A method for reducing carbon and nitrogen emissions and nutrient loss during liquid manure storage.

Abstract

This invention discloses a method for reducing carbon and nitrogen emissions and nutrient loss during liquid manure storage. By storing liquid poultry and livestock manure containing plant tannin extracts under natural atmospheric and static conditions, this invention reduces carbon and nitrogen emissions and nutrient loss during storage, increases the fertilizer value of the liquid manure, and improves its physicochemical properties and stability. The plant tannin extracts are natural plant extracts, environmentally friendly and non-toxic, with low cost and simple operation, making them suitable for large-scale application. This invention provides a highly efficient and environmentally friendly liquid manure storage technology for the livestock and poultry farming industry, and offers a sustainable liquid manure management solution.

Description

Technical Field

[0001] This invention relates to the field of agricultural waste treatment technology, specifically to a method for reducing carbon and nitrogen gas emissions and nutrient loss during the storage of liquid manure. The method aims to reduce gas emissions (such as ammonia, methane, carbon dioxide, and nitrous oxide) and nutrient loss during the storage of liquid manure by utilizing plant tannin extracts, thereby improving the storage quality and resource utilization efficiency of liquid manure. Background Technology

[0002] With the continued growth in global demand for animal products and the large-scale expansion of the livestock industry, the production of livestock and poultry manure has increased dramatically. According to FAO (2022) statistics, livestock farming contributes 14.5% of global greenhouse gas emissions (GHG), of which CH4 emissions account for more than 90%. In China, approximately 4 billion tons of livestock and poultry manure are generated annually, and although the comprehensive utilization rate reaches 76%, more than 900 million tons are still not effectively treated.

[0003] Livestock manure refers to the general term for solid and liquid excrement from livestock and poultry. It can be divided into two types: solid and liquid. Liquid livestock manure refers to the liquid excrement from livestock and poultry, mainly including feces and urine, and wastewater. Feces and urine refer to the liquid excrement, while wastewater refers to the wastewater formed by mixing feces with drinking water, bathing water, etc. Liquid livestock manure contains a large amount of nutrients such as nitrogen, phosphorus, and potassium, making it an important fertilizer and energy resource. Through storage, liquid manure can be centrally treated and utilized for resource recovery. Chicken manure, as a major byproduct of poultry farming, becomes a significant source of environmental pollution during its storage. The storage of liquid manure is a significant source of NH3, CH4, and N2O emissions, with CH4 emissions accounting for 39.0%–72.0% and NH3 emission coefficients accounting for 10.0%–18.5% of total ammonia nitrogen (TAN). Furthermore, the volatilization of nitrogen and loss of carbon during the storage of liquid manure directly reduce the agricultural value of manure, increase processing costs, and exacerbate the environmental burden.

[0004] To reduce gas emissions during liquid manure storage, existing technologies mainly include mulching, acidification, and biochar application. Mulching (such as wooden covers or straw) can reduce NH3 emissions by 51%–94%, but may increase N2O emissions, and the CH4 reduction effect is unstable (33%–39%). Acidification (such as sulfuric acid) can significantly reduce NH3 and CH4 emissions, but the operation is complex and poses safety risks. Although biochar can adsorb NH3, its emission reduction effect fluctuates significantly and may even unexpectedly increase emissions. Existing technologies generally suffer from problems such as failure of synergistic emission reduction, complex operation, and alteration of manure characteristics, necessitating the development of new, natural, stable, and multi-functional additives.

[0005] Tannic acid (TA), a natural plant extract, is widely found in plants such as chestnut, white oak, caragana, and grape. Its hydroxyl / phenolic group structure endows it with biodegradability and environmental friendliness. Therefore, developing an efficient and environmentally friendly liquid manure storage technology based on tannic acid is of great significance for reducing greenhouse gas emissions and improving the utilization rate of manure resources. Summary of the Invention

[0006] The purpose of this invention is to provide a method for reducing carbon and nitrogen gas emissions and nutrient loss during liquid manure storage. This method optimizes liquid manure storage conditions by efficiently utilizing plant tannin extracts, suppressing the emission of harmful gases such as NH3, CO2, CH4, and N2O during storage, while simultaneously reducing nitrogen and carbon losses and enhancing the fertilizer value of the liquid manure. This invention aims to solve the problems of high gas emissions, severe nutrient loss, and complex operation in existing liquid manure storage technologies, providing a sustainable liquid manure management solution for livestock and poultry farming.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for reducing carbon and nitrogen gas emissions during the storage of liquid waste, comprising the following steps:

[0009] Liquid poultry and livestock manure containing plant tannin extracts is stored under natural atmospheric and static conditions to reduce carbon and nitrogen emissions.

[0010] The plant tannin extract is one or both of chestnut tannin extract and white oak tannin extract;

[0011] The carbon and nitrogen gases are one or more of ammonia, methane, carbon dioxide, and nitrous oxide.

[0012] In the above-mentioned method for reducing carbon and nitrogen gas emissions during liquid manure storage, the liquid livestock and poultry manure is further described as liquid chicken manure, liquid cow manure, liquid pig manure, or liquid duck manure. For example, the liquid chicken manure is fresh chicken liquid manure from an egg-laying chicken farm.

[0013] The liquid poultry and livestock manure has a moisture content >60%, such as 87.9%; the term moisture content refers to the percentage of water by mass in the liquid poultry and livestock manure.

[0014] On a dry matter basis, the mass of the plant tannin extract is 0.15% to 10% of the total mass of the liquid livestock and poultry manure, such as 0.5%.

[0015] Specifically, fresh liquid manure taken from the liquid manure storage tank of a large-scale (individual) chicken farm is placed in a homemade storage box, and plant tannin extract is added to the storage box.

[0016] The tannin extract contains 60% to 85% tannins by mass, such as 75% or 85%.

[0017] The plant tannin extract is the dry matter of an aqueous extract;

[0018] The storage time is ≥30 days;

[0019] The reduction of carbon and nitrogen emissions is manifested in reducing the emission rate and / or cumulative emissions.

[0020] In the above-mentioned method for reducing carbon and nitrogen gas emissions during the storage of liquid manure, as an example, the liquid livestock and poultry manure is liquid chicken manure;

[0021] The reduction of carbon and nitrogen emissions refers to reducing the ammonia emission rate; the storage time is 30 to 60 days; the plant tannin extract is *Acer buergerianum* tannin extract, *Cephalotaxus fortunei* tannin extract, or a mixture of *Acer buergerianum* tannin extract and *Cephalotaxus fortunei* tannin extract in a mass ratio of 1:(0.5 to 1), preferably a mixture of *Acer buergerianum* tannin extract and *Cephalotaxus fortunei* tannin extract in a mass ratio of 1:1; or...

[0022] The reduction of carbon and nitrogen emissions refers to the reduction of cumulative ammonia emissions. The storage time is 30 to 60 days. The plant tannin extract is angelica tannin extract, chestnut tannin extract, or a mixture of angelica tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1), preferably a mixture of angelica tannin extract and chestnut tannin extract in a mass ratio of 1:1; or, preferably a mixture of angelica tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1), more preferably a mixture of angelica tannin extract and chestnut tannin extract in a mass ratio of 1:1; or,

[0023] The reduction of carbon and nitrogen emissions refers to reducing the carbon dioxide emission rate; the storage time is 30 to 60 days; the plant tannin extract is *Acer buergerianum* tannin extract, *Cinnamomum camphora* tannin extract, or a mixture of *Acer buergerianum* tannin extract and *Cinnamomum camphora* tannin extract in a mass ratio of 1:(0.5 to 1), preferably *Acer buergerianum* tannin extract; or...

[0024] The reduction of carbon and nitrogen emissions refers to the reduction of cumulative carbon dioxide emissions. The storage time is 30 to 60 days. The plant tannin extract is angelica tannin extract, chestnut tannin extract, or a mixture of angelica tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1), preferably angelica tannin extract; or,

[0025] The reduction of carbon and nitrogen emissions is to reduce the global warming potential. The storage time is 30 to 60 days. The plant tannin extract is scutellaria baicalensis tannin extract, chestnut tannin extract, or scutellaria baicalensis tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1), preferably scutellaria baicalensis tannin extract.

[0026] Secondly, the present invention provides a method for reducing nutrient loss during the storage of liquid manure, comprising the following steps:

[0027] Liquid poultry and livestock manure containing plant tannin extracts is stored under natural atmospheric and static conditions to reduce nutrient loss during the storage process.

[0028] The plant tannin extract is one or both of chestnut tannin extract and white oak tannin extract;

[0029] The reduction of nutrient loss during the storage of liquid feces is reflected in increasing the NH4 content of the liquid feces. + -N content, increase NO3 in liquid feces — One or more of the following: N content, increasing the organic matter content of liquid feces, and increasing the total nitrogen content of liquid feces.

[0030] In the above-mentioned method for reducing nutrient loss during the storage of liquid manure, the liquid livestock and poultry manure is further defined as liquid chicken manure, liquid cow manure, liquid pig manure, or liquid duck manure.

[0031] The liquid poultry and livestock manure has a moisture content >60%, such as 87.9%;

[0032] On a dry matter basis, the mass of the plant tannin extract is 0.15% to 10% of the total mass of the liquid livestock and poultry manure, such as 0.5%.

[0033] The tannin extract contains 60% to 85% tannins by mass, such as 75% or 85%.

[0034] The plant tannin extract is the dry matter of an aqueous extract;

[0035] The storage time is ≥30 days.

[0036] In the above-mentioned method for reducing nutrient loss during the storage of liquid manure, as an example, the liquid livestock and poultry manure is liquid chicken manure;

[0037] The reduction of nutrient loss during the storage of liquid feces is achieved by increasing the NH4 content of the liquid feces. + -N content, the storage time is 60 days, the plant tannin extract is chestnut tannin extract, white oak tannin extract or white oak tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5~1), preferably chestnut tannin extract;

[0038] The improvement of the storage quality of liquid feces is to increase NO3. — The nitrogen content, the storage time is 60 days, and the plant tannin extract is chestnut tannin extract, white oak tannin extract or white oak tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5-1), preferably white oak extract;

[0039] The reduction of nutrient loss during the storage of liquid manure is to increase the organic matter content of the liquid manure. The storage time is 60 days. The plant tannin extract is angelica tannin extract or a mixture of angelica tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5-1), preferably angelica extract.

[0040] The reduction of nutrient loss during the storage of liquid manure is achieved by increasing the total nitrogen content. The storage time is 60 days. The plant tannin extract is chestnut tannin extract, white pine tannin extract, or white pine tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5-1), preferably white pine tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5-1), and more preferably white pine tannin extract and chestnut tannin extract in a mass ratio of 1:1.

[0041] Thirdly, the present invention provides a method for reducing the conductivity of liquid poultry and livestock manure during storage, comprising the following steps:

[0042] Liquid poultry and livestock manure containing plant tannin extracts was stored under natural atmospheric and static conditions to reduce the electrical conductivity of the liquid poultry and livestock manure during storage.

[0043] The plant tannin extract is one or both of chestnut tannin extract and white oak tannin extract.

[0044] In the above-mentioned method for reducing the conductivity of liquid poultry and livestock manure during storage, the liquid poultry and livestock manure is further defined as liquid chicken manure, liquid cow manure, liquid pig manure, or liquid duck manure.

[0045] The liquid poultry and livestock manure has a moisture content >60%, such as 87.9%;

[0046] On a dry matter basis, the mass of the plant tannin extract is 0.15% to 10% of the total mass of the liquid livestock and poultry manure, such as 0.5%.

[0047] The tannin extract contains 60% to 85% tannins by mass, such as 75% or 85%.

[0048] The plant tannin extract is the dry matter of an aqueous extract;

[0049] The storage time is ≥30 days.

[0050] In the above-mentioned method for reducing the conductivity of liquid poultry and livestock manure during storage, as an example, the liquid poultry and livestock manure is liquid chicken manure, and the storage time is 30 to 60 days; preferably, the storage time is 60 days, and the plant tannin extract is chestnut tannin extract, white pine tannin extract, or white pine tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1), preferably white pine tannin extract or chestnut tannin extract.

[0051] Fourthly, the present invention provides the use of plant tannin extracts in at least one of the following:

[0052] 1) Reduce carbon and nitrogen gas emissions during the storage of liquid poultry and livestock manure, wherein the carbon and nitrogen gases are one or more of ammonia, methane, carbon dioxide, and nitrous oxide;

[0053] 2) Reduce nutrient loss during the storage of liquid poultry and livestock manure. This reduction in nutrient loss during the storage of liquid manure is reflected in increasing the NH4 content of the liquid manure. + -N content, increase NO3 in liquid feces — One or more of the following: N content, increasing liquid fecal organic matter content, and increasing liquid fecal total nitrogen content;

[0054] 3) Reduce the electrical conductivity of liquid poultry and livestock manure during storage;

[0055] 4) Reduce the abundance of Firmicutes during the storage of liquid poultry and livestock manure, and / or enrich Actinobacteria and / or Ascomycota during the storage of liquid poultry and livestock manure;

[0056] The plant tannin extract is one or both of chestnut tannin extract and white oak tannin extract.

[0057] Furthermore, the plant tannin extract is chestnut tannin extract, white pine tannin extract, or white pine tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5-1), such as white pine tannin extract and chestnut tannin extract in a mass ratio of 1:1.

[0058] In this invention, the plant tannin extract is the dry matter of an aqueous extract, specifically the dry matter obtained by concentrating and drying extracts from chestnut extracts and / or queebracho extracts obtained through aqueous extraction. The aqueous extraction method can specifically involve using water as a solvent, and dissolving the tannins in the plant wood through soaking and heating. As an example, the chestnut wood tannin extract and the white oak wood tannin extract were provided by Italian company Swarovski-Guangzhou Swarovski Technology Co., Ltd., and their preparation method is as follows: (1) First, find relevant wood from the forest (80% of the wood comes from the Piedmont and Liguria regions); (2) Transport the wood to Swarovski's factory and cut it according to local forestry regulations; (3) Crush the trunk into small pieces to increase the surface area for water extraction of tannin; (4) Impregnate the wood chips with hot water. This process is usually carried out in a closed reactor to ensure precise control of temperature and pressure: add the crushed wood chips to a reactor containing hot water (80°C to 100°C) in a certain proportion (the liquid-solid ratio is usually between 5:1 and 10:1); maintain this temperature for several hours to more than ten hours to promote the effective dissolution of tannin; during this period, it is necessary to stir regularly to ensure that the wood chips are evenly impregnated, and monitor the color change of the impregnation liquid. Dark brown is preferred, indicating that the tannin components are being effectively released; finally, a dark brown liquid is released from it. Body: Tannin; (5) Transfer the impregnation liquid to the evaporator and remove excess water by heating and evaporation; the evaporation process requires strict temperature control (not exceeding 60°C to 80°C) to avoid damage to the tannin structure by high temperature; at the same time, by monitoring the physical properties such as the density or refractive index of the liquid, determine the required tannin concentration; once the predetermined concentration is reached, stop heating immediately and prepare to proceed to the next step; (6) Atomize the concentrated liquid into tiny droplets through a high-pressure nozzle and then spray it into a high-temperature (150°C to 200°C) airflow; the high-temperature airflow quickly removes the water in the droplets, drying them into powder; during the spray drying process, the airflow temperature and outlet temperature (generally between 70°C and 90°C) must be precisely controlled to ensure the complete drying of the powder and avoid overheating; the dried powder is collected by a high-efficiency collection system such as a cyclone separator or a bag filter to ensure the purity and yield of the product; (7) Finally, a tannin extract with a wide range of applications in different fields is formed, and the corresponding tannin is extracted according to the different raw materials.

[0059] In this invention, the liquid feces (liquid feces) of livestock and poultry refers to the excrement of livestock and poultry in farms, including urine, feces and drinking water, etc.

[0060] The present invention has the following beneficial effects:

[0061] (1) Reduce carbon and nitrogen emissions: Use plant tannins to regulate the microbial community structure in liquid manure, reduce the emission of carbon and nitrogen gases (such as ammonia, carbon dioxide, methane and nitrous oxide, etc.), and reduce the greenhouse effect.

[0062] (2) Nutrient Stabilization: Plant tannin extracts can efficiently retain nutrients during the storage of liquid manure, improving its fertilizer value. Specifically, this is manifested in enhancing the nitrogen retention (NH4+) of liquid manure. + -N and TN) and enhance the stability of liquid fecal nitrogen (promoting NO3-) - -N accumulation promotes the degradation of organic matter (OM) in liquid manure and improves the composting process.

[0063] (3) Plant tannin extracts improve the physicochemical properties of liquid feces and enhance its stability.

[0064] (4) Environmentally friendly and economical: Plant tannin extract is a natural plant extract that is environmentally friendly and non-toxic, with low cost and simple operation, making it suitable for large-scale application.

[0065] (5) Promote sustainable development: Provide a high-efficiency and environmentally friendly liquid manure storage technology for the livestock and poultry farming industry, and provide a sustainable liquid manure management solution. Attached Figure Description

[0066] Figure 1 This is a photograph of the liquid manure storage and gas storage device used in the embodiments of the present invention.

[0067] Figure 2 The effects of adding plant tannins on the physicochemical properties of liquid manure during storage are described in the embodiments of this invention: a-temperature, b-electrical conductivity (EC), c-NH4+. + -N, d-NO3 — N, e-organic matter (OM), f-total nitrogen (TN), among which, Figure 2 The curve labels in bf are the same Figure 2 a.

[0068] Figure 3 This embodiment of the invention describes the effect of plant tannins on the emission rates of NH3, CO2, CH4 and N2O during the storage of liquid manure.

[0069] Figure 4 This embodiment of the invention describes the effect of plant tannins on the cumulative emissions of NH3, CO2, CH4 and N2O during the storage of liquid manure.

[0070] Figure 5 This is a comparison of the effects of plant tannins on the global warming potential during liquid manure storage in embodiments of the present invention.

[0071] Figure 6These are Venn petal diagrams of bacterial (a) and fungal (b) characteristics under different tannin treatments in this invention, as well as the relative abundance at the phylum level for bacteria (c) and fungi (d). Note: Duncan's post-hoc test was used, * indicates P < 0.05 significant difference, ** indicates P < 0.01 extremely significant difference, and *** indicates P < 0.001 extremely significant difference. Detailed Implementation

[0072] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0073] Unless otherwise specified, the methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0074] The sources of the raw materials in the following examples are as follows:

[0075] The liquid manure used was collected from large-scale (individual) chicken farms in Quzhou County, Hebei Province, and fresh chicken liquid manure was selected as the main raw material.

[0076] The tannin content in chestnut wood extract and white oak extract was 75 wt% and 85 wt%, respectively.

[0077] Example 1

[0078] In this embodiment, plant tannins were added to chicken manure and stored for more than 30 days. Temperature, weight and sampling were carried out during the storage period to observe the effects of plant tannins on the physicochemical properties and carbon and nitrogen emissions of the manure during storage.

[0079] I. Experimental Methods

[0080] Prepare 0.5% *Albizia julibrissin* extract (CT), 0.5% *Caragana korshinskii* extract (HT), and a mixed solution (MIX) of 0.25% *Albizia julibrissin* extract and 0.25% *Caragana korshinskii* extract (all solvents were distilled water, and the concentration of each solution was 250 g / L). During the experiment, each treatment group thoroughly mixed the above solutions with the matrix. All additives were formulated based on dry matter weight ratios. 0.25% and 0.5% represent the percentage of fresh weight of the matrix (substrate). During the experiment, the fresh weight of the matrix for all treatment groups was 10 kg. The amount of *Albizia julibrissin* tannin added to the CT group was 50 g, the amount of *Caragana korshinskii* tannin added to the HT group was 50 g, and the amount of *Albizia julibrissin* tannin added to the MIX group was 25 g and 25 g of *Caragana korshinskii* tannin added respectively. Specific steps are as follows:

[0081] (1) Collection of liquid manure: Fresh liquid manure was collected in a storage tank by scraping the chickens at an egg-laying chicken farm in Quzhou County, Hebei Province, and then sampled to obtain fresh chicken liquid manure. The physicochemical properties of the raw material chicken liquid manure are shown in Table 1.

[0082] Table 1. Basic Physicochemical Properties of Raw Materials

[0083]

[0084] Note: Values ​​are expressed as mean ± standard deviation.

[0085] (2) The experiment was conducted in the laboratory, and four different treatment groups were designed: control group (CK, fresh chicken manure), CT group (chicken manure + 0.5% white pine tannin), HT group (chicken manure + 0.5% chestnut tannin), and MIX group (chicken manure + 0.25% white pine tannin + 0.25% chestnut tannin).

[0086] (3) Static storage: Each group contained 10 kg of liquid feces with a dry weight of 1.21 kg (i.e., a moisture content of 87.9%). The liquid feces from the control group and each experimental group were uniformly mixed with tannic acid according to the mass ratio and then placed in a self-made storage device (size: 45cm×25cm×20cm) (see...). Figure 1 It can be stored in the atmosphere under static conditions for 60 days.

[0087] (4) Gas Collection and Analysis

[0088] Greenhouse gas sampling device: The storage device has a sampling port on top - the cover is equipped with a three-way valve suitable for collecting gas samples with a syringe, and uses a self-made gas sampling system. Figure 1 ).

[0089] Collection time: Daily from 2:30 PM to 3:30 PM, once daily. At 10, 30, and 50 minutes after sealing, gas was drawn from the chamber using a 60 mL polypropylene gas syringe and transferred to a 100 mL airtight bottle, repeated three times. The collected gas samples were stored in airtight bottles, and the concentration of greenhouse gases was determined using gas chromatography.

[0090] Ammonia determination: For NH3 emissions, before measurement, use the hollow support inside the container to fix a small cup containing 30 ml of 2% (w / v) boric acid at a height of about 1 cm above the fecal surface to absorb NH3. After sealing for 60 minutes, remove the cup, add methyl red-bromocresol green indicator, and then titrate with 1% (v / v) sulfuric acid solution. Record the titration volume, determine the NH3-N concentration, and finally calculate the NH3 emission rate and cumulative emission amount.

[0091] (5) Sample processing and analysis

[0092] Fecal samples were collected from different locations using a spoon, mixed, and then measured in triplicate. After each sampling, the liquid feces were reconstructed using a stick. Throughout the storage process, the feces remained undisturbed, and three subsamples were collected from each treatment at days 0, 9, 19, 30, 45, and 60. Each liquid fecal sample (80 g) was divided into three portions, one of which was stored at -20°C for physicochemical analysis (EC, NH4). + -N, NO3 - The sample (containing -N, OM, and TN) was partially stored at -80°C for microbial community analysis, and the other portion was dried in a 60°C oven and ground into 1 mm particles for elemental analysis (P, K).

[0093] (6) Indicator Explanation

[0094] Tannic acid, a natural polyphenol compound, possesses significant antioxidant and antibacterial activities, effectively regulating carbon (C) and nitrogen (N) emissions during chicken manure storage. The effect of tannic acid in inhibiting greenhouse gas emissions was assessed by monitoring the emissions of carbon dioxide (CO2), methane (CH4), ammonia (NH3), and nitrous oxide (N2O). Specific indicators included:

[0095]

[0096] Where FGHGs is the emission rate (mg / kg) of CO2, CH4, or N2O. -1 d -1 ), dC / dt is the slope of the line (mg m -3 h -1 The observation time for the change of gas concentration in the container over time, where V is the headspace volume of the container (m³). 3 T0 represents the standard absolute temperature (K), T represents the actual ambient temperature (°C), m represents the fresh weight of the liquid chicken manure (kg), and θ represents the moisture content of the liquid chicken manure. The unit for cumulative discharge is g / kg. -1 I represents the number of days (d) of liquid manure storage.

[0097] The formulas for calculating NH3 emission rate and cumulative emissions are as follows:

[0098]

[0099] Where F NH3 NH3 emission rate (mg kg) -1 d -1 V is the volume of the boric acid solution (L), and C is the concentration of NH3-N in the boric acid (mg / L). -1), where m is the weight of fresh feces (kg), θ is the moisture content of the feces, and t is the measurement time (h). The unit for cumulative discharge is (g·kg). -1 ); I is the number of days (d) of liquid manure storage.

[0100] Global Warming Potential (GWP) is an important indicator for measuring the impact of greenhouse gases on global warming. The calculation formula is as follows:

[0101]

[0102] Where E CH4 The cumulative emissions of CH4 (g kg) -1 E N2O Cumulative emissions of N2O (g kg) -1 E NH3 Cumulative emissions of NH3-N (g kg) -1 The total CO2 equivalent (GWP) was calculated using multiplication factors of 34 for CH4 and 298 for N2O, with an indirect N2O emission factor of 1% for NH3.

[0103] II. Experimental Results

[0104] (1) Physicochemical properties

[0105] Changes in the physicochemical properties of liquid manure during storage are shown in the figure. Figure 2 .like Figure 2 As shown, this invention reveals the regulatory effect of tannin treatment on the physicochemical properties of liquid feces during storage through multi-index dynamic monitoring.

[0106] During storage, the temperature of liquid feces in all treatment groups fluctuated with environmental conditions but remained consistently below ambient temperature, with temperature ranges of: 17.00–30.50℃ (CK), 16.30–29.50℃ (CT), 16.20–28.90℃ (HT), and 16.20–29.10℃ (MIX). Figure 2 a) The dynamic change in conductivity (EC) showed an initial decrease, followed by a rebound after day 30, reaching a peak of 5.21 mS / cm in the CK group on day 60. -1 Compared with the CK group, on day 60, the tannin-treated group (CT: 3.72 mScm) -1 HT: 4.65mS cm -1 MIX: 4.50mS cm -1 The EC values ​​of these three groups decreased by 28.59% (P<0.05), 31.80% (P<0.05), and 13.78%, respectively. Figure 2 b).

[0107] NH4 in each treatment group + -N continues to decrease ( Figure 2 c) Initially, NH4 in each treatment group + -N concentration ranged from 27.27 to 31.57 g / kg. -1 Finally (Day 60) NH4 + -N concentrations were 0.33 (CK), 0.37 (CT), 0.70 (HT), and 0.62 g / kg, respectively. -1 (MIX), and the HT treatment was significantly higher than the CK treatment by 113.12% (P<0.01). Furthermore, NO3 in the CK, HT, and MIX groups... - -N content exhibits a three-phase change pattern. Figure 2 d). By day 60, NO3 in the CT, HT, and MIX groups - -N levels were significantly lower than those in the CK group (63.39 mg / kg). -1 The percentages were 85.43% (P<0.01), 83.59% (P<0.01), and 73.95% (P<0.01) higher.

[0108] The organic matter (OM) and total nitrogen (TN) contents in the tannin-treated groups showed similar trends, with OM content rebounding after day 45, while the CK group continued to decline. Figure 2 e). The degradation rates of organic matter (OM) reached 13.06% (CK), 8.41% (CT), 15.39% (HT), and 13.95% (MIX) on day 60, respectively. Figure 2 e). In this invention, the total nitrogen (TN) content reaches its lowest value on day 45 and then rises rapidly (e). Figure 2 f). Final (day 60) CT (31.98 g / kg) -1 ), HT (34.88g kg) -1 ) and MIX (36.18g kg) -1 The TN values ​​of the CK group all exceeded those of the CK group (30.69 g / kg). -1 The MIX group showed a significant increase of 17.89% (P<0.05).

[0109] (2) Emission rates of NH3, CO2, CH4 and N2O

[0110] The emission rates of NH3, CO2, CH4 and N2O during liquid sewage storage are shown in the figure. Figure 3 .Depend on Figure 3 It can be seen that during the storage of liquid feces, the NH3 emissions from each treatment showed a trend of first increasing and then decreasing, with the peak emission period concentrated in the first 20 days. Figure 3a) On day 16, the NH3 emission rates of the CT, HT, and MIX treatments reached peak values ​​of 85.09, 88.41, and 94.59 mg·kg⁻¹, respectively. -1 ·d –1 All were lower than the control CK (108.44 mg·kg⁻¹). -1 ·d –1 CO2 emissions are concentrated and at a high rate during the first 25 days, then gradually decrease. Figure 3 b). Throughout the storage period, the CO2 emission rates of the CK, CT, HT, and MIX treatments ranged from 3.99 to 29.54 g·kg⁻¹. -1 ·d –1 2.89-20.56 g·kg -1 ·d –1 3.70-22.82 g·kg -1 ·d –1 5.03-19.69 g·kg -1 ·d –1 During the initial storage period, CT and MIX treatments reduced CH4 emissions compared to CK (248.43 mg / kg). -1 d-1) decreased by 38.75% (152.17 mg kg) -1 d-1) and 53.93% (114.46 mg kg) -1 d-1)( Figure 3 c) In contrast, HT temporarily increased CH4 emissions by 67.25% (415.50 mg / kg) on ​​day 3. -1 d-1). After day 40, CH4 emissions from all treatments stabilized at 7.06 mg kg. -1 Below day 1, this continues for up to 60 days. N2O emissions exhibit a synchronous release pattern with CO2 emissions in the first 25 days. Figure 3 (b, d). By day 50, the N2O emission rate stabilized at 1.32–1.39 μg kg. -1 d-1.

[0111] (3) Cumulative emissions of NH3, CO2, CH4 and N2O

[0112] The cumulative emissions of NH3, CO2, CH4 and N2O during liquid sewage storage are shown in the figure. Figure 4 After a 60-day storage period, tannin treatment significantly reduced the cumulative emissions of NH3 and CO2. Figure 4 (a, b) The NH3 emissions from CT, HT, and MIX treatments were 2119.38, 1919.58, and 1883.94 mg·kg, respectively. -1 ( Figure 4 a) Compared with the CK group (2434.25 mg·kg),-1 The CO2 emissions from the CT, HT, and MIX treatments were significantly reduced by 12.94% (P<0.05), 21.14% (P<0.05), and 22.61% (P<0.01), respectively. The cumulative CO2 emissions from the CT, HT, and MIX treatments were 431.47, 568.90, and 539.96 g·kg⁻¹, respectively. -1 Compared with the CK group (638.53 g·kg) -1 All three parameters showed extremely significant reductions of 32.43%, 10.90%, and 15.43% (P<0.01). Figure 4 b). In this study, CT showed the strongest CH4 emission reduction effect, with a cumulative emission reduction of 51.44% (CK: 4687.28 mg·kg). - 1)(P<0.01; Figure 4 c). In contrast, the HT and MIX treatments also showed significant CH4 emission reduction effects. There was no significant difference in cumulative N2O emissions among the treatments (CK: 105.01 μg kg). -1 CT: 106.08 μg kg -1 HT: 105.19 μg kg -1 MIX: 105.00 μg kg -1 P>0.05; Figure 4 d).

[0113] (4) Global warming potential

[0114] Global warming potential during liquid fecal storage is shown in [reference needed]. Figure 5 .Depend on Figure 5 It can be seen that CH4 emissions dominated the greenhouse effect across all treatment groups, accounting for 92.42–96.37% of the total GWP, followed by NH3 (3.61–7.54%), while the contribution of N2O was negligible. Specifically, the greenhouse effects caused by CH4 emissions in the CK, CT, HT, and MIX treatments were 159.37, 77.38, 152.89, and 109.81 kgCO2-eq t, respectively. -1 The greenhouse effects caused by NH3 emissions are 7.25, 6.32, 5.72, and 5.61 kg CO2-eq t, respectively. -1 The greenhouse effect caused by N2O emissions is 0.03 kg CO2 - eq t -1 Furthermore, the global warming potential (GWP) of the CT, HT, and MIX groups was reduced by 49.76% (P<0.05), 9.57%, and 32.27% respectively compared to the CK group.

[0115] (5) Relative abundance of microbial communities

[0116] Based on OTU analysis Figure 6(a) and (b) tannic acid treatment significantly altered the microbial community specificity in the liquid fecal storage system. Except for the MIX group, the number of unique bacterial OTUs in the other treatment groups (CK, CT, HT) decreased significantly over time. Figure 6 a). By day 60, the number of unique bacterial OTUs was highest in the MIX group (823), while it decreased to the lowest in the CK group (620). The fungal community showed the opposite trend: the number of unique fungal OTUs was significantly reduced in the MIX group (92), while it increased in other treatment groups, with the CT group reaching the maximum (396). Figure 6 b). On day 60, the dominant bacterial phyla in all treatment groups were Firmicutes, Bacteroidetes, Actinobacteriota, Proteobacteria, Desulfobacterota, Synergistota, and Patescibacteria, accounting for a total of 98.01%-98.76%. Figure 6 c). Tannic acid treatment significantly reduced the abundance of Firmicutes (3.85%-14.13% lower than CK, P<0.05), with the lowest proportion in the MIX group (30.57%). CT and HT treatments significantly enriched Actinobacteria (3.24% and 3.71% higher than CK, respectively). The fungal community was dominated by Ascomycota, Basidiomycota, unclassified Fungi, and Mortierellomycota (98.96%-99.46%). Figure 6 d). Tannic acid treatment significantly enriched Ascomycota (CT group increased by 14.83%).

[0117] In summary, the results above demonstrate that the application of the plant tannin extract of this invention in reducing gas emissions and nutrient loss during liquid manure storage is specifically reflected in the following aspects:

[0118] (1) Tannin treatment significantly inhibited electrolyte accumulation and reduced salt accumulation. By day 60, the conductivity (EC) of the CT, HT, and MIX groups was significantly lower than the peak value of the CK group (5.21 mS / cm). -1 The levels decreased by 28.59% (3.72 mS cm) respectively. -1 ), 31.80% (4.65mS cm) -1 ) and 13.78% (4.50 mS cm -1 The HT group showed the largest decrease (P<0.05).

[0119] (2) Tannin treatment alters the nitrogen transformation pathway, delaying ammonium nitrogen loss and promoting nitrate nitrogen accumulation through a dual regulatory mechanism, and NH4 in the HT and MIX groups + -N retention was significantly better in the HT group than in the CK group. After 60 days of storage, the NH4 content in the HT group was significantly higher. + -N concentration (0.70 g kg) -1 Compared to CK (0.33g kg) -1 The NO3 level increased by 113.12% (P<0.01) in the CT, HT, and MIX groups, while the NO3 level in these groups also decreased. - -N level was lower than CK (63.39 mg / kg) -1 The percentages increased by 85.43%, 83.59%, and 73.95%, respectively (all P < 0.01).

[0120] (3) Tannin treatment accelerates the decomposition of recalcitrant organic matter, and the combined nitrogen-fixing effect of compound tannins (MIX) is the best. Among them, the HT group has the highest OM degradation rate of 15.39%, while the TN content of the MIX group is 36.18 g / kg. -1 Compared to CK (30.69g kg) -1 The percentage increased significantly by 17.89% (P<0.05).

[0121] (4) Tannin treatment significantly reduced NH3 and CO2 emissions. The cumulative NH3 emissions in the CT and HT groups were significantly lower than those in the CK group (2434.25 mg / kg). -1 The concentrations decreased by 12.94% (2119.38 mg / kg) respectively. -1 ) and 21.14% (1919.58 mg kg) -1 (All P<0.05), while the CO2 emission reduction effect was the most prominent in the CT group (431.47g kg). -1 Compared to CK (638.53g kg) -1 The CH4 emissions in the CT group decreased significantly by 32.43% (P<0.01). Furthermore, the cumulative CH4 emissions in the CT group (4687.28 mg / kg) were significantly reduced. -1 It decreased by 51.44% (P<0.01).

[0122] (5) Tannins improve the greenhouse effect by regulating CH4 emissions; the global warming potential (GWP) of the CT group is lower than that of the CK group (166.65 kg CO2-eq t). -1 The carbon and nitrogen emissions were significantly reduced by 49.76% (P<0.05), with CH4 contributing 95.3% to the reduction. The GWP of the MIX group decreased by 32.27%, demonstrating the technological advantage of compound tannin treatment in the synergistic reduction of carbon and nitrogen emissions.

[0123] (6) Tannic acid treatment significantly altered the microbial community structure in the liquid manure storage system, thereby affecting its functional characteristics. Bacterial community analysis showed that tannic acid treatment (especially the MIX group) maintained a high number of unique OTUs, while the control group (CK) showed a significant decrease, indicating that tannic acid may optimize the storage environment by regulating microbial diversity. Regarding dominant bacteria, tannic acid treatment significantly reduced the abundance of Firmicutes (decreased by 3.85%-14.13%), while enriching Actinobacteriota, with increases of 3.24% and 3.71% in the CT and HT groups, respectively, suggesting that tannic acid may inhibit the growth of certain gas-producing bacteria while promoting the colonization of beneficial bacteria. The trend of fungal community changes was opposite to that of bacteria. Tannic acid treatment (e.g., the CT group) significantly increased the abundance of Ascomycota (+14.83%), while the unique fungal OTUs decreased in the MIX group, suggesting that different treatments had different effects on the fungal community. In summary, tannic acid may synergistically inhibit the emission of NH3, CO2, and CH4 by reshaping the composition of the microbial community (such as reducing Firmicutes, enriching Actinobacteria, and Ascomycota), providing a microbiological basis for reducing the release of greenhouse gases and pollutants during the storage of manure.

[0124] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A method for reducing carbon and nitrogen gas emissions during the storage of liquid feces, characterized in that, Includes the following steps: Liquid poultry and livestock manure containing plant tannin extracts is stored under natural atmospheric and static conditions to reduce carbon and nitrogen emissions. The plant tannin extract is one or both of chestnut tannin extract and white oak tannin extract; The carbon and nitrogen gas is one or more of ammonia, carbon dioxide, and nitrous oxide.

2. The method for reducing carbon and nitrogen gas emissions during liquid manure storage according to claim 1, characterized in that: The liquid poultry and livestock manure is liquid chicken manure, liquid cow manure, liquid pig manure, or liquid duck manure; and / or, The liquid poultry and livestock manure has a water content >60%; and / or, On a dry matter basis, the mass of the plant tannin extract is 0.15% to 10% of the total mass of the liquid poultry and livestock manure; and / or, The tannin extract contains 60%–85% tannins by mass; and / or, The plant tannin extract is the dry matter of an aqueous extract; and / or, The storage time is ≥30 days; and / or, The reduction of carbon and nitrogen emissions during the liquid manure storage process is manifested in reducing the emission rate and / or cumulative emission amount.

3. The method for reducing carbon and nitrogen gas emissions during liquid manure storage according to claim 2, characterized in that: The reduction of carbon and nitrogen gas emissions during the liquid manure storage process is to reduce the ammonia emission rate. The storage time is 30 to 60 days. The plant tannin extract is scutellaria barbata tannin extract, chestnut tannin extract, or scutellaria barbata tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1).

4. The method for reducing carbon and nitrogen gas emissions during liquid manure storage according to claim 3, characterized in that: The plant tannin extract is composed of white oak tannin extract and chestnut tannin extract in a mass ratio of 1:

1.

5. The method for reducing carbon and nitrogen gas emissions during liquid manure storage according to claim 2, characterized in that: The reduction of carbon and nitrogen gas emissions during the liquid manure storage process is to reduce the cumulative ammonia emissions. The storage time is 30 to 60 days. The plant tannin extract is angelica tannin extract, chestnut tannin extract, or angelica tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1).

6. The method for reducing carbon and nitrogen gas emissions during liquid manure storage according to claim 5, characterized in that: The plant tannin extract is composed of white oak tannin extract and chestnut tannin extract in a mass ratio of 1:

1.

7. The method for reducing carbon and nitrogen gas emissions during liquid manure storage according to claim 2, characterized in that: The reduction of carbon and nitrogen gas emissions during the liquid manure storage process is to reduce the carbon dioxide emission rate. The storage time is 30 to 60 days. The plant tannin extract is scutellaria barbata tannin extract, chestnut tannin extract, or scutellaria barbata tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1).

8. The method for reducing carbon and nitrogen gas emissions during liquid manure storage according to claim 2, characterized in that: The reduction of carbon and nitrogen gas emissions during the liquid manure storage process is to reduce the cumulative carbon dioxide emissions. The storage time is 30 to 60 days. The plant tannin extract is scutellaria barbata tannin extract, chestnut tannin extract, or scutellaria barbata tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1).

9. The method for reducing carbon and nitrogen gas emissions during liquid manure storage according to claim 2, characterized in that: The reduction of carbon and nitrogen emissions during the liquid manure storage process is to reduce the global warming potential. The storage time is 30 to 60 days. The plant tannin extract is sclerotium tannin extract, chestnut tannin extract, or sclerotium tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5 to 1).

10. A method for reducing nutrient loss during liquid manure storage, characterized in that, Includes the following steps: Liquid poultry and livestock manure containing plant tannin extracts is stored under natural atmospheric and static conditions to reduce nutrient loss during the storage process. The plant tannin extract is one or both of chestnut tannin extract and white oak tannin extract; The reduction of nutrient loss during liquid manure storage is reflected in increasing the NH4 content of the liquid manure. + -N content, increase NO3 in liquid feces - One or more of the following: -N content, increasing the total nitrogen content of liquid feces.

11. The method for reducing nutrient loss during liquid manure storage according to claim 10, characterized in that: The liquid poultry and livestock manure is liquid chicken manure, liquid cow manure, liquid pig manure, or liquid duck manure; and / or, The liquid poultry and livestock manure has a water content >60%; and / or, On a dry matter basis, the mass of the plant tannin extract is 0.15% to 10% of the total mass of the liquid poultry and livestock manure; and / or, The tannin extract contains 60%–85% tannins by mass; and / or, The plant tannin extract is the dry matter of an aqueous extract; and / or, The storage time is ≥30 days.

12. The method for reducing nutrient loss during liquid manure storage according to claim 11, characterized in that: The reduction of nutrient loss during liquid manure storage is achieved by increasing the NH4 content of the liquid manure. + -N content, the storage time is 60 days, and the plant tannin extract is chestnut tannin extract, white pine tannin extract or white pine tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5~1).

13. The method for reducing nutrient loss during liquid manure storage according to claim 11, characterized in that: The reduction of nutrient loss during liquid manure storage is to increase NO3. - -N content, the storage time is 60 days, and the plant tannin extract is chestnut tannin extract, white pine tannin extract or white pine tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5~1).

14. The method for reducing nutrient loss during liquid manure storage according to claim 11, characterized in that: The reduction of nutrient loss during liquid manure storage is to increase total nitrogen content. The storage time is 60 days. The plant tannin extract is chestnut tannin extract, white oak tannin extract, or white oak tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5-1).

15. The method for reducing nutrient loss during liquid manure storage according to claim 14, characterized in that: The plant tannin extract is composed of white oak tannin extract and chestnut tannin extract in a mass ratio of 1:

1.

16. A method for reducing the conductivity of liquid poultry and livestock manure during storage, characterized in that, Includes the following steps: Liquid poultry and livestock manure containing plant tannin extracts was stored under natural atmospheric and static conditions to reduce the electrical conductivity of the liquid poultry and livestock manure during storage. The plant tannin extract is one or both of chestnut tannin extract and white oak tannin extract.

17. The method for reducing the conductivity of liquid poultry and livestock manure during storage according to claim 16, characterized in that: The liquid poultry and livestock manure is liquid chicken manure, liquid cow manure, liquid pig manure, or liquid duck manure; and / or, The liquid poultry and livestock manure has a water content >60%; and / or, On a dry matter basis, the mass of the plant tannin extract is 0.15% to 10% of the total mass of the liquid poultry and livestock manure; and / or, The tannin extract contains 60%–85% tannins by mass; and / or, The plant tannin extract is the dry matter of an aqueous extract; and / or, The storage time is ≥30 days.

18. The method for reducing the conductivity of liquid poultry and livestock manure during storage according to claim 17, characterized in that: The storage period is 30 to 60 days.

19. The method for reducing the conductivity of liquid poultry and livestock manure during storage according to claim 18, characterized in that: The storage time is 60 days, and the plant tannin extract is chestnut tannin extract, white pine tannin extract, or white pine tannin extract and chestnut tannin extract in a mass ratio of 1:(0.5-1).

20. The use of plant tannin extracts in at least one of the following: 1) Reduce carbon and nitrogen gas emissions during the storage of liquid poultry and livestock manure, wherein the carbon and nitrogen gases are one or more of ammonia, carbon dioxide, and nitrous oxide; 2) Reduce nutrient loss during the storage of liquid poultry and livestock manure. This reduction in nutrient loss during the storage of liquid poultry and livestock manure is reflected in increasing the NH4 content of the liquid manure. + -N content, increase NO3 in liquid feces - One or more of the following: -N content, increasing the total nitrogen content of liquid feces; 3) Reduce the conductivity of liquid poultry and livestock manure during storage; 4) Reduce the abundance of Firmicutes during the storage of liquid poultry and livestock manure, and / or enrich Actinobacteria and / or Ascomycota during the storage of liquid poultry and livestock manure; The plant tannin extract is one or both of chestnut tannin extract and white oak tannin extract.

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