the surface of the temperature-regulating river sand layer. The working pressure is 0.05-0.1MPa, the flow rate per hole is 0.6L / h, the hole spacing is 15cm, and there is one tape per ridge. The length is consistent with the length of the ridge. To prevent sand particles from clogging the tape, 200-mesh water-permeable non-woven fabric is wrapped around the outside of the drip irrigation tape. One tape is laid on each ridge.

[0041] S3. Planting and Early Management:

[0042] On August 20, 2023, healthy tomato seedlings with 6 leaves and 1 heart and uniform growth were selected and planted on the ridges with a plant spacing of 40cm. One row was planted per ridge, with about 2,200 plants per acre. After planting, the seedlings were thoroughly watered and the sand layer was kept at a moisture content of about 20% during the seedling establishment period.

[0043] S4. Seasonal and target-based regulation and management:

[0044] Phase 1: Autumn-Winter Transition Period (September-October 2023)

[0045] During this period, the outside temperature is still high, but the intensity of solar radiation has weakened. A transitional plan for summer heat insulation mode is implemented: the moisture content of the sand layer is controlled at 5%-12%. The lower moisture content effectively blocks the transmission of daytime high temperature to the root zone. Irrigate once every 3-5 days, with each irrigation amount of about 4-5 m³ / acre, keeping the cultivation layer moist. At the same time, the salt-directed leaching strategy is continuously implemented.

[0046] Phase Two: Overwintering Period (November 2023 to February 2024)

[0047] This period is the main low-temperature period, with the lowest outside temperature reaching -25℃. A strict winter warming mode is implemented: on sunny days, the temperature inside the greenhouse can reach 25-30℃. Between 10:00 and 15:00, the temperature-regulating sand layer is irrigated with a small flow rate and high frequency using drip irrigation tape. Each irrigation lasts about 8-12 minutes, with an interval of 1-1.5 hours, and is irrigated 2-3 times to keep the moisture content of the sand layer stable at 18%-22%. The sand layer can be squeezed into a ball by hand and crumbles when dropped.

[0048] Nighttime monitoring of soil temperature at a depth of 10cm in the cultivation layer showed an increase of 2.8-3.5℃ compared to the traditional trough planting method. In the traditional trough planting method, the nighttime temperature at this layer often drops to 9-11℃, while in this embodiment it is maintained at 12-14℃, effectively ensuring root activity.

[0049] Meanwhile, through continuous top-down irrigation, the EC value of the water and fertilizer infiltration solution remained below 1.5 mS / cm in the cultivation layer, while the EC value at the bottom of the rock wool water-retaining layer reached 4-5 mS / cm, proving that the salt was successfully leached in a directional manner and stored ectopically below the root zone.

[0050] Phase Three: Summering Period (May-June 2024)

[0051] This period marks the end of the harvest and the management before pulling up the seedlings. During the daytime, extreme temperatures inside the greenhouse can reach 42-45℃, necessitating strict summer insulation measures.

[0052] Significantly reduce irrigation frequency to once every 5-7 days, each time only wetting the middle and lower part of the cultivation layer, keeping the moisture content of the temperature-regulating sand layer ≤5%, and the surface of the sand layer is dry and loose, forming a dry sand heat barrier layer.

[0053] Meanwhile, salt migration irrigation should be carried out once every 10 days on a cloudy evening: irrigation amount 10 This process increases the moisture content of the cultivation layer substrate from approximately 15% to 25%-30%. The strong substrate suction of the rock wool water-retaining layer creates a water potential gradient pointing downwards, driving dissolved salts to migrate downwards in the form of unsaturated flow and store them in the rock wool layer. Within 48 hours after irrigation, the EC value at the bottom 10cm of the cultivation layer decreases by 15%-25% compared to before irrigation, and the moisture content of the sand layer naturally drops back to ≤5%, restoring the heat insulation performance of dry sand.

[0054] When the temperature inside the greenhouse exceeds 38℃, during the peak high-temperature period from 12:00 to 14:00, the drip irrigation tape is turned on for intermittent instantaneous spraying, each spray lasting about 1.5 minutes, with an interval of 30 minutes. The trace amount of water evaporates to remove the latent heat on the ridge surface, and the temperature of the cultivation layer is monitored, which reduces the temperature by 4-5℃ compared to traditional trough planting.

[0055] S5. Results and Benefits:

[0056] Based on calculations over a complete production cycle, the core data for this embodiment are as follows:

[0057] Matrix dosage: 53.6% in this method. The traditional trench planting method (trench width 0.6m, trench depth 0.27m, trench spacing 1.5m, substrate filling rate 100%) requires a substrate dosage of 72. This method saves 26%; it should be noted that although the root zone volume is reduced, the root vitality and health level are significantly better than traditional trench planting through precise control of rhizosphere temperature and targeted leaching of salt, which partially compensates for the limiting effect of root zone space on yield, ultimately achieving a yield increase of 22.3%;

[0058] Water saving rate: 42%, total irrigation water consumption during the entire growth period: 182 Traditional trench planting is 314 ;

[0059] Fertilizer saving rate: 26%, the total net nutrient input during the entire growth period is 48 kg / mu, while the traditional trough planting is 65 kg / mu;

[0060] Labor saving: 81%, the comprehensive labor required for land preparation and ridge building, daily water and fertilizer management is 8 man-mu, while traditional trough planting is 42 man-mu;

[0061] Yield: 11,250 kg / mu, compared to 9,200 kg / mu for traditional trough planting, representing a 22.3% increase;

[0062] Quality: The soluble solids content of tomatoes is 5.8%, compared to 4.9% for traditional trough cultivation; the vitamin C content is 18.2 mg / 100g, compared to 15.3 mg / 100g for traditional trough cultivation, an increase of about 18%; the incidence of blossom-end rot has decreased by 78%, and the marketable fruit rate has increased from 78% to 93%.

[0063] Example 2 (Cucumber Cultivation Application)

[0064] This embodiment was carried out in Greenhouse No. 2 of Dongdong Gobi Agricultural Industrial Park, Suzhou District, Jiuquan City, Gansu Province. The specifications were the same as in Embodiment 1. The crop was cucumber (variety: Jinyou 35), and it was cultivated as a single crop for overwintering.

[0065] S1. Ridge Group Construction:

[0066] The ridge structure parameters are the same as in Example 1: the trapezoidal ridge has a bottom width of 0.5m, a top width of 0.3m, a height of 0.3m, and a ridge spacing of 1.5m.

[0067] The bottom water-retaining layer is made of 7cm thick rock wool, the middle cultivation layer is made of 20cm thick organic substrate, peat moss: mushroom residue: perlite = 3:1:1, and it has been decomposed for 60 days. The top temperature-regulating layer is made of 3cm thick washed river sand, which is laid on the top surface of the cultivation layer.

[0068] S2. Irrigation System:

[0069] Using drip irrigation tape of the same specifications as in Example 1, one tape is laid per row, inside the shallow layer of sand.

[0070] S3. Planting:

[0071] On September 15, 2023, grafted cucumber seedlings were planted with black-seeded pumpkin as rootstock, with a plant spacing of 35cm and approximately 2,500 seedlings per acre.

[0072] S4. Key Control Nodes:

[0073] Winter warming management (December to February of the following year):

[0074] Cucumbers are extremely sensitive to low temperatures. Physiological disorders occur when the root zone temperature is below 12℃. In this embodiment, the winter warming mode is strictly implemented: on sunny winter days from 10:00 to 15:00, high-frequency irrigation is carried out three times (10 minutes each time, with an interval of 1 hour). The moisture content of the sand layer is maintained at 20%-25%, and the minimum root zone temperature of the cultivation layer is maintained at 13.5-15.0℃ at night, which is about 4℃ higher than the traditional trough planting control (9-11℃).

[0075] Springtime salt return prevention management (March to May):

[0076] During this period, evaporation increases, highlighting the problem of salt accumulation on the surface in traditional sand culture. In this embodiment, by continuously circulating downwards for clean water, the EC value of the cultivation layer is consistently controlled below 1.8 mS / cm. This threshold is set based on the salt tolerance of the cucumber variety "Jinyou 35" (which can tolerate a substrate EC value below 2.0 mS / cm). Under the directional leaching effect of this method, the actual EC value of the cultivation layer fluctuates between 1.2 and 1.8 mS / cm, far from reaching the stress level. The bottom of the rock wool water-retaining layer becomes a salt-rich area (EC value 3.5-4.2 mS / cm), and the cucumber roots are completely in a low-salt safe zone.

[0077] S5. Results and Benefits:

[0078] Yield: 12,800 kg / mu, compared to 10,500 kg / mu for traditional trough planting, representing an increase of 21.9%;

[0079] Water saving rate: 40.5%, total irrigation water consumption during the entire growth period: 205 The traditional trough planting control was 345. ;

[0080] Fertilizer saving rate: 25.8%, total pure nutrient input during the entire growth period is 52 kg / mu, compared to 70 kg / mu for traditional trough planting control;

[0081] Quality: The soluble sugar content of cucumbers increased by 16.5%, and the straightness rate of cucumber strips increased from 82% to 95%.

[0082] Example 3 (Application in Chili Pepper Cultivation)

[0083] This embodiment was carried out in the same industrial park, with chili peppers (variety: Longjiao No. 5) as the crop, and adopting autumn-delayed overwintering long-season cultivation.

[0084] S1. Ridge Group Construction:

[0085] The parameters of the trapezoidal ridges are the same as those in Examples 1 and 2, but the ridge spacing is adjusted to 1.0m to adapt to the chili plant type, the thickness of the organic substrate in the cultivation layer is adjusted to 18cm, the thickness of the rock wool in the water retention layer is 7cm, and the thickness of the river sand in the temperature regulation layer is 3cm.

[0086] S2-S3: Irrigation system and planting method refer to Example 1.

[0087] S4. Key Control Nodes:

[0088] During the overwintering period, a strict winter warming mode was implemented, with the sand layer moisture content maintained at 18%-22%. The rhizosphere night temperature was 2.5-3.0℃ higher than the control. Since the pepper roots are shallow and more sensitive to salinity, the EC value of the cultivation layer was always below 1.2mS / cm through continuous downward water flow.

[0089] S5. Results and Benefits:

[0090] Yield: 5600 kg of fresh peppers per mu (667 square meters), compared to 4600 kg / mu (667 square meters) with traditional trench planting, representing an increase of 21.7%.

[0091] Water saving rate: 42.3%, total irrigation water consumption during the entire growth period: 168 The traditional trough planting control was 291. ;

[0092] Fertilizer saving rate: 26.5%, total pure nutrient input during the entire growth period is 39 kg / mu, compared to 53 kg / mu for traditional trough planting control.

[0093] Example 4 (Comparison Test of Different Water Retention Layer Thicknesses)

[0094] To verify the optimal range of the water-retaining layer thickness, a control plot was set up in the same greenhouse. Other conditions were the same as in Example 1 (tomato cultivation), except that the thickness of the rock wool water-retaining layer was changed to three treatments: 5cm, 7cm, and 10cm.

[0095] The results are shown in the table below:

[0096]

[0097] The test results show that a 7cm rock wool layer can achieve excellent water retention, buffering and anti-salinization effects, with no significant difference from the 10cm treatment. Considering the overall cost, 7cm is the optimal economic thickness.

[0098] Example 5 (Comparative Test of Different River Sand Temperature-Regulating Layer Thicknesses)

[0099] To verify the optimal range of the temperature-regulating layer thickness, three treatments of 2cm, 3cm, and 5cm were set, with other conditions the same as in Example 1 (tomato cultivation).

[0100] The results are shown in the table below:

[0101]

[0102] The experimental results show that a 3cm layer of river sand has sufficient heat storage capacity and coverage effect, and is the optimal economic thickness for two-way regulation in winter and summer.

[0103] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. The present invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for cultivating vegetables in a solar greenhouse using a three-layer substrate, characterized in that, Includes the following steps: S1. Construct a three-layer composite cultivation ridge: On the ground surface inside the greenhouse, ridges are made along the width or length of the greenhouse; a water-retaining layer, a cultivation layer, and a temperature-regulating layer are laid on the ridges from bottom to top; the ridges are evenly distributed along the length or width of the greenhouse. The water-retaining layer is made of mineral materials and has a thickness of 5-10cm; The cultivation layer is formed by laying an organic substrate on the water-retaining layer, and the thickness is 15-25cm. The temperature-regulating layer is made of river sand laid on top of the cultivation layer, and has a thickness of 3-5cm. S2. Install the irrigation system: Drip irrigation tape is laid on the surface of the temperature-regulating layer; S3. Seasonal time-based water and temperature control and anti-salinity irrigation management Winter warming mode: On sunny winter days, the temperature regulating layer is irrigated through the drip irrigation tape, so that the water content of the river sand in the temperature regulating layer reaches 20%-30% after irrigation and drops back to 15%-20% during the day. Summer heat insulation mode: During the high-temperature period in summer, irrigation is controlled to ensure that the moisture content of the river sand in the temperature-regulating layer is ≤5%. Simultaneously, deep leaching irrigation (8-10g) is carried out every 7-10 days on cloudy days or in the evening. The time for sand layer to rehydrate is controlled by utilizing lower temperatures and weaker evaporation conditions, and the moisture content of the sand layer is allowed to naturally drop to ≤5% by subsequently stopping irrigation. Salt leaching: Irrigation is carried out from top to bottom through the drip irrigation tape, forming a clean water flow that points towards the water-retaining layer in the three-layer composite cultivation structure. The salt accumulated during cultivation is leached downwards and temporarily stored in the water-retaining layer or its interface to maintain the low-salt microenvironment of the cultivation layer and eliminate the stress of salt accumulation on the root system.

2. The method for three-layer substrate cultivation of vegetables in a solar greenhouse according to claim 1, characterized in that: In step S1, the thickness of the water-retaining layer is 7cm, the thickness of the cultivation layer is 20cm, the thickness of the temperature-regulating layer is 3cm, and the mineral material is rock wool.

3. The method for three-layer substrate cultivation of vegetables in a solar greenhouse according to claim 1, characterized in that, The ridge has a trapezoidal structure, with a bottom width of 0.5m, a top width of 0.3m, a height of 0.3m, and a ridge spacing of 1.0-1.5m.

4. The method for three-layer substrate cultivation of vegetables in a solar greenhouse according to claim 1, characterized in that: In step S1, the organic substrate is made by mixing peat moss, mushroom residue and perlite in a volume ratio of 3:1:1 and then fully fermenting and decomposing it.

5. The method for three-layer substrate cultivation of vegetables in a solar greenhouse according to claim 1, characterized in that: In the summer heat insulation mode of step S3, it is also included that, based on the water content of the river sand in the temperature regulating layer being ≤5%, instantaneous spraying is carried out during the peak temperature period of each day, and the latent heat is carried away by the evaporation of surface water, thereby further enhancing the cooling effect.

6. The method for three-layer substrate cultivation of vegetables in a solar greenhouse according to claim 1, characterized in that: The vegetable is one of the following: tomato, pepper, or cucumber.

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