Gardening waste compost, preparation method thereof, and method for preparing cultivation soil using the compost

Abstract

The application discloses a kind of garden greening waste compost, its preparation method, and the method for preparing cultivation soil using compost, the garden greening waste of the present application is mixed uniformly with kaolin, and then is subjected to composting fermentation treatment, to prepare garden greening waste compost;Compost is mixed uniformly with soil to obtain cultivation soil.The organic matter of the waste compost of the present application is completely decomposed, the humus content is high, the quality of compost product is improved, and after the compost prepared by the method of the present application is applied or mixed with soil, not only has the effect of holding stable organic matter such as humus, but also provides a good and stable substrate environment for plant growth;It also improves the carbon sequestration and emission reduction capacity of compost product and cultivation soil, increases the holding of soil organic carbon and the storage capacity of soil carbon pool.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for utilizing garden greening waste, in particular to a composting method for garden greening waste, a prepared compost and a cultivation soil. BACKGROUND

[0002] Composting has become the main method for treating garden greening waste. The urban green area in China is continuously increasing, and a large amount of garden greening waste mainly composed of natural litter, pruned branches and leaves, and dead plant residues is generated, thus the problem of treating and utilizing the waste arises. The early treatment methods such as incineration and landfill are gradually eliminated due to their pollution and land resource occupation.

[0003] Degree of decomposition is the degree of composting of compost, i.e. the degree of stable humus formed after the mineralization and humification of organic matter in compost. In a certain sense, the humus content of compost determines the quality of compost. Through the degradation of microorganisms, the compost with high humus content is stabilized and harmless, and when applied, it does not bring adverse effects to crop growth and soil microbial activity. In the existing composting process of garden greening waste, the high content of lignocellulose which is difficult to degrade makes the compost product have low humic acid content, which leads to the fact that the existing compost, after being applied to the soil, not only provides a large amount of fresh carbon and nitrogen sources for microorganisms, stimulates microbial activity, but also increases the release of CO2 in the soil, causing the stability of soil organic carbon to decrease.

[0004] Currently, few studies on additives for composting of garden greening waste involve the influence of compost on carbon emission (i.e. CO2 release). Among the commonly used additives for composting of garden greening waste, for example, microbial additives can directly change the dominant population of microorganisms in compost, and introduce microorganisms with stronger decomposition ability and stronger stress resistance, which can more directly accelerate the composting process. However, after these microorganisms enter the soil with the compost, the activity of the original carbon-fixing microorganisms in the soil decreases, the mineralization activity of the soil increases, and the soil's ability to fix carbon and other nutrients decreases. For example, feces, kitchen garbage and sludge adjusting agents can accelerate the start-up and subsequent sustained temperature rise of compost, but they will release a large amount of greenhouse gases, causing environmental pollution, and the heavy metal substances in them will also reduce the quality of compost. SUMMARY

[0005] The purpose of the present invention is to address the problems of low cellulose degradation rate, low humic acid content, accelerated soil CO2 release and reduced soil carbon stability in the existing use of garden waste compost. The present invention provides a composting method for garden waste, prepared compost and cultivation soil prepared using the compost. The compost prepared by the method of the present invention is low in price and simple in method, promotes the decomposition of organic matter (especially cellulose, hemicellulose and lignin) in garden waste and has a high humus content; it has a good fixation effect on stable organic matter such as humus, improves the quality of the compost product, and provides a good and stable matrix environment for plant growth; and the prepared cultivation soil or the soil after applying the waste compost of the present invention has improved carbon sequestration and emission reduction capabilities, increases the fixation of soil organic carbon and soil carbon storage, and is of great significance to achieving the long-term goal of national carbon neutrality.

[0006] To achieve the purpose of the present invention, the present invention provides a composting method for landscaping waste, comprising mixing the landscaping waste and kaolin evenly and then performing a pile fermentation treatment.

[0007] The mass ratio of the landscaping waste to kaolin is 100:(7-15), preferably 100:10.

[0008] In particular, landscaping waste refers to natural fallen matter, pruned branches and leaves, and dead plant remains in urban green spaces.

[0009] In particular, the raw material greening waste is crushed into particles with a particle size of 5-20 mm and then mixed with kaolin.

[0010] In particular, the main mineral component of the kaolin is kaolinite, and the chemical formula is 2SiO2·Al2O3·2H2O.

[0011] In particular, the kaolin has a particle size of 80±2 μm, a pH of 6.7-7.6, a moisture content of <0.5%, a SiO2 content of 52±0.5%, and an Al2O3 content of 45±0.5%.

[0012] In particular, before the pile fermentation treatment, the C / N value of the mixed material of landscaping waste and kaolin is adjusted to 25-30.

[0013] In particular, during the pile fermentation process, the moisture content of the fermentation material in the pile is controlled to be 60-70%.

[0014] In particular, during the pile fermentation process, the pile is watered and turned every 5-7 days so that the moisture content of the fermented material in the pile is 60%-70%.

[0015] In particular, during the composting process, if the temperature of the pile remains above 50°C for at least 10 days and the temperature of the pile drops below 40°C and no longer rises, the compost is mature.

[0016] Another aspect of the present invention provides a landscaping waste compost prepared according to the above method.

[0017] The pH of the garden waste compost is 7-8; the EC value is 1.2-2.0 mS / cm; the total nitrogen content is 2-3%; the total organic matter content is 50-55%; the total humic acid content is 3.5-5%, of which fulvic acid content is 1.5-2%; and the humic acid content is 2-3%.

[0018] In particular, the total nitrogen content of the garden waste compost reaches 20-22 g / kg; the total organic matter content reaches more than 500 g / kg; the humic acid content reaches more than 39 g / kg; the fulvic acid content reaches more than 18 g / kg; and the humic acid content reaches more than 21 g / kg.

[0019] In particular, the carbon-nitrogen ratio of the landscaping waste compost is lower than 16, preferably 13-15.

[0020] Another aspect of the present invention provides a method for preparing cultivation soil from gardening waste compost, comprising uniformly mixing the gardening waste compost prepared according to the above method with soil in a mass ratio of (1-10):100.

[0021] The garden waste compost is air-dried and crushed to a size of 0.2 mm or less and mixed evenly with the air-dried soil in proportion.

[0022] Particularly, the moisture content of the garden waste compost after air-drying is 5-8%; the moisture content of the soil after air-drying is 2-3%.

[0023] Another aspect of the present invention provides a cultivation soil prepared according to the above method.

[0024] The method for composting garden waste comprises the following steps: mixing the garden waste with kaolinite to obtain compost material; and aerobically fermenting the compost material to obtain the compost.

[0025] Landscaping waste mainly consists of natural fallen leaves, pruned branches and leaves, and dead plant remains in urban green spaces.

[0026] Kaolin is a common clay mineral in nature. Its main mineral component is kaolinite, and its chemical formula is 2SiO2·Al2O3·2H2O.

[0027] The landscaping waste is crushed to a particle size of 5-20mm.

[0028] Kaolin particle size ≤ 0.15mm, effective content ≥ 97%.

[0029] The dry mass ratio of landscaping waste to kaolin is 10:1.

[0030] The weight ratio of the carbon source C and the nitrogen source N in the pile is adjusted to 25-35:1.

[0031] During the fermentation process, watering is used to control the moisture content of the product to be between 60% and 70%.

[0032] The temperature of the pile was measured every 3 days and the pile was watered and turned every 6 days.

[0033] Water and turn the pile to control the moisture content at 60%-70%.

[0034] The temperature of the pile should be above 50°C for at least 10 days. When the temperature of the pile drops below 40°C and does not rise any more, the compost is considered mature.

[0035] The multiple effects of clay mineral additives in the composting process and product application can solve the above problems. Kaolin is a relatively common type of clay mineral. On the one hand, it can adsorb free substrates and enzymes to form a suitable decomposition site for microorganisms, promote the decomposition of organic matter, and increase the humus content of compost products. On the other hand, it can react with active functional groups in humus through active atomic groups and chemical bonds to form organic and inorganic composite colloids. After compost application, it can achieve the effect of fixing stable organic matter such as humus, and improve the carbon sequestration and emission reduction capacity of compost products.

[0036] To address the problems of low lignocellulose degradation and humic acid content in garden waste compost, and the accelerated release of CO₂ from soil and reduced soil carbon stability after application of the compost product to the soil, the present invention promotes the degradation of lignocellulose in garden waste compost by adding kaolin, thereby increasing the fulvic acid and total humic acid content in the garden waste compost. Furthermore, the application of the garden waste compost reduces the impact of soil organic carbon mineralization, reduces soil CO₂ release, enhances carbon sequestration capacity, and improves soil organic carbon stability.

[0037] Compared with the prior art, the present invention has the following advantages and benefits:

[0038] 1. The preparation method of the garden waste compost of the present invention is simple and easy to operate, and the composting fermentation conditions are mild, which is suitable for promotion;

[0039] 2. The kaolin added during the fermentation process of preparing compost in the present invention not only absorbs free substrates and enzymes, forming a suitable site for decomposition activities of microorganisms, promoting the decomposition of organic matter, and increasing the humus content of the compost product; it also reacts with active functional groups in the humus through active atomic groups and chemical bonds to form organic and inorganic composite colloids, achieving the effect of fixing stable organic matter such as humus after the compost is applied, thereby improving the carbon sequestration and emission reduction capabilities of the compost product.

[0040] 3. The compost product of the present invention has high quality and fully decomposes organic matter, especially the degradation rates of cellulose, hemicellulose and lignin are significantly improved. The degradation rates of hemicellulose, cellulose and lignin reach 27.64%, 55.82% and 21.93%, respectively, which are 4.70%, 5.82% and 5.13% higher than those in compost without adding kaolin.

[0041] 4. The compost of this invention has high levels of total organic matter and humus, with total humic acid reaching 39.83 g / kg, humic acid reaching 21.30 g / kg, and fulvic acid reaching 18.53 g / kg. Kaolin enhances the compost's ability to absorb and retain humic acid, particularly fulvic acid.

[0042] 5. Application of the compost of the present invention or cultivation soil obtained by mixing the compost of the present invention with soil reduces the mineralization rate of soil organic carbon and reduces the cumulative mineralization amount; while the organic carbon content of the soil increases, and the soil carbon sequestration capacity increases; and the content of PAC, a low-oxidation active component of soil organic carbon, increases, thereby improving soil stability.

[0043] The compost product of the present invention reduces the mineralization rate of organic carbon in cultivated soil, reduces the cumulative mineralization amount, increases the organic carbon content in soil, and improves the carbon sequestration capacity of soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The temperature curves of the compost pile under two treatment methods for landscaping waste;

[0045] Figure 2 This is a curve diagram showing the changes in the cumulative mineralization of soil organic carbon under two treatments in the soil incubation experiment;

[0046] Figure 3 This is a curve diagram showing the change of soil organic carbon mineralization rate under two treatments in the soil incubation experiment;

[0047] Figure 4 This is the result of measuring total organic carbon content in soil under two treatments in soil incubation experiment;

[0048] Figure 5 This is an analysis chart of the proportion of oxidized and stable components of soil organic carbon in the two treatments of the soil incubation experiment. DETAILED DESCRIPTION

[0049] The present application will be further described below in connection with specific embodiments, and its advantages and features will be more apparent from the description. However, these embodiments are only exemplary, and do not constitute any limitation on the scope of the present application. Those skilled in the art should understand that modifications or substitutions can be made to the details and forms of the technical solutions of the present application without departing from the spirit and scope of the present application, and such modifications and substitutions all fall within the protection scope of the present application.

[0050] Example 1 Pretreatment of landscaping waste

[0051] 1. Collection of compost raw materials

[0052] The landscaping waste was collected from Beijing Xiangshan Park in summer and autumn of 2021, including natural litter, pruned branches and leaves, and dead plant residues in the park.

[0053] The plant species in the landscaping waste included Ginkgo biloba, Pinus tabulaeformis, Cotinus coggygria, Platycladus orientalis, Sabina chinensis, Pinus bungeana, Robinia pseudoacacia, Malus toringoides, Prunus armeniaca, Broussonetia papyrifera, Acer truncatum, Koelreuteria paniculata, Prunus persica, Salix matsudana, Ulmus pumila, Aesculus chinensis, Gleditsia sinensis, Buxus microphylla, Forsythia suspensa, etc.

[0054] In addition to the landscaping waste collected from Beijing Xiangshan Park, other landscaping, agroforestry, and fishery waste are also suitable for the present application.

[0055] The kaolin and urea were obtained from commercial sources, wherein: the kaolin had a particle size of 80±2 μm, a pH of 6.7-7.6, a water content of <0.5%, a SiO2 content of 52±0.5%, and an Al2O3 content of 45±0.5%; the urea had a particle size of 1.18 mm-3.35 mm, and a total nitrogen content of ≥46.0%.

[0056] 2. Composting raw material crushing treatment

[0057] After the landscaping waste was air-dried, a diesel-driven crusher was used for the first crushing treatment to a particle size of less than 50 mm, and then an electric-driven vertical blade crusher was used for the second crushing treatment to a particle size of 5-20 mm of landscaping waste fragments.

[0058] 3. Determination of physicochemical properties of landscaping waste fragments

[0059] 3-1) Determination of water content

[0060] 100 g of landscaping waste fragment sample was oven-dried at 65°C to a constant weight, and the difference in sample weight before and after drying was the water content of the sample. The determination results are shown in Table 1.

[0061] 3-2) pH and electrical conductivity (EC)

[0062] A sample of 5 g of dried garden waste was weighed into a plastic bottle and extracted with deionized water at a solid-liquid ratio of 1:10. After oscillation for 1 h, the supernatant was taken and the pH and EC of the sample were measured using a pH meter and a conductivity meter, respectively. The measurement results are shown in Table 1.

[0063] 3-3) Total organic carbon content (TOC)

[0064] The TOC was measured by potassium dichromate volumetric method (dilution heat method). A sample of 0.05 g of dried garden waste after being sieved through a 0.2 mm sieve was added with 10 ml of 1 mol / L potassium dichromate solution and 20 ml of concentrated sulfuric acid. After the sample was fully reacted, o-phenanthroline indicator was added, and the solution was titrated with 0.5 mol / L ferrous sulfate solution. The TOC was calculated according to formula (1), and the measurement results are shown in Table 1.

[0065] The total organic carbon content (TOC) was calculated according to formula (1):

[0066]

[0067] In formula (1), c is the concentration of the ferrous sulfate solution (mol / L); V0 is the volume of the ferrous sulfate solution used for blank titration (ml); V is the volume of the ferrous sulfate solution used for sample titration (ml); m is the mass of the dried sample (g); and 1.33 is the oxidation correction coefficient.

[0068] 3-4) C / N

[0069] The C / N is the ratio of the total organic carbon content (TOC) to the total nitrogen content (TN). The total nitrogen content (TN) was measured using a Kjeldahl apparatus, and the calculation results are shown in Table 1.

[0070] 3-5) Seed germination index (GI)

[0071] A sample of 5 g of dried garden waste was weighed into a plastic bottle and extracted with deionized water at a solid-liquid ratio of 1:10. After oscillation for 1 h, the supernatant was taken and 5 ml of the supernatant was added to a culture dish lined with filter paper; at the same time, 5 ml of deionized water was also added to a culture dish lined with filter paper as a control treatment. Twenty cabbage seeds were placed in each culture dish, and the culture dishes were incubated in a dark incubator at 25°C for 48 h. The germination rate and root length of the garden waste sample and the control treatment were measured, and the GI value was calculated according to formula (2). The measurement results are shown in Table 1.

[0072]

[0073] In formula (2), l is the average seed root length (mm); g0 is the germination rate of the control treatment seeds (%); and g is the germination rate of the sample seeds (%).

[0074] Table 1: Basic properties of the test garden greening waste:

[0075] Density (kg / m 3 )]]> Moisture content (%) TOC (g / kg) C / N pH EC (mS / cm) GI 242.75 34.67 489.108 60.1 7.57 0.956 0.933

[0076] Example 2 Composting of landscaping waste

[0077] 1. Composting arrangement

[0078] The test site for composting landscaping waste is a greenhouse, which is a single-building single-film greenhouse covering an area of ​​more than 280 square meters. There are manual roller shutters on both sides of the greenhouse for ventilation.

[0079] Choose a suitable location and clean the cement floor, ensuring there is sufficient space to water and turn the pile.

[0080] Use a plastic box of known volume (e.g. 20L) to take out 1m 3 The landscaping waste was weighed and recorded (242.75 kg), and the density of the raw material was calculated, see Table 1.

[0081] 2. Compost raw material preparation

[0082] 2-1) Measure 1m 3 The landscaping waste fragments are used for composting, and the weight of the landscaping waste fragments is weighed (242.75 kg); and the landscaping waste fragments are set aside;

[0083] 2-2) Calculate the moisture content of 1m 3 The dry mass of landscaping waste debris is 158.59 kg;

[0084] 2-3) Weighing kaolin (15.86 kg) in an amount corresponding to 10% (typically 7-15%) of the absolute dry weight of the garden waste fragments, and adding the kaolin to the garden waste fragments and mixing uniformly;

[0085] In addition to 10% of the absolute dry weight of the landscaping waste fragments, other addition amounts of kaolin, such as 7-15%, are also applicable to the present invention.

[0086] 2-4) Weigh 7.43 g of urea and add it to the raw materials (garden waste and kaolin) to adjust the C / N ratio of the pile to 30 (typically 25-30). Calculate the amount of nitrogen required to adjust the C / N ratio to 30 based on the original organic matter content and total nitrogen content of the raw materials. Assuming a urea nitrogen content of 46%, the required urea content is 7.43 g.

[0087] 2-5) After the raw materials (green waste fragments, kaolin, and urea) are evenly mixed, they are piled in a greenhouse to form a nearly conical compost pile with a bottom surface of r = 1m and h = 1m;

[0088] 3. Compost fermentation treatment

[0089] Water the compost pile to control the moisture content of the raw materials in the pile to 65±5% (i.e. 60%-70%); carry out compost fermentation treatment, wherein, during the fermentation process

[0090] The pile body temperature is measured every three days. In the specific embodiment of the present invention, the pile body temperature measurement at around 11:00 am is used as an example for explanation. The probe thermometer is inserted into five different positions of the pile body to measure the temperature. The ambient temperature is measured using a curved tube thermometer. The measurement results are as follows: Figure 1 The position of the thermometer inserted into the pile body is determined according to conventional methods and approaches in the art.

[0091] The compost is watered and turned every 6 days (usually 5-7 days) to make the moisture content of the raw materials in the compost body 65±5% (i.e. 60%-70%).

[0092] The temperature of the pile should be above 50°C for at least 10 days. When the temperature of the pile drops below 40°C and does not rise any more, the compost is considered mature.

[0093] 4. Compost sample collection and determination

[0094] Sampling was carried out at the end of composting using the 5-point sampling method, i.e. sampling was carried out at 5 points, about 40 cm deep from the top of the pile.

[0095] All the collected compost samples were mixed and divided into three samples, which were placed indoors to air dry naturally. After air drying, part of each sample was used for pH, EC, and GI index determination, part was crushed with a grinder and passed through a 0.15mm sieve, and part was used for other index determination.

[0096] 4-1) Determination of pH and EC

[0097] 5 g of air-dried compost sample was weighed into a plastic bottle and extracted with deionized water at a solid-liquid ratio of 1:10. After shaking for 1 h, the sample was removed and allowed to stand. The supernatant was aspirated and the pH and EC of the compost sample were measured using a pH meter and a conductivity meter, respectively. The results are shown in Table 2.

[0098] 4-2) Total nitrogen content (TN) was determined using a Kjeldahl nitrogen analyzer. The results are shown in Table 2.

[0099] 4-3) Total organic carbon (TOC) was determined using the potassium dichromate volumetric method (dilution heat method). Weigh 0.05 g of sieved air-dried compost sample, add 10 ml of 1 mol / L potassium dichromate solution and 20 ml of concentrated sulfuric acid. After the sample fully reacts, add o-phenanthroline indicator and calibrate with 0.5 mol / L ferrous sulfate solution. TOC was calculated according to formula (1). The results are shown in Table 2.

[0100] Calculate total organic carbon content (TOC):

[0101]

[0102] Where: c is the concentration of ferrous sulfate solution (mol / L); V0 is the volume of ferrous sulfate solution used in blank titration (ml); V is the volume of ferrous sulfate solution used in sample titration (ml); m is the mass of the dried compost sample (g); and 1.33 is the oxidation correction factor.

[0103] 4-4) Determination of humic acid content

[0104] The total humic acid content is determined using the sodium pyrophosphate extraction-potassium dichromate volumetric method. Weigh 2 g of sieved, air-dried compost sample and extract it with 10 ml of 1 mol / L sodium pyrophosphate solution. The supernatant is then reacted with 10 ml of 1 mol / L potassium dichromate solution and 20 ml of concentrated sulfuric acid. The o-phenanthroline indicator is added, and the total humic acid content is determined using 0.5 mol / L ferrous sulfate solution.

[0105] The supernatant was again drawn off and the pH adjusted to 1-1.5. After standing in a water bath, the mixture was centrifuged and washed. The washed precipitate was measured using the potassium dichromate volumetric method (heat of dilution method) to determine the humic acid content (HA). The fulvic acid content (FA) was determined from the total humic acid (HA). The results are shown in Table 2.

[0106] 4-5) Seed Germination Index (GI) Determination Method

[0107] Weigh 5g of air-dried compost sample into a plastic bottle and extract it with deionized water at a solid-to-liquid ratio of 1:10. After shaking for 1 hour, remove the bottle and let it stand. 5ml of the supernatant was then added to a Petri dish lined with filter paper. Also, 5ml of deionized water was added to a Petri dish lined with filter paper as a control. Twenty cabbage seeds were placed in each Petri dish and incubated in a dark incubator at 25°C for 48 hours. The germination rate and root length of the air-dried compost sample and the control treatment were measured. The GI value was calculated according to formula (2). The results are shown in Table 3:

[0108]

[0109] In formula (2), l is the average seed root length (mm); g0 is the seed germination rate of the control treatment (%); g is the seed germination rate of the air-dried compost sample (%).

[0110] 4-6) Determination of cellulose, hemicellulose and lignin content

[0111] The content of cellulose, hemicellulose and lignin in the dried compost sample was determined by the 72% sulfuric acid hydrolysis method and DNS reducing sugar determination method, which were improved according to the reference method (Determination of cellulose, hemicellulose and lignin in rice hull, Xiong Sumin et al., Grain and Feed Industry, 2005, No. 8, pp. 40-41). The specific method is as follows:

[0112] Cellulose content determination: 5 ml of acetic acid and nitric acid mixture (volume ratio 1:1) was added to 0.05 g of dried compost sample sieved through 0.15 mm sieve, and heated in a boiling water bath for 25 min. After cooling and centrifugation, a precipitate was obtained. 10 ml of 10% sulfuric acid and 10 ml of 0.1 mol / L potassium dichromate solution were added to the precipitate, and after 10 min in a boiling water bath, it was poured into a flask. After the solution cooled, 5 ml of 20% KI solution and 1 ml of 0.5% starch solution were added, and it was titrated with 0.2 mol / L sodium thiosulfate solution. The content of cellulose in the dried compost sample was determined, and the results are shown in Table 3.

[0113] Hemicellulose content determination: 10 ml of 80% calcium nitrate solution was added to 0.05 g of dried compost sample sieved through 0.15 mm sieve, and heated on an electric stove. After boiling for 5 min, it was cooled and centrifuged. The precipitate was washed with hot water for 3 times, and then 10 ml of 2 mol / L hydrochloric acid was added to the precipitate and boiled in a boiling water bath for 45 min. After cooling and centrifugation, the supernatant was transferred to a 100 ml volumetric flask. The precipitate was washed for 3 times, and the washing liquid was added to the volumetric flask. 1 drop of phenolphthalein was added, and it was neutralized to rose color with NaOH solution. After dilution to the mark, it was filtered into a beaker, and the first few drops of filtrate were discarded. 2 ml of the filtrate was taken in a test tube, and 1.5 ml of DNS reagent was added. After 5 min in a boiling water bath, the absorbance was measured at 540 nm wavelength, and the results were analyzed by comparing with the glucose standard curve. The results are shown in Table 3.

[0114] Lignin content determination: 0.05 g of air-dried compost sample sieved through 0.15 mm was taken in a centrifuge tube, 10 ml of 1% acetic acid was added, shaken and centrifuged. The precipitate was washed once with 5 ml of 1% acetic acid and then 3-4 ml of a mixture of ethanol and diethyl ether (1:1 by volume) was added. The mixture was allowed to stand for 3 min and the supernatant was discarded. This was repeated twice more. The precipitate in the centrifuge tube was dried in a boiling water bath. To the precipitate, 3 ml of 72% sulfuric acid was added and mixed well with a glass rod. The mixture was allowed to stand at room temperature for 16 h to dissolve all the cellulose. Then 10 ml of distilled water was added to the tube, mixed well with a glass rod and kept in a boiling water bath for 5 min. After cooling, 5 ml of distilled water and 0.5 ml of 10% barium chloride solution was added, mixed well and centrifuged. The precipitate was washed twice with distilled water and then 10 ml of 10% sulfuric acid and 0.1 mol / L potassium dichromate solution was added to the washed lignin precipitate. The tube was kept in a boiling water bath for 15 min with occasional stirring. After cooling, the contents of the tube were transferred to a beaker for titration and the residual portion was washed with 15-20 ml of distilled water. Then 5 ml of 20% KI solution and 1 ml of 0.5% starch solution was added to the beaker and titrated with sodium thiosulfate. The results are given in Table 3.

[0115] 4-7) Determination of degradation rate of cellulose, hemicellulose and lignin

[0116] 5 g of the sample was weighed and burned at 550°C for 6 h. The residual weight was taken as the ash content (g / kg). The results are given in Table 3.

[0117] The degradation rate of cellulose, hemicellulose or lignin was calculated according to equation (3) respectively. The results are given in Table 3.

[0118] Table 3:

[0119]

[0120] wherein c is the cellulose, hemicellulose or lignin content at the end of composting (g / kg); a is the ash content at the end of composting (g / kg); c0is the cellulose, hemicellulose or lignin content at the beginning of composting (g / kg); a0is the ash content at the beginning of composting (g / kg).

[0121] Comparative Example 1

[0122] Example 2 was repeated except that kaolin was not added to the raw material in the compost raw material preparation step of step 2).

[0123] The compost temperature was monitored as in Figure 1 .

[0124] The results of the compost body temperature test show that the landscaping waste composting experiment lasted a total of 67 days. Example 2 and Control Example 1 entered the high temperature period on the 24th and 41st days, respectively, with the highest temperatures reaching 56.8°C and 55.4°C. The cumulative duration of the high temperature period was 22 days and 11 days, respectively. The addition of kaolin caused the landscaping waste compost to enter the high temperature period earlier and last longer.

[0125] The temperature of the pile should be above 50°C for at least 10 days. When the temperature of the pile drops below 40°C and does not rise any more, the compost is considered mature.

[0126] At the end of composting, samples were taken and the performance of the compost samples was tested. The test results are shown in Tables 2 and 3.

[0127] Table 2 Physical and chemical properties of landscaping waste compost after each treatment

[0128]

[0129]

[0130] Note: pH is acidity, TOC is total organic carbon content, C / N is carbon-nitrogen ratio, TN is total nitrogen content.

[0131] The test results in Table 2 are as follows:

[0132] 1. In Table 2, at the end of composting, the pH, EC, total nitrogen content, and total organic matter content of Example 1 and Control 1 were 7.41 and 7.31, 1.558 mS / cm and 1.773 mS / cm, 21.153 g / kg and 22.833 g / kg, and 514.757 g / kg and 535.904 g / kg, respectively. Because kaolin has the ability to adsorb salt ions, the EC value of Example 2 was significantly lower than that of Control 1.

[0133] 2. In Table 2, at the end of composting, the total humic acid content of Example 2 was 39.83 g / kg, 8.9% higher than that of Control Example 1. The humic acid content was 26.93% lower than that of Control Example 1, and the fulvic acid content was 149.39% higher than that of Control Example 1. Kaolin improves the ability of compost to absorb and retain humic acid, especially fulvic acid.

[0134] The present invention promotes the degradation of lignocellulose in garden waste compost by adding kaolin, thereby increasing the fulvic acid and total humic acid contents of the garden waste compost; after application of the garden waste compost prepared by the method of the present invention, the impact on soil organic carbon mineralization is reduced, the CO2 release of the soil is reduced, the carbon sequestration capacity is enhanced, and the stability of soil organic carbon is improved.

[0135] Table 3 Maturity index values ​​of landscaping waste compost before and after each treatment

[0136]

[0137] The test results in Table 3 are as follows:

[0138] 1. At the end of composting fermentation, the C / N values ​​of the compost samples of Example 2 and Control Example 1 were 14.1 and 13.6, respectively, both lower than 16, reaching the maturity standard. The GI values ​​of Example 2 and Control Example 1 were 0.92 and 0.96, respectively, reaching above 0.8, reaching the maturity standard.

[0139] 2. At the end of composting, the degradation rates of hemicellulose, cellulose, and lignin in Example 2 were 27.64%, 55.82%, and 21.93%, respectively; the degradation rates of hemicellulose, cellulose, and lignin in Control Example 1 were 26.4%, 52.75%, and 20.86%, respectively. The degradation rates of hemicellulose, cellulose, and lignin in Example 2 were all higher than those in Control Example 1. The degradation rates of hemicellulose, cellulose, and lignin increased by 4.70%, 5.82%, and 5.13%, respectively.

[0140] Kaolin promotes the degradation of landscaping waste. On the one hand, kaolin adsorbs free substrates and enzymes, creating a suitable habitat for microbial decomposition, promoting the decomposition of organic matter and increasing the humus content of compost products. On the other hand, it interacts with active functional groups in humus through active atomic groups and chemical bonds, forming an organic-inorganic composite colloid. After composting, it achieves a strong immobilization effect on stable organic matter such as humus, enhancing the compost's ability to sequester carbon and reduce emissions.

[0141] In the compost fermentation process of the method of the present invention, kaolin not only serves as a fermentation additive but also has multiple effects during the application of the compost product, thereby increasing the content of humus and organic matter in the compost product, and further increasing the ability to stabilize and fix organic matter after the compost product is applied, thereby improving carbon sequestration and emission reduction.

[0142] Test Example 1

[0143] 1. Pretreatment of soil culture test materials

[0144] The surface soil (0-10 cm) was collected from the flower base in Xiangshan Park, Beijing, and the test soil was prepared by removing gravel, fine roots, and fallen debris from the collected surface soil. The soil was thoroughly mixed and naturally air-dried (moisture content was 2.56%, usually 2-3%). The soil was then crushed and passed through a 0.2 mm sieve to obtain the test soil for later use.

[0145] The compost products of Example 2 and Comparative Example 1 were air-dried naturally (moisture content: 6.55%, typically 5-8%), ground through a 0.2 mm sieve, and prepared into test compost samples for use.

[0146] 2. Arrangement of soil incubation test

[0147] The test compost samples of Example 2 and Comparative Example 1 were respectively applied to 800 ml sealed jars containing 200 g of test soil, and the application amount of the test compost samples was 5% of the mass of the test soil (i.e., 10 g of the test compost samples was added to each sealed jar, typically 1%-10%).

[0148] After the soil was mixed evenly, distilled water was uniformly sprayed into the mixed soil using a micro-sprayer to make the mixed soil moist to a moisture content of 20%.

[0149] The sealed jars were then placed in an incubator at 25°C for 7 days to stabilize the CO2 release from the soil.

[0150] Afterwards, the moisture content of the soil was corrected to 20% by weighing and the soil was turned over.

[0151] The CO2 emission amount of the soil was determined according to the following method, and the details are as follows:

[0152] A 30 ml plastic vial containing 20 ml of 1 mol / L NaOH solution was placed in the sealed jar, and the sealed incubation was continued at 25°C, which was recorded as 0 days from the start of incubation.

[0153] The plastic vial was removed at 1, 3, 7 days and every 7 days thereafter, and a new NaOH solution (20 ml, 1 mol / L) was added. The removed plastic vial was sealed and reserved for measurement.

[0154] The moisture content was corrected by weighing at 1, 3, 7 days and every 7 days thereafter, and the soil was turned over, and the incubation was continued until 119 days.

[0155] 3. Monitoring of soil organic carbon mineralization amount

[0156] The CO2 emission amount of the soil was determined by alkali absorption method. The NaOH solution to be measured in the plastic vial in the incubation was transferred to a conical flask, 20 ml of 1 mol / L BaCl2 solution was added for reaction, phenothalin indicator was added dropwise, and the unreacted NaOH solution content was determined by using 0.5 mol / L dilute HCl as a standard.

[0157] The cumulative mineralization amount (MC) of soil organic carbon at different incubation times was calculated according to formula (4), and the determination results are shown in Table 2. Figure 2

[0158] ​MC(mg / kg)=N(V0-V)×22×5×12 / 44 (4)

[0159] In formula (4), N is the concentration of HCl solution (mol / L); V0 is the volume of HCl solution used in blank titration (ml); V is the volume of HCl solution used in sample titration (ml);

[0160] The soil organic carbon mineralization rate was calculated according to formula (5). The results are as follows: Figure 3 :

[0161] Organic carbon mineralization rate (mg / ( kg d ))=MC / culture days (5)

[0162] In formula (5): MC is the cumulative mineralization of soil organic carbon (mg / kg);

[0163] The results of soil organic carbon cumulative mineralization (MC) are shown in Figure 2 .

[0164] Depend on Figure 2 From the soil organic carbon cumulative mineralization curve, it can be seen that: with the extension of the incubation time, the cumulative mineralization of soil organic carbon gradually increases. The cumulative mineralization of organic carbon in the soil after the garden waste compost fermented with the addition of kaolin compost according to the method of the present invention is lower than that without the addition of kaolin compost, and as time goes by, the difference in cumulative mineralization gradually increases. Therefore, compared with the soil of the control example (i.e., without the use of kaolin compost), the increase in the cumulative carbon emissions of the soil prepared by the compost using the method of the present invention is reduced, the carbon emissions of the soil are reduced, and the purpose of carbon sequestration and emission reduction is achieved.

[0165] The results of soil organic carbon mineralization rate determination are shown in Figure 3 .

[0166] Depend on Figure 3 It can be seen from the soil organic carbon mineralization rate curve that: then with the extension of the incubation time, the soil organic carbon mineralization rate gradually decreases. The organic carbon mineralization rate of the soil after the garden waste compost fermented with the addition of kaolin compost according to the method of the present invention is lower than the organic carbon mineralization rate of the soil without the addition of kaolin compost. Therefore, the soil carbon emission rate of the compost prepared by the method of the present invention is lower, which is more conducive to reducing the carbon emission of the soil and achieving the purpose of carbon sequestration and emission reduction.

[0167] Figure 2 and Figure 3The middle soil incubation test lasted for 119 days. The organic carbon mineralization rates of Example 2 and Control Example 1 showed a slow downward trend, decreasing from the initial 64.50 mg / (kg·d), 70.08 mg / (kg·d) to 28.92 mg / (kg·d), 32.41 mg / (kg·d) respectively. The organic carbon mineralization rates of the two treatments were Example 1 < Control Example 1. At 119 days, the cumulative mineralization amounts of Example 1 and Control Example 1 were 5353.95 mg / kg and 6077.40 mg / kg respectively. It is shown that the addition of kaolin reduces the soil organic carbon mineralization rate after the compost is applied to the soil. Although the cumulative mineralization amount gradually increases, the increase of the soil organic carbon mineralization amount using the compost of the application is relatively reduced compared with other soils using compost, achieving the effect of reducing soil carbon emission and carbon sequestration.

[0168] Test Example 2

[0169] 1. Pretreatment of soil incubation test materials

[0170] The same as Test Example 1;

[0171] 2. Arrangement of soil incubation test

[0172] The test compost samples of Example 2 and Control Example 1 were respectively applied to 600 ml sealed jars containing 200 g of test soil for incubation. The application amount of test compost sample was 5% of the mass of test soil (i.e. 10 g of test compost sample was added to each sealed jar). Each treatment was repeated 3 times, with a total of 6 incubation jars.

[0173] After the soil was mixed evenly, distilled water was sprayed uniformly using a micro-sprayer to make the soil moist to a water content of 20%.

[0174] Then the sealed jars were placed in an incubator at 25°C for 7 days of pre-incubation to stabilize the carbon dioxide release of the soil.

[0175] After the pre-incubation, the soil water content was corrected to 20% by weighing and the soil was turned over.

[0176] The incubation was continued at 25°C under sealed conditions, recorded as 0 days of incubation start.

[0177] The water content was corrected by weighing at 1, 3, 7 days and every 7 days thereafter, and the soil was turned over before continuing the incubation to 119 days.

[0178] 3. Determination of soil samples

[0179] After the soil incubation, the soil was stirred evenly, collected and dried. The dried soil was sieved through a 0.15 mm sieve to obtain dried soil samples.

[0180] 3-1) Total organic carbon content (TOC)

[0181] The determination was performed using the potassium dichromate volumetric method (heat of dilution method). Weigh 0.5 g of a dried sample, passed through a 0.15 mm sieve, and add 10 ml of a 1 mol / L potassium dichromate solution and 20 ml of concentrated sulfuric acid. After the sample has fully reacted, add an o-phenanthroline indicator and calibrate with a 0.5 mol / L ferrous sulfate solution. The TOC of soil prepared from garden waste compost using the method of the present invention was calculated according to formula (1).

[0182] Calculate total organic carbon content (TOC):

[0183]

[0184] In formula (1), c is the concentration of ferrous sulfate solution (mol / L); V0 is the volume of ferrous sulfate solution used for blank titration (ml); V is the volume of ferrous sulfate solution used for sample titration (ml); m is the mass of the soil sample after drying and sieving the soil prepared by the method of the present invention using the garden waste compost (g); and 1.33 is the oxidation correction coefficient.

[0185] The results of total organic carbon (TOC) are shown in Figure 4 .

[0186] Depend on Figure 4 The total organic carbon content measured by the method showed that at 119 days, the soil organic carbon content in Example 2 and Control Example 1 was 62.28 g / kg and 59.95 g / kg, respectively. The addition of kaolin increased the soil organic carbon content after the compost was applied to the soil, improving the soil's carbon sequestration capacity.

[0187] 3-2) Organic carbon oxidation stable components

[0188] The improved Walkley-Black method was used to determine the oxidation-stable components of organic carbon, which were divided into four components.

[0189] After 10 ml of potassium dichromate (1 mol / L) was added to each soil sample (0.5 g), 20 ml of H2SO4 with an acid-water ratio of 1:2 (equivalent to 6 mol / L), 1:1 (equivalent to 9 mol / L), and 2:1 (equivalent to 12 mol / L) was added, respectively, and then 0.5 mol / L FeSO4 was used for calibration. The measured organic carbon was recorded as 6, 9, and 12 mol / L organic carbon, respectively. Thus, four oxidation-stable organic carbon components were obtained: 6 mol / L organic carbon was the high-oxidation-activity organic carbon component (VAC); 9 mol / L organic carbon minus 6 mol / L organic carbon was the medium-oxidation-activity organic carbon component (AC); 12 mol / L organic carbon minus 9 mol / L organic carbon was the low-oxidation-activity organic carbon component (PAC); and total organic carbon minus 12 mol / L organic carbon was the stable organic carbon component (IAC). The determination results of the contents of the oxidation-stable soil organic carbon components are shown in Table 1. Figure 5 .

[0190] The soil organic carbon activity index was calculated according to formula (6), and the soil stability index was calculated according to formula (7):

[0191]

[0192]

[0193] In formula (6), TOC is the total organic matter content of the dried soil sample (g / kg);

[0194] The activity index of Example 2 and the control example 1 calculated by the formula was 2.29 and 2.37, respectively, and the stability index was 0.28 and 0.20, respectively. The activity index of Example 2 was smaller than that of the control example 1, and the stability index of Example 2 was greater than that of the control example 1. The soil carbon of Example 2 was more stable, and the soil carbon of the control example 1 was more active.

[0195] From the determination results Figure 5 It can be seen from the determination results that, at the 119th day of soil incubation, the PAC component content of Example 1 was increased by 75.32% compared with that of the control example 1, and the other three components had no significant difference (P<0.05). The addition of kaolin increased the content of the low-oxidation-activity component PAC of soil organic carbon, thereby improving the stability of the soil.

[0196] It is shown that the addition of kaolin improves the stability of the organic carbon in the soil after the compost is applied to the soil. The improvement of the stability of the organic carbon indicates that the soil carbon is not easily disturbed, which is beneficial to the carbon sequestration of the soil.

[0197] The above embodiments of the present application are only exemplary and do not constitute any limitation on the scope of the present application. Those skilled in the art should understand that the details and forms of the technical solutions of the present application can be modified or replaced without departing from the spirit and scope of the present application, and such modifications and replacements all fall within the protection scope of the present application.

Claims

1. A method for preparing compost from landscaping waste, characterized in that: Follow these steps: The landscaping waste and kaolin are evenly mixed and the C / N ratio of the mixture is adjusted to 25-30, and then piled for fermentation. During the pile fermentation process, the pile is watered and turned every 5-7 days so that the moisture content of the fermented material in the pile is 60%-70%. The pile temperature is kept above 50°C for at least 10 days. When the pile temperature drops to below 40°C and no longer rises, the compost is considered mature.

2. The preparation method according to claim 1, wherein The mass ratio of the landscaping waste to kaolin is 100:(7-15).

3. The preparation method according to claim 1, wherein The mass ratio of the landscaping waste to kaolin is 100:

10.

4. A landscaping waste compost, characterized by: Prepared according to the method according to any one of claims 1 to 3.

5. A method for preparing cultivation soil using the compost of landscaping waste as claimed in claim 4, characterized in that: The landscaping waste compost as claimed in claim 4 is evenly mixed with soil in a mass ratio of (1-10):

100.

6. The method according to claim 5, wherein: The garden waste compost is air-dried and crushed to a particle size of ≤0.2 mm, and mixed evenly with the air-dried soil in proportion.

7. A cultivation soil characterized by: Prepared according to the method as claimed in claim 5 or 6.

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