Corn and soybean strip-shaped composite planting method

Abstract

The invention discloses a corn and soybean strip-shaped composite planting method, and belongs to the technical field of agricultural planting. Comprising the following steps: step 1, preparing land: crushing the soil by using mechanical equipment, and uniformly releasing a nitrogen-phosphorus fertilizer into the dry land; 2, ridging and film mulching are conducted, after land preparation is completed, ridging is conducted, the ridge width is 160 cm, the ditch width is 60 cm, and the ridge height is 20 cm; a biodegradable weeding mulching film is selected as the mulching film; step 3, sowing management: corn sowing operation is carried out in late May, soybean sowing operation is carried out in mid-late June, and a planting mode is corn and soybean intercropping planting; the corn is planted on the ridge edge, and the soybean is planted on the ridge; 4, harvesting management, wherein harvesting is conducted after the corn and the soybeans are mature. The mulching film is covered with a biodegradable weeding mulching film; in the composite planting process, a continuous weeding barrier can be formed, weed growth is remarkably inhibited, and the defects of mechanical weeding and chemical weeding in the prior art can be overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural planting, and specifically relates to a corn and soybean strip composite planting method. Background Art

[0002] Corn and soybeans are important food, feed and oil crops. Due to the limitation of cultivated land area, my country's current self-sufficiency rate of corn and soybeans is seriously insufficient, and the contradiction between supply and demand is prominent. In order to improve land utilization and achieve a win-win situation for corn and soybean production, the country vigorously promotes the strip compound planting model of soybeans and corn. The growth period of corn and soybeans overlaps with that of most weeds, and they will suffer from various weed damage during the production process; the compound planting of corn and soybeans further increases the difficulty of preventing and controlling weeds in the field. Soybeans are dicotyledons, and corn is a monocotyledon. Under compound planting conditions, appropriate herbicides and application methods must be selected. If the selection or application method is inappropriate, it will cause losses to corn or soybean production.

[0003] The prior art includes a Chinese invention patent with application number: CN202210338490.0, which discloses a method for mixed planting of corn and soybeans, which includes the following steps: (1) deep rotary tillage of the soil, loosening the tillage layer and the plow bottom layer, crushing and mixing the loosened soil, and then paving; (2) sequentially arranged corn strips, soybean strips, corn strips, and alfalfa strips are used as a strip, and multiple strips are planted in sequence, with corn planted in four rows per strip, and soybeans and alfalfa planted in two rows per strip, wherein the row spacing of corn in the corn strip is 65 cm, the row spacing of soybeans in the soybean strip is 30 cm, and the row spacing of alfalfa in the alfalfa strip is 30 cm; alfalfa is additionally planted, and the corn is close to the shorter soybeans and alfalfa, respectively.

[0004] In the above-mentioned prior art, the types of crops are mixed. If mechanical weeding equipment is used, alfalfa strips and corn strips are arranged alternately, and it is difficult for the mechanical weeding equipment to flexibly turn between wide and narrow rows. In addition, the root system of alfalfa is shallow, and intertillage is easy to damage the roots. Another problem is that when alfalfa is not harvested, its short plants cannot effectively suppress weeds. On the contrary, due to insufficient shade, it may provide growth space for broad-leaved weeds such as quinoa and amaranth. If chemical weeding is used, the sensitivity of corn, soybeans and alfalfa to herbicides varies significantly. There is no uniformly applicable broad-spectrum herbicide. During chemical weeding, it is necessary to apply the medicine in different strips accurately. However, in actual operation, it is very easy to cause drug damage due to liquid drift, thereby resulting in reduced production.

[0005] The use of degradable mulch films loaded with herbicides during the planting process can take into account the weed control of various types of crops. However, there is still huge room for improvement in the mechanical properties and slow-release properties of the mulch films currently available.

[0006] Therefore, in order to solve the above problems, the present application provides a method for strip-shaped composite planting of corn and soybeans. Summary of the invention

[0007] In order to solve the defects in the above technical solutions, the purpose of the present invention is to provide a method for strip-shaped composite planting of corn and soybeans. The purpose of the present invention can be achieved by the following technical solutions: A method for strip-shaped composite planting of corn and soybeans, comprising the following steps: Step 1: Prepare the land: Use mechanical equipment to break up the soil and evenly release nitrogen and phosphorus fertilizers into the dry land; Step 2, ridge formation and film covering: after the land is prepared, ridge formation is performed, wherein the ridge width is 160 cm, the ditch width is 60 cm, and the ridge height is 20 cm; the film covering is biodegradable weed-killing film; Step 3, sowing management: Select late May to carry out corn sowing operations, and mid-to-late June to carry out soybean sowing operations. The planting mode is intercropping of corn and soybeans; corn is planted on the edge of the ridge, and soybeans are planted on the ridge; Step 4: Harvest management: Harvest corn and soybeans after they mature. Corn husks are harvested directly in the field; soybeans are collected together with the plants into net bags; The biodegradable weed-killing film in step 2 comprises, by weight: 6-12 parts of polyvinyl alcohol, 3-6 parts of starch, 2-3 parts of glycerol, 0.05-0.1 parts of rosin, 0.05-0.1 parts of glyceryl monostearate, 1.8-3.2 parts of modified bentonite loaded with herbicides, and an appropriate amount of deionized water.

[0008] Furthermore, in step 1, mechanical equipment is used to fully break up the soil, and rotary tillage is adopted to ensure that there are no debris such as gravel and straw residues in the soil; Furthermore, in step 1, when applying fertilizer, 150 kg of nitrogen fertilizer and 90 kg of phosphorus fertilizer are applied to each hectare of dry land.

[0009] Furthermore, the preparation method of the biodegradable weed killer film is as follows: deionized water is added to starch to prepare a starch solution with a mass fraction of 10%, and then magnetically stirred at high speed in a water bath at 80 degrees Celsius to form a gelatinized liquid; polyvinyl alcohol is added to deionized water to prepare a polyvinyl alcohol solution with a mass fraction of 10%, and magnetically stirred for 15 minutes to fully disperse it; then it is slowly poured into the gelatinized liquid; then rosin, glyceryl monostearate and modified bentonite loaded with herbicides are added to the reaction container, and stirring is continued for 3 hours; finally, the fully mixed film-forming liquid is spread on the molding mold to form a liquid layer of uniform thickness, and it is placed in a 50-degree Celsius oven to dry for 24 hours to prepare a biodegradable weed killer film.

[0010] Furthermore, the starch used in the preparation of the biodegradable weed-killing film is corn starch; Furthermore, the preparation method of the modified bentonite is: put bentonite into a three-necked flask equipped with a stirring device, add distilled water into the three-necked flask, stir until it is fully dissolved, then add the modified lignin solution, stir for 5 hours in a constant temperature water bath at 70°C, cool to room temperature after the reaction is completed, and finally filter and separate the precipitate, and dry the precipitate at 50°C for 48 hours; that is, the modified bentonite is prepared.

[0011] In specific implementation, the bentonite can also be pretreated to obtain refined bentonite: take 50g of bentonite, slowly add it to 250ml of deionized water under mechanical stirring, fully stir for 15min, continue to add 650ml of water, stir for 45min, let it stand for 1h, take the upper suspension, and adjust the pH of the suspension to acidic, heat for 10-15min, and after flocculent precipitates appear in the suspension, continue to stand for 2h, filter, and dry to prepare the pretreated bentonite.

[0012] Furthermore, the preparation method of the modified lignin is: adding alkali lignin and deionized water into a reaction vessel equipped with a reflux and stirring device, adjusting the pH value to 11 with sodium hydroxide; then adding diethylenetriamine, stirring and dissolving, and heating to 95°C; then, slowly adding a formaldehyde solution with a mass fraction of 37% by a peristaltic pump within 30 minutes; finally, obtaining a modified lignin solution by reacting at 95°C for 3 hours.

[0013] Furthermore, in step 2, when covering the film, the film needs to be spread flat and tightened, as close to the ridge surface as possible, and both sides of the film need to be compacted with soil; Furthermore, in the sowing management of step 3, the width of a complete planting belt is 2.2m, the row spacing of corn is 30cm*60cm, the row spacing of soybean is 20cm*40cm, and the row spacing of corn and soybean is 60cm; Furthermore, during sowing in step 3, one corn seedling is left in each hole and two soybean seedlings are left in each hole; Furthermore, the preparation method of the modified bentonite loaded with herbicide is: dissolving the herbicide in an organic solvent to form a supersaturated solution of the herbicide, then adding 1.8 parts of the modified bentonite, stirring for 2 hours until it is evenly dispersed, and then vacuuming the solution. After the modified bentonite is fully loaded with the herbicide, separating and drying, the modified bentonite loaded with the herbicide is prepared.

[0014] Preferably, the modified bentonite loaded with herbicides includes modified bentonite loaded with cornfield herbicides and modified bentonite loaded with soybean field herbicides; Preferably, the herbicide loaded by the modified bentonite loaded with cornfield herbicides is any one of 2,4-D butyl ester and chlorotoluron; The CAS of the chlorotoluron is: 15545-48-9.

[0015] Preferably, the herbicide loaded on the modified bentonite loaded with soybean field herbicide is any one of imazethapyr and promethazine; The CAS of the prometryn is: 7287-19-6.

[0016] Preferably, in the preparation of the biodegradable weed killing film, the molding mold has a partition; the film-forming liquid of modified bentonite loaded with soybean field herbicide is spread and covered in the middle of the molding mold after being separated by the partition; the film-forming liquid of modified bentonite loaded with corn field herbicide is spread and covered in both sides of the mold after being isolated; and it is ensured that the two film-forming liquids are well combined at the contact boundary but not mixed with each other, and finally form a liquid layer of uniform thickness.

[0017] The present invention has the beneficial effects: 1. The planting method of the present application adopts a biodegradable weed control film; in the composite planting process, it can form a continuous weed control barrier, significantly inhibit the growth of weeds, overcome the drawbacks of mechanical weed control and chemical weed control in the prior art, and has no pesticide damage to crops, and the degradable film is also more environmentally friendly; 2. The biodegradable weed control film in step 2 of the present application is added with rosin. The ring structure in its chemical structure can be used as a rigid group to significantly improve the tensile strength of the film through filling. The addition of rosin also improves the crystallinity of the material, thereby improving the tensile strength of the film; making the film in the field less likely to be damaged during crop growth and able to continuously exert its weed control effect; 3. Unmodified bentonite has a limited specific surface area, a single surface charge, and a limited loading capacity for herbicides, and cannot maintain the release of herbicides over a long period. The present application introduces modified lignin to extend the release period of herbicides. The most important thing is that rosin can react with polyvinyl alcohol and starch to generate ester groups, increase the length of the molecular chain, make the molecular chain easier to entangle, and increase the viscosity of the system. The modified bentonite can also form hydrogen bonds with polyvinyl alcohol and starch, so that the movement of the molecular chain of the system is restricted. The synergistic effect of the two can further increase the viscosity of the film material, and can also enhance the mechanical properties of the film, thereby having a wider range of application scenarios. 4. The biodegradable weed control film covered by the present application can also be prepared by a zoned solution casting method, and the film is loaded with corn field herbicides and soybean field herbicides at the same time, so that chemical weed control of crops in the composite planting process can be achieved more specifically, which can significantly reduce the labor input required for traditional weed control. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment, and the illustrative embodiments of the present invention and its description are only used to explain the present invention, and are not used as limitation of the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper limit and lower limit of these smaller ranges can be independently included or excluded in the scope.

[0019] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0020] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0021] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0022] The "parts" indicated in the following examples are all parts by weight.

[0023] Example 1 A corn and soybean strip composite planting method comprises the following steps: Step 1: Prepare the land: Use mechanical equipment to break up the soil and evenly release nitrogen and phosphorus fertilizers into the dry land; Step 2, ridge formation and film covering: after the land is prepared, ridge formation is performed, wherein the ridge width is 160 cm, the ditch width is 60 cm, and the ridge height is 20 cm; the film covering is biodegradable weed-killing film; Step 3, sowing management: Select late May to carry out corn sowing operations, and mid-to-late June to carry out soybean sowing operations. The planting mode is intercropping of corn and soybeans; corn is planted on the edge of the ridge, and soybeans are planted on the ridge; Step 4: Harvest management: Harvest corn and soybeans after they are mature. Corn husks are harvested directly in the field; soybeans are put into net bags together with the plants.

[0024] In the specific implementation, the step 1 uses mechanical equipment to fully break up the soil to enhance soil permeability, and adopts rotary tillage to ensure that there are no debris such as gravel and straw residues in the soil, thereby improving the soil structure and creating planting conditions for the healthy growth of corn and soybeans; In the specific implementation, in step 1, when applying fertilizer, 150 kg of nitrogen fertilizer and 90 kg of phosphorus fertilizer are applied to each hectare of dry land; In the specific implementation, in step 2, when covering the film, the film needs to be spread flat and tightened, as close to the ridge surface as possible, and the two sides of the film need to be compacted with soil; In the specific implementation, in the sowing management of step 3, the width of a complete planting belt is 2.2m, the row spacing of corn is 30cm*60cm, the row spacing of soybean is 20cm*40cm, and the row spacing of corn and soybean is 60cm; In specific implementation, when sowing in step 3, one corn seedling is left in each hole and two soybean seedlings are left in each hole; In specific implementation, the biodegradable weed control film in step 2 includes, by weight: 6 parts of polyvinyl alcohol, 3 parts of starch, 2 parts of glycerol, 0.05 parts of rosin, 0.05 parts of glyceryl monostearate, 1.8 parts of modified bentonite loaded with herbicide, and an appropriate amount of deionized water.

[0025] The preparation method of the biodegradable weed-killing film is as follows: deionized water is added to 3 parts of corn starch to prepare a starch solution with a mass fraction of 10%, and then magnetically stirred at high speed in a water bath at 80 degrees Celsius to form a gelatinized liquid; 6 parts of polyvinyl alcohol are added to deionized water to prepare a polyvinyl alcohol solution with a mass fraction of 10%, and magnetically stirred for 15 minutes to fully disperse it; then it is slowly poured into the gelatinized liquid; then rosin, glyceryl monostearate and modified bentonite loaded with herbicides are added to the reaction container, and stirring is continued for 3 hours; finally, the fully mixed film-forming liquid is evenly spread on the molding mold to form a liquid layer of uniform thickness, and it is placed in a 50-degree Celsius oven to dry for 24 hours to prepare the biodegradable weed-killing film.

[0026] In specific implementation, the preparation method of the modified bentonite is as follows: 20g of bentonite is put into a three-necked flask equipped with a stirring device, 800mL of distilled water is added to the three-necked flask, and stirred until it is fully dissolved, and then 22g of modified lignin solution is added, and stirred at a speed of 300r / min for 5h in a constant temperature water bath at 70°C, and after the reaction is completed, it is cooled to room temperature, and finally filtered to separate the precipitate, and the precipitate is dried at 50°C for 48h; that is, the modified bentonite is prepared.

[0027] In specific implementation, the bentonite can also be pretreated to obtain refined bentonite: take 50g of bentonite, slowly add it to 250ml of deionized water under mechanical stirring, fully stir for 15min, continue to add 650ml of water, stir for 45min, let it stand for 1h, take the upper suspension, and adjust the pH of the suspension to acidic, heat for 10-15min, and after flocculent precipitates appear in the suspension, continue to stand for 2h, filter, and dry to prepare the pretreated bentonite.

[0028] In specific implementation, the preparation method of the modified lignin is as follows: 20 g of alkali lignin and 30 mL of deionized water are added to a reaction vessel equipped with a reflux and stirring device, and the pH value is adjusted to 11 with sodium hydroxide; then 10 g of diethylenetriamine is added, stirred to make it evenly dissolved, and heated to 95°C; then, a total of 31.5 g of a formaldehyde solution with a mass fraction of 37% is slowly added dropwise through a peristaltic pump within 30 minutes; finally, a modified lignin solution is obtained by performing a grafting reaction at 95°C for 3 hours.

[0029] In a specific implementation, the preparation method of the modified bentonite loaded with herbicides is as follows: the herbicide is dissolved in acetone to form a supersaturated solution of the herbicide, and then 1.8 parts of the modified bentonite are added, stirred for 2 hours until uniformly dispersed, and then vacuumed. After the modified bentonite is fully loaded with the herbicide, the modified bentonite is separated and dried to prepare the modified bentonite loaded with herbicides.

[0030] In a specific implementation, the modified bentonite loaded with herbicides includes modified bentonite loaded with cornfield herbicides and modified bentonite loaded with soybean field herbicides; The herbicide loaded by the modified bentonite loaded with cornfield herbicide is 2,4-D butyl ester; The herbicide loaded by the modified bentonite loaded with soybean field herbicide is imazethapyr; In a specific implementation, in the preparation of the biodegradable weed killing film, the molding mold is provided with a partition; the film-forming liquid of modified bentonite loaded with soybean field herbicide is spread and covered in the middle of the molding mold after being isolated by the partition; the film-forming liquid of modified bentonite loaded with corn field herbicide is spread and covered in both sides of the mold after being isolated; and it is ensured that the two film-forming liquids are well combined at the contact boundary but not mixed with each other, and finally a liquid layer of uniform thickness is formed.

[0031] Example 2 In a corn-soybean strip composite planting method in Example 1, during planting, biodegradable weed control film is used for covering in step 2. The biodegradable weed control film comprises the following ingredients in parts by weight: 8 parts of polyvinyl alcohol, 4 parts of starch, 2 parts of glycerol, 0.07 parts of rosin, 0.07 parts of glyceryl monostearate, 2.3 parts of modified bentonite loaded with herbicide, and an appropriate amount of deionized water.

[0032] In a specific implementation, the modified bentonite loaded with herbicides includes modified bentonite loaded with cornfield herbicides and modified bentonite loaded with soybean field herbicides; The herbicide loaded by the modified bentonite loaded with cornfield herbicide is chlorotoluron; The herbicide loaded by the modified bentonite loaded with soybean field herbicide is promethazine; The preparation method of the biodegradable weed killing film and the modified bentonite loaded with herbicides are the same as those in Example 1.

[0033] Example 3 In a corn-soybean strip composite planting method in Example 1, during planting, biodegradable weed control film is used for covering in step 2. The biodegradable weed control film comprises the following ingredients in parts by weight: 10 parts of polyvinyl alcohol, 5 parts of starch, 2.7 parts of glycerol, 0.08 parts of rosin, 0.08 parts of glyceryl monostearate, 2.8 parts of modified bentonite loaded with herbicide, and an appropriate amount of deionized water.

[0034] In a specific implementation, the modified bentonite loaded with herbicides includes modified bentonite loaded with cornfield herbicides and modified bentonite loaded with soybean field herbicides; The herbicide loaded by the modified bentonite loaded with cornfield herbicide is chlorotoluron; The herbicide loaded by the modified bentonite loaded with soybean field herbicide is imazethapyr; The preparation method of the biodegradable weed killing film and the modified bentonite loaded with herbicides are the same as those in Example 1.

[0035] Example 4 A corn-soybean strip composite planting method in Example 1 is adopted, and a biodegradable weed control film is used for covering in step 2 during planting. The biodegradable weed control film comprises the following components in parts by weight: 12 parts of polyvinyl alcohol, 6 parts of starch, 3 parts of glycerol, 0.1 parts of rosin, 0.1 parts of glyceryl monostearate, 3.2 parts of modified bentonite loaded with herbicide, and an appropriate amount of deionized water.

[0036] In a specific implementation, the modified bentonite loaded with herbicides includes modified bentonite loaded with cornfield herbicides and modified bentonite loaded with soybean field herbicides; The herbicide loaded by the modified bentonite loaded with cornfield herbicide is 2,4-D butyl ester; The herbicide loaded by the modified bentonite loaded with soybean field herbicide is imazethapyr; The preparation method of the biodegradable weed killing film and the modified bentonite loaded with herbicides are the same as those in Example 1.

[0037] Comparative Example 1 A corn-soybean strip composite planting method in Example 1 is adopted, and a biodegradable weed control film is used for covering in step 2 during planting. The biodegradable weed control film comprises the following components in parts by weight: 10 parts of polyvinyl alcohol, 5 parts of starch, 2.7 parts of glycerol, 0.08 parts of rosin, 0.08 parts of glyceryl monostearate, 2.8 parts of bentonite loaded with herbicide, and an appropriate amount of deionized water.

[0038] The method for preparing the biodegradable herbicide film and the method for loading the herbicide are the same as those in Example 3, except that no modification operation is performed on the bentonite; instead, the operation of the complex herbicide is directly performed.

[0039] Comparative Example 2 A corn-soybean strip composite planting method in Example 1 is adopted, and a biodegradable weed control film is used for covering in step 2 during planting. The biodegradable weed control film comprises the following components in parts by weight: 10 parts of polyvinyl alcohol, 5 parts of starch, 2.7 parts of glycerol monostearate, 0.08 parts of glyceryl monostearate, 2.8 parts of bentonite loaded with herbicide, and an appropriate amount of deionized water.

[0040] The method for preparing the biodegradable herbicide film and the method for loading the herbicide are the same as those in Example 3, except that no modification operation is performed on the bentonite; instead, the operation of the complex herbicide is directly performed, and the addition of rosin is omitted.

[0041] Comparative Example 3 A corn-soybean strip composite planting method in Example 1 is adopted, and a biodegradable weed control film is used for covering in step 2 during planting. The biodegradable weed control film comprises the following components in parts by weight: 10 parts of polyvinyl alcohol, 5 parts of starch, 2.7 parts of glycerol monostearate, 0.08 parts of glyceryl monostearate, 2.8 parts of modified bentonite loaded with herbicide, and an appropriate amount of deionized water.

[0042] The preparation method of the biodegradable herbicide film and the modified bentonite loaded with herbicides are the same as those in Example 3, except that the addition of rosin is omitted.

[0043] Test example A method for strip-shaped composite planting of corn and soybeans is provided, wherein a test field in a certain area of ​​Sichuan is selected, and composite planting of corn and soybeans is performed according to the planting method of Example 1, wherein the corn variety is Zhenghong No. 6 and the soybean variety is Gongqiudou No. 5; The test field was divided into 8 parts, 7 of which were respectively treated with the planting methods of Examples 1-4 and Comparative Examples 1-3 and the biodegradable weed control film selected in step 2, and 1 of which, as a blank control group, was treated with the planting method of Example 1, except that the film covering operation in step 2 was not performed; finally, the harvested yield was weighed, and the data are shown in Table 1: Table 1 Yield analysis: The blank control is unmulched, and its yield is most seriously affected by weeds, and the yield is the lowest; and the mulching reduces soil moisture evaporation, so that the crop's water utilization efficiency is improved; and the yields of Examples 1-4 using the scheme of the present application are all higher than those of Comparative Examples 1-3; This shows that the planting method of Examples 1-4 of the present application adopts a biodegradable weed control film; in the composite planting process, it can form a continuous weed control barrier, significantly inhibit the growth of weeds, and can overcome the drawbacks of mechanical and chemical weed control in the prior art, and has no pesticide damage to crops, and the degradable mulch film is also more environmentally friendly; it can significantly increase crop yields.

[0044] Step 2: Test the mechanical properties of biodegradable weed control film: refer to GB / T 35795-2017 "Fully biodegradable agricultural ground covering film" to complete the performance test of tensile load and right-angle tear load of the film; refer to GB / T37841-2019 "Test method for puncture resistance of plastic film and sheeting" to complete the test of puncture resistance strength. The thickness of the film used in the test is 0.02mm; the test results are shown in Table 2; Step 2: Determination of the cumulative release amount and release time of the herbicide using biodegradable herbicides for mulching: Add the mulch films prepared in Examples 1-4 and Comparative Examples 1-3 into a dialysis bag and place them in a mixture of 3000 ml of methanol: water (20:80) as a release medium, stir at 500 r / min, take the mixture regularly at different time intervals, dilute, and analyze the herbicide content. When the cumulative release amount of the herbicide reaches a stable state, that is, when the cumulative release amount of the herbicide no longer increases, record the time to reach the stable release amount. The test results are shown in Table 2. Table 2 Comprehensive performance analysis: Comparative Example 1 uses unmodified bentonite, and its various mechanical properties and stable release time are greatly different from those of Examples 1-4 of the present application, while Comparative Example 2 omits the addition of rosin and also uses unmodified bentonite, and its various performances are also the worst among the comparative examples. The possible reasons are: the biodegradable weed control film is added with rosin, and the cyclic structure in its chemical structure can be used as a rigid group to significantly improve the tensile strength of the film through filling, and the addition of rosin also improves the crystallinity of the material, thereby improving the tensile strength of the film; making the film in the field less likely to be damaged during crop growth and able to continue to play a weed control role. The invention has the following effects; and the specific surface area of ​​unmodified bentonite is limited, the surface charge is single, the loading capacity of the herbicide is limited, and the release of the herbicide cannot be maintained over a long period. The present invention introduces modified lignin to extend the release period of the herbicide; and the most important thing is that rosin can react with polyvinyl alcohol and starch to generate ester groups, increase the length of the molecular chain, make the molecular chain easier to entangle, and increase the viscosity of the system; and the modified bentonite can also form hydrogen bonds with polyvinyl alcohol and starch, so that the movement of the molecular chain of the system is restricted; under the synergistic effect of the two, the viscosity of the film material can be further improved, and the mechanical properties of the film can be enhanced, so that it has a wider range of application scenarios.

[0045] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A corn and soybean strip composite planting method, characterized in that: The following steps are involved: Step 1: Prepare the land: Use mechanical equipment to break up the soil and evenly release nitrogen and phosphorus fertilizers into the dry land; Step 2, ridge formation and film covering: after the land is prepared, ridge formation is performed, wherein the ridge width is 160 cm, the ditch width is 60 cm, and the ridge height is 20 cm; the film covering is biodegradable weed-killing film; Step 3, sowing management: Select late May to carry out corn sowing operations, and mid-to-late June to carry out soybean sowing operations. The planting mode is intercropping of corn and soybeans; corn is planted on the edge of the ridge, and soybeans are planted on the ridge; Step 4: Harvest management: Harvest corn and soybeans after they mature. Corn husks are harvested directly in the field; soybeans are collected together with the plants into net bags; The biodegradable weed-killing film in step 2 comprises, by weight: 6-12 parts of polyvinyl alcohol, 3-6 parts of starch, 2-3 parts of glycerol, 0.05-0.1 parts of rosin, 0.05-0.1 parts of glyceryl monostearate, 1.8-3.2 parts of modified bentonite loaded with herbicides, and an appropriate amount of deionized water.

2. A corn and soybean strip composite planting method as claimed in claim 1, characterized in that: The step 1 uses mechanical equipment to fully break up the soil, and adopts a rotary tillage method to ensure that there are no gravel, straw residues or other debris in the soil.

3. A corn-soybean strip composite planting method as claimed in claim 1, characterized in that: In the step 2, when covering the film, the film needs to be spread flat and tightened, attached to the ridge surface, and both sides of the film need to be compacted with soil.

4. The method for strip-shaped composite planting of corn and soybeans as claimed in claim 1, characterized in that: In the sowing management of step 3, the width of a complete planting belt is 2.2m, the row spacing of corn plants is 30cm*60cm, the row spacing of soybean plants is 20cm*40cm, and the row spacing of corn and soybean is 60cm.

5. The method for strip-shaped composite planting of corn and soybeans as claimed in claim 1, characterized in that: During sowing in step 3, one corn seedling and two soybean seedlings are left in each hole.

6. The method for strip-shaped composite planting of corn and soybeans as claimed in claim 1, characterized in that: The biodegradable weed-killing film in step 2 includes, by weight: 10 parts of polyvinyl alcohol, 5 parts of starch, 2.7 parts of glycerol, 0.08 parts of rosin, 0.08 parts of glyceryl monostearate, 2.8 parts of modified bentonite loaded with herbicides, and an appropriate amount of deionized water.

7. The corn and soybean strip composite planting method according to any one of claims 1 to 6, characterized in that: The preparation method of the biodegradable weed-killing film in step 2 is as follows: add deionized water to starch, and then stir it magnetically at high speed in a water bath at 80 degrees Celsius to form a gelatinized liquid; add polyvinyl alcohol to deionized water, stir it magnetically for 15 minutes, and after it is fully dispersed, slowly pour it into the gelatinized liquid; then add rosin, glyceryl monostearate and modified bentonite loaded with herbicides to the reaction container, and continue stirring for 3 hours; finally, spread the film-forming liquid on the mold to form a liquid layer of uniform thickness, and place it in a 50-degree Celsius oven to dry for 24 hours to prepare the biodegradable weed-killing film.

8. The corn and soybean strip composite planting method according to any one of claims 1 to 6, characterized in that: The preparation method of the modified bentonite loaded with herbicide is as follows: dissolving the herbicide in an organic solvent to form a supersaturated solution of the herbicide, then adding 1.8 parts of the modified bentonite, stirring for 2 hours until the solution is evenly dispersed, and then performing a vacuum treatment. After the modified bentonite is fully loaded with the herbicide, separating and drying, the modified bentonite loaded with the herbicide is prepared.

9. The corn and soybean strip composite planting method according to any one of claims 1 to 6, characterized in that: The preparation method of the modified bentonite is as follows: put bentonite into a three-necked flask equipped with a stirring device, add distilled water into the three-necked flask, stir until it is fully dissolved, then add the modified lignin solution, stir for 5 hours in a constant temperature water bath at 70°C, cool to room temperature after the reaction is completed, and finally filter and separate the precipitate, and dry the precipitate at 50°C for 48 hours; that is, the modified bentonite is prepared; the preparation method of the modified lignin is as follows: add alkali lignin and deionized water into a reaction container equipped with a reflux and stirring device, and adjust the pH value to 11 with sodium hydroxide; then add diethylenetriamine, stir and dissolve, and heat to 95°C; then, slowly drop a formaldehyde solution with a mass fraction of 37% through a peristaltic pump within 30 minutes; finally, react at 95°C for 3 hours to obtain a modified lignin solution.

10. The method for strip-shaped composite planting of corn and soybeans as claimed in claim 8, characterized in that: The modified bentonite loaded with herbicides includes modified bentonite loaded with cornfield herbicides and modified bentonite loaded with soybean field herbicides; The herbicide loaded by the modified bentonite loaded with cornfield herbicides is any one of 2,4-D butyl ester and chlorotoluron; The herbicide loaded by the modified bentonite loaded with soybean field herbicide is any one of imazethapyr and promethazine.

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