CN115677398B - Solid-state fermentation composite fish offal and tobacco waste organic fertilizer and production method and application thereof - Google Patents

Abstract

The invention provides a solid-state fermentation composite fish scraps and tobacco waste organic fertilizer and a production method and application thereof. The invention utilizes microbial fermentation technology, takes cheap composite fish scraps and tobacco waste as fermentation substrates, mixes inorganic salts and inorganic nitrogen sources to prepare solid fermentation medium, and inoculates composite bacterial agents of Bacillus subtilis, red yeast and Rhizopus oryzae to obtain fermented organic fertilizer after solid-state fermentation. The invention has low cost and simple preparation method, and has the functions of increasing vegetable yield, improving quality, increasing soil nutrients and the like.

Description

A solid-state fermentation composite fish scraps and tobacco waste organic fertilizer and its production method and application

Technical Field

The invention belongs to the field of fertilizers, and in particular relates to a solid-state fermented composite fish scraps and tobacco waste organic fertilizer and a production method and application thereof.

Background Art

In agricultural production, organic fertilizers are widely favored in the agricultural market. Most of the organic fertilizers used at home and abroad are high-efficiency fertilizers rich in organic matter prepared from organic waste. In the process of aquatic product processing, 40-55% of fish by-products are not used, including fish heads, fish bones, fish tails, fish skins, fish viscera, etc. Fish waste contains a large amount of high-quality protein and a variety of active substances. At present, fish waste is mainly used to prepare bioactive peptides, process animal feed, fish protein fertilizer, and nitrogen source culture medium.

As my country attaches great importance to the development of green agriculture, the development of other agricultural organic wastes to transform organic high-efficiency soil fertilizers has become a new way for the sustainable development of modern agriculture. Therefore, the transformation of aquatic product waste resources has gradually become a hot topic. Abundant low-value fish resources and aquatic product processing waste can become an important source of green ecological organic fertilizers, which can increase the added value of the aquatic product processing industry and avoid environmental pollution.

As a functional fertilizer, fish protein fertilizer has attracted the attention of growers. This fertilizer contains a variety of active substances such as small molecule peptides, amino acids, taurine, vitamins, and rich trace elements such as calcium and magnesium. Fish waste can be processed into stable liquid or solid fertilizers and combined with other materials to produce fish compost or as a substrate for anaerobic digestion. It has the potential to improve soil by improving soil microbial activity and soil structure and stimulating root growth.

Tobacco waste contains a large amount of nutrients such as potassium and phosphorus that are easily absorbed by plants. It is a green and low-cost resource for preparing seedling substrates. It can also be used to make activated carbon, organic fertilizers and chicken feed. Nicotine exists in tobacco waste. Directly returning it to the field will lead to reduced plant growth indicators and cause environmental pollution. Using microbial fermentation technology to treat tobacco waste can reduce harmful components in the waste, and at the same time is conducive to the improvement of soil structure and the supplement of nutrients.

Fish waste contains rich nutrients such as minerals, fats, proteins, etc. Currently, the utilization of fish waste is mainly focused on the preparation of liquid fish protein fertilizer in agriculture, and there is less research on fish waste and plant waste straw as fermentation substrates.

Summary of the invention

The purpose of the present invention is to provide a solid-state fermentation composite fish scraps and tobacco waste organic fertilizer and a production method, which utilizes fish scraps and tobacco waste. After microbial fermentation, macromolecules such as protein, lipid and cellulose in the waste are decomposed and then converted into nutrients that can be directly absorbed and utilized by plants.

Another object of the present invention is to provide an application of solid-state fermented composite fish waste and tobacco waste organic fertilizer for crop fertilizer, which is directly applied as base fertilizer. The fermented organic fertilizer prepared by the present invention can promote crop growth, improve soil nutrients, and provide a new direction for the high-value utilization of organic waste, so that it can be used as an organic fertilizer for crops in agriculture.

The specific technical solutions of the present invention are as follows:

A method for producing solid-state fermentation composite fish scraps and tobacco waste organic fertilizer comprises: mixing fish scraps and tobacco waste as a fermentation matrix, mixing in inorganic salts and inorganic nitrogen sources, sterilizing at high temperature, inoculating a mixed bacterial agent, and performing solid-state fermentation to produce solid organic fertilizer.

The fish scraps are: fish heads, fish viscera, fish fins, fish tails, fish bones or a mixture of residual fish meat thereof, which are sterilized at 121° C., crushed by a tissue grinder, and dried at 50° C.; the fish scraps are fish scraps of crucian carp, grass carp or silver carp.

The tobacco waste is any one or a mixture of tobacco leaves and tobacco stems discarded from cigarette factories, which are dried in an oven at 50° C. and then crushed into particles.

The mass of the tobacco waste is 5-40% of the total mass of the fish scraps and the tobacco waste; preferably, the mass of the tobacco waste is 30% of the total mass of the fish scraps and the tobacco waste;

The amount of the inorganic salt is 0.5-1.5% of the total mass of the fish scraps and tobacco waste, preferably 0.5%;

The inorganic salt is selected from potassium dihydrogen phosphate (K ₂ HPO _{4 )} , potassium dihydrogen phosphate (KH ₂ PO ₄₎ or sodium chloride (NaCl); preferably sodium chloride (NaCl);

The amount of the inorganic nitrogen source is 0.5-2.0% of the total mass of the fish scraps and tobacco waste, preferably 1.0%;

The inorganic nitrogen source is selected from ammonium nitrate NH ₄ NO ₃ or sodium nitrate NaNO ₃ ; preferably ammonium nitrate NH ₄ NO ₃ ;

The inoculation amount of the mixed bacterial agent is 1×10 ¹⁰ -5×10 ¹⁰ CFU/g, preferably 4×10 ¹⁰ CFU/g, based on the total mass of fish scraps and tobacco waste.

The mixed bacterial agent is a mixed bacteria of Bacillus subtilis, red yeast and Rhizopus oryzae; the total number of live bacteria of the strains of Bacillus subtilis, red yeast and Rhizopus oryzae is 2:1:3;

The solid-state fermentation temperature is 30°C-36°C and the fermentation time is 20 days, preferably 34°C;

The invention provides a solid-state fermentation composite fish scraps and tobacco waste organic fertilizer, which is prepared by adopting the above method.

The invention provides an application of solid-state fermented composite fish scraps and tobacco waste organic fertilizer for use as crop fertilizer.

The application method of the solid-state fermentation composite fish scraps and tobacco waste organic fertilizer is as follows: the solid-state fermentation composite fish scraps and tobacco waste organic fertilizer are mixed with soil at a mixing ratio of 10-30 g/kg soil.

The solid-state fermentation composite fish scraps and tobacco waste organic fertilizer is particularly suitable for being used as a fertilizer for Shanghai greens and peppers, and can promote their growth and increase the chlorophyll content.

The solid-state fermentation composite fish scraps and tobacco waste organic fertilizer can increase the ammonium nitrogen, available phosphorus and quick-acting potassium contents of the soil, wherein the ammonium nitrogen content of the soil is increased to 55-360 mg/kg, the available phosphorus content is increased to 82-190 mg/kg, and the quick-acting potassium content is increased to 36-105 mg/kg; and the urease activity in the soil is increased by 3.0-3.6 mg/g, the sucrase activity is increased by 1.5 mg/g-1.9 mg/g, and the catalase activity is increased by 3.5 (U/h·g)-4.00 (U/h·g).

The biological organic fertilizer prepared by the invention has good effects on improving soil and cultivating strong seedlings of crops.

The present invention utilizes microbial fermentation technology, takes cheap composite fish scraps and tobacco waste as fermentation substrates, mixes inorganic salts and inorganic nitrogen sources to prepare solid fermentation medium, and inoculates composite bacterial agents of Bacillus subtilis, red yeast and Rhizopus oryzae to obtain fermented organic fertilizer after solid-state fermentation. The invention has low cost and simple preparation method, and has the functions of increasing vegetable yield, improving quality, increasing soil nutrients and the like.

The mixed strain fermentation of Bacillus subtilis, red yeast and Rhizopus oryzae adopted in the present invention has the advantage of coordinated interaction: in the fermentation test, yeast and Rhizopus oryzae are saccharified and fermented synchronously, Rhizopus oryzae can produce cellulase, and utilize cellulose, starch and the like in the fermentation matrix to generate sugar, while red yeast utilizes sugar for growth metabolism, which reduces the product inhibition effect, promotes the growth of yeast, and improves the fermentation rate. Bacillus subtilis can produce a variety of biologically active substances, such as digestive enzymes, vitamins, organic acids, small peptides and growth-promoting factors. Therefore, the synergistic effect of strains is used to improve the utilization efficiency of substrates, which is better than single strain fermentation. Moreover, the present invention adopts the solid-state fermentation method of organic waste to make organic fertilizer, and the fish scraps used are rich in nutrients such as protein and lipids, and the tobacco waste contains a large amount of nutrients such as potassium and phosphorus that are easily absorbed by plants. It is a green, low-cost fertilizer resource, and it is easy to obtain, and it can increase the added value of the aquatic product processing industry and avoid environmental pollution. Fish scraps and tobacco waste were fermented under solid conditions using mixed microorganisms, 0.5% sodium chloride and 1% ammonium nitrate were added, mixed strains of Bacillus subtilis, red yeast and Rhizopus oryzae were used as fermentation agents, and the solid fermentation conditions were 30% tobacco waste addition, 4×10 ¹⁰ CFU/g inoculation amount and 34°C fermentation temperature. Organic fertilizer could be obtained after a fermentation period of 20 days, and the fermentation method was simple to operate.

The solid-state fermented organic fertilizer of the present invention has high fertilizer efficiency. When the fermented organic fertilizer is applied as base fertilizer, when the base fertilizer is 20g/kg, the seedling height of green vegetables and peppers is 4.5cm and 5.3cm respectively, which increases by 95.65% and 32.5%; the fresh weight is increased by 0.129g and 0.1627g respectively, and the dry weight is increased by 0.006g and 0.0042g compared with the fresh weight of the control group without applying fermented fertilizer. The chlorophyll content of green vegetables and peppers is 17.124mg/g and 16.278mg/g respectively, which is 18.53% and 195.4% higher than that of the control group, and there is a significant difference. After the fermented organic fertilizer is applied as base fertilizer, the ammonium nitrogen content in the soil is 355mg/kg, the effective phosphorus is 172.33mg/kg, and the quick-acting potassium is 36.63mg/kg, which is significantly higher than that of the control group. In addition, the enzyme activities of urease, catalase and sucrase in the soil also increased. Soil enzyme activity is an important indicator for evaluating the physical and chemical properties and fertility of the soil, and can indirectly reflect the conversion of certain nutrients in the soil. It can be seen that fermented organic fertilizer can increase soil nutrients and provide nutrients for plants.

Compared with the prior art, the present invention uses mixed fish scraps and tobacco waste as main raw materials, and utilizes microbial solid fermentation to produce organic fertilizer required for plant growth, thus providing a new method for waste treatment in the aquatic and tobacco industries and solving the problem of environmental pressure caused by waste.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a protease activity detection plate;

Fig. 2 is a lipase activity detection plate;

Fig. 3 is a cellulase activity detection plate;

Figure 4 shows the effects of different inorganic nitrogen sources and inorganic salts on the total number of viable bacteria; a shows the effects of different inorganic nitrogen sources on the total number of viable bacteria; b shows the effects of different inorganic salts on the total number of viable bacteria;

Figure 5 shows the effect of sodium chloride and ammonium nitrate content on the total number of viable bacteria;

FIG6 shows the effect of different fermentation conditions on the fermentation substrate;

Figure 7 shows the changing trends of organic matter, available phosphorus, available potassium, and cellulose content during the fermentation process; a is the organic matter content, b is the available phosphorus content, c is the available potassium content, and d is the cellulose content;

Figure 8 shows the effect of fermented fertilizer on the growth of green vegetables;

Figure 9 shows the effect of fermented fertilizer on pepper growth;

Figure 10 shows the effect of fermented fertilizer on chlorophyll content of vegetables;

Figure 11 shows the effect of fermented fertilizer on soil urease activity;

FIG12 shows the effect of fermented fertilizer on soil sucrase activity;

Figure 13 shows the effect of fermented fertilizer on soil catalase activity.

DETAILED DESCRIPTION

The present invention is further described below in conjunction with the following examples.

Example 1

A method for producing solid-state fermentation composite fish scraps and tobacco waste organic fertilizer comprises: mixing fish scraps and tobacco waste as a fermentation matrix, mixing in inorganic salts and inorganic nitrogen sources, sterilizing at high temperature, inoculating a mixed bacterial agent, and performing solid-state fermentation to produce solid organic fertilizer.

The fish scraps are fish heads, fish viscera, fish fins, fish tails, fish bones or a mixture of residual fish meat thereof, which are sterilized at high temperature, crushed and dried; the fish scraps are fish scraps of crucian carp, grass carp or silver carp. The tobacco waste is a mixture of any one or both of tobacco leaves or tobacco stems discarded from a cigarette factory, which are dried in an oven at 50°C and crushed into granules. The basic physical and chemical properties of the fish scraps and tobacco waste used in Example 1 are shown in Table 1.

Table 1 Basic physical and chemical properties of fish scraps and tobacco waste

The mass of the tobacco waste is 30% of the total mass of the fish scraps and the tobacco waste; the inorganic salt is selected from sodium chloride NaCl; the inorganic nitrogen source is selected from _ammonium nitrate _NH4NO3 ; the amount of the inorganic salt is 0.5% of the total mass of the fish scraps and the tobacco waste; the amount of the inorganic nitrogen source is 1.0% of the total mass of the fish scraps and the tobacco waste; the mixed bacterial agent is inoculated with 4.0× ¹⁰¹⁰ CFU/g; the mixed bacterial agent is a mixed bacteria of Bacillus subtilis, red yeast and Rhizopus oryzae; the strain ratio of Bacillus subtilis, red yeast and Rhizopus oryzae is 2:1:3; the solid-state fermentation is performed at a fermentation temperature of 34°C for 20 days.

Example 2

The activation and enzyme activity detection of Bacillus subtilis, red yeast and Rhizopus oryzae strains are as follows:

Activation of fermentation strains:

Bacillus subtilis, Rhodotorula taiwanensis, and Rhizopus oryzae are commercially available strains. The strains are streaked on LB or PDA solid medium, and a single colony is picked and inoculated into a liquid medium. After culturing for 24 hours, the resultant is used as a fermentation broth.

Enzyme activity detection of fermentation strains:

The enzyme activity was determined by the hydrolysis circle detection method. A hole (1 cm in diameter) was punched on the protease, esterase and cellulase enzyme activity detection medium, and 200 μl of the above fermentation liquid was respectively inoculated into the plate well. Each strain was repeated 3 times. Red yeast and Rhizopus oryzae were cultured at 28°C, and Bacillus subtilis was cultured at 35°C. After 5 days of culture, the cellulose culture medium was stained with 1 mg/mL Congo red for 1 hour. After the stain was poured out, it was immersed in 1 mol/L NaCl solution for 1 hour to observe whether a transparent circle was generated. The results are shown in Figures 1 to 3.

As shown in Figures 1, 2 and 3, there are obvious hydrolysis circles on the plate, and the strains Bacillus subtilis and Rhizopus oryzae have the ability to produce protease, esterase and cellulase, and red yeast has the ability to produce protease and esterase. It also further illustrates that the present invention uses Bacillus subtilis, red yeast and Rhizopus oryzae to ferment fish scraps and tobacco waste.

Example 3

According to the method of Example 1, the addition amount of culture medium, inorganic nitrogen source, inorganic salt and raw material selection were changed, the usage ratio of tobacco waste, the strain ratio of Bacillus subtilis, red yeast and Rhizopus oryzae in the mixed inoculum, the inoculation amount, the fermentation temperature, etc. were adjusted, and the fermentation results were compared, as follows:

1) Changes in the number of strains using fermentation substrate as culture medium

Based on the fermentation broth of Example 2, 5% of single-bacteria fermentation broth and mixed bacterial broth (Bacillus subtilis: red yeast: Rhizopus oryzae ratio of 1:1:1) were inoculated into LB, PDA and liquid culture medium of mixed fermentation matrix composed of fish scraps and tobacco, respectively. After culturing for 2 days, the total number of microorganisms was calculated by the dilution spread plate method.

Table 2 Changes in the number of bacterial species in different culture media

In Table 2, the bacteria is Bacillus subtilis, and the fungi are Rhodotorula yeast and Rhizopus oryzae.

2) Fermentation matrix optimization

On the basis of the fermentation substrate of Example 1, inorganic nitrogen sources ((NH4) _2SO4 , _NH4NO3 , _NH4Cl , and _NaNO3 ) and inorganic salts ( _{K2HPO4 , KH2PO4} , _MgSO4 , and _NaCl ) with the same nitrogen content were added respectively, and the ratio of Bacillus subtilis, red yeast, and Rhizopus oryzae was 1:1:1 for inoculation _of mixed strains; the inoculation amount was 4× ¹⁰¹⁰ CFU/g, and the fermentation was carried out _at 34°C for 3 days. The total number of microorganisms was calculated by the plate count method, and the addition amount was set to 0, 0.5%, 1%, 1.5%, and 2%. The results are shown in Figures 4 and 5. Under the same composition and conditions, with ammonium nitrate as the inorganic nitrogen source and sodium chloride as the inorganic salt ion, the total number of viable bacteria was 3.3×108 CFU/mL, 2.21× ¹⁰⁸ CFU/mL, and 1.67× ¹⁰⁸ CFU/mL, respectively. CFU/mL, and changing its concentration to explore the effect on bacterial growth, with the increase of sodium chloride content, the number of viable bacteria showed a downward trend; while the total number of viable bacteria increased with the increase of ammonium nitrate content, at 1%, the maximum total number of viable bacteria was 4.2×10 ⁸ CFU/mL, when it was greater than 1%, the total number of viable bacteria began to decrease, so 0.5% sodium chloride and 1% ammonium nitrate were added to the fermentation matrix. It is further proved that the most suitable inorganic nitrogen source and inorganic salt for bacterial growth are NH ₄ NO ₃ and NaCl, and the NH ₄ NO ₃ and NaCl selected by the present invention are the best.

3) Effect of tobacco addition on fermentation effect

Weigh 20g of fermentation substrate, set the amount of tobacco added to (5%, 10%, 20%, 30%, 40%), place in a 50ml conical flask, sterilize, inoculate with mixed bacterial agent, inoculate amount 4×10 ¹⁰ CFU/g, the ratio of Bacillus subtilis, red yeast, and Rhizopus oryzae is 2:1:3, and culture at 34℃ for 3 days.

4) Effect of inoculation amount on fermentation effect

Weigh 20g of fermentation substrate with a tobacco content of 30% and place it in a 50ml Erlenmeyer flask. After sterilization, inoculate the strains of Bacillus subtilis, red yeast, and Rhizopus oryzae in a ratio of 2:1:3, with final concentrations of 1, 2, 3, 4, and 5×10 ¹⁰ CFU/g, and culture at 34°C for 3 days.

5) Effect of the ratio of each strain on the fermentation effect

Weigh 20g of fermentation substrate with a tobacco content of 30% and place it in a 50ml conical flask. After sterilization, inoculate strains of Bacillus subtilis, red yeast and Rhizopus oryzae, and set the ratio of Bacillus subtilis, red yeast and Rhizopus oryzae to 2:1:1, 2:1:2, 2:1:3, 2:1:4 and 2:1:5, and ferment at 34°C for 3 days.

6) Study on the effect of temperature on fermentation effect

Among the fermentation strains, the optimum growth temperature of Bacillus is 30-37°C, and the optimum growth temperature of red yeast is 27-36°C. The optimum temperature of Rhizopus oryzae is 28-37°C, so 26°C, 28°C, 30°C, 32°C, 34°C, and 36°C were selected for experimental comparison.

After fermentation according to the above method, the influence of various factors on the fermentation effect was judged according to the content of soluble peptides in the fermentation broth, and the results are shown in Figure 6. It can be seen that in the solid-state fermentation of mixed strains, the content of soluble peptides first increased with the increase of tobacco addition (a in Figure 6), and when it reached 40%, the content was the lowest. The reason may be that the nicotine component in tobacco has an inhibitory effect on the strain, affecting the growth and enzyme activity of the strain. The soluble peptide content is the highest when the inoculation amount is 4×10 ¹⁰ CFU/g (b in Figure 6). When the inoculation amount exceeds this, the strain does not fully bind to the substrate, so the fermentation effect is poor. Too much inoculation leads to growth competition between strains, and too fast growth leads to nutrient deficiency, so the soluble peptide content in the fermentation broth is not high. The optimal ratio of mixed strains of Bacillus subtilis: red yeast: Rhizopus oryzae is 2:1:3. Suitable temperature is conducive to the normal metabolic activities of microorganisms. When the temperature is low, the metabolism of enzymes and other substances in the microorganisms is slow, the growth metabolism of the microorganisms slows down, and the soluble peptide content is low; when the temperature rises to 34°C, the soluble peptide content reaches its peak, which is the most suitable condition for the growth and metabolism of microorganisms. After that, as the temperature rises, some strains are not suitable and their life activities slow down or even disappear, and the microbial fermentation slows down, resulting in a decrease in the soluble peptide content.

7) Orthogonal test comparison of composite strain fermentation

According to the method of Example 1, the amount of tobacco added, the amount of inoculation, and the temperature were selected as variables for comparison. The comparison conditions are shown in Table 1, which proves that the fermentation conditions of Example 1 of the present invention are optimal.

Table 3 Fermentation process optimization

Table 4 Results of orthogonal experimental design for fermentation process optimization

Note: The data in the table are mean ± standard deviation. _{K i} value is the sum of the test indicators corresponding to the level of factor i.

When the optimal ratio of the mixed strain ratio is Bacillus subtilis: red yeast: Rhizopus oryzae is 2:1:3, it can be seen from the range analysis results in Table 3 that the order of primary and secondary factors with soluble peptide content as an indicator is B>C>A; the optimal level combination is A ₂ B ₂ C ₃ , that is, the tobacco waste addition amount is 30%, the inoculation amount is 4×10 ¹⁰ CFU/g, and the fermentation temperature is 34°C. It is verified by experiments that the conditions set in Example 1 of the present invention are optimal.

Example 4

The invention discloses an application of solid-state fermented composite fish scraps and tobacco waste organic fertilizer for use as crop fertilizer.

First, fermentation was performed according to the method of Example 1, and samples were collected every 2 days and mixed thoroughly before sampling. Each sample was air-dried and used for analysis of ammonium nitrogen, available phosphorus, available potassium and organic matter. The determination of cellulose was carried out by concentrated sulfuric acid hydrolysis; the determination of soluble peptides was carried out by Folin phenol method; the determination methods of moisture content, pH, total nitrogen and organic matter were based on the organic fertilizer industry standard of the Agricultural Industry Standard of the People's Republic of China (NY525-2012); the determination of ammonium nitrogen, available phosphorus and available potassium was carried out by TFC various types of direct-reading soil fertilizer rapid testers. The results are shown in Figure 7.

During the 20 days of fermentation, the organic matter content showed a gradual downward trend (Figure 7a), and then decreased by 34.27%, indicating that the organic waste was fully fermented and the organic matter was easily decomposed and utilized. The contents of available phosphorus and available potassium increased significantly (Figure 7b, 7c), increasing by 137.2% and 193.63%, respectively. At the end of fermentation, the contents of organic matter, available phosphorus, and available potassium were 47.26%, 3.76%, and 7.78%, respectively, all higher than the quality standards of organic fertilizers in my country (NY525-2012). The cellulose in the fermentation product was also degraded by 65.15% during the fermentation process. The physical and chemical quality test of the fermented fertilizer is shown in Table 5.

Table 5 Physical and chemical quality test results of fermented fertilizer

Inspection items Test results NY525-2012 Amino Nitrogen 0.51 P ₂ O ₅ (%) 3.755 N(%) 16.037 _K2O (%) 7.784 Total nutrients (N+P ₂ O ₅ +K ₂ O) (dry basis)/% 27.576 ≥5.0 Moisture/% 7.26 ≤30 color brown Brown or grayish brown

According to the above results, it is shown that after fermentation by the method of the present invention, the organic fertilizer has a high effective component and is suitable as an organic fertilizer for crops.

Apply the above fermented organic fertilizer:

The experiment set up 4 treatments, namely CK: garden soil without adding fertilizer; T1: fertilizer amount of 10g/kg; T2: fertilizer amount of 20g/kg; T3: fertilizer amount of 30g/kg. According to the above proportions, the organic fertilizer prepared in Example 1 was mixed with garden soil and applied as a base fertilizer at one time. 20 green vegetable and pepper seeds were sown in each treatment group, and 3 replicates were set for each treatment group. They were placed in a light constant temperature incubator for growth. The conditions of the light incubator were light intensity of 5000lx, light-dark ratio of 12h:12h, and 25°C. After 15 days of cultivation, the stem length, fresh weight, dry weight and chlorophyll of the vegetables were measured to obtain the most suitable crop sowing and fertilization amount.

The soil samples with different treatments were air-dried and used for the determination of soil physical and chemical properties and enzyme activities. The soil urease activity was determined by phenol-sodium hypochlorite colorimetry, the soil catalase activity was determined by potassium permanganate titration, and the soil sucrase activity was determined by 3,5-dinitrosalicylic acid colorimetry.

1) Effects of different fertilization rates on stem length, fresh weight and dry weight of vegetables

It can be seen from Table 6, Figure 8 and Figure 9 that fermented fertilizer has a significant promoting effect on the growth of vegetables. Compared with the control group, the treatment groups T1, T2 and T3 when fermented fertilizer was used as basal fertilizer can improve the germination rate of green vegetable seeds, and promote the stem length, fresh weight and dry weight of green vegetable and pepper seeds. The best effect was achieved when the basal fertilizer of group T2 was 20g/kg. The seedling heights of green vegetables and peppers were 4.5cm and 5.3cm, respectively, an increase of 95.65% and 32.5%; their fresh weight increased by 0.129g and 0.1627g, respectively, and their dry weight increased by 0.006g and 0.0042g compared with the fresh weight without fermented fertilizer. It can be seen that after the application of fermented fertilizer, the growth effect of vegetables is better than that of soil matrix.

Table 6 Effects of fermented fertilizer on stem length, fresh weight and dry weight of vegetables

Note: The data in the table are mean ± standard deviation; * indicates that the difference between different treatments reaches 5% significant level. The same below.

2) Effects of different fertilization amounts on chlorophyll content in vegetables

Chlorophyll content is often used as an important indicator to assess the ability of plants to adapt to the environment and their growth status. As shown in Figure 9, different amounts of fertilizer have different effects on the chlorophyll content of vegetable leaves. As the amount of fertilizer increases, the chlorophyll content shows an upward trend. When it reaches 20g/kg, the chlorophyll content is the highest. The chlorophyll content of green vegetables and peppers is 17.124mg/g and 16.278mg/g, respectively, which is 18.53% and 195.4% higher than the control group, showing significant differences.

3) Effect of fermented fertilizer on soil nutrients

Table 7 Test results of soil nitrogen, phosphorus and potassium after planting vegetables in soils with different treatments

Soil provides plants with mineral elements needed for physiological activities. Nitrogen fertilizer can increase the photosynthetic rate of plants, increase the activity of antioxidant enzymes in plants, and promote plant growth; phosphorus and potassium can regulate the metabolic process of plants and promote good development of plants. The soil nutrients of different treatment groups were measured. As shown in Table 5, the fertilized T1, T2, and T3 treatment groups can significantly increase the content of ammonium nitrogen, available phosphorus, and available potassium in the soil. With the increase in the amount of fertilizer, the ammonium nitrogen content was the highest in the T2 group of 20g/kg/mu; the available potassium was the least in the T2 group. It can be seen that the application of organic fertilizer provides nutrients for the soil, and under the action of microorganisms, it decomposes and releases various elements needed by plants, accelerates the conversion rate of fertilizers, improves the degree of fertilizer conversion, enhances fertilizer efficiency, and provides a source of nutrition for plants.

4) Effects of fermented fertilizer on soil enzyme activity

Urease in soil is a key enzyme in the nitrogen cycle, which can promote the hydrolysis of urea. The formed NH ₃ is one of the nitrogen sources for plants, and its activity can reflect the nitrogen supply capacity and level of the soil. The soil urease activity of different treatment groups was measured and the results were analyzed. As shown in Figure 11, the urease activity of the T2 treatment group was the highest at 3.565 mg/g, which was significantly higher than that of the control group. The urease activities of the T1 and T3 groups were 2.890 mg/g and 3.342 mg/g, respectively, which were not significantly different from the control group.

Sucrase comes from plant roots and microorganisms, can catalyze the hydrolysis of sucrose into glucose and sucrose, and plays an important role in the carbon and nitrogen cycle of the soil. As shown in Figure 12, in the garden soil without adding fermented fertilizer, the sucrase activity is 0.527 mg/g, and the sucrase activities of treatment groups T1, T2, and T3 are 1.760 mg/g, 1.863 mg/g, and 1.570 mg/g, respectively. Compared with the control group, the sucrase activity increased greatly after adding different amounts of fermented fertilizer, among which the enzyme activity of the T2 treatment group was the largest. As the amount of fermented fertilizer added increased, the sucrase activity tended to decrease, but there was still a significant difference.

Hydrogen peroxide is produced by the biochemical oxidation reaction of organic matter during the process of biological respiration. Its accumulation will have a toxic effect on organisms and soil. The catalase in the soil can enzymatically decompose hydrogen peroxide into water and oxygen, thereby eliminating the toxic effect of hydrogen peroxide. As shown in Figure 13, with the increase of fermentation fertilizer, the catalase activity first increased and then decreased. The catalase activities of the T1 and T2 groups were 4.00 (U/h·g) and 3.591 (U/h·g), respectively, which were increased by 25.74% and 12.89% respectively compared with the control group, with significant differences.

Claims (3)

1. The production method of the solid state fermentation composite fish offal and tobacco waste organic fertilizer is characterized by comprising the following steps: mixing fish scraps and tobacco waste to obtain a fermentation substrate, mixing inorganic salt and an inorganic nitrogen source, sterilizing at high temperature, inoculating a mixed microbial inoculum, and performing solid fermentation to prepare a solid organic fertilizer;

The fish offal is: sterilizing fish head, viscera, fin, tail, bone or their residue fish meat mixture at high temperature, mincing, and drying;

the tobacco waste is any one or a mixture of two of waste tobacco leaves and tobacco stems in a cigarette factory, and is crushed into particles after being dried in a baking oven at 50 ℃;

The physical and chemical properties of the fish offal are as follows: 42.8% of total nitrogen, 48.5% of fat, 0.019% of total sugar, 0.87% of NaCl, 6.16% of pH and 73.31% of organic matters;

The physical and chemical properties of the tobacco waste are as follows: total nitrogen 2.01%, total sugar 0.14%, naCl 1.97%, pH 4.90 and organic matters 56.81%;

The mass of the tobacco waste is 30% of the total mass of the fish offal and the tobacco waste; the inorganic salt is sodium chloride NaCl; the inorganic nitrogen source is ammonium nitrate NH ₄NO₃; the consumption of the inorganic salt is 0.5% of the total mass of the fish offal and the tobacco waste; the consumption of the inorganic nitrogen source is 1.0% of the total mass of the fish offal and the tobacco waste; the inoculation amount of the mixed microbial inoculum is 4.0 multiplied by 10 ¹⁰ CFU/g; the mixed bacterial agent is a mixed bacterial of bacillus subtilis, rhodotorula and rhizopus oryzae; the total ratio of the live strains of the bacillus subtilis, the rhodotorula and the rhizopus oryzae is 2:1:3; the solid state fermentation is carried out for 20 days at 34 ℃.

2. A solid state fermentation composite fish offal and tobacco waste organic fertilizer produced by the production method of claim 1.

3. Use of the solid state fermentation composite fish offal and tobacco waste organic fertilizer produced by the production method of claim 1, which is characterized by being used for crops.