Kitchen waste compost product fertilizing method for reducing N2O emission of farmland

Abstract

The invention discloses a kitchen waste compost product fertilizing method capable of reducing N2O emission of farmland, and relates to the technical field of biology. The fertilizing method comprises the step of applying kitchen waste compost to farmland instead of part of chemical fertilizer. According to the kitchen waste compost capable of reducing N2O emission of the farmland, disclosed by the invention, the high-quality kitchen waste compost can be prepared by inoculating the compost raw material containing the crop straws, the kitchen waste and the fly ash with the mixed microbial inoculum and carrying out aerobic compost fermentation treatment. Wherein the fly ash is rich in aluminosilicate minerals, can adjust the pH value of the compost substrate, provides certain trace elements, and can promote the balance of microbial communities, thereby being beneficial to reducing the generation of N2O. The compost product can be used for replacing part of chemical fertilizer to be applied to farmland, not only can reduce the emission of greenhouse gas N2O, but also can improve the soil structure, improve the crop yield and quality, and realize the win-win situation of environmental and economic benefits.

Description

Technical Field

[0001] The present invention relates to the field of biotechnology, and particularly to a method for applying a food waste compost product to reduce N2O emissions in farmland. Background Art

[0002] In the process of rapid urbanization, the generation of food waste has been continuously increasing. Among them, food waste has become an important object for environmental governance due to its characteristics of high water content and high organic matter content. The harmless treatment and resource utilization of food waste are important links for realizing nutrient cycling and sustainable development. At present, after classification and aging treatment, kitchen waste can be used as a raw material for organic fertilizer production after meeting the requirements of safety evaluation indicators.

[0003] Farmland fertilization is one of the main sources of greenhouse gas nitrous oxide (N2O) emissions. Optimizing fertilization methods and reducing N2O emissions have become research hotspots in the field of agricultural environmental protection. At present, research on the regulation of N2O emissions by partial substitution of chemical fertilizers with organic fertilizers mainly focuses on traditional organic fertilizers such as animal manure, and there are significant differences in the effects of different types of organic fertilizers on N2O emissions. Based on this background, the present invention conducts research on the environmental effects of applying food waste compost products to farmland, and intends to develop a method for reducing N2O emissions in farmland by applying food waste compost products, so as to provide a scientific basis and technical support for the sustainable development of agriculture. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for applying a food waste compost product to reduce N2O emissions in farmland to solve the problems existing in the above-mentioned prior art. By developing a food waste compost product to replace part of the chemical fertilizers applied to farmland, the present invention can not only reduce the emissions of greenhouse gas N2O, but also improve the soil structure, increase the crop yield and quality, and achieve a win-win situation of environmental and economic benefits.

[0005] To achieve the above purpose, the present invention provides the following solution:

[0006] The present invention provides a preparation method of a food waste compost for reducing N2O emissions in farmland, including the step of inoculating a mixed microbial agent into compost raw materials and performing aerobic composting fermentation treatment to obtain the food waste compost;

[0007] The mixed microbial agent includes Thermophilic Streptomyces, Streptomyces pratensis, Bacillus subtilis and Lactobacillus plantarum;

[0008] The compost raw materials include crop straws, kitchen waste and fly ash.

[0009] Furthermore, the Thermophilicomyces lanuginosus is Thermophilicomyces lanuginosus CICC 41717; the Streptomyces pratensis is Streptomyces pratensis CICC 11009; the Bacillus subtilis is Bacillus subtilis CICC 24713; and the Lactobacillus plantarum is Lactobacillus plantarum ACCC 10533.

[0010] Furthermore, the quantity ratio of the Thermophilicomyces lanuginosus, the Streptomyces pratensis, the Bacillus subtilis, and the Lactobacillus plantarum is 2:1.5:1:1.

[0011] Furthermore, the mass ratio of the crop straw, the kitchen waste, and the fly ash is 10:9:1.

[0012] Furthermore, the crop straw includes wheat straw.

[0013] Furthermore, the time for the aerobic composting fermentation treatment is 30 days; and / or;

[0014] The aerobic composting fermentation treatment adopts an intermittent ventilation method, starting the fan once every 1 h, blowing air for 20 min each time, and the ventilation rate is 0.5 L·kg -1 DM·min -1 , and turning the pile once a week.

[0015] The present invention also provides a kitchen waste compost prepared by the above preparation method.

[0016] The present invention also provides the application of the above kitchen waste compost in reducing N2O emissions in farmland.

[0017] The present invention also provides a method for applying a kitchen waste compost product for reducing N2O emissions in farmland, including the step of applying the above kitchen waste compost to replace part of the chemical fertilizer in farmland.

[0018] Furthermore, the ratio of the nitrogen application amount of the chemical fertilizer applied to the nitrogen application amount of the kitchen waste compost is 7:3.

[0019] The present invention discloses the following technical effects:

[0020] The present invention develops a kitchen waste compost for reducing N2O emissions in farmland. By inoculating a mixed bacterium agent into a compost raw material containing crop straw, kitchen waste, and fly ash, and performing aerobic composting fermentation treatment, a high-quality kitchen waste compost can be prepared. Among them, the fly ash is rich in aluminosilicate minerals, which can adjust the pH value of the compost matrix and provide certain trace elements, can promote the balance of the microbial community, and reduce the generation of N2O. This compost product can be used to replace part of the chemical fertilizer applied to farmland, which can not only reduce the emission of the greenhouse gas N2O, but also improve the soil structure, increase the crop yield and quality, and achieve a win-win situation of environmental and economic benefits.

[0021] The present invention not only realizes the harmless treatment of kitchen waste and fly ash, but also converts them into valuable resources for agricultural production, promotes the development of circular economy, and has remarkable technological innovation and practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 It is a statistical chart of the cumulative N2O emissions of different fertilization treatments;

[0024] Figure 2 It is a statistical chart of the N2O emission factors of different fertilization treatments;

[0025] Figure 3 It is a statistical chart of the yields of different fertilization treatments. DETAILED DESCRIPTION OF THE INVENTION

[0026] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0027] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0028] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0029] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the description of the present invention, which are obvious to those skilled in the art. Other embodiments obtained from the description of the present invention are obvious to those skilled in the art. The description and examples of the present invention are merely exemplary.

[0030] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0031] In the following examples, Thermomyces lanuginosus was purchased from the China Center of Industrial Culture Collection (CICC), and the strain number is CICC 41717; Streptomyces pratensis was purchased from the China Center of Industrial Culture Collection, and the strain number is CICC 11009; Bacillus subtilis was purchased from the China Center of Industrial Culture Collection, and the strain number is CICC 24713; Lactobacillus plantarum was purchased from the Agricultural Culture Collection of China (ACCC), and the strain number is ACCC 10533; Streptomyces microflavus was purchased from the China Center of Industrial Culture Collection (CICC), and the strain number is CICC 23627.

[0032] PDA liquid medium: 200 g / L of potatoes and 20 g / L of sucrose.

[0033] PDA solid medium: 200 g / L of potatoes, 20 g / L of sucrose and 20 g / L of agar.

[0034] LB liquid medium: 10 g / L of tryptone, 5 g / L of yeast extract and 10 g / L of sodium chloride.

[0035] LB solid medium: 10 g / L of tryptone, 5 g / L of yeast extract, 10 g / L of sodium chloride and 20 g / L of agar.

[0036] Example 1

[0037] Preparation of aerobic compost from food waste

[0038] 1. Preparation of Thermomyces lanuginosus agent

[0039] (1) Solid slant culture: Inoculate Thermomyces lanuginosus in PDA solid medium and incubate at 45 °C for 3 days to activate the strain.

[0040] (2) Primary seed culture: The activated strain from step (1) is inoculated into a PDA liquid medium and cultured at 45°C and 150 rpm for 3 days to obtain a primary seed solution.

[0041] (3) Secondary seed culture: The primary seed solution obtained in step (2) is inoculated into a 5-L Erlenmeyer flask (containing PDA liquid medium) at an inoculation amount of 8% and cultured at 45°C and 160 rpm for 3 days to obtain a secondary seed solution.

[0042] (4) The secondary seed solution is inoculated into a fermenter containing PDA liquid medium at an inoculation amount of 3%. After culturing at 45°C for 5 days, a fermentation broth is obtained, and the concentration is controlled at 10 7 CFU / mL or higher.

[0043] (5) The concentration of the fermentation broth is diluted to 10 6 CFU / mL to obtain a Thermoactinomyces vulgaris agent for standby.

[0044] 2. Preparation of Streptomyces pratensis agent

[0045] (1) Solid slant culture: Streptomyces pratensis is inoculated into a PDA solid medium and cultured at a constant temperature of 25°C for 3 days to activate the strain.

[0046] (2) Primary seed culture: The activated strain from step (1) is inoculated into a PDA liquid medium and cultured at 25°C and 150 rpm for 3 days to obtain a primary seed solution.

[0047] (3) Secondary seed culture: The primary seed solution obtained in step (2) is inoculated into a 5-L Erlenmeyer flask (containing PDA liquid medium) at an inoculation amount of 8% and cultured at 25°C and 160 rpm for 3 days to obtain a secondary seed solution.

[0048] (4) The secondary seed solution is inoculated into a fermenter containing PDA liquid medium at an inoculation amount of 3%. After culturing at 25°C for 5 days, a fermentation broth is obtained, and the concentration is controlled at 10 7 CFU / mL or higher.

[0049] (5) The concentration of the fermentation broth is diluted to 10 6 CFU / mL to obtain a Streptomyces pratensis agent for standby.

[0050] 3. Preparation of Bacillus subtilis agent

[0051] (1) Solid slant culture: Bacillus subtilis is inoculated into an LB solid medium and cultured at a constant temperature of 37°C for 1 day to activate the strain.

[0052] (2) Primary seed culture: The activated strain from step (1) was inoculated into LB liquid medium and cultured at 37 °C and 160 rpm for 1 day to obtain the primary seed solution.

[0053] (3) Secondary seed culture: The primary seed solution obtained in step (2) was inoculated into a 5 L Erlenmeyer flask (containing LB liquid medium) at an inoculation amount of 8%, and cultured at 37 °C and 170 rpm for 1 day to obtain the secondary seed solution.

[0054] (4) The secondary seed solution obtained in step (3) was inoculated into the fermentation medium (i.e., LB liquid medium) at an inoculation amount of 10%, and fermented and cultured at 37 °C and 180 rpm for 3 days to obtain the fermentation broth, with the concentration controlled at 10 8 CFU / mL or more.

[0055] (5) The concentration of the fermentation broth was diluted to 10 6 CFU / mL to obtain the Bacillus subtilis bacterium agent for standby.

[0056] 4. Preparation of Lactobacillus plantarum bacterium agent

[0057] (1) Solid slant culture: Lactobacillus plantarum was inoculated into LB solid medium and cultured at a constant temperature of 30 °C for 1 day to activate the strain.

[0058] (2) Primary seed culture: The activated strain from step (1) was inoculated into LB liquid medium and cultured at 30 °C and 160 rpm for 1 day to obtain the primary seed solution.

[0059] (3) Secondary seed culture: The primary seed solution obtained in step (2) was inoculated into a 5 L Erlenmeyer flask (containing LB liquid medium) at an inoculation amount of 8%, and cultured at 30 °C and 170 rpm for 1 day to obtain the secondary seed solution.

[0060] (4) The secondary seed solution obtained in step (3) was inoculated into the fermentation medium (i.e., LB liquid medium) at an inoculation amount of 10%, and fermented and cultured at 30 °C and 180 rpm for 2 days to obtain the fermentation broth, with the concentration controlled at 10 8 CFU / mL or more.

[0061] (5) The concentration of the fermentation broth was diluted to 10 6 CFU / mL to obtain the Lactobacillus plantarum bacterium agent for standby.

[0062] 5. Preparation of food waste compost

[0063] The Thermoactinomyces vulgaris bacterium agent, Streptomyces pratensis bacterium agent, Bacillus subtilis bacterium agent and Lactobacillus plantarum bacterium agent were mixed evenly according to the volume ratio of 2:1.5:1:1 to obtain the mixed bacterium agent.

[0064] The wheat straw and kitchen waste are mechanically crushed, wherein the length of the wheat straw after crushing is controlled to be 2-6 cm, and the particle size of the kitchen waste after crushing is controlled to be 2-6 cm.

[0065] After mechanically crushed wheat straw and kitchen waste were mixed with fly ash, mixed bacterial agents were added (wherein the mass ratio of wheat straw, kitchen waste, fly ash and mixed bacterial agents was 10:9:1:1), the water content was adjusted to 50%, and after being mixed evenly, they were placed in a vertical composting fermentation tower for 30 days of aerobic composting fermentation treatment to obtain food waste compost. During the composting treatment, intermittent ventilation was used, and the fan was started once every 1 hour, and each blowing was 20 minutes, with a ventilation rate of 0.5L·kg -1 DM·min -1 , turn the pile once a week.

[0066] Comparative Example 1

[0067] Same as Example 1, except that Streptomyces praecox was replaced by Streptomyces tenuiflavus.

[0068] Comparative Example 2

[0069] The same as Example 1, except that fly ash is not added during the preparation of the kitchen waste compost.

[0070] Example 2

[0071] 1. Experimental Methods

[0072] 1.1 Experimental groups and fertilization methods

[0073] In the same experimental field, 21 experimental plots were set up (repeated 3 times, that is, 3 experimental plots were used as one experimental group), with an area of 20m 2 , randomized block arrangement, before the start of the experiment, a 50 cm wide and 0.8 mm thick plastic tablecloth was buried between adjacent plots and replicates to prevent the interaction of water and fertilizer between plots. A total of two seasons of leafy vegetables were planted, namely Chinese cabbage (March 14, 2024-April 19, 2024) and water spinach (July 22, 2024-August 26, 2024). The experimental groups and fertilization methods are shown in Table 1.

[0074] According to field survey data, the amount of nitrogen fertilizer applied to leafy vegetables is 375 kg N ha -1 , Phosphate fertilizer 225kg P2O5ha -1 and potash fertilizer 263kg K2O ha -1, the ratio of base fertilizer nitrogen application rate to topdressing nitrogen application rate is 6:4, and the ratio of organic fertilizer nitrogen application rate to chemical fertilizer nitrogen application rate is 3:7. Phosphate fertilizer, potassium fertilizer and organic fertilizer are applied as base fertilizer at one time. The specific application rate of organic fertilizer is calculated according to 30% of the total nitrogen application rate and the nitrogen content (TN) of organic fertilizer.

[0075] Table 1 Experimental groups and fertilization methods

[0076]

[0077] 1.2 Index detection

[0078] Soil gas sampling is carried out on the 1st, 3rd, 5th and 9th days after base fertilizer application and topdressing application. Regular sampling is carried out every 4 days during the remaining periods. After the crops are mature and harvested, sampling is carried out every 1 week. The sampling time is generally between 8:30-11:30 in the morning.

[0079] The emission flux of N2O in soil is determined by the static dark box-gas chromatography method. The sampling area consists of a stainless steel base (diameter 42 cm × height 10 cm) and a sampling box (diameter 40 cm × height 30 cm). A Teflon tube and a temperature probe pass through the top of the sampling box for collecting the gas inside the box and measuring the temperature. The base is inserted into the soil, and the upper water tank ensures the tightness of the sampling box and remains unchanged throughout the crop growth season. The sampling box is covered with heat-insulating materials to minimize the increase in indoor air temperature in the hot season. At 0, 10, 20 and 30 minutes after covering the sampling box, 4 gas samples are collected from the sampling box with a 60 mL plastic syringe connected to the sampling gas pipe through a three-way stopcock. After sampling, the sampled gas is injected into a 12 mL vacuum bottle and taken back to the laboratory, and a gas chromatograph (Agilent 7890, Agilent Technologies, Inc., Santa Clara, CA, USA) is used to measure the N2O concentration.

[0080] The calculation method is as follows:

[0081] N2O emission flux:

[0082]

[0083] Among them, F represents the emission flux of soil N2O (μg N m -2 h -1 ); k i is the unit conversion coefficient (0.001); P0 (1013 hPa) and P respectively represent the standard atmospheric pressure of the test site and the atmospheric pressure inside the sampling box, and P0 / P≈1; T (°C) represents the average air temperature inside the sampling box during sampling; M represents the molecular weight of N2 in N2O molecules (28 g N mol -1);V is the molar volume of gas (22.4 L / mol) under standard atmospheric pressure of 1013 hPa and 273 K -1 );H (m) represents the height of the sampling chamber; dc / dt represents the rate of change of N2O concentration in the sampling chamber, and this coefficient is obtained by establishing a linear regression curve between concentration and time (R 2 > 0.85). c (μL·L -1 ) is the N2O concentration, and t (h) is the sealing time of the sampling chamber.

[0084] The cumulative N2O emission (kg N ha -1 ) can be obtained by summing up the daily N2O emission fluxes, and for the dates without gas sampling, it is calculated by linear interpolation.

[0085] N2O emission factor: EF = (E j - E CK ) / N j × 100%

[0086] In the formula, E i and E CK respectively represent the cumulative N2O emissions (kg N ha -1 ) under the conditions of fertilization and non - nitrogen - fertilizer application; N i represents the nitrogen application rate of each treatment (kg N ha -1 ); i represents different fertilization treatments.

[0087] 2. Experimental results

[0088] The cumulative N2O emissions of different fertilization treatments are shown in Figure 1 . In two growing seasons (pakchoi and water spinach seasons), the FWA treatment reduced the cumulative N2O emissions. The emissions were approximately 1.9 kg N ha -1 . In terms of emission control, it was more effective than the traditional chemical fertilizer (CF) and traditional chicken manure (CM) treatments. Among them, the cumulative emissions of the traditional chicken manure (CM) treatment were higher than 4.7 kg N ha -1 . Compared with the traditional chicken manure (CM) treatment, the N2O emissions of the FWA treatment in the pakchoi season were significantly reduced (P < 0.05), and a similar trend was also shown in the water spinach season, indicating that the method of the present invention has good emission reduction potential. In addition, the N2O emissions of the CM treatment were the highest and had large fluctuations in the pakchoi season, indicating that significant differences in the sources of organic materials significantly affected the emission effect. The preferred food waste composting (FWD) treatment of the present invention has a low N2O emission risk.

[0089] Figure 2Statistical results of N2O emission factors for different fertilization treatments. The N2O emission factor can be used to measure the N2O emission efficiency caused by unit nitrogen input under different fertilization treatments, and directly compare the N2O emission reduction benefits of each treatment. In the two crop seasons of pakchoi season and water spinach season, the emission factors of food waste compost (FWA) treatment were lower than those of other treatments. The largest emission factor among all treatments appeared in the traditional chicken manure (CM) treatment, which was 1.91%. Figure 3 The results further verified the fertilization method proposed by the present invention, which uses aerobic composting of food waste to replace part of the nitrogen fertilizer input, can effectively control the N2O emission efficiency during the nitrogen transformation process and reduce the N2O emission intensity.

[0090] The statistical results of the yields of different fertilization treatments are shown in Figure 3 . The results showed that applying chemical fertilizer (CF) and combined organic and inorganic fertilizers (CM, FWA, FWD) in the pakchoi season could increase the yield. Among them, the FWA treatment had the highest yield, which was about 4 times higher than that of the nitrogen-free control (CK) treatment. In the water spinach season, the yields of all nitrogen application treatments (CF, CM, FWA, FWD) were significantly higher than that of the nitrogen-free control CK treatment (5.42 t ha -1 ); the yield of the aerobic composting of food waste (FWA) treatment reached about 37.59 t ha -1 , indicating that on the basis of realizing N2O emission reduction, the present invention does not sacrifice the yield, and has the feasibility of popularization.

[0091] Based on the above analysis, the aerobic composting treatment of food waste by the method of the present invention reduces the total N2O emission and emission intensity in both crop seasons, while ensuring a yield output comparable to that of traditional chemical fertilizer treatment, realizing "emission reduction without yield reduction". The resource utilization of food waste has good environmental benefits and agricultural application potential.

[0092] The embodiments described above are only used to describe the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of food waste compost for reducing N2O emissions from farmland, characterized in that, It includes the step of inoculating a mixed microbial agent into compost raw materials and performing aerobic composting fermentation to obtain the kitchen waste compost; The mixed microbial agent includes Thermophilicomyces lanuginosus, Streptomyces pratensis, Bacillus subtilis and Lactobacillus plantarum; The compost raw materials include crop straws, kitchen waste and fly ash.

2. The preparation method according to claim 1, characterized in that, The Thermophilicomyces lanuginosus is Thermophilicomyces lanuginosus CICC 41717; the Streptomyces pratensis is Streptomyces pratensis CICC 11009; the Bacillus subtilis is Bacillus subtilis CICC 24713; the Lactobacillus plantarum is Lactobacillus plantarum ACCC 10533.

3. The preparation method according to claim 2, characterized in that, The quantity ratio of the Thermophilicomyces lanuginosus, the Streptomyces pratensis, the Bacillus subtilis and the Lactobacillus plantarum is 2:1.5:1:

1.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the crop straws, the kitchen waste and the fly ash is 10:9:

1.

5. The preparation method according to claim 4, wherein The crop straws include wheat straws.

6. The preparation method according to claim 1, characterized in that, The time of the aerobic composting fermentation is 30 days; and / or; The aerobic composting fermentation treatment adopts an intermittent ventilation method, starting the fan once every 1 h, blowing air for 20 min each time, and the ventilation rate is 0.5 L·kg -1 DM·min -1 , and turning the pile once a week.

7. A kitchen waste compost prepared by the preparation method according to any one of claims 1-6.

8. An application of the kitchen waste compost according to claim 7 in reducing N2O emissions in farmland.

9. A method for applying a food waste compost product to reduce N2O emissions in farmland, characterized in that, It includes the step of applying the kitchen waste compost according to claim 7 to replace part of the chemical fertilizers to farmland.

10. The method for applying the food waste compost product to reduce N2O emissions in farmland according to claim 9, wherein The proportion of the nitrogen application amount of the applied chemical fertilizers to that of the kitchen waste compost is 7:3.

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