Nutrition bowl for desert tree planting and preparation method thereof

Abstract

The invention discloses a nutrition bowl for desert tree planting and a preparation method thereof, and belongs to the technical field of nutrition bowls for trees. Cow dung, straw and other raw materials are mixed with loess to prepare a concave bowl, and then polylactic acid films with different degradation rates are prepared to coat the concave bowl, so that the concave bowl becomes a nutrition bowl for water storage and fertilizer conservation; when the fertilizer is used in cooperation in the desert tree planting process, water loss can be effectively inhibited, the absorption and utilization rate of saplings to water and nutrients is improved, the transplanting survival rate of the saplings is increased, the growth condition of the saplings is improved, and therefore the desertification control effect is improved; the tree planting cost is greatly reduced, and the method has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of nutrient pots for trees, and in particular to a nutrient pot for desert tree planting and a preparation method thereof. Background Art

[0002] The technology of tree planting and afforestation for wind prevention and sand control has achieved success in the long-term practice of desert ecological management, and has produced certain ecological benefits. The advantages are that the technical operation is simple and easy to master, and it can be organized and implemented on a large scale. By building large-scale windbreak and sand-fixation shelter forests, the wind speed can be reduced, and the harm of sandstorm disasters to farmland and residential areas can be reduced. When planting trees in sandy land, the seedlings are mostly with soil balls. When watering, it is required that the soil balls be soaked with water. However, the surrounding of the soil balls is all sand grains, and a large amount of the irrigated water leaks through the sand grain gaps, and only a small amount is adsorbed by the soil balls, resulting in extremely limited water available for plants. In addition, the nutrients in sandy soil are extremely poor, resulting in a severe lack of nutrients required for plant growth. If artificial matrix improvement is carried out, the cost of sand control will be greatly increased. In the existing methods, materials such as covering with rice straw, wood chips or applying polyacrylamide are used to improve the water retention of sandy soil, but the effect is poor, still resulting in low survival rate of desert tree planting, and the dosage is large, greatly increasing the cost of sand control.

[0003] Therefore, at present, it is necessary to find a material with good water storage and fertilizer retention effects to inhibit water loss during desert tree planting, meet the water and nutrient requirements of saplings, and thus improve the survival rate of desert tree planting and enhance the sand control effect. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a nutrient pot for desert tree planting and a preparation method thereof. By mixing raw materials such as cow dung, straw, and loess and pressing them into a concave sandwich pot, and covering the inner and outer layers of the pot with polylactic acid films with different degradation rates, a nutrient pot with strong fertilizer and water retention ability is obtained for use in the process of tree planting, which inhibits water loss, ensures the supply of water and nutrients, and thus improves the tree planting survival rate.

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

[0006] A nutrient pot for desert tree planting, the nutrient pot is composed of an inner layer film, a sandwich layer, and an outer layer film, and the nutrient pot includes the following raw materials:

[0007] Inner layer film: polylactic acid, dimethylformamide, diglycolic acid, p-tert-butylaniline, polyethylene glycol;

[0008] Sandwich layer: straw, cow dung, loess, Bacillus subtilis, arbuscular mycorrhizal fungi, mineral source fulvic acid potassium, sodium carboxymethyl cellulose;

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

[0010] Further, the arbuscular mycorrhizal fungi are any one of Glomus mosseae, Glomus versiforme, and Glomus intraradices.

[0011] The present invention also discloses a preparation method of the nutrient bowl, and the specific preparation method of the nutrient bowl is as follows:

[0012] The inner layer film and the outer layer film are correspondingly sleeved on the inside and outside of the sandwich layer to completely cover the sandwich layer to obtain the nutrient bowl.

[0013] Further, the preparation methods of the inner layer film, the sandwich layer, and the outer layer film of the nutrient bowl are as follows:

[0014] Inner layer film: Put the polylactic acid-dimethylformamide mixed solution into a reaction kettle, add diglycolic acid and p-tert-butylaniline, seal and react at 45-55 °C for 60-90 min. After the reaction is completed, add polyethylene glycol, mix evenly, vacuum dry at 45 °C, and then extrude and granulate and blow film to obtain the inner layer film;

[0015] Sandwich layer: Stir the straw, cow dung and loess evenly to obtain a mixture. Add Bacillus subtilis, arbuscular mycorrhizal fungi and mineral source fulvic acid potassium to the mixture and mix evenly. Then dissolve sodium carboxymethyl cellulose in water, add it and stir evenly. Then adjust the water content to 30-35% and adjust the pH to 6-7, and then press it into a bowl shape to obtain the sandwich layer, and place it in a cool place to dry in the shade;

[0016] Outer layer film: Put the polylactic acid-dimethylformamide mixed solution into a reaction kettle, add n-hexylamine and mix. Seal and stir and react at 45-55 °C for 1-2 h. After the reaction is completed, add dioctyl phthalate and tea polyphenols, mix evenly, vacuum rotary evaporate at 40 °C for 1 h, then add tert-amyl alcohol and mix evenly, vacuum dry at 45 °C, and then extrude and granulate and blow film to obtain the outer layer film.

[0017] Further, when preparing the inner layer film, the mass ratio of the polylactic acid-dimethylformamide mixed solution to diglycolic acid, p-tert-butylaniline, and polyethylene glycol is (15-25):(0.2-0.3):(0.3-0.5):(0.2-0.4).

[0018] Further, when preparing the sandwich layer, the volume ratio of straw, cow dung, and loess is (2.5-3):(2.5-3):(5-6).

[0019] Further, when preparing the sandwich layer, the mass ratio of the mixture, Bacillus subtilis, arbuscular mycorrhizal fungi, mineral source fulvic acid potassium, 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, when preparing the outer layer film, the mass ratio of polylactic acid - dimethylformamide, n - hexylamine, dioctyl phthalate, tea polyphenols, and tert - amyl alcohol is (15 - 25):(0.4 - 0.6):(0.2 - 0.4):(0.1 - 0.2):(0.2 - 0.3).

[0021] Furthermore, the weight of the interlayer is 6 - 7 kg, and the diameter is 30 - 50 cm.

[0022] Furthermore, the nutrient bowl is used for tree - planting in the desert. Specifically, place the nutrient bowl in the planting pit, fill the nutrient bowl with sand and then fill it with water, and then plant saplings above it.

[0023] By using agricultural production wastes such as cow dung and straw, mixing them with loess and mineral - sourced fulvic acid potassium to prepare the interlayer of the nutrient bowl, adding Bacillus subtilis and arbuscular mycorrhizal fungi to accelerate the decomposition of cow dung and straw, and the arbuscular mycorrhizal fungi improving the stress resistance of plants, the components in the interlayer of the nutrient bowl provide nutrients for plants and promote better growth of plants; covering the inner and outer layers of the nutrient bowl interlayer with a polylactic acid film that is harmless to the environment and biodegradable. When used in the tree - planting process, after filling the nutrient bowl with sand and injecting water, it can effectively prevent water loss, thereby providing sufficient water for the saplings to survive the slow - seedling period at the initial stage of transplantation, ensuring the survival rate of tree - planting. In the later stage, the roots of the saplings recover and start to extend deep into the sandy soil, and cow dung, straw, etc. in the interlayer provide nutrients for them, thus ensuring the supply of water and nutrients during the desert tree - planting process and effectively improving the survival rate of tree - planting.

[0024] Using a polylactic acid film to embed the nutrient bowl interlayer has good water - retention properties. During the gradual degradation of the polylactic acid film, the nutrients in the nutrient bowl interlayer are gradually exposed to provide nutrients for the saplings. After the saplings are transplanted, they need to go through a slow - seedling period. If the degradation time of the inner layer film is too short, it may cause the situation that the nutrients in the interlayer contact the seedlings prematurely during the slow - seedling period, resulting in seedling burning. If the degradation time is too long, it will cause the seedlings to not receive nutrient supply for a long time, affecting the survival rate and growth status. To ensure a smooth transition through the slow - seedling period and timely supply of nutrients in the later stage, the inner layer film is treated to accelerate its degradation rate. Specifically, by reacting diglycolic acid with polylactic acid and introducing polar groups to increase its polarity. When the inner layer film contacts the water injected during the tree - planting process, due to the increased polarity, the hydrolysis rate on the surface of the inner layer film accelerates, and a microporous structure gradually forms during the hydrolysis process on the surface of the inner layer film. Water molecules enter through the microporous structure to hydrolyze the inner layer of the film, and p - tert - butylaniline is added to combine with polylactic acid molecules to increase the steric hindrance effect between polylactic acid molecules, thereby increasing the molecular spacing and enlarging the pore diameter of the microporous structure formed after the hydrolysis of polylactic acid molecules on the film surface, enabling more subsequent water molecules to enter the interior to further decompose the inner layer film, and then the nutrients in the nutrient bowl interlayer are exposed in time to be provided to the saplings, ensuring timely nutrient supply.

[0025] When the inner layer of polylactic acid film is hydrolyzed, water molecules pass through the sandwich layer of the nutrient bowl and then contact the outer layer of polylactic acid film to hydrolyze it. Coupled with the decomposition of microorganisms and the like, water loss occurs. Therefore, in order to ensure more efficient utilization of water, it is necessary to extend the degradation time of the outer layer film. Therefore, in the preparation process of the outer layer of polylactic acid film in the present invention, n-hexylamine and tea polyphenols are added to react and combine with polylactic acid molecules to adjust the chemical structure of polylactic acid molecules to enhance their stability; tert-amyl alcohol is further combined with the polylactic acid molecular chain to inhibit the combination of the ends of the polylactic acid molecular chain with water, thereby reducing the hydrolysis sites of the polylactic acid film. The combined action of n-hexylamine, tea polyphenols and tert-amyl alcohol inhibits the decomposition reaction of the outer layer of polylactic acid film to maintain the stability of the outer layer of polylactic acid film. By adjusting the degradation rates of the inner and outer membranes of the nutrient bowl, while ensuring the timely supply of nutrients in the nutrient bowl, its water retention performance is improved, the utilization rate of nutrients and water by saplings is increased, the survival rate of desert tree planting is enhanced, and the desert control effect is improved.

[0026] Beneficial effects:

[0027] 1. In the present invention, by performing different treatments on polylactic acid, an inner membrane layer with an accelerated degradation rate and an outer membrane layer with a slowed degradation rate are respectively prepared. The sandwich layer prepared from substances such as cow dung and straw is coated to obtain a nutrient bowl. The inner membrane degrades faster to expose the sandwich layer and provide nutrients for saplings in a timely manner, while the outer membrane degrades slowly to better preserve the added water in the nutrient bowl. The prepared nutrient bowl can provide nutrients for saplings in a timely manner while well preserving the water in the bowl, laying a solid foundation for the survival of saplings, improving the survival rate of desert tree planting, and enhancing the desert control effect.

[0028] 2. The present invention uses a polylactic acid film to coat the nutrient bowl for water retention. The water retention effect is good and the dosage is small, which can greatly reduce the cost. Moreover, the polylactic acid film is finally decomposed into water and carbon dioxide, which is environmentally friendly; using raw materials such as straw and cow dung as nutrients provides a good treatment method for agricultural waste. Description of the drawings

[0029] Figure 1 It is a picture of the mixing material during the preparation of the sandwich layer of the nutrient bowl in Example 1 of the present invention;

[0030] Figure 2 It is a picture of the sandwich product prepared for the nutrient bowl in Example 1 of the present invention. Detailed implementation manners

[0031] The present invention will be described in detail below in conjunction with specific embodiments and drawings:

[0032] Example 1: Preparation of nutrient bowl 1

[0033] Inner layer film: Poly(lactic acid) was added to dimethylformamide in a mass ratio of poly(lactic acid):dimethylformamide = 1:15 to dissolve and obtain a poly(lactic acid)-dimethylformamide mixture. 20 kg of the poly(lactic acid)-dimethylformamide mixture was put into a reaction kettle, 0.25 kg of diglycolic acid and 0.4 kg of p-tert-butylaniline were added, and the reaction was sealed at 50 °C for 70 min. After the reaction was completed, 0.3 kg of polyethylene glycol was added, and after mixing evenly, it was vacuum dried at 45 °C. After drying, it was put into a twin-screw extruder for extrusion granulation. The conditions of the extruder were set as follows: the temperatures of the first to fifth zones were 150 °C, 165 °C, 180 °C, 190 °C, and 190 °C respectively, the screw speed was 150 rpm. After granulation, blown film was carried out to obtain the inner layer film. When setting the conditions of the blown film machine, the temperatures of the feeding zone, melting zone, and die head zone were 150 °C, 180 °C, and 180 °C respectively, the screw speed was 60 rpm, the draw ratio was 6 m / min, and the blow-up ratio was 3;

[0034] Interlayer: Straw, cow dung, and loess were evenly stirred in a volume ratio of 2.5:2.5:5 to obtain a mixture. 0.05 kg of Bacillus subtilis, 0.04 kg of arbuscular mycorrhizal fungi, and 0.05 kg of mineral source fulvic acid potassium were added to 9 kg of the mixture and mixed evenly. Then, 0.009 kg of sodium carboxymethyl cellulose was dissolved in 0.9 kg of water and added and stirred evenly. Then, the water content was adjusted to about 32%, the pH was adjusted to 6.5, and then 6.5 kg was taken and put into a steel bowl with a diameter of 40 cm and covered with a plastic film cloth. After being pressed into a concave round-bottomed bowl, it was taken out to obtain the interlayer, and it was placed in a cool place to dry in the shade for later use;

[0035] Outer layer film: Poly(lactic acid) was added to dimethylformamide in a mass ratio of poly(lactic acid):dimethylformamide = 1:15 to dissolve and obtain a poly(lactic acid)-dimethylformamide mixture. 20 kg of the poly(lactic acid)-dimethylformamide mixture was put into a reaction kettle, 0.5 kg of n-hexylamine was added and mixed. The reaction 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 after mixing evenly, it was vacuum rotary evaporated at 40 °C for 1 h. Then, 0.25 kg of tert-amyl alcohol was added and mixed evenly, and then it was vacuum dried at 45 °C. Granulation and blown film were carried out under the same conditions as the inner layer film to obtain the outer layer film;

[0036] Nutrient bowl: The inner layer film and the outer layer film were respectively sleeved on the inner and outer parts of the interlayer to just completely cover the interlayer to obtain the nutrient bowl.

[0037] Example 2: Preparation of nutrient bowl II

[0038] Inner layer film: Dissolve polylactic acid in dimethylformamide according to the mass ratio of polylactic acid: dimethylformamide = 1:15 to obtain a polylactic acid-dimethylformamide mixture. Put 15 kg of the polylactic acid-dimethylformamide mixture into a reaction kettle, add 0.2 kg of diglycolic acid and 0.3 kg of p-tert-butylaniline, seal and react at 45 °C for 90 min. After the reaction is completed, add 0.2 kg of polyethylene glycol, mix evenly, and then vacuum dry at 45 °C. After drying, put it into a twin-screw extruder for extrusion granulation. The conditions of the extruder are set as follows: the temperatures of the first to fifth zones are 150 °C, 165 °C, 180 °C, 190 °C, and 190 °C respectively, the screw speed is 150 rpm. After granulation, blow molding is carried out to obtain the inner layer film. When setting the conditions of the blow molding machine, the temperatures of the feeding zone, melting zone, and die head zone are 150 °C, 180 °C, and 180 °C respectively, the screw speed is 60 rpm, the draw ratio is 6 m / min, and the blow-up ratio is 3;

[0039] Interlayer: Stir the straw, cow dung, and loess evenly according to the 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 source fulvic acid potassium to 8 kg of the mixture and mix evenly. Then dissolve 0.008 kg of sodium carboxymethyl cellulose in 0.8 kg of water, add it and mix evenly. Then adjust the water content to 30% and adjust the pH to 6. Then take 6 kg and put it into a steel bowl with a diameter of 40 cm and covered with a plastic film cloth. After pressing it into a concave round-bottomed bowl, take it out to obtain the interlayer, and place it in a cool place to dry for later use;

[0040] Outer layer film: Dissolve polylactic acid in dimethylformamide according to the mass ratio of polylactic acid: dimethylformamide = 1:15 to obtain a polylactic acid-dimethylformamide mixture. Put 15 kg of the polylactic acid-dimethylformamide mixture into a reaction kettle, add 0.4 kg of n-hexylamine and mix. Stir and react at 45 °C for 2 h. After the reaction is completed, add 0.2 kg of dioctyl phthalate and 0.1 kg of tea polyphenols, mix evenly, and then carry out vacuum rotary evaporation at 40 °C for 1 h. Then add 0.2 kg of tert-amyl alcohol and mix evenly, and then vacuum dry at 45 °C. Granulation and blow molding are carried out under the same conditions as the inner layer film to obtain the outer layer film;

[0041] Nutrient bowl: The inner layer film and the outer layer film are respectively sleeved on the inner and outer parts of the interlayer to just completely cover the interlayer to obtain the nutrient bowl.

[0042] Example 3: Preparation of the nutrient bowl III

[0043] Inner layer film: Poly lactic acid was added to dimethylformamide according to the mass ratio of poly lactic acid: dimethylformamide = 1:15 to dissolve and obtain a poly lactic acid-dimethylformamide mixture. 25 kg of the poly lactic acid-dimethylformamide mixture was put into a reaction kettle, 0.3 kg of diglycolic acid and 0.5 kg of p-tert-butylaniline were added, and the reaction was sealed at 55 °C for 60 min. After the reaction was completed, 0.4 kg of polyethylene glycol was added, and after mixing evenly, it was vacuum dried at 45 °C. After drying, it was put into a twin-screw extruder for extrusion granulation. The conditions of the extruder were set as follows: the temperatures of the first zone to the fifth zone were 150 °C, 165 °C, 180 °C, 190 °C, and 190 °C respectively, the screw speed was 150 rpm. After granulation, blown film was carried out to obtain the inner layer film. When setting the conditions of the blown film machine, the temperatures of the feeding zone, the melting zone, and the die head zone were 150 °C, 180 °C, and 180 °C respectively, the screw speed was 60 rpm, the draw ratio was 6 m / min, and the blow-up ratio was 3;

[0044] Interlayer: Straw, cow dung, and loess were evenly mixed by turning according to the volume ratio of 2.5:2.5:5 to obtain a mixture. 0.06 kg of Bacillus subtilis, 0.04 kg of arbuscular mycorrhizal fungi, and 0.06 kg of mineral source fulvic acid potassium were added to 10 kg of the mixture and mixed evenly. Then, 0.01 kg of sodium carboxymethyl cellulose was dissolved in 1 kg of water, added and mixed evenly. Then, the water content was adjusted to 35%, the pH was adjusted to 7, and 8 kg was taken and put into a steel bowl with a diameter of 40 cm and covered with a plastic film cloth. After being pressed into a concave round-bottomed bowl shape, it was taken out to obtain the interlayer, and it was placed in a cool place to dry in the shade for later use;

[0045] Outer layer film: Poly lactic acid was added to dimethylformamide according to the mass ratio of poly lactic acid: dimethylformamide = 1:15 to dissolve and obtain a poly lactic acid-dimethylformamide mixture. 25 kg of the poly lactic acid-dimethylformamide mixture was put into a reaction kettle, 0.6 kg of n-hexylamine was added and mixed. The reaction 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. After mixing evenly, it was vacuum rotary evaporated at 40 °C for 1 h. Then, 0.3 kg of tert-amyl alcohol was added and mixed evenly, and then it was vacuum dried at 45 °C. Granulation and blown film were carried out under the same conditions as those of the inner layer film to obtain the outer layer film;

[0046] Nutrient bowl: The inner layer film and the outer layer film were correspondingly sleeved on the inside and outside of the interlayer just to completely cover the interlayer to obtain the nutrient bowl.

[0047] Comparative example 1: Preparation of nutrient bowl

[0048] In comparison with Example 1, the difference was only that mineral source fulvic acid potassium was not added during the preparation of the interlayer of the nutrient bowl in Comparative Example 1, and the remaining steps were the same as those in Example 1.

[0049] Comparative example 2: Preparation of nutrient bowl

[0050] In contrast to Example 1, the only difference is that diglycolic acid is not added during the preparation of the inner layer film of the nursery pot in Comparative Example 2, and the remaining steps are the same as those in Example 1.

[0051] Comparative Example 3: Preparation of nursery pot

[0052] In contrast to Example 1, the only difference is that p-tert-butylaniline is not added during the preparation of the inner layer film of the nursery pot in Comparative Example 3, and the remaining steps are the same as those in Example 1.

[0053] Comparative Example 4: Preparation of nursery pot

[0054] In contrast to Example 1, the only difference is that the reaction temperature in the reaction kettle is room temperature during the preparation of the inner layer film of the nursery pot in Comparative Example 4, and the remaining steps are the same as those in Example 1.

[0055] Comparative Example 5: Preparation of nursery pot

[0056] In contrast to Example 1, the only difference is that the addition amounts of diglycolic acid and p-tert-butylaniline are 0.5 kg and 0.7 kg respectively during the preparation of the inner layer film of the nursery pot in Comparative Example 5, and the remaining steps are the same as those in Example 1.

[0057] Comparative Example 6: Preparation of nursery pot

[0058] In contrast to Example 1, the only difference is that n-hexylamine is not added for sealing reaction during the preparation of the outer layer film of the nursery pot in Comparative Example 6, and the remaining steps are the same as those in Example 1. The specific preparation of the outer layer film is as follows:

[0059] Add polylactic acid to dimethylformamide according to the mass ratio of polylactic acid:dimethylformamide = 1:15 to dissolve and obtain a polylactic acid-dimethylformamide mixed solution. Put 20 kg of the polylactic acid-dimethylformamide mixed solution into a reaction kettle, add 0.3 kg of dioctyl phthalate and 0.15 kg of tea polyphenols, mix evenly, then perform vacuum rotary evaporation at 40 °C for 1 h, and then add 0.25 kg of tert-amyl alcohol, mix evenly, and perform vacuum drying at 45 °C. Granulation and film blowing are carried out under the same conditions as the inner layer film to obtain the outer layer film.

[0060] Comparative Example 7: Preparation of nursery pot

[0061] In contrast to Example 1, the only difference is that tea polyphenols are not added during the preparation of the outer layer film of the nursery pot in Comparative Example 7, and the remaining steps are the same as those in Example 1.

[0062] Comparative Example 8: Preparation of nursery pot

[0063] In contrast to Example 1, the only difference is that tert-amyl alcohol is not added during the preparation of the outer layer film of the nursery pot in Comparative Example 8, and the remaining steps are the same as those in Example 1.

[0064] Comparative Example 9: Preparation of nursery pot

[0065] In contrast to Example 1, the difference is only that the reaction temperature in the reaction kettle during the preparation of the outer layer film of the nursery pot in Comparative Example 9 is room temperature, and the remaining steps are the same as those in Example 1.

[0066] Comparative Example 10: Preparation of nursery pots

[0067] In contrast to Example 1, the difference is only that there is no inner layer film and outer layer film during the preparation of the nursery pot in Comparative Example 10, that is, the nursery pot is directly prepared from the interlayer.

[0068] Experiment 1: Membrane degradation detection experiment

[0069] The degradation performance of the inner layer films prepared in Example 1 and Comparative Examples 2-5 and the outer layer films prepared in Example 1 and Comparative Examples 6-9 was measured. The specific method is as follows:

[0070] Mix sand, loess, well-rotted cow dung, and straw evenly according to a mass ratio of 10:2:1:1, then add Bacillus subtilis and arbuscular mycorrhizal fungi and mix evenly. The addition amounts are both 2 g / kg, and then adjust the water content to 80% and adjust the pH to 6.5 to obtain the experimental soil.

[0071] Take the inner layer films prepared in Example 1 and Comparative Examples 2-5 and the outer layer films prepared in Example 1 and Comparative Examples 6-9 and bury them in the experimental soil respectively. Water regularly to keep the water content of the experimental soil at 80%. Measure the degradation rate of each group of films after 15 days and 30 days respectively. Three repeated experiments were carried out, and the average data are shown in Tables 1 and 2:

[0072] Table 1

[0073]

[0074] Table 2

[0075]

[0076] According to the data analysis in Tables 1 and 2, it can be seen that:

[0077] (1) After treating polylactic acid according to the method of the present invention and making a film, the degradation performance can be adjusted preferably to obtain an inner layer film with a faster degradation rate and an outer layer film with a slower degradation rate. Furthermore, after coating the interlayer of the nursery pot, it can not only ensure that the nutrients in the interlayer can be provided in time, but also better inhibit the loss of water, improve the utilization efficiency of water and nutrients by the saplings, and ensure the effect of desert tree planting.

[0078] (2) In Comparative Example 2, diglycolic acid was not added during the preparation of the inner layer film. In Comparative Example 3, p-tert-butylaniline was not added during the preparation of the inner layer film. The degradation rate of the inner layer film in Comparative Example 2 and Comparative Example 3 decreased significantly compared with that of the inner layer film in Example 1. In Comparative Example 5, a large amount of diglycolic acid and p-tert-butylaniline were added during the preparation of the inner layer film. The degradation rate of the inner layer film increased compared with that of Example 1, and the degradation rate reached a relatively high level on the 15th day, which was instead unfavorable for the water retention and later fertilizer release performance of the nursery pot.

[0079] (3) In Comparative Example 6, n-hexylamine was not added during the preparation of the outer layer film. In Comparative Example 7, tea polyphenols were not added during the preparation of the outer layer film. The stability of the polylactic acid molecular chain of the outer layer film in Comparative Example 6 and Comparative Example 7 was poor, and it degraded faster in the experimental soil. In Comparative Example 8, tert-amyl alcohol was not added during the preparation of the outer layer film. The polylactic acid molecules of the outer layer film were more vulnerable to water molecule attack and degradation, and the degradation rate was faster than that of the outer layer film in Example 1.

[0080] Experiment 2: Determination of the water storage and fertilizer retention effect of the nursery pot

[0081] 1. Experimental site and method: The nursery pots prepared in Example 1 and Comparative Examples 1-10 were used for desert tree planting experiments in a desertified area in Bultai, Ordos, Inner Mongolia. The specific use method of the nursery pot was as follows: Dig a planting pit, place the nursery pot at a depth of 20 cm below the root system of the sapling in the planting pit, fill the nursery pot with sand and then fill it with water, and then plant the sapling above. The transplanted saplings were nitraria seedlings with the same growth status and a seedling height of about 30 cm. 40 saplings were transplanted in each group. An experimental blank control group was added. The blank control group did not use a nursery pot, but directly poured the same amount of water.

[0082] 2. Result detection: The survival rate of the saplings in each group was counted 50 days after the sapling transplantation. 10 saplings were randomly selected 12 months later to count the average height of the transplanted seedlings in each group. The experiment was repeated three times, and the data obtained are shown in Table 3:

[0083] Table 3

[0084]

[0085]

[0086] According to the data analysis in Table 3, it can be seen that:

[0087] (1) Compared with Comparative Examples 1-10 and the blank control group, the survival rate and plant height of nitraria in Example 1 were the best. The survival rate could reach 88.3%, and the plant height reached 96.5 cm after 12 months. It shows that the nursery pot prepared by the present invention can store water and fertilizer for the saplings, can well provide water for the saplings to slow down the seedlings, and timely provide nutrients such as cow dung organic matter, improve the utilization rate of water and nutrients by the saplings, and thus improve the survival rate of the saplings and the later growth status during the desert tree planting process.

[0088] (2) The nutrient bowl in Comparative Example 1 did not add mineral-source fulvic acid potassium, resulting in a reduction in nutrient supply. Moreover, when adding mineral-source fulvic acid potassium, the growth of Nitraria tangutorum was affected to a certain extent.

[0089] (3) In Comparative Examples 2 and 3, the degradation rate of the inner layer film was slow, which affected the nutrient supply in the sandwich layer of the nutrient bowl and thus affected the growth of Nitraria tangutorum to a certain extent.

[0090] (4) In Comparative Examples 6, 7, and 8, the degradation rate of the outer layer film of the nutrient bowl was fast, which in turn reduced the water retention of the nutrient bowl. The reduction in water supply affected the survival rate of Nitraria tangutorum seedlings. In Comparative Example 10, without the inner and outer film layers, both the survival rate and the growth of the plants were significantly reduced, indicating that the inner and outer layers of the film play an important role in ensuring the utilization of nutrients and water by the seedlings.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention. The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. A nutrient pot for planting trees in the desert, characterized in that: The nutrient bowl is composed of an inner membrane, an interlayer and an outer membrane, and the nutrient bowl includes the following raw materials: Inner layer film: polylactic acid, dimethylformamide, diglycolic acid, p-tert-butylaniline, polyethylene glycol; Interlayer: straw, cow dung, loess, Bacillus subtilis, arbuscular mycorrhizal fungi, mineral potassium humate, sodium carboxymethyl cellulose; Outer film: polylactic acid, dimethylformamide, n-hexylamine, dioctyl phthalate, tea polyphenols, tert-amyl alcohol.

2. A nutrient pot for planting trees in deserts according to claim 1, characterized in that: The arbuscular mycorrhizal fungus is any one of Glomus mosseae, Glomus terrestris, and Glomus intraradical.

3. A method for preparing a nutrient pot for planting trees in the desert, characterized in that: The preparation method of the nutrient pot is as follows: The inner layer membrane and the outer layer membrane are correspondingly put on the inner and outer sides of the sandwich layer to completely cover the sandwich layer to obtain the nutrient pot.

4. The method for preparing a nutrient pot for planting trees in deserts according to claim 3, characterized in that: The preparation methods of the inner layer membrane, the interlayer membrane and the outer layer membrane of the nutrient pot are as follows: Inner film: Put the polylactic acid-dimethylformamide mixed liquid into a reactor, add diglycolic acid and p-tert-butylaniline, and react at 45-55°C for 60-90 minutes in a sealed state. After the reaction is completed, add polyethylene glycol, mix well, and dry in vacuum at 45°C. Then extrude and granulate, and blow film to obtain the inner film. Interlayer: Stir straw, cow dung and loess to obtain a mixture, add Bacillus subtilis, arbuscular mycorrhizal fungi and mineral potassium humate to the mixture and mix well, then add sodium carboxymethyl cellulose to dissolve it in water and stir well, then adjust the water content to 30-35%, adjust the pH to 6-7 and press it into a bowl to obtain an interlayer; Outer film: Put the polylactic acid-dimethylformamide mixed liquid into a reactor, add n-hexylamine and mix, seal and stir to react for 1-2 hours at 45-55°C, add dioctyl phthalate and tea polyphenols after the reaction is completed, mix well, and then vacuum rotary evaporate at 40°C for 1 hour, then add tert-amyl alcohol and mix well, and then vacuum dry at 45°C, and then extrude granulate and blow film to obtain the outer film.

5. The method for preparing a nutrient pot for planting trees in deserts according to claim 4, characterized in that: When preparing the inner layer film, the mass ratio of the polylactic acid-dimethylformamide mixed liquid to diglycolic acid, p-tert-butylaniline and polyethylene glycol is (15-25): (0.2-0.3): (0.3-0.5): (0.2-0.4).

6. The method for preparing a nutrient pot for planting trees in deserts according to claim 5, characterized in that: When preparing the interlayer, the volume ratio of straw, cow dung and loess is (2.5-3): (2.5-3): (5-6).

7. The method for preparing a nutrient pot for planting trees in deserts according to claim 6, characterized in that: When preparing the interlayer, the mass ratio of the mixture, Bacillus subtilis, arbuscular mycorrhizal fungi, mineral 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).

8. The method for preparing a nutrient pot for planting trees in deserts according to claim 7, characterized in that: When preparing the outer film, the mass ratio of polylactic acid-dimethylformamide, n-hexylamine, dioctyl phthalate, tea polyphenols and tert-amyl alcohol is (15-25): (0.4-0.6): (0.2-0.4): (0.1-0.2): (0.2-0.3).

9. The method for preparing a nutrient pot for planting trees in deserts according to claim 8, characterized in that: The interlayer weighs 6-7 kg and has a diameter of 30-50 cm.

10. The method for preparing a nutrient pot for planting trees in deserts according to claim 9, characterized in that: The nutrient pot is used when planting trees in the desert. Specifically, the nutrient pot is placed in a planting pit, filled with sand and then filled with water, and then the seedlings are planted on the nutrient pot.

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