Nutrient pot for desert tree planting and preparation method thereof

Abstract

This invention discloses a nutrient pot for desert afforestation and its preparation method, belonging to the technical field of nutrient pots for trees. The invention mixes raw materials such as cow dung and straw with loess to prepare a concave pot. Then, a polylactic acid membrane with a different degradation rate is prepared to cover the concave pot, making it a water-retaining and fertilizer-conserving nutrient pot. When used in conjunction with other methods during desert afforestation, it can effectively inhibit water loss, improve the absorption and utilization rate of water and nutrients by seedlings, enhance the survival rate and growth of transplanted seedlings, thereby improving the desertification control effect. Furthermore, water and nutrients can be added at once, eliminating the need for multiple subsequent waterings to ensure a high survival rate, greatly reducing afforestation costs and showing promising application prospects.

Description

Technical Field

[0001] This invention relates to the field of tree nutrient pot technology, and in particular to a nutrient pot for desert tree planting and its preparation method. Background Technology

[0002] Afforestation for windbreak and sand control has been successful in long-term desert ecological management, generating certain ecological benefits. Its advantages include simple operation, ease of mastery, and large-scale implementation. By constructing large-scale windbreak and sand control forests, wind speed is reduced, mitigating the damage of wind and sand disasters to farmland and residential areas. However, when planting trees in sandy areas, seedlings are often planted with soil balls. Watering requires the soil ball to be thoroughly soaked, but the soil ball is surrounded by sand particles, causing a large amount of water to seep through the sand, with only a small amount absorbed by the soil ball, resulting in extremely limited usable water for the plants. Furthermore, sandy soil is extremely nutrient-poor, leading to a severe lack of nutrients required for plant growth. Artificial substrate improvement would significantly increase the cost of sand control. Existing methods use materials such as straw, sawdust, or polyacrylamide to improve soil water retention, but the effects are poor, still resulting in low survival rates for desert trees, and the large quantities used significantly increase the cost of sand control.

[0003] Therefore, it is currently necessary to find a material with good water retention and fertilizer retention effects to inhibit water loss during desert afforestation, meet the seedlings' needs for water and nutrients, and thus improve the survival rate of desert afforestation and enhance the effect of desertification control. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a nutrient pot for desert tree planting and its preparation method. By mixing raw materials such as cow dung, straw, and loess and pressing them into a concave sandwich pot, and then coating the pot with polylactic acid membranes with different degradation rates, a nutrient pot with strong fertilizer and water retention capacity is obtained. This pot is used in the tree planting process to inhibit water loss, ensure water and nutrient supply, and thus improve the survival rate of the planted trees.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] A nutrient pot for planting trees in the desert, the nutrient pot is composed of an inner membrane, a sandwich layer and an outer membrane, and the nutrient pot comprises the following raw materials:

[0007] Inner membrane: polylactic acid, dimethylformamide, diethylene glycol, p-tert-butylaniline, polyethylene glycol;

[0008] Interlayer: straw, cow dung, loess, Bacillus subtilis, arbuscular mycorrhizal fungi, mineral-derived potassium humate, sodium carboxymethyl cellulose;

[0009] Outer membrane: polylactic acid, dimethylformamide, n-hexylamine, dioctyl phthalate, tea polyphenols, tert-amyl alcohol.

[0010] Furthermore, the arbuscular mycorrhizal fungus is any one of *Glomus moses*, *Glomus terrestrialus*, or *Glomus endorrhizos*.

[0011] The present invention also discloses a method for preparing the nutrient pot, the specific method of which is as follows:

[0012] The inner and outer membranes are fitted onto the inside and outside of the interlayer to completely cover the interlayer and obtain the nutrient pot.

[0013] Furthermore, the preparation methods for the inner membrane, interlayer, and outer membrane of the nutrient pot are as follows:

[0014] Inner membrane: A mixture of polylactic acid and dimethylformamide is placed in a reaction vessel, and diethylene glycol and p-tert-butylaniline are added. The mixture is sealed and reacted at 45-55°C for 60-90 minutes. After the reaction is completed, polyethylene glycol is added, and the mixture is mixed evenly. The mixture is then vacuum dried at 45°C, and then extruded, granulated, and blown to obtain the inner membrane.

[0015] Sandwich layer: Straw, cow dung and loess are mixed evenly to obtain a mixture. Bacillus subtilis, arbuscular mycorrhizal fungi and mineral-derived potassium humate are added to the mixture and mixed evenly. Then, sodium carboxymethyl cellulose is dissolved in water and added and mixed evenly. The moisture content is adjusted to 30-35% and the pH is adjusted to 6-7. The mixture is then pressed into a bowl shape to obtain a sandwich layer and placed in a cool place to air dry.

[0016] Outer membrane: Polylactic acid-dimethylformamide mixture is placed in a reaction vessel, n-hexylamine is added and mixed, and the mixture is sealed and stirred at 45-55℃ for 1-2 hours. After the reaction is completed, dioctyl phthalate and tea polyphenols are added, mixed evenly, and then vacuum rotary evaporated at 40℃ for 1 hour. Then tert-amyl alcohol is added and mixed evenly, and then vacuum dried at 45℃. The outer membrane is then extruded, granulated, and blown into a film.

[0017] Furthermore, during the preparation of the inner layer membrane, the mass ratio of the polylactic acid-dimethylformamide mixture to diethylene glycol, p-tert-butylaniline, and polyethylene glycol is (15-25):(0.2-0.3):(0.3-0.5):(0.2-0.4).

[0018] Furthermore, the volume ratio of straw, cow dung, and loess during the preparation of the interlayer is (2.5-3):(2.5-3):(5-6).

[0019] Furthermore, during the preparation of the sandwich layer, the mass ratio of the mixture, Bacillus subtilis, arbuscular mycorrhizal fungi, mineral-derived potassium humate, and sodium carboxymethyl cellulose is (8-10):(0.05-0.06):(0.03-0.04):(0.03-0.06):(0.008-0.01).

[0020] Furthermore, the mass ratio of polylactic acid-dimethylformamide, n-hexylamine, dioctyl phthalate, tea polyphenols, and tert-amyl alcohol during the preparation of the outer membrane is (15-25):(0.4-0.6):(0.2-0.4):(0.1-0.2):(0.2-0.3).

[0021] Furthermore, the interlayer weighs 6-7 kg and has a diameter of 30-50 cm.

[0022] Furthermore, the nutrient pots are used when planting trees in the desert. Specifically, the nutrient pots are placed in the planting pit, filled with sand and then filled with water, and then the seedlings are planted on top.

[0023] By preparing the nutrient pot interlayer using agricultural waste such as cow dung and straw mixed with loess and mineral-derived potassium humate, and adding Bacillus subtilis and arbuscular mycorrhizal fungi to accelerate the decomposition of cow dung and straw, and arbuscular mycorrhizal fungi to enhance plant stress resistance, the various components in the nutrient pot interlayer provide nutrients to the plants and promote better plant growth. The nutrient pot interlayer is then covered inside and out with an environmentally friendly, biodegradable polylactic acid film. During the planting process, sand is filled into the nutrient pot and water is injected to effectively prevent water loss, thus providing sufficient water for the seedlings to overcome the initial transplanting recovery period and ensuring a high survival rate. Later, as the seedling roots recover and begin to extend deeper into the sand, the cow dung and straw in the interlayer provide nutrients, ensuring a stable supply of water and nutrients during desert planting and effectively improving the survival rate of the planted trees.

[0024] Using polylactic acid (PLA) membranes to encase the nutrient pot layers provides excellent water retention. As the PLA membrane gradually degrades, nutrients within the nutrient pot layers are gradually exposed, providing nourishment to the seedlings. After transplanting, seedlings need a period of recovery. If the inner membrane degrades too quickly, nutrients in the membrane may prematurely contact the seedlings during this recovery period, causing burns. Conversely, if the degradation time is too long, the seedlings may not receive sufficient nutrients for an extended period, affecting survival rates and growth. To ensure a smooth transition through the seedling establishment period and timely nutrient supply, the inner membrane is treated to accelerate its degradation rate. Specifically, polar groups are introduced by reacting diethylene glycol with polylactic acid to increase its polarity. When the inner membrane comes into contact with water injected during planting, the increased polarity accelerates the hydrolysis rate on the inner membrane surface, gradually forming a microporous structure. Water molecules enter through this microporous structure to hydrolyze the inner membrane. Additionally, p-tert-butylaniline is added to combine with polylactic acid molecules, increasing the steric hindrance between polylactic acid molecules and thus increasing the intermolecular distance. This enlarges the pore size of the microporous structure formed after the hydrolysis of polylactic acid molecules on the membrane surface, allowing more water molecules to enter and further decompose the inner membrane. Consequently, the nutrients in the nutrient pot's interlayer are exposed and provided to the seedlings, ensuring a timely nutrient supply.

[0025] When the inner polylactic acid (PLA) membrane hydrolyzes, water molecules pass through the interlayer of the nutrient pot and come into contact with the outer PLA membrane, causing further hydrolysis. Combined with decomposition by microorganisms, this leads to water loss. Therefore, to ensure more efficient water utilization, it is necessary to extend the degradation time of the outer membrane. This invention adds hexylamine and tea polyphenols to the PLA membrane during its preparation, reacting and combining with PLA molecules to adjust the chemical structure of the PLA molecules and enhance their stability. Tert-amyl alcohol further binds to the PLA molecular chain, inhibiting the binding of water to the chain ends, thereby reducing the hydrolysis sites of the PLA membrane. The combined action of hexylamine, tea polyphenols, and tert-amyl alcohol inhibits the decomposition reaction of the PLA outer membrane, maintaining its stability. By adjusting the degradation rates of the inner and outer membranes in the nutrient pot, the water retention capacity is improved while ensuring timely nutrient supply, increasing the seedlings' utilization of nutrients and water, improving the survival rate of desert afforestation, and enhancing desertification control.

[0026] Beneficial effects:

[0027] 1. This invention prepares an inner membrane layer with a faster degradation rate and an outer membrane layer with a slower degradation rate by treating polylactic acid in different ways. These are then used to coat a layer made from materials such as cow dung and straw to create a nutrient pot. The faster degradation of the inner membrane exposes the interlayer, providing nutrients to the seedlings in a timely manner. The slower degradation of the outer membrane better preserves the moisture added to the nutrient pot. The prepared nutrient pot provides nutrients to the seedlings while effectively retaining moisture, laying a solid foundation for seedling survival, improving the survival rate of desert afforestation, and enhancing desertification control.

[0028] 2. This invention uses polylactic acid membrane to coat the nutrient pots for water retention, which has a good water retention effect and requires less material, thus greatly reducing costs. Furthermore, the polylactic acid membrane eventually decomposes into water and carbon dioxide, which is environmentally friendly. It also uses straw, cow manure, and other raw materials as nutrients, providing a better method for treating agricultural waste. Attached Figure Description

[0029] Figure 1 The image shows the mixing process during the preparation of the nutrient pot sandwich layer in Embodiment 1 of the present invention.

[0030] Figure 2 This is an image of the sandwiched product prepared in the nutrient pot in Embodiment 1 of the present invention. Detailed Implementation

[0031] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings:

[0032] Example 1: Preparation of Nutrient Pots

[0033] Inner membrane: Polylactic acid (PLA) was dissolved in dimethylformamide at a mass ratio of 1:15 to obtain a PLA-dimethylformamide mixture. 20 kg of the PLA-dimethylformamide mixture was placed in a reactor, and 0.25 kg of diethylene glycol and 0.4 kg of p-tert-butylaniline were added. The mixture was sealed and reacted at 50°C for 70 min. After the reaction was completed, 0.3 kg of polyethylene glycol was added, and the mixture was mixed evenly and then vacuum dried at 45°C. After drying, the mixture was extruded and granulated using a twin-screw extruder. The extruder conditions were set as follows: the temperatures of zones one to five were 150°C, 165°C, 180°C, 190°C, and 190°C, respectively, and the screw speed was 150 rpm. After granulation, the inner membrane layer was obtained by blown film extrusion. The conditions of the blown film extruder were set as follows: the temperatures of the feed zone, melt zone, and die zone were 150°C, 180°C, and 180°C, respectively; the screw speed was 60 rpm; the traction ratio was 6 m / min; and the blow-up ratio was 3.

[0034] Layering: Mix straw, cow dung, and loess in a volume ratio of 2.5:2.5:5 to obtain a mixture. Add 0.05 kg of Bacillus subtilis, 0.04 kg of arbuscular mycorrhizal fungi, and 0.05 kg of mineral-derived potassium humate to 9 kg of the mixture and mix well. Then add 0.009 kg of sodium carboxymethyl cellulose dissolved in 0.9 kg of water and mix well. Adjust the moisture content to about 32% and the pH to 6.5. Take 6.5 kg and put it into a steel bowl with a diameter of 40 cm and covered with a plastic film. Press it into a concave round bottom bowl and remove it to obtain the layer. Place it in a cool place to air dry for later use.

[0035] Outer membrane: Polylactic acid was dissolved in dimethylformamide at a mass ratio of 1:15 to obtain a polylactic acid-dimethylformamide mixture. 20 kg of the polylactic acid-dimethylformamide mixture was placed in a reaction vessel, and 0.5 kg of n-hexylamine was added and mixed. The mixture was sealed and stirred at 50°C for 1.5 h. After the reaction was completed, 0.3 kg of dioctyl phthalate and 0.15 kg of tea polyphenols were added and mixed evenly. The mixture was then vacuum rotary evaporated at 40°C for 1 h. Then, 0.25 kg of tert-amyl alcohol was added and mixed evenly. The mixture was then vacuum dried at 45°C. Granulation and blown film were carried out under the same conditions as the inner membrane to obtain the outer membrane.

[0036] Nutrient pot: The inner and outer membranes are placed inside and outside the interlayer to completely cover the interlayer, thus obtaining the nutrient pot.

[0037] Example 2: Preparation of Nutrient Pots

[0038] Inner membrane: Polylactic acid (PLA) was dissolved in dimethylformamide at a mass ratio of 1:15 to obtain a PLA-dimethylformamide mixture. 15 kg of the PLA-dimethylformamide mixture was placed in a reactor, and 0.2 kg of diethylene glycol and 0.3 kg of p-tert-butylaniline were added. The mixture was sealed and reacted at 45°C for 90 min. After the reaction was completed, 0.2 kg of polyethylene glycol was added, and the mixture was mixed evenly and then vacuum dried at 45°C. After drying, the mixture was extruded and granulated using a twin-screw extruder. The extruder conditions were set as follows: the temperatures of zones one to five were 150°C, 165°C, 180°C, 190°C, and 190°C, respectively, and the screw speed was 150 rpm. After granulation, the inner membrane layer was obtained by blown film extrusion. The conditions of the blown film extruder were set as follows: the temperatures of the feed zone, melt zone, and die zone were 150°C, 180°C, and 180°C, respectively; the screw speed was 60 rpm; the traction ratio was 6 m / min; and the blow-up ratio was 3.

[0039] Layering: Mix straw, cow dung, and loess in a volume ratio of 2.5:2.5:5 to obtain a mixture. Add 0.05 kg of Bacillus subtilis, 0.04 kg of arbuscular mycorrhizal fungi, and 0.03 kg of mineral-derived potassium humate to 8 kg of the mixture and mix well. Then add 0.008 kg of sodium carboxymethyl cellulose dissolved in 0.8 kg of water and mix well. Adjust the moisture content to 30% and the pH to 6. Take 6 kg and put it into a steel bowl with a diameter of 40 cm and covered with a plastic film. Press it into a concave round bottom bowl and remove it to obtain the layer. Place it in a cool place to air dry for later use.

[0040] Outer membrane: Polylactic acid was dissolved in dimethylformamide at a mass ratio of 1:15 to obtain a polylactic acid-dimethylformamide mixture. 15 kg of the polylactic acid-dimethylformamide mixture was placed in a reaction vessel, and 0.4 kg of n-hexylamine was added and mixed. The mixture was sealed and stirred at 45°C for 2 hours. After the reaction was completed, 0.2 kg of dioctyl phthalate and 0.1 kg of tea polyphenols were added and mixed evenly. The mixture was then vacuum rotary evaporated at 40°C for 1 hour. Then, 0.2 kg of tert-amyl alcohol was added and mixed evenly. The mixture was then vacuum dried at 45°C. Granulation and blown film were carried out under the same conditions as the inner membrane to obtain the outer membrane.

[0041] Nutrient pot: The inner and outer membranes are placed inside and outside the interlayer to completely cover the interlayer, thus obtaining the nutrient pot.

[0042] Example 3: Preparation of Nutrient Pots

[0043] Inner membrane: Polylactic acid (PLA) was dissolved in dimethylformamide at a mass ratio of 1:15 to obtain a PLA-dimethylformamide mixture. 25 kg of the PLA-dimethylformamide mixture was placed in a reactor, and 0.3 kg of diethylene glycol and 0.5 kg of p-tert-butylaniline were added. The mixture was sealed and reacted at 55°C for 60 min. After the reaction was completed, 0.4 kg of polyethylene glycol was added, and the mixture was mixed evenly and then vacuum dried at 45°C. After drying, the mixture was extruded and granulated using a twin-screw extruder. The extruder conditions were set as follows: the temperatures of zones one to five were 150°C, 165°C, 180°C, 190°C, and 190°C, respectively, and the screw speed was 150 rpm. After granulation, the inner membrane layer was obtained by blown film extrusion. The conditions of the blown film extruder were set as follows: the temperatures of the feed zone, melt zone, and die zone were 150°C, 180°C, and 180°C, respectively; the screw speed was 60 rpm; the traction ratio was 6 m / min; and the blow-up ratio was 3.

[0044] Sandwich layer: Mix straw, cow dung, and loess in a volume ratio of 2.5:2.5:5 to obtain a mixture. Add 0.06 kg of Bacillus subtilis, 0.04 kg of arbuscular mycorrhizal fungi, and 0.06 kg of mineral-derived potassium humate to 10 kg of the mixture and mix well. Then add 0.01 kg of sodium carboxymethyl cellulose dissolved in 1 kg of water and mix well. Adjust the moisture content to 35% and the pH to 7. Take 8 kg and put it into a steel bowl with a diameter of 40 cm and covered with a plastic film. Press it into a concave round bottom bowl shape and remove it to obtain the sandwich layer. Place it in a cool place to air dry for later use.

[0045] Outer membrane: Polylactic acid was dissolved in dimethylformamide at a mass ratio of 1:15 to obtain a polylactic acid-dimethylformamide mixture. 25 kg of the polylactic acid-dimethylformamide mixture was placed in a reaction vessel, and 0.6 kg of n-hexylamine was added and mixed. The mixture was sealed and stirred at 55°C for 1 h. After the reaction was completed, 0.4 kg of dioctyl phthalate and 0.2 kg of tea polyphenols were added and mixed evenly. The mixture was then vacuum rotary evaporated at 40°C for 1 h. Then, 0.3 kg of tert-amyl alcohol was added and mixed evenly. The mixture was then vacuum dried at 45°C. Granulation and blown film were carried out under the same conditions as the inner membrane to obtain the outer membrane.

[0046] Nutrient pot: The inner and outer membranes are placed inside and outside the interlayer to completely cover the interlayer.

[0047] Comparative Example 1: Preparation of Nursery Pots

[0048] Compared with Example 1, the only difference is that potassium humate from mineral source was not added when preparing the nutrient pot sandwich in Comparative Example 1, while the other steps are the same as in Example 1.

[0049] Comparative Example 2: Preparation of Nursery Pots

[0050] Compared with Example 1, the only difference is that diethylene glycol was not added during the preparation of the inner layer membrane of the nutrient pot in Comparative Example 2, while the other steps were the same as in Example 1.

[0051] Comparative Example 3: Preparation of Nursery Pots

[0052] Compared with Example 1, the only difference is that p-tert-butylaniline was not added during the preparation of the inner layer membrane of the nutrient pot in Comparative Example 3, while the other steps were the same as in Example 1.

[0053] Comparative Example 4: Preparation of Nursery Pots

[0054] Compared with Example 1, the only difference is that the reaction temperature in the reactor was room temperature when the inner layer membrane of the nutrient pot was prepared in Comparative Example 4, and the rest of the steps were the same as in Example 1.

[0055] Comparative Example 5: Preparation of Nursery Pots

[0056] Compared with Example 1, the only difference is that in Comparative Example 5, the amount of diethylene glycol and p-tert-butylaniline added during the preparation of the inner layer membrane of the nutrient pot is 0.5 kg and 0.7 kg, respectively. All other steps are the same as in Example 1.

[0057] Comparative Example 6: Preparation of Nursery Pots

[0058] Compared with Example 1, the only difference is that in Comparative Example 6, hexylamine was not added for sealing during the preparation of the outer membrane of the nutrient pot. All other steps were the same as in Example 1. The specific preparation of the outer membrane is shown below:

[0059] Polylactic acid (PLA) was dissolved in dimethylformamide at a mass ratio of 1:15 to obtain a PLA-dimethylformamide mixture. 20 kg of the PLA-dimethylformamide mixture was placed in a reactor, and 0.3 kg of dioctyl phthalate and 0.15 kg of tea polyphenols were added. After mixing evenly, the mixture was vacuum rotary evaporated at 40°C for 1 hour. Then, 0.25 kg of tert-amyl alcohol was added and mixed evenly. The mixture was then vacuum dried at 45°C. Granulation and blown film were carried out under the same conditions as the inner layer membrane to obtain the outer layer membrane.

[0060] Comparative Example 7: Preparation of Nursery Pots

[0061] Compared with Example 1, the only difference is that tea polyphenols were not added during the preparation of the outer membrane of the nutrient pot in Comparative Example 7, while the other steps were the same as in Example 1.

[0062] Comparative Example 8: Preparation of Nutrient Pots

[0063] Compared with Example 1, the only difference is that tert-amyl alcohol was not added during the preparation of the outer membrane of the nutrient pot in Comparative Example 8, while the other steps were the same as in Example 1.

[0064] Comparative Example 9: Preparation of Nursery Pots

[0065] Compared with Example 1, the only difference is that the reaction temperature in the reactor was room temperature when the outer membrane of the nutrient pot was prepared in Comparative Example 9, and all other steps were the same as in Example 1.

[0066] Comparative Example 10: Preparation of Nutrient Pots

[0067] Compared with Example 1, the only difference is that in Comparative Example 10, the nutrient pot was prepared without an inner and outer membrane, that is, the nutrient pot was directly prepared with a sandwich structure.

[0068] Experiment 1: Membrane Degradability Detection Experiment

[0069] The degradation performance of the inner membranes prepared in Examples 1 and 2-5, and the outer membranes prepared in Examples 1 and 6-9 were determined using the following methods:

[0070] Sand, loess, well-rotted cow manure, and straw were mixed evenly in a mass ratio of 10:2:1:1. Then, Bacillus subtilis and arbuscular mycorrhizal fungi were added and mixed evenly at a rate of 2 g / kg. The moisture content was then adjusted to 80%, and the pH was adjusted to 6.5 to obtain the experimental soil.

[0071] The inner membranes prepared in Examples 1 and Comparative Examples 2-5, and the outer membranes prepared in Examples 1 and Comparative Examples 6-9, were buried in the experimental soil. The soil moisture content was maintained at 80% by regular watering. The degradation rate of each group of membranes was measured after 15 days and 30 days. The average data obtained from the three repeated experiments are shown in Tables 1 and 2.

[0072] Table 1

[0073]

[0074] Table 2

[0075]

[0076] Based on the data analysis in Tables 1 and 2, we can conclude that:

[0077] (1) After processing polylactic acid according to the method of the present invention, the degradation performance can be better adjusted to obtain an inner membrane that degrades faster and an outer membrane that degrades slower. This membrane can then be used to cover the interlayer of the nutrient pot, which can ensure that nutrients in the interlayer can be provided in a timely manner and can better inhibit water loss, thereby improving the seedling's efficiency in utilizing water and nutrients and ensuring the effect of desert afforestation.

[0078] (2) No diethylene glycol was added during the preparation of the inner membrane in Comparative Example 2, and no p-tert-butylaniline was added during the preparation of the inner membrane in Comparative Example 3. The degradation rate of the inner membrane in Comparative Examples 2 and 3 was significantly lower than that in Example 1. In Comparative Example 5, the amount of diethylene glycol and p-tert-butylaniline added during the preparation of the inner membrane was large, and the degradation rate of the inner membrane increased compared with Example 1. The degradation rate reached a high level on the 15th day, which was not conducive to the water retention and fertilizer release performance of the nutrient pot.

[0079] (3) No hexylamine was added during the preparation of the outer membrane in Comparative Example 6, and no tea polyphenols were added during the preparation of the outer membrane in Comparative Example 7. The polylactic acid molecular chains of the outer membranes in Comparative Examples 6 and 7 were less stable and degraded faster in the experimental soil. No tert-amyl alcohol was added during the preparation of the outer membrane in Comparative Example 8. The polylactic acid molecules of the outer membrane were more susceptible to degradation by water molecules, and the degradation rate was faster than that of the outer membrane in Example 1.

[0080] Experiment 2: Determination of the water retention and fertilizer retention effect of nutrient pots

[0081] 1. Experimental location and method: The nutrient pots prepared in Example 1 and Comparative Examples 1-10 were used to conduct a desert tree planting experiment in a desertified area in Burtai, Ordos, Inner Mongolia. The specific method of using the nutrient pots was as follows: a planting pit was dug, and the nutrient pots were placed in the planting pit at a depth of 20cm from the bottom of the seedling roots. Sand was filled into the nutrient pots and then water was added. The seedlings were planted on top. The seedlings selected for transplanting were white thorn seedlings with uniform growth and a height of about 30cm. 40 seedlings were transplanted in each group. A blank control group was added to the experiment. The blank control group did not use nutrient pots, but was directly watered with the same amount of water.

[0082] 2. Results Detection: The survival rate of seedlings in each group was counted 50 days after transplanting. Twelve months later, 10 seedlings were randomly selected to calculate the average height of each group. The results were repeated three times. The data are shown in Table 3.

[0083] Table 3

[0084]

[0085]

[0086] Based on the data analysis in Table 3, we can conclude that:

[0087] (1) Compared with Comparative Examples 1-10 and the blank control group, Example 1 showed the best survival rate and plant height of Nitraria tangutorum. The survival rate reached 88.3%, and the plant height reached 96.5 cm after 12 months. This indicates that the nutrient pot prepared by the present invention can effectively store water and fertilizer for the seedlings, provide water for the seedlings to recover, and provide nutrients such as cow manure and organic matter in a timely manner, thereby improving the seedlings' utilization rate of water and nutrients, and thus improving the survival rate and later growth of seedlings during desert afforestation.

[0088] (2) In Comparative Example 1, the nutrient pots did not contain potassium humate, resulting in reduced nutrient supply. In contrast, the addition of potassium humate affected the growth of white thorn to some extent.

[0089] (3) The slow degradation rate of the inner membrane in Comparative Examples 2 and 3 affected the nutrient supply of the interlayer of the nutrient pot, which in turn affected the growth of white thorn to a certain extent.

[0090] (4) In Comparative Examples 6, 7 and 8, the outer membrane of the nutrient pot degraded rapidly, which reduced the water retention of the nutrient pot and the reduced water supply affected the survival rate of the white thorn seedlings. In Comparative Example 10, the survival rate and plant growth were significantly reduced in the nutrient pot without inner and outer membranes, indicating that the inner and outer membranes play an important role in ensuring the seedlings' utilization of nutrients and water.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although 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. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A method for preparing a nutrient pot for planting trees in the desert, characterized in that, The nutrient pot is composed of an inner membrane, a sandwich layer, and an outer membrane, and the nutrient pot includes the following raw materials: Inner membrane: polylactic acid, dimethylformamide, diethylene glycol, p-tert-butylaniline, polyethylene glycol; Interlayer: straw, cow dung, loess, Bacillus subtilis, arbuscular mycorrhizal fungi, mineral-derived potassium humate, sodium carboxymethyl cellulose; Outer membrane: polylactic acid, dimethylformamide, n-hexylamine, dioctyl phthalate, tea polyphenols, tert-amyl alcohol; The specific method for preparing the nutrient pot is as follows: The inner and outer membranes are fitted onto the inner and outer sides of the interlayer to completely cover the interlayer and obtain the nutrient pot; The preparation methods for the inner membrane, interlayer, and outer membrane of the nutrient pot are as follows: Inner membrane: The polylactic acid-dimethylformamide mixture is placed in a reaction vessel, diethylene glycol and p-tert-butylaniline are added, and the mixture is sealed and reacted at 45-55°C for 60-90 minutes. After the reaction is completed, polyethylene glycol is added, and the mixture is mixed evenly and then vacuum dried at 45°C. The mixture is then extruded, granulated, and blown into a film to obtain the inner membrane. Sandwich layer: Straw, cow dung and loess are mixed evenly to obtain a mixture. Bacillus subtilis, arbuscular mycorrhizal fungi and mineral potassium humate are added to the mixture and mixed evenly. Then, sodium carboxymethyl cellulose is dissolved in water and added and mixed evenly. The moisture content is adjusted to 30-35% and the pH is adjusted to 6-7. Then it is pressed into a bowl shape to obtain a sandwich layer. Outer membrane: Polylactic acid-dimethylformamide mixture is placed in a reaction vessel, n-hexylamine is added and mixed, and the mixture is sealed and stirred at 45-55℃ for 1-2 hours. After the reaction is completed, dioctyl phthalate and tea polyphenols are added, mixed evenly, and then vacuum rotary evaporated at 40℃ for 1 hour. Then tert-amyl alcohol is added and mixed evenly, and then vacuum dried at 45℃. Finally, the outer membrane is obtained by extrusion granulation and blown film.

2. The method for preparing a nutrient pot for desert afforestation according to claim 1, characterized in that, The arbuscular mycorrhizal fungi are any one of *Glomus mossicae*, *Glomus terrestrialis*, or *Glomus endorrhizos*.

3. The method for preparing a nutrient pot for desert afforestation according to claim 2, characterized in that, The mass ratio of polylactic acid-dimethylformamide mixture to diethylene glycol, p-tert-butylaniline, and polyethylene glycol during the preparation of the inner layer membrane is (15-25):(0.2-0.3):(0.3-0.5):(0.2-0.4).

4. The method for preparing a nutrient pot for desert afforestation according to claim 3, characterized in that, The volume ratio of straw, cow dung, and loess during the preparation of the sandwich layer is (2.5-3):(2.5-3):(5-6).

5. The method for preparing a nutrient pot for desert afforestation according to claim 4, characterized in that, The mass ratio of the mixture, Bacillus subtilis, arbuscular mycorrhizal fungi, mineral-derived potassium humate, and sodium carboxymethyl cellulose during the preparation of the sandwich layer is (8-10):(0.05-0.06):(0.03-0.04):(0.03-0.06):(0.008-0.01).

6. The method for preparing a nutrient pot for desert afforestation according to claim 5, characterized in that, The mass ratio of polylactic acid-dimethylformamide, n-hexylamine, dioctyl phthalate, tea polyphenols, and tert-amyl alcohol in the preparation of the outer membrane is (15-25):(0.4-0.6):(0.2-0.4):(0.1-0.2):(0.2-0.3).

7. The method for preparing a nutrient pot for desert afforestation according to claim 6, characterized in that, The interlayer weighs 6-7 kg and has a diameter of 30-50 cm.

8. The method for preparing a nutrient pot for desert afforestation according to claim 7, characterized in that, The nutrient pots are used when planting trees in the desert. Specifically, the nutrient pots are placed in the planting pit, filled with sand and then filled with water, and then the seedlings are planted on top.

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