Soil conditioner capable of relieving continuous cropping obstacles of eggplants

Abstract

The invention discloses a soil conditioner capable of relieving continuous cropping obstacles of eggplants. A preparation method of the soil conditioner comprises the following steps: (1) preparing earthworm manure; (2) preparing a decomposed fertilizer; (3) preparing bacillus-biochar; and (4) preparing the soil conditioner. The soil conditioner prepared by the invention effectively reduces the accumulation of phenolic acid in soil after continuous cropping of eggplants, provides nutrient substances required by growth of the eggplants, further reduces the incidence rate of verticillium wilt of the eggplants, relieves continuous cropping obstacles of the eggplants, and finally improves the yield of the eggplants in the continuous cropping soil.

Description

Technical Field

[0001] The invention relates to the field of soil conditioners, and in particular to a soil conditioner capable of alleviating eggplant continuous cropping obstacles. Background Art

[0002] Lishui City, Zhejiang Province has a long history of high-altitude vegetable cultivation. Eggplant, as an important nightshade vegetable in Lishui City, has a high economic value. The mountain eggplant industry has become a pillar industry for the prosperity of local rural industries, increased farmers' income, and common prosperity. However, in recent years, with the rapid development of the mountain eggplant industry, due to the large number of mountains and small land in mountainous areas, it is difficult to carry out efficient and reasonable crop rotation. After many years of continuous planting of eggplant, mountain eggplants are affected by soil-borne diseases such as Verticillium wilt, and continuous cropping obstacles are becoming increasingly serious, affecting the sustainable development of the industry.

[0003] Continuous cropping disorder refers to the phenomenon that after planting the same type or family of crops on the same land for two or more consecutive years, soil quality deteriorates, the risk of pests and diseases increases, and then the yield and quality of crops decrease. This phenomenon is the result of modern intensive and large-scale agricultural production methods, and it is also an inevitable practical problem in agricultural production. There are many factors that cause continuous cropping disorder in eggplant, which is mainly related to the rhizosphere soil environment. During the growth of eggplant, the roots will secrete phenolic acids, including coumaric acid, parahydroxybenzoic acid, cinnamic acid, etc. These phenolic acids are released into the soil and continue to accumulate, causing direct or indirect poisoning to the plants. Phenolic acids will directly affect the soil microbial structure and promote the growth of pathogenic fungi. The hyphae of pathogenic fungi can serve as food for root-knot nematodes, increasing the number of root-knot nematodes in the soil, and ultimately causing eggplant plants to be short, grow slowly, produce less fruits, or even die. When the cinnamic acid secreted by the roots of eggplant accumulates to a certain concentration, it produces an allelopathic effect on the eggplant itself, inhibiting the growth of eggplant and increasing the risk of disease infection. For example, the incidence of Verticillium wilt in eggplants grown in continuous cropping soil will increase.

[0004] The soil type in Lishui mountainous areas is mostly red soil. Under the influence of the humid and hot climate, the content of organic and inorganic acids in the red soil increases, making the red soil itself acidic. The large amount of phenolic acid produced by continuous cropping will further aggravate the acidification of the red soil, and ultimately seriously affect the quality and yield of eggplant. In order to alleviate the obstacles of continuous cropping of eggplant, a soil conditioner that can provide nutrients for the growth of eggplant and optimize the soil environment is needed. Summary of the invention

[0005] In view of the problems that continuous eggplant cropping causes destruction of microbial structure and increased disease incidence of eggplant, the present invention provides a method for preparing a soil conditioner, which is used to improve the soil microbial structure, reduce the accumulation of phenolic acid in the soil, and thus increase the eggplant yield.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] A soil conditioner capable of alleviating eggplant continuous cropping obstacles, the preparation of the soil conditioner comprising the following steps:

[0008] (1) Preparation of earthworm manure: Crush eggplant straw into 10-20 mesh, mix with cow dung and use as base material. Spread the base material evenly on the breeding bed. 2 Inoculate 1.5 kg of earthworms, culture at a temperature of 23-27° C. and a humidity of 30-50%, and when 80-90% of the base material is converted into earthworm castings, sieve out the earthworms to obtain earthworm castings fertilizer;

[0009] (2) Preparation of decomposed fertilizer: Peel, straw, and earthworm manure obtained in step (1) are crushed into 20-30 meshes, and mineral rock is ground into 10-15 meshes, mixed evenly, and 1-3% (fresh weight) of yeast inoculant is added to the mixture, and the mixture is placed in an environment of 45-55° C. to decompose for 14-28 days, and the decomposed mixture is placed in an oven at 80-90° C. to dry the moisture content to 15-20%, thereby obtaining decomposed fertilizer;

[0010] (3) Preparation of Bacillus-biochar: Add microbial powder to LB sterile liquid culture medium and culture at 28-32° C. for 12-18 hours to obtain first-generation microorganisms, then add the cultured bacterial solution to a fresh sterile culture medium to make the bacterial concentration 5-10%, and culture at 28-32° C. at a speed of 150-200 rpm for 6-10 hours to obtain second-generation microorganisms, repeat the second-generation microorganism culture steps to culture third-generation microorganisms, mix the third-generation microbial solution with biochar, and shake at 28-32° C. at 150-200 rpm for 1-3 hours, then filter the mixture and dry at 25-30° C. for 12-18 hours to obtain Bacillus-biochar;

[0011] (4) Preparation of soil conditioner: Bentonite and peat are crushed into 10-20 mesh respectively, and then mixed evenly with the decomposed fertilizer and Bacillus-biochar prepared in steps (2-3) according to a certain proportion, and then put into a granulator to form particles with a diameter of 2-4 mm to obtain a soil conditioner.

[0012] Preferably, in step (1), the mass ratio of eggplant straw to cow dung is 1:(1-1.6).

[0013] Preferably, the fruit peel in step (2) includes one or more of apple peel, banana peel, watermelon peel, orange peel, mango peel and pear peel.

[0014] Preferably, the mineral rock in step (2) includes one or more of dolomite, mica, calcite and quartz.

[0015] Preferably, in step (2), the ratio of the fruit peel to the straw is 1:1, the mass ratio of the earthworm manure to the fruit peel is 1:(0.4-0.6), and the mass ratio of the earthworm manure to the mineral rock is 1:(0.32-0.48).

[0016] Preferably, the biochar described in step (3) is one of straw nano biochar and rice husk nano biochar, and its preparation method is specifically as follows: the biomass material (straw or rice husk) is placed in an oven at 100-110°C for 5-6 hours, then placed in a pyrolysis tank, pyrolyzed at 450-550°C for 4.5-6.5 hours, and after pyrolysis, ground with a ball mill at a speed of 250-350 rpm for 20-28 hours. After grinding, sieve with a 180-220 mesh screen to obtain the desired nano biochar.

[0017] Preferably, the microbial powder in step (3) contains Bacillus subtilis and Bacillus megaterium in a mass ratio of 1:1, the ratio of the mass of the microbial powder (g) to the volume of the LB sterile liquid culture medium (ml) is 1:(40-60), and the ratio of the volume of the third-generation microbial liquid (ml) to the mass of the biochar (g) is 1:(0.6-1).

[0018] Preferably, in step (4), the mass ratio of bentonite, peat, Bacillus-biochar, and decomposed fertilizer is (5-10): (3-5): (10-15): (25-35).

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The Bacillus in the soil conditioner prepared by the present invention can decompose phenolic acid in the soil, effectively reduce the phenolic acid content in the soil after continuous eggplant cropping, reduce the proportion of pathogenic bacteria in the soil, and work together with organic fertilizers such as earthworm castings to improve the soil microbial structure, thereby reducing the incidence of eggplant Verticillium wilt. In addition, the presence of biochar, organic fertilizer, etc. in the conditioner increases the survival rate of Bacillus, and improves the overall performance of the conditioner to a certain extent.

[0021] 2. The soil conditioner prepared by the present invention can improve the serious problem of red soil acidification after continuous cropping under hot and humid climate conditions, adjust the pH to a value suitable for eggplant growth, and effectively increase the activity of urease and phosphatase in the red soil after continuous cropping, and increase the content of nitrogen, phosphorus and potassium. In addition, the soil conditioner contains a large amount of organic fertilizer, which can not only supplement the nutrients required for eggplant growth, but also increase the content of amorphous iron oxides in the red soil after continuous cropping, and improve the preservation capacity of organic carbon in the red soil.

[0022] Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] none DETAILED DESCRIPTION

[0024] The present invention is specifically described below by way of examples, which are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. It should be understood that after reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

[0025] The preparation method of the nano biochar used in the embodiments and comparative examples is as follows: the straw or rice husk is placed in an oven at 105°C for 5.5 hours, then placed in a pyrolysis tank and pyrolyzed at 500°C for 5.5 hours. After pyrolysis, it is ground in a ball mill at 300 rpm for 24 hours. After grinding, it is sieved with a 200-mesh sieve to obtain the desired nano biochar.

[0026] Example 1

[0027] The preparation steps of the soil conditioner capable of alleviating the obstacle of continuous eggplant cropping are as follows:

[0028] (1) Preparation of earthworm manure: 10 parts of eggplant straw were crushed into 15 mesh and mixed evenly with 13 parts of cow dung as the base material. The base material was evenly spread on the breeding bed, with a thickness of 1 m 2 Inoculate 1.5 kg of earthworms and culture them at 25°C and 40% humidity. When 85% of the base material is converted into earthworm castings, sieve out the earthworms to obtain earthworm castings fertilizer.

[0029] (2) Preparation of decomposed fertilizer: 13 parts of peels (6 parts of apple peels and 7 parts of watermelon peels), 13 parts of straws, and 25 parts of earthworm manure obtained in step (1) are crushed to 25 meshes respectively, and 10 parts of mineral rocks (5 parts of dolomite and 5 parts of mica) are ground to 12 meshes, mixed evenly, and 2% (fresh weight) of yeast inoculant is added to the mixture, and the mixture is placed in an environment of 50° C. to decompose for 21 days, and the decomposed mixture is placed in an oven at 85° C. to dry the moisture content to 18%, thereby obtaining decomposed fertilizer;

[0030] (3) Preparation of Bacillus-biochar: 20 g of microbial powder (containing Bacillus subtilis and Bacillus megaterium in a mass ratio of 1:1) was added to 1000 ml of LB sterile liquid culture medium and cultured at 30°C for 15 h to obtain the first generation of microorganisms. The cultured bacterial solution was then added to a fresh sterile culture medium to make the bacterial concentration 8%, and cultured at 30°C at a speed of 180 rpm for 8 h to obtain the second generation of microorganisms. The second generation microorganism culture steps were repeated to culture the third generation of microorganisms. 1000 ml of the third generation microbial bacterial solution was evenly mixed with 800 g of straw nano-biochar, and the mixture was shaken at 30°C at 180 rpm for 2 h. The mixture was then filtered and dried at 28°C for 15 h to obtain Bacillus-biochar.

[0031] (4) Preparation of soil conditioner: 8 parts of bentonite and 4 parts of peat were crushed into 15 mesh respectively, and then mixed evenly with 30 parts of decomposed fertilizer and 13 parts of Bacillus-biochar prepared in steps (2-3), and then put into a granulator to form particles with a diameter of 2-4 mm to obtain a soil conditioner.

[0032] Example 2

[0033] The preparation steps of the soil conditioner capable of alleviating the obstacle of continuous eggplant cropping are as follows:

[0034] (1) Preparation of earthworm manure: 10 parts of eggplant straw were crushed into 10 meshes, mixed evenly with 10 parts of cow dung as the base material, and the base material was evenly spread on the breeding bed, with a thickness of 1 m 2 Inoculate 1.5 kg of earthworms and culture them at 23°C and 30% humidity. When 80% of the base material is converted into earthworm castings, sieve out the earthworms to obtain earthworm castings fertilizer.

[0035] (2) Preparation of decomposed fertilizer: 10 parts of peels (5 parts of banana peels, 5 parts of orange peels), 10 parts of straw, and 25 parts of earthworm manure obtained in step (1) are crushed to 20 meshes respectively, and 8 parts of mineral rocks (4 parts of mica, 4 parts of quartz) are ground to 10 meshes, mixed evenly, and 1% (fresh weight) of yeast inoculant is added to the mixture, and the mixture is placed in an environment of 45° C. to decompose for 14 days, and the decomposed mixture is placed in an oven at 80° C. to dry the moisture content to 15%, thereby obtaining decomposed fertilizer;

[0036] (3) Preparation of Bacillus-biochar: 20 g of microbial powder (containing Bacillus subtilis and Bacillus megaterium in a mass ratio of 1:1) was added to 800 ml of LB sterile liquid culture medium and cultured at 28°C for 12 h to obtain the first generation of microorganisms. The cultured bacterial solution was then added to a fresh sterile culture medium to make the bacterial concentration 5%, and cultured at 28°C at a speed of 150 rpm for 6 h to obtain the second generation of microorganisms. The second generation microorganism culture steps were repeated to culture the third generation of microorganisms. 1000 ml of the third generation microbial bacterial solution was evenly mixed with 600 g of rice husk nano-biochar, and the mixture was shaken at 150 rpm for 1 h at 28°C. The mixture was then filtered and dried at 25°C for 12 h to obtain Bacillus-biochar.

[0037] (4) Preparation of soil conditioner: 5 parts of bentonite and 3 parts of peat were crushed into 10 meshes respectively, and then mixed evenly with 25 parts of decomposed fertilizer and 10 parts of Bacillus-biochar prepared in steps (2-3), and then put into a granulator to form particles with a diameter of 2-4 mm to obtain a soil conditioner.

[0038] Example 3

[0039] The preparation steps of the soil conditioner capable of alleviating the obstacle of continuous eggplant cropping are as follows:

[0040] (1) Preparation of earthworm manure: 10 parts of eggplant straw were crushed into 20 meshes and mixed evenly with 16 parts of cow dung as the base material. The base material was evenly spread on the breeding bed, with a thickness of 1 m 2 Inoculate 1.5 kg of earthworms and culture them at 27°C and 50% humidity. When 90% of the base material is converted into earthworm castings, sieve out the earthworms to obtain earthworm castings fertilizer.

[0041] (2) Preparation of decomposed fertilizer: 15 parts of peels (7 parts of apple peels and 8 parts of mango peels), 15 parts of straws, and 25 parts of earthworm manure obtained in step (1) are crushed to 30 meshes respectively, and 12 parts of mineral rocks (6 parts of calcite and 6 parts of quartz) are ground to 15 meshes, mixed evenly, and 3% (fresh weight) of yeast inoculant is added to the mixture, and the mixture is placed in an environment of 55° C. to decompose for 28 days, and the decomposed mixture is placed in an oven at 90° C. to dry the moisture content to 20%, thereby obtaining decomposed fertilizer;

[0042] (3) Preparation of Bacillus-biochar: 20 g of microbial powder (containing Bacillus subtilis and Bacillus megaterium in a mass ratio of 1:1) was added to 1200 ml of LB sterile liquid culture medium and cultured at 32°C for 18 h to obtain the first generation of microorganisms. The cultured bacterial solution was then added to a fresh sterile culture medium to make the bacterial concentration 10%, and cultured at 32°C at a speed of 200 rpm for 10 h to obtain the second generation of microorganisms. The second generation microorganism culture steps were repeated to culture the third generation of microorganisms. 1000 ml of the third generation microbial bacterial solution was evenly mixed with 1000 g of straw nano-biochar, and the mixture was shaken at 200 rpm at 32°C for 3 h. The mixture was then filtered and dried at 30°C for 18 h to obtain Bacillus-biochar.

[0043] (4) Preparation of soil conditioner: 10 parts of bentonite and 5 parts of peat were crushed to 20 mesh respectively, and then mixed evenly with 35 parts of decomposed fertilizer and 15 parts of Bacillus-biochar prepared in steps (2-3), and then put into a granulator to form particles with a diameter of 2-4 mm to obtain a soil conditioner.

[0044] Comparative Example 1

[0045] The preparation steps of the soil conditioner without mineral rocks:

[0046] In step (2), no mineral rock is added during the preparation of the decomposed fertilizer, and the remaining steps are the same as those in Example 1.

[0047] Comparative Example 2

[0048] The preparation steps of the soil conditioner without Bacillus:

[0049] (1) Preparation of earthworm castings: same as in Example 1;

[0050] (2) Preparation of decomposed fertilizer: same as in Example 1;

[0051] (3) Preparation of soil conditioner: 8 parts of bentonite and 4 parts of peat were crushed into 15 meshes respectively, and then mixed evenly with 30 parts of decomposed fertilizer and 13 parts of straw nano-biochar prepared in step (2), and then put into a granulator to form particles with a diameter of 2-4 mm to obtain a soil conditioner.

[0052] Comparative Example 3

[0053] The preparation steps of the soil conditioner without biochar:

[0054] (1) Preparation of earthworm castings: same as in Example 1;

[0055] (2) Preparation of decomposed fertilizer: same as in Example 1;

[0056] (3) Cultivation of Bacillus: without adding biochar, the cultivation steps are the same as in Example 1, that is, the third-generation microbial culture liquid is obtained;

[0057] (4) Preparation of soil conditioner: 800 g of the decomposed fertilizer of step (2) and 1000 ml of the third-generation microbial culture obtained by culture in step (3) were mixed evenly, and the mixture was shaken at 180 rpm for 2 h at 30° C., and then the mixture was filtered and dried at 28° C. for 15 h to obtain decomposed fertilizer-Bacillus. Then, 8 parts of bentonite and 4 parts of peat were crushed to 15 mesh respectively and mixed evenly with 30 parts of decomposed fertilizer-Bacillus prepared in steps (2-3), and then put into a granulator to form particles with a diameter of 2-4 mm to obtain a soil conditioner.

[0058] Experimental methods

[0059] The embodiments and comparative examples were tested, wherein the incidence and growth of eggplant Verticillium wilt, soil conditioner pH, soil total phenol and phenolic acid content, soil pH, soil microorganisms, Bacillus count, iron-reducing bacteria count, soil urease and phosphatase activity, soil total nitrogen, available phosphorus, available potassium content, amorphous iron oxide content, organic carbon content, soil microbial biomass carbon (MBC) content, etc. were tested as follows:

[0060] 1. Eggplant Verticillium wilt incidence and growth test: In early February, eggplant seeds were sown in plug trays and the soil was kept moist. When the eggplant seedlings grew to 8-10 cm and had at least 2 true leaves, they were transplanted. The red soil in Lishui where eggplant was continuously and monocultured for five years was selected as the test soil. The plots were evenly divided into small blocks of 20 m×2 m with a spacing of 0.5 m between small blocks. After the eggplants were transplanted, the spacing between rows and plants was 50 cm×50 cm. 200 g of the soil conditioner prepared in Examples 1-3 and Comparative Examples 1-3 was applied per square meter and irrigation was stopped when the saturated moisture content of the soil was 70%. Irrigation was performed regularly. Five replicates were set for each treatment. A blank control group (CK) was also set up. Fertilization was performed at 80% of the normal local dosage. The plants were cultured under this condition until early September. The number of eggplant Verticillium wilt diseased plants in each group during this period was recorded. The eggplants that reached the maturity standard were picked, and the length, diameter and weight of the eggplants were recorded. Finally, the eggplant yield of each group was calculated, and the average value of each group was calculated and recorded.

[0061] 2. Determination of pH value of soil conditioner: grind the prepared soil conditioner respectively, take 10g soil conditioner powder and add it into 10ml deionized water, stir evenly, and determine the pH value of the prepared soil conditioner by potentiometric method, and take the average value of three parallel measurements.

[0062] 3. Determination of soil physical and chemical properties: Representative soil samples were taken from each experimental group before and after planting, and impurities such as plant roots in the soil were removed for later use. The following tests were all conducted using soil samples treated in this way. Each group of tests was conducted three times in parallel and the average value was recorded:

[0063] (1) Determination of soil pH: 10 g of soil sample was added to 25 ml of deionized water and stirred evenly. The mixture was shaken in a shaker for 0.5 h. After standing for 0.5 h, the soil pH was determined using the water extraction potentiometric method.

[0064] (2) Determination of soil total nitrogen, available phosphorus, and available potassium content: Representative soil samples were collected from each experimental group. The total nitrogen content was determined by concentrated sulfuric acid catalytic digestion-Kjeldahl method, and the instrument used was KDN-04A Kjeldahl nitrogen analyzer (Ledi Instrument (Ningbo) Co., Ltd.); the extracted soil samples were air-dried at 25-30°C for 24 h and then crushed. They were then sieved with a 20-mesh sieve and used for the determination of available phosphorus and available potassium. The available phosphorus content was determined by sodium bicarbonate extraction-molybdenum antimony colorimetry, and the instrument used was 930F fluorescence spectrophotometer (Shanghai Yidian Analytical Instrument Co., Ltd.); the available potassium content was determined by ammonium acetate extraction-flame photometry, and the instrument used was 6400A flame photometer (Shanghai Xinyi Precision Instrument Co., Ltd.).

[0065] (3) Determination of organic carbon content: Determine by potassium dichromate external heating method. Weigh 0.5000g soil sample and put it into a hard test tube. Add 0.1g silver sulfate. Use a pipette to add 5ml potassium dichromate standard solution. Then use a syringe to add 5ml concentrated sulfuric acid and carefully rotate and shake. Preheat the oil pan to 185℃-190℃. Insert the hard test tube with the sample into a wire cage. Then put it into the oil pan and heat it. Control the temperature in the oil pan to 170℃-180℃ and keep the solution boiling for 5min. After cooling, transfer the digestion solution in the test tube into a 150ml conical flask. Add 4 drops of o-phenanthroline indicator and titrate with 0.2mol / l ammonium ferrous sulfate standard solution. Use quartz sand to make 2 blank samples. Calculate by the following formula: W (organic C) / 10 -2 =0.8000*5.0 / V0*(V0-V)*0.003*1.10*100 / m, wherein 0.8000-concentration of potassium dichromate standard solution mol / l, 5.0-volume of potassium dichromate standard solution ml, V0-volume of blank consumed ammonium ferrous sulfate standard solution ml, V-volume of sample consumed ammonium ferrous sulfate standard solution ml, 0.003-1 / 4 millimolar mass of carbon atom g, 1.10-oxidation correction coefficient, m-sample mass g.

[0066] (4) Determination of soil microbial biomass carbon (MBC): 12.50 g of fresh soil was weighed into an aluminum box for each group and placed in a vacuum dryer (with a baked cake containing alcohol-free chloroform). The dryer was sealed with vaseline and evacuated. The vacuum degree was controlled below -0.07 MPa. The chloroform was boiled for 3-5 min and then the valve was closed. The soil was incubated in the dark at 25 °C for 24 h. Another soil sample of equal weight was placed in an extraction bottle and placed in the dark for 24 h. After the fumigation, all the soil samples were immediately transferred from the aluminum box to the extraction bottle, and 50 mL of 0.5 M K2SO4 solution was added. The soil was shaken at 200 rpm for 30 min and filtered with quantitative filter paper into a 50 mL plastic bottle. The organic carbon content of the extract was determined using a TOC instrument. Finally, the MBC content was obtained by subtraction.

[0067] (5) Determination of amorphous iron oxides: Amorphous iron was extracted using the oxalic acid-ammonium oxalate method. 1.0000 g of soil sample was weighed and placed in a 50 ml centrifuge tube. 50 ml of 0.2 M ammonium oxalate buffer solution (pH = 3.2) was added at a soil-liquid ratio of 1:50. The tube was stoppered and placed in a double-layer cloth bag with a black outer layer and a red inner layer. The bag mouth was wrapped to avoid light and prevent photochemical reactions. After oscillation for 2 h, the tube was immediately centrifuged and the clear liquid was poured into a triangle plate with a stopper for testing. The tube was diluted 10 times and measured using ICP.

[0068] (6) Determination of soil urease and phosphatase activities: The activity of soil urease was determined by the sodium phenol-sodium hypochlorite colorimetric method, and the activity of phosphatase was determined by the disodium phenyl phosphate colorimetric method.

[0069] (7) Determination of total phenol and phenolic acid content in soil: 25 g of soil sample was taken from each group and 25 mL of 1 mol·L -1 The NaOH solution was allowed to stand for 24 h at 210 r·min -1 After shaking on a shaker for 30 min, the mixture was centrifuged at 8000 × g for 10 min to separate the supernatant. -1 The solution was adjusted to pH 2.5 with hydrochloric acid to precipitate humic acid. After standing for 2 hours, the solution was centrifuged at 8000×g for 10 minutes. The supernatant was separated and stored at 4°C for analysis. The total phenol content was determined by Folin phenol colorimetry, and the content of p-hydroxybenzoic acid and ferulic acid was determined by HPLC.

[0070] 4. Determination of soil microorganism quantity: Representative soil samples were taken from each experimental group before and after planting, and impurities such as plant roots in the soil were removed and dried for later use. The soil samples were diluted to 10% with deionized water. 1 , 10 2 , 10 3 , 10 4 , 10 5 , 10 6 , 10 7Times, save for later use, the following tests are all carried out with soil samples treated by this method, and the average value of each group of data is recorded:

[0071] (1) Determination of iron-reducing bacteria: By using ferric citrate solid medium as a selective medium and the spread plate method, facultative anaerobic and strict anaerobic iron-reducing strains can be isolated from the soil. After the culture is completed, the grown colonies are counted and their content is calculated.

[0072] (2) Soil microorganism determination: Soil microorganism counts were determined using the dilution plate method. Bacteria were measured using beef extract peptone medium and fungi were measured using Martin agar medium. The number of soil microorganisms was expressed as the number of colonies formed per gram of dry soil.

[0073] (3) Number of Bacillus: Take 0.1 ml of each diluted solution and place it on a sterile starch medium plate. Use a sterilized spreading stick to evenly spread the bacterial solution on the starch medium plate. Place the plate upside down in a 28°C incubator and culture it for 24-48 h. Observe and count the number of Bacillus.

[0074] The test results are shown in Tables 1 to 7.

[0075] Tables 1 and 2 show the basic physical and chemical properties of the red soil used in the experiment, as well as the total phenol and phenolic acid content, amorphous iron oxide content, and urease and phosphatase activity data in the red soil. The red soil used had been planted with eggplant for five consecutive years before the experiment. The data in Table 1 show that the pH of the red soil after continuous cropping is low, and eggplant is suitable for growing in soil with a pH of 6 to 7. When the pH is lower than 5, the growth of eggplant will be restricted. By observing the data of total phenol, p-hydroxybenzoic acid and ferulic acid content in Table 2, it can be seen that there are more phenolic acids in the red soil after continuous cropping. Phenolic acid is a kind of allelopathic substance secreted by plant roots. Accumulation in the soil will have an allelopathic effect on eggplant, inhibit the growth of eggplant, increase the incidence of eggplant Verticillium wilt, and ultimately lead to eggplant yield reduction or even death. Observing the data in Table 2, it can be seen that the urease and phosphatase activities of the red soil used in the experiment are low, and the content of amorphous iron oxide is low, which will lead to a greater lack of nutrients in the red soil, and the ability to preserve nutrients such as organic carbon will be further weakened, which will eventually affect the normal growth of eggplant.

[0076] Table 1: Basic physical and chemical properties of soil used in the experiment

[0077]

[0078] Table 2: Total phenol and phenolic acid content, amorphous iron oxide content, and urease and phosphatase activities in the soil used in the experiment

[0079]

[0080] Table 3 shows the pH of soil conditioners of Examples 1 to 3 and Comparative Examples 1 to 3. By comparing the data in Table 3, it can be seen that, overall, the pH of soil conditioners prepared in Examples 1 to 3 is relatively high, and theoretically can adjust the soil pH after continuous cropping and alleviate the problem of soil acidification. By comparing the data of Examples 1 to 3 and Comparative Example 1, it can be seen that the pH of soil conditioners in Examples 1 to 3 is significantly higher than that in Comparative Example 1. This is because mineral rocks are added to the preparation process of decomposed fertilizer in Examples 1 to 3. The mineral rocks and earthworm manure organic matter are decomposed together, which can not only enrich the nutrients in the organic fertilizer, but also release Ca in the decomposition process. 2+ Mg 2+ The basic cations such as biochar significantly increase the pH of the decomposed fertilizer, and ultimately increase the overall pH of the soil conditioner. By observing the data of Examples 1 to 3 and Comparative Example 3, it can be seen that biochar has a certain promoting effect on the increase of the pH of the soil conditioner.

[0081] Table 3: pH of soil conditioners of Examples 1 to 3 and Comparative Examples 1 to 3

[0082]

[0083] Table 4 shows the incidence and growth of eggplant Verticillium wilt in Examples 1 to 3 and Comparative Examples 1 to 3. It can be seen from the data of the incidence of Verticillium wilt that the incidence of Verticillium wilt in Examples 1 to 3 is significantly lower than that in Comparative Examples 1 to 3 and the blank control, indicating that the soil conditioner prepared by the present invention can effectively inhibit the occurrence of eggplant Verticillium wilt. By comparing the growth of eggplants and observing the data of the length, diameter, weight and yield of eggplants, it can be seen that the overall yield of Examples 1 to 3 is higher than that of Comparative Examples 1 to 3 and the blank control group, indicating that the soil conditioner prepared by the present invention promotes the growth and development of eggplants and increases the yield of eggplants. Combined with Tables 5 to 7, it can be seen that the increase in eggplant yield is related to the performance of the conditioner of the present invention, such as improving soil physical and chemical properties (Tables 5 and 6), reducing soil phenolic acid content (Table 6), and improving soil microbial structure (Table 7).

[0084] Table 4: Incidence and growth of eggplant Verticillium wilt in Examples 1 to 3 and Comparative Examples 1 to 3

[0085]

[0086]

[0087] Table 5 shows the basic physical and chemical properties of the soil after application of Examples 1 to 3 and Comparative Examples 1 to 3. By observing the soil pH data in Table 5, it can be seen that the soil pH of Examples 1 to 3 is higher than that of Comparative Examples 1 to 3 and the blank control, indicating that the soil conditioner prepared by the present invention can improve the problem of red soil acidification after continuous cropping and adjust the red soil pH to a value suitable for eggplant growth. By observing the data of Comparative Example 1 and Examples 1 to 3, it can be seen that mineral rocks play an important role in the pH adjustment process. This is because mineral rocks release Ca 2+ Mg 2+ In addition, the regulating effect of Examples 1 to 3 on soil pH is better than that of Comparative Example 3, indicating that biochar also plays a role in regulating soil pH. By comparing the effects of Examples 1 to 3 and Comparative Example 2 on pH, it can be found that Bacillus has little regulating effect on soil pH.

[0088] The soil organic carbon and microbial biomass carbon of Examples 1 to 3 in Table 5 are significantly higher than those of Comparative Examples 1 to 3, indicating that the addition of mineral rocks, nano-biochar, and microbial powder can increase the organic carbon and microbial biomass carbon content in the soil. In addition, the nitrogen, phosphorus, and potassium contents of the embodiments are significantly improved, indicating that the soil conditioner prepared by the present invention can supplement the necessary nutrients required for the growth of eggplant. The nitrogen content of Comparative Example 3 is significantly lower than that of other embodiments and comparative examples. This is because biochar can improve the problem of increased soil ammonia emissions and reduce soil nitrogen loss. Since the soil conditioner materials prepared by the present invention are all naturally obtained, there are no chemically synthesized reagents, and will not cause pollution to the soil, which is in line with the concept of sustainable development.

[0089] Table 5: Basic physical and chemical properties of soil after application of Examples 1 to 3 and Comparative Examples 1 to 3

[0090]

[0091] Table 6 shows the total phenol and phenolic acid content, amorphous iron oxide content, and urease and phosphatase activities of the soil after application of Examples 1 to 3 and Comparative Examples 1 to 3. By observing the soil phenolic acid content data in the table, it can be seen that the soil phenolic acid content of Examples 1 to 3 is lower than that of other groups, indicating that the soil conditioner prepared by the present invention can reduce the phenolic acid content in the soil. By comparing the data of Examples 1 to 3 and Comparative Example 2, it can be seen that the phenolic acid content of Examples 1 to 3 is significantly lower than that of Comparative Example 2. Combined with Table 7, the number of Bacillus in the soil of Examples 1 to 3 is higher than that of other groups, proving that the reduction of phenolic acid is mainly due to the Bacillus in the soil conditioner being able to effectively decompose phenolic acid in the soil. The soil phenolic acid content of Comparative Example 3 in Table 6 is higher than that of other examples, indicating that the presence of nano-biochar may be beneficial to the reduction of soil phenolic acid content. At the same time, combined with the results of Bacillus number determination in Table 7, it can be seen that the specific reason for this phenomenon may be that nano-biochar can adsorb phenolic acids in the soil, and its porous structure can provide a habitat for Bacillus, protect Bacillus, reduce the impact of the soil environment on Bacillus, and improve the survival rate of Bacillus, which is convenient for the Bacillus on the biochar to efficiently degrade phenolic acids.

[0092] From the observation of the content of amorphous iron oxides in Table 6, it can be seen that the content of amorphous iron oxides in Examples 1 to 3 is higher than that in the comparative example and the blank control group, indicating that the soil conditioner prepared by the present invention increases the content of amorphous iron oxides in red soil. Combined with the analysis of the content of iron-reducing bacteria in Table 7, this is because the soil conditioner increases the pH of the soil after continuous cropping, which is more suitable for the growth and reproduction of iron-reducing bacteria. In addition, the presence of a large amount of organic fertilizer, in the eggplant planting process, a large amount of irrigation is required to form an anaerobic environment, which is conducive to the iron-reducing bacteria to convert the crystalline iron oxides in the red soil into amorphous iron oxides. Amorphous iron oxides have a large specific surface area and high adsorption affinity, which is conducive to the fixation of organic carbon in the soil, resulting in the phenomenon that the content of soil organic carbon in Examples 1 to 3 in Table 5 is higher than that in other groups.

[0093] The soil urease activity and soil phosphatase activity of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 6 are both improved. This is because the decomposed fertilizer of the present invention contains urease and phosphatase, which directly increases the content of these two enzymes in the red soil, and the increase in urease and phosphatase activities is conducive to the increase of nitrogen and phosphorus in the red soil, resulting in the phenomenon that the nitrogen and phosphorus content of Examples 1 to 3 in Table 5 is higher than that of other groups. In addition, by comparing the data of Examples 1 to 3 and Comparative Examples 1 to 3, it can be seen that microbial powder, nano-biochar, and mineral rocks can increase the activity of urease and phosphatase.

[0094] Table 6: Total phenol and phenolic acid content, amorphous iron oxide content and urease and phosphatase activities in soil after application of Examples 1 to 3 and Comparative Examples 1 to 3

[0095]

[0096]

[0097] Table 7: Soil microbial structure and the number of Bacillus and iron-reducing bacteria after application of Examples 1 to 3 and Comparative Examples 1 to 3

[0098]

[0099]

[0100] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements or modifications made based on the present invention to solve basically the same technical problems and achieve basically the same technical effects are all included in the protection scope of the present invention.

Claims

1. A soil conditioner capable of alleviating eggplant continuous cropping obstacles, characterized in that: The preparation of the soil conditioner comprises the following steps: (1) Preparation of earthworm manure: crush eggplant straw into 10-20 meshes, mix with cow dung and use as base material, spread the base material evenly on the culture bed, inoculate 1.5 kg of earthworms per 1 m2, and culture at a temperature of 23-27° C. and a humidity of 30-50%. When 80-90% of the base material is converted into earthworm manure, screen out the earthworms to obtain earthworm manure; (2) Preparation of decomposed fertilizer: Peel, straw, and earthworm manure obtained in step (1) are crushed into 20-30 meshes, and mineral rock is ground into 10-15 meshes, mixed evenly, and 1-3% (fresh weight) of yeast inoculant is added to the mixture, and the mixture is placed in an environment of 45-55° C. to decompose for 14-28 days, and the decomposed mixture is placed in an oven at 80-90° C. to dry the moisture content to 15-20%, thereby obtaining decomposed fertilizer; (3) Preparation of Bacillus-biochar: Add microbial powder to LB sterile liquid culture medium and culture at 28-32° C. for 12-18 hours to obtain first-generation microorganisms, then add the cultured bacterial solution to a fresh sterile culture medium to make the bacterial concentration 5-10%, and culture at 28-32° C. at a speed of 150-200 rpm for 6-10 hours to obtain second-generation microorganisms, repeat the second-generation microorganism culture steps to culture third-generation microorganisms, mix the third-generation microbial solution with biochar, and shake at 28-32° C. at 150-200 rpm for 1-3 hours, then filter the mixture and dry at 25-30° C. for 12-18 hours to obtain Bacillus-biochar; (4) Preparation of soil conditioner: Bentonite and peat are crushed into 10-20 mesh respectively, and then mixed evenly with the decomposed fertilizer and Bacillus-biochar prepared in steps (2-3) according to a certain proportion, and then put into a granulator to form particles with a diameter of 2-4 mm to obtain a soil conditioner.

2. The method for preparing a soil conditioner capable of alleviating eggplant continuous cropping obstacles according to claim 1, characterized in that: In step (1), the mass ratio of eggplant straw to cow dung is 1:(1-1.6).

3. The method for preparing a soil conditioner capable of alleviating eggplant continuous cropping obstacles according to claim 1, characterized in that: The fruit peel in step (2) includes one or more of apple peel, banana peel, watermelon peel, orange peel, mango peel and pear peel.

4. The method for preparing a soil conditioner capable of alleviating eggplant continuous cropping obstacles according to claim 1, characterized in that: The mineral rock in step (2) includes one or more of dolomite, mica, calcite and quartz.

5. The method for preparing a soil conditioner capable of alleviating eggplant continuous cropping obstacles according to claim 1, characterized in that: In step (2), the ratio of the fruit peel to the straw is 1:1, the mass ratio of the earthworm manure to the fruit peel is 1:(0.4-0.6), and the mass ratio of the earthworm manure to the mineral rock is 1:(0.32-0.48).

6. The method for preparing a soil conditioner capable of alleviating eggplant continuous cropping obstacles according to claim 1, characterized in that: The biochar described in step (3) is one of straw nano biochar and rice husk nano biochar, and its preparation method is specifically as follows: the biomass material (straw or rice husk) is placed in an oven at 100-110°C for 5-6 hours, then placed in a pyrolysis tank, pyrolyzed at 450-550°C for 4.5-6.5 hours, and after pyrolysis, ground with a ball mill at a speed of 250-350 rpm for 20-28 hours. After grinding, the material is sieved with a 180-220 mesh screen to obtain the desired nano biochar.

7. The method for preparing a soil conditioner capable of alleviating eggplant continuous cropping obstacles according to claim 1, characterized in that: The microbial powder in step (3) contains Bacillus subtilis and Bacillus megaterium in a mass ratio of 1:1, the ratio of the mass of the microbial powder (g) to the volume of the LB sterile liquid culture medium (ml) is 1:(40-60), and the ratio of the volume of the third-generation microbial liquid (ml) to the mass of the biochar (g) is 1:(0.6-1).

8. The method for preparing a soil conditioner capable of alleviating eggplant continuous cropping obstacles according to claim 1, characterized in that: In step (4), the mass ratio of bentonite, peat, Bacillus-biochar and decomposed fertilizer is (5-10): (3-5): (10-15): (25-35).

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