Method for improving quality of compost organic fertilizer and reducing emission of ammonia

Abstract

The invention provides a method for improving the quality of a compost organic fertilizer and reducing emission of ammonia. The method for improving the quality of the compost organic fertilizer and reducing the ammonia emission comprises the steps that biochar (BC) and fulvic acid (FA) are added into the compost organic fertilizer for compost treatment, the compost organic fertilizer comprises compost formed by mixing livestock manure and straw, and the compost organic fertilizer comprises, by weight, 10-20 parts of biochar and 2-4 parts of fulvic acid, and 76-88 parts of a compost organic fertilizer. The charcoal and the fulvic acid can reduce the conductivity of the compost, effectively slow down ammonia volatilization in the composting process, increase the germination index and improve the total nitrogen content.

Description

Technical Field

[0001] The present invention relates to the field of fertilizers, and in particular to a method for improving the quality of compost organic fertilizers and reducing ammonia emissions. Background Art

[0002] Composting is a widely used bioconversion technology that converts organic waste into stable humus-like materials that can be used as nutrient-rich organic fertilizers or for improving the physical and chemical properties of soil. With the growing global demand for low-cholesterol meat products, the poultry industry contributes 82% of the livestock population. According to a report by the National Bureau of Statistics in 2017, China produces about 3.8 billion tons of poultry and livestock manure each year, of which poultry manure accounts for nearly 40%. Poultry manure contains rich organic matter and nutrients such as nitrogen (N) and phosphorus (P), so it is widely used as a fertilizer in agricultural applications. If used properly, it can reduce the use of inorganic fertilizers by about 30%. However, the direct use of untreated poultry manure may cause a series of environmental problems, including air and water pollution, the release of phytotoxic substances and human pathogens. To address these problems, composting is considered to be an economical and efficient means of treating and controlling poultry manure. During the composting process, microorganisms eventually decompose unstable substances in the compost into stable and usable organic matter. Maturity, nutrient content, organic matter content, pH, germination index, etc. are the main quality evaluation indicators of compost. However, the risks of potential pollutants and pathogens and the production of greenhouse gases and harmful gases have limited the application of composting to a certain extent. In addition, most composts are very lacking in nutrients, especially N loss caused by NH3 volatilization, and fertilizers or plant nutrients need to be added for nutrient supplementation to meet the nutrient conditions required for crop growth. Therefore, it becomes crucial to optimize the treatment of poultry manure when used as compost, which can enhance the practicality of poultry manure in agricultural applications. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. The present invention can improve the quality of compost organic fertilizer and reduce ammonia emission by adding biochar and fulvic acid to compost organic fertilizer.

[0004] Specifically, the present invention provides the following technical solutions:

[0005] A first aspect of the present invention provides a method for improving the quality of compost organic fertilizer and reducing ammonia emissions, comprising: adding biochar and fulvic acid to compost organic fertilizer for composting, wherein the compost organic fertilizer comprises a compost mixed with poultry manure and straw; wherein, in parts by weight, the biochar is 10 to 20 parts, the fulvic acid is 2 to 4 parts, and the compost is 76 to 88 parts.

[0006] In some embodiments of the present invention, the mass ratio of the poultry manure to the straw is (1-4):1.

[0007] In some embodiments of the present invention, the moisture content is maintained at 50-70% during the composting process.

[0008] In some embodiments of the present invention, the composting treatment time is 20 to 40 days. According to a preferred embodiment, the composting treatment time is 25 to 35 days.

[0009] In some embodiments of the present invention, the composting treatment includes turning the compost mixture every 3-6 days, and adding a proper amount of water each time the compost is turned to keep the moisture content at 50-70%.

[0010] In some embodiments of the present invention, the composting treatment includes turning the compost on the 1st, 4th, 7th, 10th, 13th, 17th, 21st and 30th day of the composting treatment, and adding an appropriate amount of water each time the compost is turned to maintain its moisture content at 55-65%.

[0011] In some embodiments of the present invention, the biochar and the fulvic acid can improve the quality of the compost, including at least one of the following:

[0012] (1) Increase total nitrogen and humus content;

[0013] (2) Reduce conductivity and ammonia volatilization;

[0014] (3) Improve germination index and adjust pH.

[0015] In some embodiments of the present invention, the quality of the compost organic fertilizer is compared with that without adding biochar and fulvic acid, and the germination index is improved by at least 20%.

[0016] In some embodiments of the present invention, the quality of the composted organic fertilizer is compared to that without adding biochar and fulvic acid, and the volatilization of ammonia is reduced by at least 40%.

[0017] In some embodiments of the present invention, the quality of the composted organic fertilizer is compared to that without adding biochar and fulvic acid, and the conductivity is reduced by at least 10%.

[0018] The beneficial effects achieved by the present invention are:

[0019] The use of fulvic acid and biochar as compost additives can provide a new and beneficial method for improving the efficiency and quality of aerobic composting, including increasing total nitrogen and HSs content, reducing EC and ammonia volatilization, increasing GI and adjusting pH. These advantages help to enhance the retention of nutrients during the composting process, reduce the emission of harmful gases and reduce the production of phytotoxicity. In addition, the addition of FA can increase the content of dissolved organic matter (DOM) in the compost, and the addition of BC can increase the humification degree of the compost. The addition of both at the same time has the best effect of reducing NH3 volatilization and increasing HA content. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention provides a dynamic change of temperature, pH value and conductivity in the composting process.

[0021] Figure 2 It is the ammonia volatilization flux and the cumulative ammonia volatilization flux in the composting process provided by the embodiments of the present invention.

[0022] Figure 3 The present invention provides the content of total nitrogen and total phosphorus and the germination index in the compost product according to the embodiment of the present invention.

[0023] Figure 4 The present invention provides the content of total humus, fulvic acid, humic acid and the ratio of humic acid to fulvic acid in the compost product provided by the embodiment of the present invention.

[0024] Figure 5 These are three fluorescence parameters of soluble organic matter and the maximum fluorescence intensity of four components in the compost product provided according to the embodiments of the present invention. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0026] The present invention provides a method for reducing ammonia in compost, comprising: adding biochar and fulvic acid to the compost organic fertilizer for composting, wherein the compost organic fertilizer comprises compost mixed with poultry manure and straw;

[0027] Wherein, in parts by weight, the biochar is 10 to 20 parts, the fulvic acid is 2 to 4 parts, and the compost organic fertilizer is 76 to 88 parts. According to a preferred embodiment, the mass ratio of the biochar to the fulvic acid is 3:1.

[0028] Biochar (BC) can increase carbon storage in the soil, improve soil permeability, and absorb nutrients in the soil. Fulvic acid (FA) can alleviate salt stress, promote plant root growth, and increase root absorption of nutrients. Biochar and fulvic acid contain carbon-based materials. Using biochar and fulvic acid as compost additives can change the composting process and improve the quality of compost. It increases the effective accumulated temperature and pH of the compost, reduces the electrical conductivity of the compost, effectively slows down the volatilization of ammonia during the composting process, increases the germination index, and increases the total nitrogen content. FA and FA+BC treatments significantly increased the total humus content of the compost. In addition, the addition of BC can increase the fluorescence index (FI) and humification index (HIX) of the compost, and the addition of BC and FA can increase the autogenic index (BIX) of the compost. Taking 15% biochar and 3% fulvic acid as an example, FA and FA+BC treatments significantly increased the total humus content of compost, increasing by 12.6% and 12.8% respectively, and the humic acid content of BC+HA treatment compost increased significantly by 38.9%, and the humic acid / fulvic acid ratio of all treatment composts increased by 8.2%-44.9%. Both BC and FA can improve the quality of compost, and the combination of the two can effectively reduce ammonia volatilization and increase the humic acid (HA) content of compost, which provides a new idea for improving compost efficiency and quality and alleviating the emission of harmful gases from compost.

[0029] According to a specific embodiment, the mass ratio of poultry manure to straw is (1-4):1. According to a preferred embodiment, the mass ratio of poultry manure to straw is (1-3):1, more preferably (1-2):1. The poultry manure mentioned includes but is not limited to chicken, duck, goose and other manure. The straw mentioned can be, for example, the straw of crops such as wheat, corn, rice, potato, rapeseed, cotton, sugarcane, etc.

[0030] The composting treatment time is 20 to 40 days, preferably 25 to 35 days, for example 30 days.

[0031] According to a specific embodiment, the composting treatment includes turning the compost mixture every 3-6 days, and adding a proper amount of water each time the compost is turned to keep the moisture content at 50-70%, preferably 55%-65%.

[0032] After the biochar, the fulvic acid and the compost organic fertilizer are mixed, the quality of the compost organic fertilizer can be improved, including at least one of the following:

[0033] (1) Increase total nitrogen and humus content;

[0034] (2) Reduce conductivity and ammonia volatilization;

[0035] (3) Improve germination index and adjust pH.

[0036] According to a specific embodiment, the quality of the compost organic fertilizer is compared to that without adding biochar and fulvic acid, and the germination index is improved by at least 20%. According to a preferred embodiment, the germination index is improved by at least 23%, 25%, 28%, 30%, 33%, 35%, 38%, 40%, 43%, 45%, 48%, 50%, etc.

[0037] In some embodiments of the present invention, the quality of the compost organic fertilizer is compared to that without adding biochar and fulvic acid, and the volatility of ammonia is reduced by at least 40%. According to a preferred embodiment, the volatility of ammonia is reduced by at least 43%, 45%, 48%, 50%, 53%, 55%.

[0038] In some embodiments of the present invention, the quality of the compost organic fertilizer is compared to that without adding biochar and fulvic acid, and the conductivity is reduced by at least 10%. According to a preferred embodiment, the conductivity is reduced by at least 12%, 15%, 18%, 20%, etc.

[0039] The technical scheme of the present invention is described below by specific examples. It should be noted that these examples are only used to facilitate the understanding of those skilled in the art and should not be regarded as limiting the scope of protection of the present invention. Unless otherwise specified, the reagents used in the examples can be obtained commercially.

[0040] Example 1

[0041] Example 1 The following experiment was designed to study the mixing of fulvic acid and biochar with compost. Chicken manure was purchased from Musen Fertilizer Industry, wheat straw was purchased from Huifeng Straw Agricultural Products Deep Processing, and wheat straw was crushed into 1-2 cm for later use. The biochar and fulvic acid used were purchased from Nanjing Qinfeng Straw Technology Co., Ltd.

[0042] Chicken manure and wheat straw were mixed in a fresh weight ratio of 1.5:1 and composted in a homemade compost box to make its initial moisture content 60%. The outer shell and liner of the box are made of PP material, and the center is made of EPS polystyrene foam, which has thermal insulation function. The size of each box is 640×490×70mm and the volume is 60L. The compost box consists of a closed cylindrical cover, a bracket, a temperature recorder, an air pump, etc.

[0043] Four composting treatments were designed, as shown below. During the composting process, the moisture content of the compost raw materials in each treatment was maintained at about 60%. The entire aerobic composting cycle was 30 days.

[0044]

[0045]

[0046] In the table, 3% and 15% are the mass fractions of fulvic acid and biochar in the total mass of the compost mixture, respectively.

[0047] The compost was turned on the 1st, 4th, 7th, 10th, 13th, 17th, 21st and 30th days of composting, and samples were taken from the pile and stored for future use. At the same time, during the composting period, a temperature recorder (RC-4) was used to record the temperature fluctuations in the upper, middle and lower parts of the compost. The average value was taken as the daily temperature, which was used to calculate the effective accumulated temperature of the compost.

[0048] Effective accumulated temperature formula: T = ∑(T i -T0)×Δt (1)

[0049] T i is the compost temperature at time i, T0 is the starting temperature (biological zero) when microorganisms in the compost multiply in large quantities, 15°C is taken as the biological zero of the composting reaction, Δt is T i Duration.

[0050] The experimental results are as follows Figure 1 As shown in (a), the ambient temperature ranged from 30.7 to 36.3°C during composting, and the dynamic change trends of all treatment composts in the three typical stages of warming period, high temperature period and maturity period were almost the same. The temperature of all treatment composts reached a peak value (68.1-70.5°C) within the first week, and dropped to near the ambient temperature and stabilized after the 29th day (30.4-32.9°C). The highest temperature of the CK, BC and BC+FA treatment composts appeared on the 4th day and the temperatures were close, while the highest temperature of the FA treatment compost appeared on the 3rd day and was lower than that of other treatments. Throughout the composting process, the effective accumulated temperature of all treatment composts was higher than that of CK, and the overall performance was BC>BC+FA>FA>CK.

[0051] Example 2

[0052] Example 2 A portion of the samples preserved in Example 1 were used to measure pH and electrical conductivity (EC).

[0053] The calculation methods of pH, conductivity and germination index (GI) are as follows:

[0054] About 2 g of fresh compost sample was taken and mixed with deionized water at a mass-to-volume ratio of 1:10. The mixture was shaken for 30 min and then allowed to stand for 10 min. After that, the filtrate was collected after centrifugation (30 min, 3200 rpm) and filtration, and then pH and EC were measured using a multi-parameter analyzer.

[0055] In addition, for each compost sample, weigh 10g of fresh sample, add 100mL of distilled water, shake for 1 hour, place at room temperature for 24 hours, and then filter. Take 5mL of filtrate, place it in a 9cm culture dish covered with filter paper, and sow 10 plump rape seeds. Cultivate in a constant temperature incubator at 28℃ for 48 hours, and distilled water is used as a control. The calculation formula is as follows: The following formula is calculated.

[0056] Germination Index Formula:

[0057] In the formula (2), R1 is the germination rate of seeds in compost extract (%), L1 is the root length of seeds in compost extract (mm), R2 is the germination rate of seeds in distilled water (%), and L2 is the root length of seeds in distilled water (mm).

[0058] The results of the test are as follows Figure 1 As shown in (b), the initial pH range of the compost was 6.57-6.74, and then rapidly increased to 8.38-8.71 in the first 4 days. From the 7th day to the end of composting, the pH was stable at 8.42-8.84. After entering the high temperature period (composting temperature was greater than 60°C), the pH of the composts treated with FA and BC was significantly higher than that of CK. At the end of the high temperature period, the pH of the composts treated with CK, except for CK, decreased to varying degrees. From the end of the maturity period (composting temperature was around 40°C) to the end of composting, the pH of the compost was BC>BC+FA>FA>CK, among which the pH of the composts treated with BC and BC+FA was significantly higher than that of CK. As shown in Figure 1 As shown in (b), the increase in compost pH in the initial stage was caused by the decomposition and ammoniaization of organic matter. Due to the alkalinity of biochar itself, the pH of the compost treated with biochar remained at a high level after 13 days and was significantly higher than that of the control group at the end of the maturity period.

[0059] Electrical conductivity (EC) reflects the soluble salt content of compost and is often used to determine the phytotoxicity of compost. Figure 1 As shown in (c), the conductivity of all treated composts increased from the initial 3.69-4.25 mS cm -1 , increased to 5.64-6.81mS cm at the end of composting -1 The conductivity of all treatment composts dropped to the lowest level (3.05-3.37 mS cm) on the 4th day. -1 ) and increased to a higher value (4.22-5.29 mS cm) at the end of the high temperature period. -1 ), and then slowly increased after entering the mature stage until the end of composting. There was no significant difference in the conductivity of the composts of each treatment at the lowest point, but from the end of the high temperature period to the end of composting, the conductivity of the CK and FA treatments was significantly higher than that of the BC and BC+FA treatments.

[0060] A GI greater than 50% is a characteristic of mature compost, while in order to avoid phytotoxicity of the compost, the GI should be greater than 80%. Figure 3 As shown in (c), the germination index of the composts treated with BC or BC+FA was significantly higher than that of the CK and FA treatments. In this study, although the GI of the compost treated with FA was greater than 50%, it did not reach the level of non-phytotoxicity. The GI of the composts treated with BC and BC+FA was significantly increased, reaching the level of non-phytotoxicity (germination index greater than 80%).

[0061] Example 3

[0062] Example 3 A portion of the samples of Example 1 were air-dried and ground to determine total nitrogen and total phosphorus. Ammonia (NH3) was collected at the same time to determine the volatilization amount of NH3.

[0063] The calculation method of total nitrogen and total phosphorus content is as follows:

[0064] Take an appropriate amount of dry sample to determine the total nitrogen and total phosphorus of the final compost product. The total nitrogen was determined by an elemental analyzer, and the total phosphorus was determined using inductively coupled plasma optical emission spectrometry (ICP-OES, Optima, TM8000, Perkin Elmer).

[0065] Ammonia was collected once a day for the first 24 days, and once every two days thereafter (8:00-9:00 in the morning and 15:00-16:00 in the afternoon). NH3 was captured at the outlet of the fermenter with 2% boric acid by mass, then titrated with dilute sulfuric acid (0.01 M), and the cumulative NH3 volatilization flux was calculated.

[0066] The experimental results showed that after the composting was completed, the total nitrogen content of the composts treated with FA, BC and BC+FA was significantly higher than that of CK (P<0.05), among which the total nitrogen content of the compost treated with FA was the highest (2.30%, Figure 3 -a). Unlike total nitrogen, there was no significant difference in total phosphorus content among the treatment composts ( Figure 3 -b).

[0067] Adding biochar and fulvic acid can significantly increase the total nitrogen content of compost ( Figure 3 -a), both of which can fix nitrogen in compost by adsorption or complexation, reducing nitrogen volatilization and leaching, which is also reflected in the results of cumulative NH3 volatilization flux ( Figure 2 -b).

[0068] NH3 volatilization is an effective indicator for evaluating composting rate and is also the main form of nitrogen loss that affects compost quality. The NH3 volatilization flux changes in the composts of each treatment were similar ( Figure 2During the warming and high temperature periods, the NH3 volatilization flux of all treatment composts was the lowest (24.08-74.90 kg hm -2 d -1 ) appeared on the third day, with the highest value except CK (765.10-1385.73kghm -2 d -1 ) appeared on the 6th day. Before entering the maturity stage, the NH3 volatilization flux of CK was higher than that of other treatments (except the 6th day); after entering the maturity stage, the NH3 volatilization flux of all treatment composts decreased to a lower value and maintained until the end of composting. During the entire composting process, the cumulative NH3 volatilization flux was expressed as BC+FA <FA<BC<CK( Figure 2 -b). At the end of composting, the cumulative NH3 volatilization fluxes of FA, BC and FA+BC treatments were reduced by 44.85%, 27.64% and 48.11% compared with CK ( Figure 2 -a).

[0069] Example 4

[0070] Example 4 Total humic substances (HSs), humic acid (FA) and fulvic acid (HA) were measured on a portion of the samples of Example 1.

[0071] The determination methods of HSs, HA and FA are as follows:

[0072] Weigh 2.50 g of air-dried compost sample sieved through a 60-mesh sieve and transfer it to a 250 mL conical flask. Add 50 mL of NaOH-Na2P2O7 extract (0.1 M NaOH + 0.1 M Na2P2O7, volume ratio 1:1) and spin at 180 r·min at 25 °C. -1 After shaking, transfer the extract into a centrifuge tube and centrifuge at 6000 r / min. -1 Centrifuge for 10 minutes and collect the supernatant. Repeat the same steps for the residual sample three times, combine the supernatants obtained each time, filter, dilute and measure TOC, which is the total humus content.

[0073] Take about 20.00 mL of the supernatant obtained in the previous step and place it in a small beaker. Slowly add 6 mol·L -1 HCl solution and continue stirring with a glass rod until a flocculent precipitate is formed. Then place the small beaker in a 70℃ constant temperature water bath and keep it for 30 minutes to allow the humic acid to fully precipitate, and then leave it at room temperature overnight. The next day, filter or centrifuge the sample in the beaker, and the resulting precipitate is washed with 0.01mol·L -1Wash with HCl solution until the filtrate is colorless. The supernatant obtained is the fulvic acid solution, and the precipitate is humic acid. After diluting the fulvic acid solution, its content is determined using a TOC meter; the humic acid content is calculated by subtracting the total humus and fulvic acid content. Each sample is measured in triplicate, and the results are expressed as the average of the three measurements.

[0074] HSs are the main organic carbon pool in the soil and play an important role in promoting soil structure formation and nutrient accumulation. HA and FA are two important components of HSs. HA has a more significant effect on improving soil structure, retaining water and fertilizer, and maintaining long-term soil health, while FA plays a greater role in improving short-term nutrient absorption by plants. Generally, an increase in the HA content in compost means that the humification degree of the compost has deepened, indicating that the compost is developing towards a more mature stage. After the composting is completed, the HSs contained in the compost, such as Figure 4 As shown in (a), the HSs content of the composts treated with FA and BC+FA was significantly higher than that of the composts treated with BC and CK. Compared with CK, the FA content of the composts treated with FA was significantly increased, while the FA content of the composts treated with BC and BC+FA was significantly decreased ( Figure 4 -b); Among all treatments, the HA content of the compost in the BC+FA treatment was significantly higher than that in the CK and BC treatments ( Figure 4 -c), the HA / FA values ​​of the composts treated with BC and BC+FA were significantly higher than those of CK ( Figure 4 -d). Generally speaking, mature compost contains higher HA content and lower FA content. The higher the HA ratio, the better the quality of humus (which is important for the maintenance of soil nutrients and the formation of soil structure). Therefore, BC and BC+FA treatments can promote the maturity and stability of compost and improve the quality of compost.

[0075] Example 5

[0076] Example 5 Soluble organic matter (DOM) and its components were determined for a portion of the samples in Example 1. The calculation method of DOM is as follows:

[0077] 5 g of compost sample was dissolved in 50 mL of deionized water (ratio 1:10, w / v), and after shaking for 24 h, the extract was centrifuged at 6000 rpm for 15 min and then filtered through a 0.45 μm membrane. Three-dimensional fluorescence emission matrix (3D-EEM) with emission wavelength (EM) in the range of 200-900 nm and excitation wavelength (EX) in the range of 200-900 nm was used to analyze different types of dissolved organic matter (DOM) in the samples. Based on the EEM data, the volume percentage of DOM was calculated by a numerical method and divided into five regions: aromatic protein I (EX: 220-250nm; EM: 280-330nm), aromatic protein II (EX: 220-250nm; EM: 330-380nm), fulvic acid-like substances (EX: 220-250nm; EM: 380-550nm), soluble microbial metabolic byproducts (EX: 250-450nm; EM: 280-380nm) and humic acid-like substances (EX: 250-450nm; EM: 380-550nm).

[0078] In addition, three key fluorescence characteristic parameters, namely fluorescence index (FI), autogenic index (BIX) and humification index (HIX), were determined. By decomposing the EEM spectra into multiple independent fluorescence components, we applied parallel factor analysis (PARAFAC) to establish a model that helps track the origin of DOM and the changes in each component.

[0079] Figure 5 (a) shows the relative contents of four components, including component 1 (Ex / Em=350nm / 440nm, humus-like), component 2 (Ex / Em=395nm / 494nm, humus-like affected by the dark culture environment of lakes), component 3 (Ex / Em=295nm / 418nm, terrestrial humus) and component 4 (Ex / Em=330nm / 396nm, marine humus). The addition of biochar and fulvic acid significantly changed the fluorescence intensity of each DOM component in the compost. Among them, the fluorescence intensity of component 1, component 3 and component 4 in the FA and BC+FA treated composts was significantly increased compared with the control group, increasing by 10.56%, 15.12% and 30.21% respectively, while the BC treatment was the opposite, decreasing by 17.89%, 15.51% and 16.91% respectively. In addition, although the fluorescence intensity of component 3 in the BC+FA treated compost was significantly reduced, component 4 was significantly increased. There was no significant change in the fluorescence intensity of component 2 in the composts of each treatment. To further evaluate the effect of adding biochar and fulvic acid on the quality of compost, the fluorescence parameters BIX, FI and HIX ( Figure 5-b). Compared with CK, the BIX of all treatments increased significantly, among which the BIX of BC+FA treatment was the highest (0.6298), significantly higher than other treatments. The autogenic index (BIX) can characterize the relative proportion of autogenic sources of DOM. The higher the BIX value, the stronger the autogenic characteristics of DOM in the compost, that is, DOM is more derived from biological activities rather than the input of external organic matter. Adding fulvic acid and biochar can increase the microbial activity in the compost ( Figure 5 -b), promoting the degradation and transformation of organic matter in the compost to form DOM through microbial degradation and transformation. The FI and HIX of the BC treatment were significantly higher than those of the CK, while the opposite was true for the BC+FA treatment; in addition, the HIX of the FA-treated compost was significantly lower than that of the CK. The fluorescence index (FI) is an indicator to measure the ratio of aromatic amino acids to non-aromatic compounds in DOM, which can be used to indicate the origin and decomposition level of humus in DOM. Due to the highly aromatic characteristics of biochar, the addition of biochar delivers more aromatic compounds to the compost, resulting in an increase in the FI of the compost. The humification index (HIX) indicates the degree of humification of DOM, and the high or low index reflects the relative content of humus in DOM and the complexity of the molecular structure. When the HIX value is higher, it means that the higher the degree of humification, the more complex the molecular structure in DOM. Adding biochar alone can increase the humification degree of the compost, while the addition of fulvic acid reduces the humification degree of the compost, but the increase (2.84%) and decrease (1.49%-1.53%) are not large ( Figure 5 -b).

[0080] This study showed that the use of fulvic acid and biochar as compost additives can provide a new and beneficial method for improving the efficiency and quality of aerobic composting, including increasing total nitrogen and HSs content, reducing conductivity and NH3 volatilization, improving germination index and adjusting pH. These advantages help to enhance the retention of nutrients during composting, reduce the emission of harmful gases and reduce the production of phytotoxicity. In addition, the addition of FA can increase the content of DOM in compost, and the addition of BC can improve the humification degree of compost. The addition of fulvic acid and biochar alone has different focuses on improving the quality of compost. The simultaneous addition of both comprehensively optimizes various indicators related to compost quality and has the best effect of reducing NH3 volatilization and increasing HA content.

[0081] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "specific implementation methods", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Those of ordinary skill in the art can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for improving the quality of compost organic fertilizer and reducing ammonia emissions, characterized in that: include: adding biochar and fulvic acid to composted organic fertilizer for composting, wherein the composted organic fertilizer includes compost mixed with poultry manure and straw; In parts by weight, the biochar is 10 to 20 parts, the fulvic acid is 2 to 4 parts, and the compost organic fertilizer is 76 to 88 parts.

2. The method according to claim 1, characterized in that The mass ratio of the poultry manure to the straw is (1-4):

1.

3. The method according to claim 1, characterized in that: The water content is maintained at 50-70% during the composting process.

4. The method according to claim 1, characterized in that: The composting time is 20 to 40 days.

5. The method according to claim 1, characterized in that: The composting treatment includes turning the compost mixture every 3-6 days, and adding a proper amount of water each time the compost is turned to keep the water content at 50-70%.

6. The method according to claim 1, characterized in that The composting treatment comprises turning the compost on the first, fourth, seventh, tenth, thirteenth, seventeenth, twenty-first and thirtyth days of the composting treatment, and adding a proper amount of water each time the compost is turned to keep the water content at 55-65%.

7. The method according to claim 1, characterized in that The quality of the compost organic fertilizer is improved compared to the compost organic fertilizer without adding biochar and fulvic acid, including at least one of the following: (1) Increase the content of total nitrogen and humus (HSs); (2) Reduce electrical conductivity (EC) and ammonia volatilization; (3) Improve the germination index (GI) and adjust the pH.

8. The method according to claim 7, characterized in that The quality of the compost organic fertilizer is compared with that without adding biochar and fulvic acid, and the germination index is improved by at least 20%.

9. The method according to claim 7, characterized in that: The quality of the compost organic fertilizer is compared with that without adding biochar and fulvic acid, and the volatilization amount of ammonia is reduced by at least 40%.

10. The method according to claim 7, characterized in that The quality of the compost organic fertilizer is compared with that without adding biochar and fulvic acid, and the conductivity is reduced by at least 10%.

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