A cultivation substrate and its preparation process

Abstract

This invention relates to the field of cultivation substrate technology, and more particularly to a cultivation substrate and its preparation process. The cultivation substrate, from bottom to top, comprises: a perlite granule layer, a first fiber substrate layer, a magnesium ammonium phosphate slow-release fertilizer layer, a temperature-sensitive water-retaining agent layer, and a second fiber substrate layer; the thickness ratio of the perlite granule layer, the first fiber substrate layer, the magnesium ammonium phosphate slow-release fertilizer layer, the temperature-sensitive water-retaining agent layer, and the second fiber substrate layer is 5-10:20-40:1-2:0.1-1:10-30; the perlite granule layer is made of perlite granules with a particle size of 2-4 mm. This invention effectively achieves the synergistic effect of vertical water penetration and lateral diffusion, and can retain water under low temperature and high humidity conditions, while releasing water and increasing porosity under high temperature and low humidity conditions. The system exhibits excellent stability, effectively preventing nutrient loss, and can stably maintain the substrate state even after long-term use.

Description

Technical Field

[0001] This invention relates to the field of cultivation substrate technology, and in particular to a cultivation substrate and its preparation process. Background Technology

[0002] In the field of seed and seedling cultivation, the physical structure, water and fertilizer retention capacity, and microbial activity of the cultivation substrate are key factors affecting seedling survival rate. In the fields of facility-based seedling cultivation and intensive cultivation, the physical structure and functional regulation of the cultivation substrate directly determine the root development and stress resistance of seedlings.

[0003] Traditional substrates primarily consist of natural materials such as peat, coconut coir, and vermiculite, with peat playing a dominant role due to its unique physicochemical properties. As an incomplete decomposition product of swamp plant remains, peat has a high organic matter content (>50%) and low bulk density (0.04-0.27 g / cm³). 3 Its advantages, such as high porosity (79-98%), provide a good initial growth environment for seedlings.

[0004] However, as modern agriculture places increasing demands on the controllability of cultivation conditions, these traditional substrates have gradually revealed systemic defects: during the periodic alternation of wet and dry conditions, the fiber network of peat substrate is prone to irreversible pore collapse, which severely hinders root oxygen exchange. This is a key factor causing root rot and stunted growth in transplanted seedlings.

[0005] Current technologies for improving water retention generally employ modifications by adding synthetic water-retaining agents. While water-absorbing resins, such as sodium polyacrylate, can increase the water retention rate of the substrate, these materials exhibit high pore filling rates upon absorbing water and swelling, leading to a decrease in the gas diffusion coefficient. More seriously, the interfacial bonding between the resin and peat fiber is weak, making them prone to phase separation under alternating temperature and humidity conditions, forming localized closed-cell structures. This exacerbates the anisotropy of water and air permeability in the substrate. Furthermore, conventional water-retaining materials lack environmental responsiveness and cannot dynamically adjust water supply according to plant transpiration requirements. In high-temperature, high-light periods, they can actually intensify water stress within the substrate, severely hindering large-scale crop production.

[0006] Therefore, developing cultivation substrates with adaptive adjustment functions, stable systems, and good water retention and air permeability has become an urgent technical problem to be solved in the field of agricultural cultivation substrates. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a cultivation substrate and its preparation process.

[0008] A cultivation substrate, from bottom to top, comprises: a perlite granule layer, a first fiber substrate layer, a magnesium ammonium phosphate slow-release fertilizer layer, a temperature-sensitive water-retaining agent layer, and a second fiber substrate layer; the thickness ratio of the perlite granule layer, the first fiber substrate layer, the magnesium ammonium phosphate slow-release fertilizer layer, the temperature-sensitive water-retaining agent layer, and the second fiber substrate layer is 5-10:20-40:1-2:0.1-1:10-30; the raw material for the perlite granule layer is perlite granules with a particle size of 2-4 mm.

[0009] Preferably, the raw materials for both the first fiber substrate layer and the second fiber substrate layer are fiber substrates, and the raw materials for the fiber substrates include: coconut coir and cassava residue, with a mass ratio of coconut coir to cassava residue of 10-20:1-5.

[0010] Preferably, the fiber substrate is prepared by the following specific steps: coconut coir and cassava residue are mixed evenly, crushed to a particle size ≤2mm, added to sodium hydroxide solution and left to stand for 5-10h, filtered, washed with water until neutral, dried until the system moisture content is 5-10%, sent to a steam explosion tank, and 1.5-2MPa saturated steam is introduced and maintained for 100-120s before instantaneous depressurization.

[0011] Preferably, the concentration of the sodium hydroxide solution is 0.5-1.5 mol / L.

[0012] Preferably, the drying temperature is 70-80℃.

[0013] Preferably, the raw material of the temperature-sensitive water-retaining agent layer is a temperature-sensitive water-retaining agent, and the raw materials of the temperature-sensitive water-retaining agent include, by weight, 5-20 parts of peat, 1-5 parts of bamboo powder, 1-2 parts of N-isopropylacrylamide, 0.001-0.01 parts of N,N'-methylenebisacrylamide, and 0.01-0.1 parts of initiator.

[0014] Preferably, the temperature-sensitive water-retaining agent is prepared by the following steps: peat and bamboo powder are added to sodium hydroxide solution, refluxed and stirred at 70-90℃ for 1-2 hours, cooled to room temperature, and the pH of the system is adjusted to 6.5-7 with 1mol / L hydrochloric acid. The mixture is filtered, washed, and vacuum dried. N-isopropylacrylamide and N,N'-methylenebisacrylamide are added and mixed. An initiator is added under nitrogen protection, and the mixture is stirred at 60-70℃ for 1-2 hours. Potassium dihydrogen phosphate solution is added and stirring is continued for 10-30 minutes. The mixture is then vacuum dried.

[0015] Preferably, the initiator is a persulfate, specifically ammonium persulfate.

[0016] Preferably, the concentration of the sodium hydroxide solution is 0.5-1.5 mol / L.

[0017] Preferably, the concentration of the potassium dihydrogen phosphate solution is 0.5-1 mol / L.

[0018] The preparation method of the above-mentioned cultivation substrate includes the following steps: laying a layer of perlite granules at the bottom, covering the perlite granule layer with a first fiber substrate layer, then laying magnesium ammonium phosphate slow-release fertilizer and a temperature-sensitive water-retaining agent layer evenly in sequence, covering the temperature-sensitive water-retaining agent layer with a second fiber substrate layer, rolling and compacting, and irradiating for sterilization.

[0019] Preferably, the roller pressing pressure is 0.1-0.15 MPa.

[0020] Preferably, using 60 Sterilization is performed by Co-γ irradiation with a dose of 3-8 kGy.

[0021] Beneficial effects:

[0022] This invention combines coconut coir and cassava residue and treats them with sodium hydroxide, which promotes internal swelling to form a microporous structure. Then, through steam explosion, the internal pore structure is rich. The resulting fiber substrate not only has excellent adsorption properties, but also has excellent water retention and air permeability.

[0023] Due to its small adsorption capacity, peat loses nutrients very quickly. This invention addresses this by treating peat and bamboo powder with sodium hydroxide, which disrupts the crystalline structure of lignin and cellulose, exposing more hydroxyl sites. N-isopropylacrylamide then combines with the above product via free radical polymerization. The resulting temperature-sensitive water-retaining agent exhibits expansion and water absorption at low temperatures, while shrinking to release moisture at temperatures above 32°C. Simultaneously, the adsorbed nutrients desorb more rapidly with increasing temperature. When combined with magnesium ammonium phosphate slow-release fertilizer, this achieves a synergistic slow release of water and nutrients.

[0024] This invention lays a layer of perlite particles at the bottom, and then sequentially covers a first fiber substrate layer, a magnesium ammonium phosphate slow-release fertilizer layer, a temperature-sensitive water-retaining agent layer, and a second fiber substrate layer. This effectively achieves the synergistic effect of vertical water penetration and horizontal diffusion. Moreover, it can lock in water at low temperature and high humidity, while shrinking and releasing water and forming internal interconnected pores at high temperature (>32℃) to promote gas exchange. The system has excellent stability and can effectively prevent the loss of nutrients. Even after long-term use, it can stably maintain the matrix state.

[0025] Cultivation experiments have confirmed that the cultivation substrate of this invention produces Dendrobium officinale with good growth. Compared with traditional substrates, Dendrobium officinale grown in the cultivation substrate of this invention has a higher survival rate, better growth, and higher polysaccharide content. This enables the sustainable development and utilization of Dendrobium officinale resources and is worthy of promotion and application. Attached Figure Description

[0026] Figure 1 This is a comparison chart of the bulk density and water holding capacity of the cultivation substrates obtained in Example 5 and Comparative Examples 1-2.

[0027] Figure 2 This is a comparison chart of the total porosity and air-water ratio of the cultivation substrates obtained in Example 5 and Comparative Examples 1-2.

[0028] Figure 3 This is a comparison chart of the moisture release rate and porosity change rate of the cultivation substrates obtained in Example 5 and Comparative Examples 1-2 after standing at 35°C for 8 hours.

[0029] Figure 4 The above-ground and underground fresh weights of Dendrobium officinale in each group were compared at 180 days in a comparative experiment using the cultivation substrates obtained in Example 5 and Comparative Examples 1-2.

[0030] Figure 5 This is a comparative experiment on the transplantation of Dendrobium officinale using the cultivation substrates obtained in Example 5 and Comparative Examples 1-2. The figures show the comparison of the longest root system and polysaccharide content of Dendrobium officinale in each group at 180 days.

[0031] Figure 6 The above-ground and underground fresh weights of Dendrobium officinale in each group were compared after 180 days in three comparative experiments using the cultivation substrates obtained in Example 5 and Comparative Examples 1-2.

[0032] Figure 7 The image shows a comparison of the longest roots and polysaccharide content of Dendrobium officinale in each group after 180 days, based on three transplanting experiments using the cultivation substrates obtained in Example 5 and Comparative Examples 1-2.

[0033] Figure 8 The total porosity and air-water ratio of the cultivation substrates obtained in Example 5 and Comparative Examples 1-2 were compared in three transplanting experiments of Dendrobium officinale. After transplanting, the total porosity and air-water ratio of the cultivation substrates in each group were compared. Detailed Implementation

[0034] The present invention will be further explained below with reference to specific embodiments.

[0035] The magnesium ammonium phosphate slow-release fertilizer used below was purchased from Shandong Mousheng Marine Technology Co., Ltd.

[0036] Example 1

[0037] A cultivation substrate comprises, from bottom to top: a 5mm thick perlite granule layer, a 20mm thick first fiber substrate layer, a 1mm thick magnesium ammonium phosphate slow-release fertilizer layer, a 0.1mm thick temperature-sensitive water-retaining agent layer, and a 10mm thick second fiber substrate layer.

[0038] The raw material for the perlite particle layer is perlite particles with a particle size of 2mm.

[0039] The raw materials for both the first and second fiber substrate layers are fiber substrates. The fiber substrates are prepared using the following specific steps: 1000g of coconut coir and 100g of cassava residue are mixed evenly, crushed to a particle size ≤2mm, added to 5000g of 0.5mol / L sodium hydroxide solution and left to stand for 5h, filtered, washed with water to neutral, dried at 70℃ until the system moisture content is 5%, and sent to a steam explosion tank. 1.5MPa saturated steam is introduced and maintained for 100s before instantaneous depressurization.

[0040] The raw material for the temperature-sensitive water-retaining agent layer is a temperature-sensitive water-retaining agent, which is prepared using the following steps: 500g of peat and 100g of bamboo powder are added to 4000g of a 0.5mol / L sodium hydroxide solution, refluxed and stirred at 70℃ for 1h, cooled to room temperature, and the pH of the system is adjusted to 6.5-7 using 1mol / L hydrochloric acid. The mixture is filtered, washed, and vacuum dried. 100g of N-isopropylacrylamide and 0.1g of N,N'-methylenebisacrylamide are added and mixed. Under nitrogen protection, 1g of ammonium persulfate is added, and the mixture is stirred at 60℃ for 1h. 500g of a 0.5mol / L potassium dihydrogen phosphate solution is added, and the mixture is stirred for another 10min. The mixture is then vacuum dried.

[0041] The preparation method of the above-mentioned cultivation substrate includes the following steps: laying a layer of perlite granules as the bottom layer, covering the perlite granule layer with a first fiber substrate layer, then evenly laying a layer of magnesium ammonium phosphate slow-release fertilizer and a temperature-sensitive water-retaining agent layer in sequence, and then covering the temperature-sensitive water-retaining agent layer with a second fiber substrate layer, compacting it with a roller at 0.1 MPa, and using... 60 Sterilization was performed by Co-γ irradiation at a dose of 5 kGy.

[0042] Example 2

[0043] A cultivation substrate comprises, from bottom to top: a 10mm thick perlite granule layer, a 40mm thick first fiber substrate layer, a 2mm thick magnesium ammonium phosphate slow-release fertilizer layer, a 1mm thick temperature-sensitive water-retaining agent layer, and a 30mm thick second fiber substrate layer.

[0044] The raw material for the perlite particle layer is perlite particles with a particle size of 4mm.

[0045] The raw materials for both the first and second fiber substrate layers are fiber substrates. The fiber substrates are prepared using the following specific steps: 2000g of coconut coir and 500g of cassava residue are mixed evenly, crushed to a particle size ≤2mm, added to 10000g of 1.5mol / L sodium hydroxide solution, left to stand for 10h, filtered, washed with water to neutral, dried at 80℃ until the system moisture content is 10%, and sent to a steam explosion tank. 2MPa saturated steam is introduced and maintained for 120s before instantaneous depressurization.

[0046] The raw material for the temperature-sensitive water-retaining agent layer is a temperature-sensitive water-retaining agent, which is prepared using the following steps: 2000g of peat and 500g of bamboo powder are added to 10000g of a 1.5mol / L sodium hydroxide solution, refluxed and stirred at 90℃ for 2h, cooled to room temperature, and the pH of the system is adjusted to 6.5-7 using 1mol / L hydrochloric acid. The mixture is filtered, washed, and vacuum dried. 200g of N-isopropylacrylamide and 1g of N,N'-methylenebisacrylamide are added and mixed. Under nitrogen protection, 10g of ammonium persulfate is added, and the mixture is stirred at 70℃ for 2h. 1000g of a 1mol / L potassium dihydrogen phosphate solution is added, and the mixture is stirred for another 30min. The mixture is then vacuum dried.

[0047] The preparation method of the above-mentioned cultivation substrate includes the following steps: laying a layer of perlite granules as the bottom layer, covering the perlite granule layer with a first fiber substrate layer, then evenly laying a layer of magnesium ammonium phosphate slow-release fertilizer and a temperature-sensitive water-retaining agent layer in sequence, and then covering the temperature-sensitive water-retaining agent layer with a second fiber substrate layer, compacting it with a roller at 0.15 MPa, and using... 60 Sterilization was performed by Co-γ irradiation with a dose of 8 kGy.

[0048] Example 3

[0049] A cultivation substrate comprises, from bottom to top: a perlite granule layer with a thickness of 7 mm, a first fiber substrate layer with a thickness of 35 mm, a magnesium ammonium phosphate slow-release fertilizer layer with a thickness of 1.2 mm, a temperature-sensitive water-retaining agent layer with a thickness of 0.8 mm, and a second fiber substrate layer with a thickness of 15 mm.

[0050] The raw material for the perlite particle layer is perlite particles with a particle size of 3.5 mm.

[0051] The raw materials for both the first and second fiber substrate layers are fiber substrates. The fiber substrates are prepared using the following specific steps: 1200g of coconut coir and 400g of cassava residue are mixed evenly, crushed to a particle size ≤2mm, added to 7000g of 1.2mol / L sodium hydroxide solution and left to stand for 7h, filtered, washed with water to neutral, dried at 77℃ until the system moisture content is 7%, and sent to a steam explosion tank. 1.9MPa saturated steam is introduced and maintained for 105s before instantaneous depressurization.

[0052] The raw material for the temperature-sensitive water-retaining agent layer is a temperature-sensitive water-retaining agent, which is prepared using the following steps: 1600g of peat and 200g of bamboo powder are added to 8000g of a 0.8mol / L sodium hydroxide solution, refluxed and stirred at 85℃ for 80min, cooled to room temperature, and the pH of the system is adjusted to 6.5-7 using 1mol / L hydrochloric acid. The mixture is filtered, washed, and vacuum dried. 180g of N-isopropylacrylamide and 0.3g of N,N'-methylenebisacrylamide are added and mixed. Under nitrogen protection, 8g of ammonium persulfate is added, and the mixture is stirred at 62℃ for 100min. 700g of a 0.8mol / L potassium dihydrogen phosphate solution is added, and the mixture is stirred for another 15min. The mixture is then vacuum dried.

[0053] The preparation method of the above-mentioned cultivation substrate includes the following steps: laying a layer of perlite granules as the bottom layer, covering the perlite granule layer with a first fiber substrate layer, then evenly laying a layer of magnesium ammonium phosphate slow-release fertilizer and a temperature-sensitive water-retaining agent layer in sequence, and then covering the temperature-sensitive water-retaining agent layer with a second fiber substrate layer, compacting it with a roller at 0.13 MPa, and using... 60 Sterilization was performed by Co-γ irradiation at a dose of 6 kGy.

[0054] Example 4

[0055] A cultivation substrate comprises, from bottom to top: a perlite granule layer with a thickness of 9 mm, a first fiber substrate layer with a thickness of 25 mm, a magnesium ammonium phosphate slow-release fertilizer layer with a thickness of 1.8 mm, a temperature-sensitive water-retaining agent layer with a thickness of 0.2 mm, and a second fiber substrate layer with a thickness of 25 mm.

[0056] The raw material for the perlite granular layer is perlite granules with a particle size of 2.5 mm.

[0057] The raw materials for both the first and second fiber substrate layers are fiber substrates. The fiber substrates are prepared using the following specific steps: 1800g of coconut coir and 200g of cassava residue are mixed evenly, crushed to a particle size ≤2mm, added to 9000g of 0.8mol / L sodium hydroxide solution and left to stand for 9h, filtered, washed with water to neutral, dried at 73℃ until the system moisture content is 9%, and sent to a steam explosion tank. 1.6MPa saturated steam is introduced and maintained for 115s before instantaneous depressurization.

[0058] The raw material for the temperature-sensitive water-retaining agent layer is a temperature-sensitive water-retaining agent, which is prepared using the following steps: 800g of peat and 400g of bamboo powder are added to 6000g of a 1.2mol / L sodium hydroxide solution, refluxed and stirred at 75℃ for 100min, cooled to room temperature, and the pH of the system is adjusted to 6.5-7 using 1mol / L hydrochloric acid. The mixture is filtered, washed, and vacuum dried. 120g of N-isopropylacrylamide and 0.7g of N,N'-methylenebisacrylamide are added and mixed. Under nitrogen protection, 4g of ammonium persulfate is added, and the mixture is stirred at 68℃ for 80min. 900g of a 0.6mol / L potassium dihydrogen phosphate solution is added, and the mixture is stirred for another 25min. The mixture is then vacuum dried.

[0059] The preparation method of the above-mentioned cultivation substrate includes the following steps: laying a layer of perlite granules as the bottom layer, covering the perlite granule layer with a first fiber substrate layer, then evenly laying a layer of magnesium ammonium phosphate slow-release fertilizer and a temperature-sensitive water-retaining agent layer in sequence, and then covering the temperature-sensitive water-retaining agent layer with a second fiber substrate layer, compacting it with a roller at 0.11 MPa, and using... 60 Sterilization was performed by Co-γ irradiation with a dose of 7 kGy.

[0060] Example 5

[0061] A cultivation substrate comprises, from bottom to top: a perlite granule layer with a thickness of 8 mm, a first fiber substrate layer with a thickness of 30 mm, a magnesium ammonium phosphate slow-release fertilizer layer with a thickness of 1.5 mm, a temperature-sensitive water-retaining agent layer with a thickness of 0.5 mm, and a second fiber substrate layer with a thickness of 20 mm.

[0062] The raw material for the perlite particle layer is perlite particles with a particle size of 3mm.

[0063] The raw materials for both the first and second fiber substrate layers are fiber substrates. The fiber substrates are prepared using the following specific steps: 1500g of coconut coir and 300g of cassava residue are mixed evenly, crushed to a particle size ≤2mm, added to 8000g of 1mol / L sodium hydroxide solution and left to stand for 8h, filtered, washed with water to neutralize, dried at 75℃ until the system moisture content is 8%, and sent to a steam explosion tank. 1.8MPa saturated steam is introduced and maintained for 110s before instantaneous depressurization.

[0064] The raw material for the temperature-sensitive water-retaining agent layer is a temperature-sensitive water-retaining agent, which is prepared using the following steps: 1200g of peat and 300g of bamboo powder are added to 7000g of a 1mol / L sodium hydroxide solution, refluxed and stirred at 80℃ for 90min, cooled to room temperature, and the pH of the system is adjusted to 6.5-7 using 1mol / L hydrochloric acid. The mixture is then filtered, washed, and vacuum dried. 150g of N-isopropylacrylamide and 0.5g of N,N'-methylenebisacrylamide are added, with water as the solvent, and the total solid content is controlled at 15-20%. 6g of ammonium persulfate is added under nitrogen protection, and the mixture is stirred at 65℃ for 90min. 800g of a 0.7mol / L potassium dihydrogen phosphate solution is added, and the mixture is stirred for another 20min. The mixture is then vacuum dried.

[0065] The preparation method of the above-mentioned cultivation substrate includes the following steps: laying a layer of perlite granules as the bottom layer, covering the perlite granule layer with a first fiber substrate layer, then evenly laying a layer of magnesium ammonium phosphate slow-release fertilizer and a temperature-sensitive water-retaining agent layer in sequence, and then covering the temperature-sensitive water-retaining agent layer with a second fiber substrate layer, compacting it with a roller at 0.12 MPa, and using... 60 Sterilization was performed by Co-γ irradiation at a dose of 3.2 kGy.

[0066] Comparative Example 1

[0067] A cultivation substrate comprises, from bottom to top: a perlite granule layer with a thickness of 8 mm, a first fiber substrate layer with a thickness of 30 mm, a magnesium ammonium phosphate slow-release fertilizer layer with a thickness of 1.5 mm, a water-retaining agent layer with a thickness of 0.5 mm, and a second fiber substrate layer with a thickness of 20 mm.

[0068] The raw material for the perlite particle layer is perlite particles with a particle size of 3mm.

[0069] The raw materials for both the first and second fiber substrate layers are fiber substrates. The fiber substrates are prepared using the following specific steps: 1500g of coconut coir and 300g of cassava residue are mixed evenly, crushed to a particle size ≤2mm, added to 8000g of 1mol / L sodium hydroxide solution and left to stand for 8h, filtered, washed with water to neutralize, dried at 75℃ until the system moisture content is 8%, and sent to a steam explosion tank. 1.8MPa saturated steam is introduced and maintained for 110s before instantaneous depressurization.

[0070] The raw material for the water-retaining agent layer is a water-retaining agent, which is prepared by the following steps: 1200g of peat and 300g of bamboo powder are added to 800g of a 0.7mol / L potassium dihydrogen phosphate solution and stirred for 20 minutes, then vacuum dried.

[0071] The preparation method of the above-mentioned cultivation substrate includes the following steps: laying a layer of perlite granules as the bottom layer, covering the perlite granule layer with a first fiber substrate layer, then evenly laying a layer of magnesium ammonium phosphate slow-release fertilizer and a temperature-sensitive water-retaining agent layer in sequence, and then covering the temperature-sensitive water-retaining agent layer with a second fiber substrate layer, compacting it with a roller at 0.12 MPa, and using... 60 Sterilization was performed by Co-γ irradiation at a dose of 3.2 kGy.

[0072] Comparative Example 2

[0073] A cultivation substrate comprises, from bottom to top: a perlite granule layer with a thickness of 8 mm, a first fiber substrate layer with a thickness of 30 mm, a magnesium ammonium phosphate slow-release fertilizer layer with a thickness of 1.5 mm, a temperature-sensitive water-retaining agent layer with a thickness of 0.5 mm, and a second fiber substrate layer with a thickness of 20 mm.

[0074] The raw material for the perlite particle layer is perlite particles with a particle size of 3mm.

[0075] The raw materials for both the first and second fiber substrate layers are fiber substrates. The fiber substrates are prepared using the following specific steps: 1500g of coconut coir and 300g of cassava residue are mixed evenly, crushed to a particle size ≤2mm, added to 8000g of 1mol / L sodium hydroxide solution and left to stand for 8h, filtered, washed with water to neutralize, dried at 75℃ until the system moisture content is 8%, and sent to a steam explosion tank. 1.8MPa saturated steam is introduced and maintained for 110s before instantaneous depressurization.

[0076] The raw material for the temperature-sensitive water-retaining agent layer is a temperature-sensitive water-retaining agent, which is prepared by the following steps: 1200g of peat and 300g of bamboo powder are mixed with 150g of N-isopropylacrylamide and 0.5g of N,N'-methylenebisacrylamide, with water as the solvent. The total solid content is controlled at 15-20%. 6g of ammonium persulfate is added under nitrogen protection, and the mixture is stirred at 65℃ for 90min. 800g of 0.7mol / L potassium dihydrogen phosphate solution is added, and the mixture is stirred for another 20min. The mixture is then vacuum dried.

[0077] The preparation method of the above-mentioned cultivation substrate includes the following steps: laying a layer of perlite granules as the bottom layer, covering the perlite granule layer with a first fiber substrate layer, then evenly laying a layer of magnesium ammonium phosphate slow-release fertilizer and a temperature-sensitive water-retaining agent layer in sequence, and then covering the temperature-sensitive water-retaining agent layer with a second fiber substrate layer, compacting it with a roller at 0.12 MPa, and using... 60 Sterilization was performed by Co-γ irradiation at a dose of 3.2 kGy.

[0078] The physical properties of the cultivation substrates obtained in Example 5 and Comparative Examples 1-2 were measured. A 5L beaker was weighed net (W1); the naturally air-dried cultivation substrates for each group were filled into the beaker to the 3L mark and weighed (W2); then, the beaker containing the substrate was sealed with two layers of damp gauze and soaked in water at 20℃ for 24 hours (the water level should always be at least 2cm above the top of the container). After removing it from the water, the water above the 3L mark was poured out, and the beaker was weighed in saturated water condition (W3). The damp gauze used for sealing was also weighed (W4); finally, the beaker was wrapped with damp gauze and inverted for 8 hours to allow the water (gravity water) inside to drain freely, and then weighed (W5).

[0079] Unit weight = (W2 - W1) ÷ 3000.

[0080] Water holding capacity = (W5 - W1 - W4) ÷ (W2 - W1) × 100%.

[0081] Total porosity = (W3 - W2) ÷ 3000 × 100%.

[0082] Air-to-water ratio = air porosity / water-holding porosity. Where air porosity = (W3 + W4 - W5) ÷ 3000 × 100%; water-holding porosity = total porosity - air porosity.

[0083] like Figure 1 and Figure 2 As shown, the cultivation substrate obtained in Example 5 had the lowest bulk density, while its water holding capacity, total porosity, and air-water ratio were the highest, which was superior to Comparative Examples 1-2 (P<0.05).

[0084] After the above-mentioned free-draining cultivation substrates were placed in a 35℃ 50%RH constant temperature and humidity chamber and left to stand for 8 hours, then the beakers were wrapped with the above-mentioned damp gauze and inverted for 8 hours to allow the water (gravity water) in the beakers to drain freely, and weighed (W6); then soaked in 20℃ water for 24 hours (the water level line should always be at least 2cm above the top of the container), removed from the water, and the water above the 3L mark was poured out, which is the saturated water state and weighed (W7).

[0085] Moisture release rate = (W5-W6)÷(W5-W1-W4)×100%.

[0086] Porosity change rate = (W4 + W7 - W6) ÷ (W4 + W3 - W5) × 100%.

[0087] like Figure 3 As shown, the cultivation substrate obtained in Example 5 had the highest water release rate and porosity change rate at higher temperatures, which was better than that of Comparative Examples 1-2 (P<0.05).

[0088] A comparative experiment on the transplanting of Dendrobium officinale was conducted using the cultivation substrates obtained in Example 5 and Comparative Examples 1-2. Transplanting took place from March 11 to March 16 and ended from December 15 to December 20. The experiment adopted a randomized block design with destructive sampling. Each group used the cultivation substrates obtained in Example 5 and Comparative Examples 1-2, respectively. Each group had 9 pots, with 2 Dendrobium officinale seedlings in each pot.

[0089] When planting, the roots should be spread out naturally, and the substrate should cover the entire root system. After planting, water thoroughly to settle the roots. Daily ventilation, lighting, temperature and humidity should be managed according to the conventional Dendrobium officinale planting management.

[0090] Survival rates were assessed 30 days after planting, with all groups showing survival rates greater than 90%. The number of sprouts was assessed at 60 days, with all groups showing more than 6.80 sprouts. Plant height was assessed at 90 days, with all groups showing a height greater than 5.65 cm. This confirms that the cultivation substrates in all groups can effectively protect transplanted Dendrobium officinale.

[0091] The above-ground fresh weight, underground fresh weight, and longest root system were measured after 180 days, and the polysaccharide content of Dendrobium officinale was also tested.

[0092] like Figure 4 and Figure 5 As shown, Dendrobium officinale transplanted using the cultivation substrate obtained in Example 5 had the highest above-ground fresh weight, underground fresh weight, longest root system, and polysaccharide content, which were superior to Comparative Examples 1-2 (P<0.05).

[0093] Transplant Dendrobium officinale twice more following the steps described above (i.e., transplant Dendrobium officinale a total of three times in the same cultivation substrate). During this period, no materials are added to the cultivation substrate. During the third transplanting period, Dendrobium officinale is tested (the above-ground fresh weight, underground fresh weight, and longest root system are measured after 180 days, and the polysaccharide content of Dendrobium officinale is also tested).

[0094] like Figure 6 and Figure 7 As shown, after three transplantings of Dendrobium officinale into the cultivation substrates of each group, the above-ground fresh weight, underground fresh weight, longest root system, and polysaccharide content of Dendrobium officinale obtained from the third transplanting all decreased significantly. However, when Dendrobium officinale was transplanted into the cultivation substrate obtained in Example 5, its above-ground fresh weight, underground fresh weight, longest root system, and polysaccharide content were still the highest, which was better than that of Comparative Examples 1-2 (P<0.05).

[0095] After the third transplanting, the total porosity and air-to-water ratio of the cultivation substrate in each group were tested again. Figure 8 As shown, the total porosity and air-water ratio of the cultivation substrates in each group decreased; however, the total porosity and air-water ratio of the cultivation substrate obtained in Example 5 were still the highest, which was better than that of Comparative Examples 1-2 (P<0.05).

[0096] The applicant argues that this invention, by treating coconut coir and cassava residue with sodium hydroxide, induces internal swelling and the formation of a microporous structure. Furthermore, steam explosion enriches the internal pore structure, resulting in a fiber substrate with not only excellent adsorption properties but also superior water retention and air permeability. Simultaneously, the sodium hydroxide treatment of peat and bamboo powder disrupts the crystalline structure of lignin and cellulose, exposing more hydroxyl sites. N-isopropylacrylamide, through free radical polymerization, combines with the aforementioned products, resulting in a temperature-sensitive water-retaining agent that expands and absorbs water at low temperatures, while shrinking to release moisture at temperatures above 32°C. Simultaneously, the adsorbed nutrients desorb more rapidly with increasing temperature. Combined with magnesium ammonium phosphate slow-release fertilizer, this achieves a synergistic slow release of water and nutrients. This invention, by laying a layer of perlite particles at the bottom and then sequentially covering it with a first fiber substrate layer, a magnesium ammonium phosphate slow-release fertilizer layer, a temperature-sensitive water-retaining agent layer, and a second fiber substrate layer, can effectively achieve the synergistic effect of vertical water penetration and horizontal diffusion. Moreover, it can lock in water at low temperature and high humidity, and release water and increase porosity at high temperature and low humidity. The system has excellent stability and can effectively prevent the loss of nutrients. Even after long-term use, it can stably maintain the matrix state.

[0097] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A cultivation substrate, characterized in that, From bottom to top, the layers are: perlite granules, first fiber substrate layer, magnesium ammonium phosphate slow-release fertilizer layer, temperature-sensitive water-retaining agent layer, and second fiber substrate layer. The thickness ratio of the perlite granule layer, the first fiber substrate layer, the magnesium ammonium phosphate slow-release fertilizer layer, the temperature-sensitive water-retaining agent layer, and the second fiber substrate layer is 5-10:20-40:1-2:0.1-1:10-30; The raw material for the perlite granular layer is perlite granules with a particle size of 2-4 mm; The raw material for the temperature-sensitive water-retaining agent layer is a temperature-sensitive water-retaining agent, and the raw materials of the temperature-sensitive water-retaining agent include, by weight: 5-20 parts peat, 1-5 parts bamboo powder, 1-2 parts N-isopropylacrylamide, 0.001-0.01 parts N,N'-methylenebisacrylamide, and 0.01-0.1 parts initiator; The method for preparing the temperature-sensitive water-retaining agent is as follows: peat and bamboo powder are treated in sodium hydroxide solution, then mixed with N-isopropylacrylamide and N,N'-methylenebisacrylamide, and then prepared under the action of an initiator.

2. The cultivation substrate according to claim 1, characterized in that, The raw materials for both the first and second fiber substrate layers are fiber substrates, which include coconut coir and cassava residue, with a mass ratio of 10-20:1-5.

3. The cultivation substrate according to claim 2, characterized in that, The fiber substrate is prepared by the following specific steps: coconut coir and cassava residue are mixed evenly, crushed to a particle size ≤2mm, added to sodium hydroxide solution and left to stand for 5-10h, filtered, washed with water until neutral, dried until the system moisture content is 5-10%, sent to a steam explosion tank, and 1.5-2MPa saturated steam is introduced and maintained for 100-120s before instantaneous depressurization.

4. The cultivation substrate according to claim 3, characterized in that, The concentration of sodium hydroxide solution is 0.5-1.5 mol / L.

5. The cultivation substrate according to claim 3, characterized in that, The drying temperature is 70-80℃.

6. The cultivation substrate according to claim 1, characterized in that, The thermosensitive water-retaining agent is prepared by the following steps: peat and bamboo powder are added to sodium hydroxide solution, refluxed and stirred at 70-90℃ for 1-2 hours, cooled to room temperature, filtered, washed, and vacuum dried. N-isopropylacrylamide and N,N'-methylenebisacrylamide are added and mixed. An initiator is added under nitrogen protection, and the mixture is stirred at 60-70℃ for 1-2 hours. Potassium dihydrogen phosphate solution is added and stirring is continued for 10-30 minutes. The mixture is then vacuum dried.

7. The cultivation substrate according to claim 1, characterized in that, The initiator is a persulfate, specifically ammonium persulfate.

8. The cultivation substrate according to claim 1, characterized in that, The concentration of sodium hydroxide solution is 0.5-1.5 mol / L, and the concentration of potassium dihydrogen phosphate solution is 0.5-1 mol / L.

9. A method for preparing a cultivation substrate as described in any one of claims 1-8, characterized in that, The process includes the following steps: laying a layer of perlite granules at the bottom, covering the perlite granule layer with a first fiber substrate layer, then evenly laying magnesium ammonium phosphate slow-release fertilizer and a temperature-sensitive water-retaining agent layer in sequence, covering the temperature-sensitive water-retaining agent layer with a second fiber substrate layer, rolling and compacting, and then irradiating for sterilization.

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