Composite water-soluble fertilizer for corn filling period as well as preparation method and application of composite water-soluble fertilizer

Abstract

The invention discloses a composite water-soluble fertilizer used in the pustulation period of corn and a preparation method and application thereof, and relates to the technical field of fertilizers, the composite water-soluble fertilizer comprises the following raw materials by weight: 25-35 parts of enzyme, 0.75-1.05 parts of sodium carboxymethyl cellulose, 45-65 parts of puffed potassium dihydrogen phosphate, 3-4 parts of chelated magnesium, 3-4 parts of chelated calcium, 1-2 parts of chelated zinc, and 1-2 parts of tryptophan. By using the enzyme and reasonably adjusting the ratio of all the raw materials according to the characteristics of the corn pustulation period, the problems that an existing fertilizer is not high in pertinence in the corn pustulation period and cannot accurately meet the special nutritional requirements of corn are solved, and the fertilizer has the advantages of meeting the nutritional element requirements in the corn pustulation period, being high in fertilizer utilization rate and promoting the growth and development of corn.

Description

Technical Field

[0001] The present application relates to the technical field of fertilizers. Specifically, it relates to a compound water-soluble fertilizer for the filling stage of corn, its preparation method and application. Background Art

[0002] In modern agriculture, fertilizers are one of the key factors to improve crop yield and quality. With the continuous increase in people's demand for agricultural products and the emphasis on the sustainable development of agriculture, the development of efficient, environmentally friendly and targeted fertilizers has become a research hotspot in the agricultural field. As an important food crop globally, the growth and yield of corn have an important impact on the agricultural economy. During the growth process of corn, the filling stage is a crucial stage that determines yield and quality. At this time, corn has a large and relatively special demand for nutrients, and requires sufficient and reasonably proportioned nutrient supply to promote plump and full grains.

[0003] In the related art, there is no special fertilizer for the filling stage of corn in the existing fertilizers, which cannot meet the nutritional requirements of corn during the filling stage, resulting in low fertilizer utilization rate and hindering the growth and development of corn.

[0004] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] The technical task of the present application is to address the above deficiencies by providing a compound water-soluble fertilizer for the filling stage of corn, its preparation method and application. By using enzymes and reasonably adjusting the ratio of each raw material according to the characteristics of the filling stage of corn, the present application solves the problems of the existing fertilizers having poor pertinence during the filling stage of corn and being unable to accurately meet the special nutritional requirements of corn, and has the advantages of meeting the nutritional element requirements during the filling stage of corn, high fertilizer utilization rate, and promoting the growth and development of corn.

[0006] To achieve the above object, the present application provides the following technical solutions:

[0007] According to one aspect of the present application, there is provided a compound water-soluble fertilizer for the filling stage of corn, comprising the following raw materials in parts by weight: 25 - 35 parts of enzyme, 0.75 - 1.05 parts of sodium carboxymethylcellulose, 45 - 65 parts of expanded potassium dihydrogen phosphate, 3 - 4 parts of chelated magnesium, 3 - 4 parts of chelated calcium, 1 - 2 parts of chelated zinc, and 1 - 2 parts of tryptophan.

[0008] In some embodiments, the preparation method of the enzyme comprises the following steps:

[0009] Crush corn straw and fruit residue and place them in a fermentation tank, add deionized water to obtain a mixed substrate; add cellulase and hemicellulase to the mixed substrate, and spray a mixed bacterial solution, and obtain the enzyme after fermenting for 96 h.

[0010] In some embodiments, the mixed bacterial solution is a mixed solution of white rot fungus bacterial solution, Bacillus subtilis bacterial solution, Trichoderma harzianum bacterial solution and Lactobacillus plantarum bacterial solution with a volume ratio of 1.5:1.5:1:2, and the mass ratio of the mixed substrate to the mixed bacterial solution is 100:5.

[0011] In some embodiments, the concentrations of the white rot fungus bacterial solution, the Bacillus subtilis bacterial solution, the Trichoderma harzianum bacterial solution and the Lactobacillus plantarum bacterial solution are all 1×107 CFU / mL.

[0012] In some embodiments, the mass ratio of the corn straw, the fruit residue and the deionized water is 3:7:15, and the fruit residue is a mixture of apple residue, pear residue and pineapple residue with a mass ratio of 1:1:1.

[0013] In some embodiments, the mass ratio of the cellulase and the hemicellulase is 2:1; the mass ratio of the mixed substrate to the mixture of the cellulase and the hemicellulase is 100:2.

[0014] In some embodiments, the temperature of the fermentation tank is 35±2 °C, the humidity is 60±5%, and the rotation speed is 150±10 r / min.

[0015] According to another aspect of the present application, a preparation method of a compound water-soluble fertilizer for the corn filling period is also provided, including: mixing the enzyme and sodium carboxymethylcellulose evenly and vacuum freeze-drying at -25 °C for 24 h, crushing the dried enzyme to obtain enzyme powder; adding expanded potassium dihydrogen phosphate, chelated magnesium, chelated calcium, chelated zinc and tryptophan to the enzyme powder, mixing and sieving to obtain the compound water-soluble fertilizer.

[0016] In some embodiments, the mass ratio of the enzyme to the sodium carboxymethylcellulose is 100:3.

[0017] According to another aspect of the present application, the application of the compound water-soluble fertilizer or the compound water-soluble fertilizer prepared by the preparation method in the planting during the corn filling period is also provided.

[0018] Compared with the prior art, the advantages and positive effects of the present application are as follows:

[0019] This application solves the problems that existing fertilizers lack strong pertinence during the corn filling period and cannot precisely meet the special nutritional needs of corn by using enzymes and reasonably adjusting the ratio of each raw material according to the characteristics of the corn filling period. It has the advantages of meeting the nutritional element requirements during the corn filling period, high fertilizer utilization rate, and promoting the growth and development of corn.

[0020] Furthermore, by using agricultural waste as a raw material to ferment and prepare enzymes, this application can reduce the usage amount of sucrose as a raw material for traditional enzyme preparation, and has the advantages of cost reduction and improved enzyme quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 Showing the influence of the compound water-soluble fertilizer in Embodiments 1-7 of this application on the gene expression of corn photosynthesis;

[0023] Figure 2 Showing the influence of the compound water-soluble fertilizer in the application example of this application on the mu yield of corn. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] In order to better understand the above-mentioned objects, features, and advantages of this application, the following further describes this application with reference to the drawings and embodiments. It should be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other.

[0025] The following further describes this application with reference to the drawings and specific embodiments.

[0026] Example 1:

[0027] S100. Preparation of enzymes.

[0028] S110. Preparation of mixed bacterial liquid.

[0029] Activating white rot fungus, Bacillus subtilis, Trichoderma harzianum, and Lactobacillus plantarum through a solid medium, and then expanding the culture through a liquid medium until the bacterial liquid concentration reaches 1×10 7CFU / mL. Mix the above four kinds of bacterial solutions according to a volume ratio of 1.5:1.5:1:2 to obtain a mixed bacterial solution. Among them, the preservation number of white rot fungus is ACCC30942, the preservation number of Bacillus subtilis is ACCC19743, the preservation number of Trichoderma harzianum is ACCC 32535, and the preservation number of Lactobacillus plantarum is ACCC 11118. The strains are all purchased from the China Center for Type Culture Collection of Agricultural Microorganisms.

[0030] S120. Prepare enzyme.

[0031] Crush corn straw and fruit residues (apple residue: pear residue: pineapple residue = 1:1:1) with a mass ratio of 3:7, and place them in a fermentation tank. Add deionized water according to a material-liquid ratio of 1:1.5 to obtain a mixed bottom material; add a mixture of 2% cellulase and hemicellulase according to the weight parts of the mixed bottom material. Among them, the mass ratio of cellulase to hemicellulase is 2:1, and then evenly spray the mixed bacterial solution. The mass ratio of the mixed substrate to the mixed bacterial solution is 100:5. The temperature of the fermentation tank is 35°C, the humidity is 60%, the rotation speed is 150 r / min, and ferment for 96 h to obtain the required enzyme.

[0032] S200. Preparation of compound water-soluble fertilizer.

[0033] S210. Mix the enzyme obtained in step S120 with sodium carboxymethylcellulose evenly, and vacuum freeze-dry at -25°C for 24 h. The mass ratio of the enzyme to sodium carboxymethylcellulose is 100:3. Crush the dried enzyme to obtain enzyme powder;

[0034] S220. Mix 55 parts of expanded potassium dihydrogen phosphate, 4 parts of chelated magnesium, 3 parts of chelated calcium, 1.5 parts of chelated zinc, 1.5 parts of tryptophan with 30 parts of enzyme powder, and sieve to obtain compound water-soluble fertilizer.

[0035] Example 2:

[0036] In this example, the addition amount of the enzyme powder in step S220 is 25 parts, and other steps are the same as those in Example 1.

[0037] Example 3:

[0038] In this example, the addition amount of the enzyme powder in step S220 is 35 parts, and other steps are the same as those in Example 1.

[0039] Example 4:

[0040] In this example, the addition amount of expanded potassium dihydrogen phosphate in step S220 is 45 parts, and other steps are the same as those in Example 1.

[0041] Example 5:

[0042] In this embodiment, the addition amount of the expanded potassium dihydrogen phosphate in step S220 is 65 parts, and the other steps are the same as those in Embodiment 1.

[0043] Embodiment 6:

[0044] In this embodiment, the addition amount of chelated magnesium in step S220 is 3.5 parts, the addition amount of chelated calcium is 3.5 parts, the addition amount of chelated zinc is 1 part, and the addition amount of tryptophan is 2 parts. The other steps are the same as those in Embodiment 1.

[0045] Embodiment 7:

[0046] In this embodiment, the addition amount of chelated magnesium in step S220 is 3 parts, the addition amount of chelated calcium is 4 parts, the addition amount of chelated zinc is 2 parts, and the addition amount of tryptophan is 1 part. The other steps are the same as those in Embodiment 1.

[0047] The compound water-soluble fertilizers prepared in Embodiments 1-7 were selected for a pot experiment with the same corn variety. One corn plant was planted in each pot. A total of 7 treatment groups (Embodiments 1-7) and 1 control group were set up, with 3 replicates in each group, for a total of 24 pots. The inner diameter of the pot was 50 cm, the height was 40 cm, and there were ventilation holes at the bottom. During the filling stage, the compound water-soluble fertilizers prepared in Embodiments 1-7 were sprayed. When using the compound water-soluble fertilizers, 5 mL of each group was taken and diluted 100 times for spraying. The control group was sprayed with 5 mL of clear water, and the pot management was the same in the other periods.

[0048] Index determination:

[0049] (1) Protein content: The protein content of the kernels of each corn plant was measured one week after spraying the compound water-soluble fertilizer during the filling stage of corn. Sampling and pretreatment were carried out in accordance with the national standard "GB / T 5491-1985", and then the protein content was measured using a DA7200 multi-functional near-infrared analyzer.

[0050] (2) Chlorophyll and relative expression levels of leaf photosynthetic genes: One week after spraying the compound water-soluble fertilizer during the filling stage of corn, the relative chlorophyll content of the leaves of each corn plant was measured using a SPAD-502 chlorophyll meter and recorded. And on the 0th, 3rd, and 6th days after spraying the water-soluble fertilizer, the total RNA of the leaves of each group of corn was extracted by the Trizol method, then reverse transcribed into cDNA, and then the relative expression levels of the photosynthetic genes in the corn leaves were detected by qPCR. The primer sequences used are shown in Table 1.

[0051] Table 1 Primer sequences for the experiment

[0052]

[0053] (3) Yield index: At the time of corn harvest, the average ear length, ear diameter, 100-grain weight, and group yield of each group of corn were measured.

[0054] The measurement results are shown in Table 2 andFigure 1 As shown, the protein content, relative chlorophyll content (SPAD value), relative expression level of photosynthetic genes, ear length, ear diameter, 100-grain weight, and group yield of treatment groups 1-7 (Examples 1-7) are all higher than those of the control group, indicating that the compound water-soluble fertilizer of the present application can improve the growth quality and yield of crops.

[0055] Specifically, the increase in the protein content of treatment groups 1-7 (Examples 1-7) indicates an improvement in the nutritional status of the crops; the increase in the relative chlorophyll content and the relative expression level of photosynthetic genes reflects an enhancement in photosynthesis efficiency, which helps to improve the absorption, conversion, and utilization efficiency of light energy by crop leaves, providing more energy and material basis for crop growth. The increase in ear length and ear diameter is directly related to the growth and development and structural integrity of the crops; the increase in 100-grain weight means an increase in single yield; and the final increase in group yield directly reflects the positive impact of the compound water-soluble fertilizer on improving the overall crop yield. These results comprehensively show that the compound water-soluble fertilizer of the application can effectively promote crop growth, enhance its physiological functions, and thus bring higher agricultural output.

[0056] Compared with treatment group 1, the enzyme content in treatment group 2 decreased, and the protein content decreased accordingly, indicating that enzymes play an important role in promoting protein synthesis. The decrease in its enzyme content affects the transformation and supply of nutrient elements, and thus affects protein synthesis. The enzyme content in treatment group 3 increased, but the protein content was lower than that in treatment group 1, indicating that the change in the relative proportion of other nutrient elements limits the further increase in protein. Although more enzymes activated more nutrients, other elements did not synergistically promote protein synthesis. The SPAD value of treatment group 1 was significantly higher than that of the control group, and the expression of the photosynthetic gene psbA was significantly up-regulated, indicating that the relative chlorophyll content of its leaves is high, which is beneficial to photosynthesis. The enzyme content in treatment group 2 decreased, the SPAD value was lower than that in treatment group 1, and the expression of psbA was down-regulated, indicating that enzymes have an impact on maintaining the supply and metabolism of elements related to chlorophyll synthesis. The increase in the enzyme content in treatment group 3 made the SPAD value higher than that in treatment group 2, and the expression of psbA was up-regulated, but lower than that in treatment group 1, indicating that the increase in enzymes promoted chlorophyll synthesis to a certain extent, but other factors limited the further increase in chlorophyll content and did not reach the synergistic promotion effect in treatment group 1.

[0057] Treatment group 1 showed obvious advantages in yield indicators. Its ear length reached 22.10±0.41cm, ear diameter was 5.26±0.05cm, 100-grain weight was 40.66±0.96g, and group yield was 0.87±0.03kg. Overall, the combination and ratio of the components in treatment group 1 formed a relatively optimal nutrient supply system, which enabled corn to fully absorb and utilize nutrients during growth, thereby achieving good results in all yield-related aspects. In terms of ear growth, the longer ear length and thicker ear diameter provided more space for the growth of corn kernels, which was conducive to the development and filling of corn kernels. The higher 100-grain weight further indicated that the fertilizer formula in treatment group 1 could promote the full filling of corn kernels and the accumulation of nutrients, thanks to the synergistic effect between its raw materials. This synergistic effect promoted the efficient distribution and transformation of photosynthetic products, provided a solid foundation for the weight gain of corn kernels, and ultimately achieved a higher group yield. The yield indicators of treatment group 2 were lower than those of treatment group 1 as a whole. The ear length was 19.92±0.25cm, the ear diameter was 5.02±0.05cm, the 100-grain weight was 32.35±0.93g, and the group yield was 0.53±0.00kg. Compared with treatment group 1, the enzyme content in treatment group 2 was reduced to 25 parts. Enzymes play a key role in promoting the activation and transformation of nutrients in the fertilizer system. The reduction in enzyme content caused some nutrients to be unable to be effectively absorbed and utilized by corn, affecting the growth and development of the corn ear, making the ear length and ear diameter smaller than treatment group 1. In terms of corn kernel filling, due to the relatively insufficient nutrient supply, the 100-grain weight was significantly lower than that of treatment group 1, which led to a significant decrease in group yield. This shows that the appropriateness of the enzyme content has an important influence on the overall yield formation. Too little enzyme will destroy the balance of the fertilizer formula and limit the potential of corn yield. The yield index of treatment group 3 was also lower than that of treatment group 1, with ear length of 20.89±0.59cm, ear thickness of 5.08±0.14cm, 100-grain weight of 35.97±0.96g, and group yield of 0.68±0.03kg. Although the enzyme content in treatment group 3 increased to 35 parts, the yield did not exceed that of treatment group 1. This is because while increasing the enzyme content, the relative proportion of other nutrients changed, resulting in an imbalance in nutrient supply. Excessive enzymes cause the release rate of nutrients to be out of sync with the growth needs of corn, or have an unfavorable effect on the interaction between elements in terms of yield formation. In terms of ear growth, the ear length and ear thickness did not reach the level of treatment group 1, indicating that this nutritional imbalance affected the morphological construction of the corn ear. The 100-grain weight and group yield were also lower than those of treatment group 1, further proving that a reasonable ratio between the various nutrients is crucial to achieving high yields. Simply increasing the enzyme content without considering the balance of the overall formula cannot effectively increase corn yields.

[0058] Compared with Treatment Group 1, all indicators in Treatment Group 4 decreased. The reduction in protein content was due to the decrease in the content of expanded potassium dihydrogen phosphate, which affected protein synthesis. The lower SPAD value and downregulated psbA expression indicated that chlorophyll synthesis was affected because the change in the content of expanded potassium dihydrogen phosphate affected the absorption and utilization of elements related to chlorophyll synthesis, thereby affecting photosynthesis efficiency. The weakening of photosynthesis led to a reduction in photosynthetic products, which could not provide sufficient substances for ear growth and corn kernel development, resulting in the ear length, ear diameter, 100-grain weight, and group yield being lower than those in Treatment Group 1. This shows that expanded potassium dihydrogen phosphate plays an important role in corn growth and yield formation in the compound water-soluble fertilizer formula, and changes in its content will cause a series of chain reactions, affecting the overall growth performance of corn. In Treatment Group 5, although some indicators were slightly higher than those in Treatment Group 4, there was still a gap compared with Treatment Group 1. In terms of protein content, although the expanded potassium dihydrogen phosphate increased, the change in the relative proportion of other elements led to nutritional imbalance, restricting the further increase in protein content. The higher content of expanded potassium dihydrogen phosphate changed the physical and chemical properties of the soil, such as pH, affecting the absorption of other nutrients (such as trace elements) by corn, which play important regulatory roles in enzymatic reactions during protein synthesis. In terms of chlorophyll, although the SPAD value was higher than that in Treatment Group 4 and the psbA expression was upregulated, it did not reach the level of Treatment Group 1, indicating that increasing the content of expanded potassium dihydrogen phosphate had limited promotion effect on chlorophyll synthesis because the relative deficiency of other elements restricted the smooth progress of physiological processes related to chlorophyll synthesis. In terms of yield indicators, the ear length, ear diameter, 100-grain weight, and group yield were all lower than those in Treatment Group 1, indicating that simply increasing the content of expanded potassium dihydrogen phosphate could not effectively increase the yield. Instead, it disrupted the balance relationship among elements in the fertilizer formula, affecting the comprehensive utilization efficiency of nutrients by corn and thus being unfavorable for yield formation.

[0059] Compared with Treatment Group 1, all indicators in Treatment Group 6 decreased. In terms of protein content, the changes in the content of trace elements and amino acid precursors affected the enzymatic reactions related to protein synthesis and the amino acid metabolic pathway. The lower content of chelated zinc reduced the activity of some enzymes involved in nitrogen metabolism and protein synthesis, thus limiting protein synthesis. In terms of chlorophyll, although the SPAD value was still at a relatively high level and psbA expression was upregulated, it was lower than that in Treatment Group 1 because the changes in the content of elements such as magnesium affected the synthesis and stability of chlorophyll. Magnesium is a component of chlorophyll molecules, and changes in its content will directly affect the synthesis rate and quality of chlorophyll. In terms of yield indicators, although the ear diameter was relatively close to that in Treatment Group 1, the ear length, 100-grain weight, and group yield were all lower than those in Treatment Group 1. This indicates that the change in the proportion of nutrient elements affected the distribution efficiency of photosynthetic products to the ear and corn kernels. Although the ear could still develop normally to a certain extent, the overall yield was affected. The changes in the content of trace elements and tryptophan affected the hormone balance or the process of substance transport, thus affecting the performance of yield-related traits. Compared with Treatment Group 1, all indicators in Treatment Group 7 decreased more significantly. In terms of protein synthesis, the further changes in the content of trace elements and tryptophan further disrupted the metabolic processes related to protein synthesis, resulting in a lower protein content than that in Treatment Group 1 and Treatment Group 6. In terms of chlorophyll, the decrease in the SPAD value and the downregulation of psbA expression indicated that chlorophyll synthesis and function were more severely affected, which was related to the changes in the proportion of elements such as calcium and magnesium on the structure and function of chloroplasts. In terms of yield indicators, the ear length, ear diameter, 100-grain weight, and group yield were all significantly lower than those in Treatment Group 1 because the imbalance of nutrient elements was exacerbated, seriously affecting the growth and development of maize and the accumulation and distribution of photosynthetic products. Excessive calcium antagonized with other elements, affecting the absorption and utilization of other essential elements by maize, and thus inhibiting the growth of the ear and the development of corn kernels.

[0060] Through comprehensive comparison, it can be seen that the proportion of each component in the compound water-soluble fertilizer formula in Treatment Group 1 was coordinated, achieving a good balance and synergistic promotion among protein content, relative chlorophyll content, and yield indicators. This fully reflects the importance of the proportion of each component in the compound water-soluble fertilizer formula for ensuring the growth and high yield of maize.

[0061] Table 2 Measurement Results (P<0.05)

[0062]

[0063]

[0064] Application Example:

[0065] In this application example, a method for comparative spraying experiments is provided to evaluate the effect of water-soluble fertilizers on corn yield. The experiment was conducted on 20 mu of corn fields in Qinggang County. Half of them were control fields (non-sprayed group), and the other half were experimental fields (sprayed group, using the formula of Example 1). The spraying operation was carried out during the filling stage of the corn. Each mu of the experimental field used 30 grams of water-soluble fertilizer, which was diluted 100 times before spraying, while the control field used clear water instead. During the spraying period, other management measures for the two groups of fields were kept the same. When the corn was harvested, the yield per mu of the two groups of fields was measured.

[0066] As Figure 2 shown, the measured yield per mu of the control field was 1059.81 kg, and the standard deviation was 22.78 kg, while the measured yield per mu of the experimental field was 1433.11 kg, and the standard deviation was 28.97 kg. By comparing the yield data of the two groups, it can be found that the yield per mu of the experimental field was significantly higher than that of the control field, indicating that spraying water-soluble fertilizer during the filling stage of corn had a positive effect on increasing corn yield. This was attributed to the nutrient components contained in the water-soluble fertilizer, which could be more effectively absorbed and utilized by the corn, thus promoting the growth and development of the corn and ultimately increasing the yield.

[0067] In summary, the comparative spraying experiment not only verified the potential effect of spraying the compound water-soluble fertilizer of Example 1 during the filling stage on increasing corn yield, but also provided an experimental basis for the optimization of fertilizer use in agricultural production. Through reasonable fertilizer management, crop yield can be effectively improved, and agricultural economic benefits can be increased.

[0068] Through the above specific implementation manners, those skilled in the art of the present application can easily implement the present application. However, it should be understood that the present application is not limited to the above specific implementation manners. Based on the disclosed implementation manners, those skilled in the art can arbitrarily combine different technical features to achieve different technical solutions.

Claims

1. A composite water-soluble fertilizer for corn during the grain filling period, characterized in that: The invention comprises the following raw materials in parts by weight: 25-35 parts of enzyme, 0.75-1.05 parts of sodium carboxymethyl cellulose, 45-65 parts of expanded potassium dihydrogen phosphate, 3-4 parts of chelated magnesium, 3-4 parts of chelated calcium, 1-2 parts of chelated zinc and 1-2 parts of tryptophan.

2. A composite water-soluble fertilizer for corn filling period according to claim 1, characterized in that: The preparation method of the enzyme comprises the following steps: The corn stalks and fruit residues are crushed and placed in a fermentation tank, and deionized water is added to obtain a mixed substrate; Cellulase and hemicellulase are added to the mixed substrate, and the mixed bacterial liquid is sprayed, and the enzyme is obtained after fermentation for 96 hours.

3. A composite water-soluble fertilizer for corn filling period according to claim 2, characterized in that: The mixed bacterial liquid is a mixed liquid of white rot fungi liquid, Bacillus subtilis liquid, Trichoderma harzianum liquid and Lactobacillus plantarum liquid in a volume ratio of 1.5:1.5:1:2, and the mass ratio of the mixed substrate to the mixed bacterial liquid is 100:

5.

4. A composite water-soluble fertilizer for corn filling period according to claim 3, characterized in that: The concentrations of the white rot fungus solution, the Bacillus subtilis solution, the Trichoderma harzianum solution and the Lactobacillus plantarum solution were all 1×10 7 CFU / mL.

5. A composite water-soluble fertilizer for corn filling period according to claim 2, characterized in that: The mass ratio of the corn stalks, the fruit pomace and the deionized water is 3:7:15, and the fruit pomace is apple pomace, pear pomace and pineapple pomace in a mass ratio of 1:1:

1.

6. A composite water-soluble fertilizer for corn filling period according to claim 2, characterized in that: The mass ratio of the cellulase to the hemicellulase is 2:1; the mass ratio of the mixed substrate to the mixture of the cellulase and the hemicellulase is 100:

2.

7. A composite water-soluble fertilizer for corn filling period according to claim 2, characterized in that: The temperature of the fermentation tank is 35±2°C, the humidity is 60±5%, and the rotation speed is 150±10r / min.

8. The method for preparing a composite water-soluble fertilizer for corn during the grain filling period according to claim 1, characterized in that: include: The enzyme and sodium carboxymethyl cellulose were mixed evenly and then freeze-dried at -25°C for 24 hours in a vacuum environment. The dried enzyme was crushed to obtain enzyme powder. Add expanded potassium dihydrogen phosphate, chelated magnesium, chelated calcium, chelated zinc and tryptophan to the enzyme powder, mix and sieve to obtain a composite water-soluble fertilizer.

9. The method for preparing a composite water-soluble fertilizer for corn during the grain filling period according to claim 8, characterized in that: The mass ratio of the enzyme to the sodium carboxymethyl cellulose is 100:

3.

10. Use of the composite water-soluble fertilizer according to any one of claims 1 to 7 or the composite water-soluble fertilizer prepared by the preparation method according to any one of claims 8 to 9 in planting corn during the grain filling period.

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