A method for using biogas residue to fertilize soil in relocation sites

Abstract

This invention provides a method for fertilizing relocation site soil using biogas residue, belonging to the field of relocation site soil treatment technology. The method specifically includes: S1, excavating the relocation site to a certain depth; S2, laying a certain thickness of biogas residue in the excavated area of ​​step S1; S3, backfilling the excavated soil from step S1 onto the biogas residue from step S2; S4, planting Canadian goldenrod in the area treated in step S3; S5, completely covering the Canadian goldenrod with biogas residue after harvesting, and conducting aerobic fermentation; S6, deeply tilling the area after aerobic fermentation in step S5, ensuring the goldenrod stems and / or rhizomes are thoroughly mixed with the biogas residue, and then burying it in the soil for anaerobic fermentation for several months, thus completing the soil fertilization of the relocation site. The method for fertilizing relocation site soil using biogas residue provided by this invention greatly utilizes the original soil of the relocation site and significantly improves the soil fertility.

Description

Technical Field

[0001] This invention belongs to the field of soil treatment technology for relocation sites, specifically a method for using biogas residue to fertilize soil in relocation sites. Background Technology

[0002] Using urban relocation sites for landscaping is a major way to address the shortage of available green space in densely populated urban areas and a key trend in future urban renewal. Urban relocation sites generally suffer from thin soil layers, extensive concrete hardening, large amounts of filler material, poor soil physical and chemical properties, low soil fertility, and multiple pollutions on the original surface, all of which severely hinder plant growth and development. Furthermore, frequent human activities in the urban environment further restrict root zone space, leading to poor plant survival, slow recovery, weak growth, and an imbalanced root-to-shoot ratio.

[0003] By employing ecological restoration and greening methods to transform the soil, it can be endowed with sound ecological functions, while also adding green space to the city. Furthermore, through rational soil utilization, the soil after demolition can be recycled and used to provide people with practical and aesthetically pleasing spaces. Therefore, how to safely, environmentally, and effectively enrich the soil of relocation sites in a long-term and sustainable manner is an urgent problem to be solved.

[0004] Invention application No. 201710224984.5 relates to a method for improving soil with biogas slurry. First, the biogas slurry is anaerobically fermented at 35°C for 2-5 days, then discharged into a sedimentation tank for natural sedimentation for 1 day to allow large solid particles to settle. Next, the settled biogas slurry undergoes aerobic fermentation for 1-3 days. Then, the aerobically fermented biogas slurry is separated into clear biogas slurry and biogas residue. The biogas residue is placed in a reaction vessel, and a reaction aid and water are sprayed onto the surface of the biogas residue using a sprayer to ensure uniform mixing. The mixed biogas residue is then pressed to dehydrate, dried, and pulverized. The land is then deeply tilled to a depth of 30-40 cm. During deep tilling, the clear biogas slurry and biogas residue powder are applied evenly. The treated land is left uncultivated for 2-3 months at an temperature of 25-35°C before planting. This invention mainly improves the soil through biogas slurry. The biogas slurry is one or more of pig manure, cow manure, sheep manure, chicken manure, and straw. The preparation process of biogas slurry is complicated and requires a lot of manpower and resources. Moreover, the manure of poultry and livestock usually contains excessive levels of antibiotics and heavy metals, which causes secondary pollution to the soil.

[0005] Patent application number 202210946132.8 discloses a method for preparing raw soil by treating polycyclic aromatic hydrocarbon (PAH) contaminated soil in relocation sites using kitchen waste biogas residue. The method includes the following steps: S1, initial screening of the relocation site soil to remove impurities, followed by crushing and re-screening to obtain soil with a particle size of less than 5 cm; S2, mixing the soil obtained in S1 with compost raw materials containing biogas residue at a volume ratio of 1:2~10, then adding a compound microbial agent and mixing thoroughly for aerobic fermentation; the raw soil is obtained after fermentation. This invention can eliminate harmful components in the contaminated soil of relocation sites and improve soil fertility, meeting the aeration, permeability, and various nutrient requirements for plant growth. However, the main purpose of this invention is to remove pollutants, and the active ingredient is mainly the microbial agent. Furthermore, this invention requires screening, removing impurities, crushing, and re-screening the relocation soil, involving numerous steps and a large workload. Summary of the Invention

[0006] This invention provides a low-cost, simple, and effective method for utilizing biogas residue to fertilize soil in relocation sites, specifically including the following steps:

[0007] S1. Excavate the relocation area to a certain depth below the ground;

[0008] S2. A certain thickness of biogas residue is laid in the area excavated in step S1;

[0009] S3. Backfill the soil excavated in step S1 onto the biogas residue in step S2;

[0010] S4. Plant Canadian goldenrod in the area treated in step S3.

[0011] S5. After harvesting the goldenrod from step S4, completely cover the goldenrod stems with biogas residue and carry out aerobic fermentation.

[0012] S6. Deeply till the area after aerobic fermentation in step S5, so that the platycodon and / or rhizomes of Canadian goldenrod are fully mixed with the biogas residue and buried in the soil for anaerobic fermentation for several months, thus completing the soil fertilization of the relocation site.

[0013] Canadian goldenrod is commonly found in urban and rural wastelands, near residences, abandoned sites, factory areas, hillsides, riverbanks, no-till land, roadsides, railway lines, farmland edges, and greenbelts. It is drought-tolerant and can thrive in relatively poor soil, even growing vigorously in cracks in concrete and crevices. Therefore, Canadian goldenrod can grow in the soil of relocated sites. The biogas residue laid underground competes with the roots of Canadian goldenrod for oxygen and water, thus preventing the roots from growing deeper into the ground and ensuring complete eradication later. Furthermore, deep burial of biogas residue enriches the deeper soil layers of the relocated area, promoting the survival and growth of subsequent plant species. Simultaneously, Canadian goldenrod contains flavonoids with strong antibacterial activity and endophytic fungi with secondary metabolites that inhibit plant pathogens, thus reducing the activity of various plant pathogens and laying a foundation for reducing fungal diseases when planting other plants. Biogas residue is spread on top of harvested Canadian goldenrod. The high salt content, high EC value, and high phytotoxicity of the biogas residue cause the goldenrod to wither. At the same time, the biogas residue and Canadian goldenrod undergo aerobic fermentation. The high heat generated during this process allows the Canadian goldenrod to decompose. In the later stages of aerobic fermentation, once the compost temperature reaches ambient temperature, the decomposed goldenrod stems or rhizomes are deeply plowed and buried together with the biogas residue. They then undergo anaerobic fermentation in the soil to further decompose the Canadian goldenrod, converting its organic matter into humus and other nutrients that are easily absorbed by plants, thereby increasing soil nutrients and achieving the purpose of fertilization.

[0014] Preferably, in step S1, the digging depth is 30 to 70 cm.

[0015] Preferably, in steps S2 and S5, the biogas residue includes biogas residue produced by a large-scale biogas production plant after anaerobic fermentation and solid-liquid separation treatment.

[0016] Preferably, in step S2, the thickness of the biogas residue is 10-20 cm.

[0017] Preferably, in step S5, the goldenrod is harvested before it blooms.

[0018] Preferably, in step S5, the harvested Canadian goldenrod is crushed.

[0019] Preferably, in step S5, the aerobic fermentation time is 2 to 4 months.

[0020] Preferably, in step S6, the anaerobic fermentation time is 5 to 7 months.

[0021] Preferably, in step S6, deep tillage is performed 1 to 2 times during anaerobic fermentation.

[0022] In order to ensure that the soil excavated in step S1 can be completely fertilized and improved, after the anaerobic fermentation in step S6, steps S1 to S5 are repeated until all the soil excavated in step S1 is fertilized.

[0023] Compared with the prior art, the beneficial effects of this invention are as follows:

[0024] This invention provides a method for fertilizing relocation site soil using biogas residue. Taking advantage of the high survival rate of Canadian goldenrod, it is planted in barren relocation sites, providing carbon for subsequent aerobic fermentation. Furthermore, it utilizes the flavonoids and secondary metabolites within Canadian goldenrod, which possess strong antibacterial activity against various plant pathogens, to inhibit the activity of multiple pathogenic fungi, laying a foundation for reducing fungal diseases when planting other plants. This invention also utilizes biogas residue for aerobic and anaerobic fermentation of Canadian goldenrod, fully converting the organic matter in the flower into easily absorbed humus and other nutrients, increasing soil nutrient content. By using locally sourced materials, it significantly improves the fertility of the relocation site soil. Detailed Implementation

[0025] The technical solution of the present invention will be further described and illustrated below through examples. All raw materials used in the examples are commercially available or prepared using conventional methods. The biogas residue used is biogas residue produced from kitchen waste after several dozen days of anaerobic fermentation and solid-liquid separation treatment in a large-scale biogas production plant. Its composition is safe and will not impose additional burdens or pollution on the soil.

[0026] Example 1

[0027] A method for using biogas residue to fertilize soil in relocation sites specifically includes the following steps:

[0028] S1. Dig a 70 cm deep hole in the relocation area;

[0029] S2. Lay a 20 cm thick layer of biogas residue in the area excavated in step S1;

[0030] S3. Backfill the soil excavated in step S1 onto the biogas residue in step S2 until it is level with the surrounding ground.

[0031] S4. Plant Canadian goldenrod in the area treated in step S3.

[0032] S5. Before the goldenrod planted in step S4 blooms, the goldenrod is cut and crushed and then scattered in the goldenrod planting area. Biogas residue is used to cover the goldenrod so that it is completely covered, and aerobic fermentation is carried out for 4 months.

[0033] S6. Deeply till the area after aerobic fermentation in step S5, so that the platycodon and / or rhizomes of Canadian goldenrod are fully mixed with the biogas residue and buried in the soil for anaerobic fermentation for 7 months. Deep tillage is carried out once after 3 months of anaerobic fermentation and a second deep tillage is carried out after 5 months of anaerobic fermentation.

[0034] S7. After the anaerobic fermentation in step S6 is completed, earthwork excavation is carried out, digging to a depth of 50 cm below the ground.

[0035] S8. Because the soil changes from a compacted state to a loose state after excavation and its volume increases, only 20 cm thick biogas residue is laid in the area excavated in step S7.

[0036] S9. Backfill all the unfilled soil excavated in step S1 onto the top of the biogas residue in step S8, keeping it level with the surrounding ground.

[0037] S10. Plant Canadian goldenrod in the area treated in step S9.

[0038] S11. Before the goldenrod planted in step S10 blooms, the goldenrod is cut and crushed. The crushed goldenrod stems are scattered in the goldenrod planting area. The goldenrod is completely covered with biogas residue and aerobic fermentation is carried out for 2 months.

[0039] S12. Deeply till the area after aerobic fermentation in step S11, so that the platycodon and / or rhizome of Canadian goldenrod are fully mixed with the biogas residue and buried in the soil for anaerobic fermentation for 5 months. Deep tillage is carried out once after 3 months of anaerobic fermentation.

[0040] After the anaerobic fermentation in steps S13 and S12 is completed, the soil excavated in step S7 is laid in the relocation area, thus completing the fertilization treatment of all the soil in the relocation site.

[0041] Soil samples were taken before and after fertilization for testing, as shown in Table 1. After fertilization using the biogas residue method provided by this invention, the soil in the relocation site changed from alkaline to neutral, and the EC value, organic matter, available nitrogen, and available phosphorus were effectively improved, significantly enhancing the fertility of the soil in the relocation site.

[0042] Table 1. Test data of soil before and after fertilization in Example 1.

[0043]

[0044] Example 2

[0045] A method for using biogas residue to fertilize soil in relocation sites specifically includes the following steps:

[0046] S1. Dig 30 cm down into the ground in the relocation area;

[0047] S2. Lay a 10 cm thick layer of biogas residue in the area excavated in step S1;

[0048] S3. Backfill the soil excavated in step S1 onto the biogas residue in step S2 until it is level with the surrounding ground.

[0049] S4. Plant Canadian goldenrod in the area treated in step S3.

[0050] S5. Before the goldenrod planted in step S4 blooms, the goldenrod is cut and crushed. The crushed goldenrod stems are scattered in the goldenrod planting area. Biogas residue is used to cover the goldenrod so that it is completely covered. Aerobic fermentation is carried out for 3 months.

[0051] S6. Deeply till the area after aerobic fermentation in step S5, so that the platycodon and / or rhizome of Canadian goldenrod are fully mixed with the biogas residue and buried in the soil for anaerobic fermentation for 5 months. Deep tillage is carried out once after 3 months of anaerobic fermentation.

[0052] S7. After the anaerobic fermentation in step S6 is completed, earthwork excavation is carried out, digging to a depth of 30 cm below the ground.

[0053] S8. Because the soil changes from a dense state to a loose state after excavation and its volume increases, only 10 cm thick biogas residue is laid in the area excavated in step S7.

[0054] S9. Backfill all the unfilled soil excavated in step S1 onto the top of the biogas residue in step S8, keeping it level with the surrounding ground.

[0055] S10. Plant Canadian goldenrod in the area treated in step S9.

[0056] S11. Before the goldenrod planted in step S10 blooms, the goldenrod is cut and crushed. The crushed goldenrod stems are scattered in the goldenrod planting area. Biogas residue is used to cover the goldenrod so that the goldenrod is completely covered. Aerobic fermentation is carried out for 2 months.

[0057] S12 involves deep tilling of the area after aerobic fermentation in step S11, so that the platycodon and / or rhizomes of Canadian goldenrod are fully mixed with the biogas residue and then anaerobic fermentation is carried out for 5 months. Deep tilling is carried out once after 3 months of anaerobic fermentation.

[0058] After the aerobic fermentation in steps S13 and S12 is completed, the soil excavated in step S7 is laid in the relocation area, thus completing the soil fertilization treatment at the relocation site.

[0059] Soil samples were taken before and after fertilization and tested, as shown in Table 2. After fertilization using the biogas residue method provided by this invention, the soil in the relocation site changed from alkaline to neutral, and the EC value, organic matter, alkaline nitrogen, and available phosphorus were effectively improved, significantly enhancing the fertility of the soil in the relocation site.

[0060] Table 2. Test data of soil before and after fertilization in Example 2.

[0061]

[0062] Example 3

[0063] A method for using biogas residue to fertilize soil in relocation sites specifically includes the following steps:

[0064] S1. Dig 50 cm down into the ground in the relocation area;

[0065] S2. Lay a 20 cm thick layer of biogas residue in the area excavated in step S1;

[0066] S3. Backfill the soil excavated in step S1 onto the biogas residue in step S2 until it is level with the surrounding ground.

[0067] S4. Plant Canadian goldenrod in the area treated in step S3.

[0068] S5. Before the goldenrod planted in step S4 blooms, the goldenrod is cut and crushed. The crushed goldenrod is scattered in the goldenrod planting area. Biogas residue is used to cover the goldenrod so that it is completely covered. Aerobic fermentation is carried out for 2 months.

[0069] S6. Deeply till the area after anaerobic fermentation in step S5, so that the platycodon and / or rhizome of Canadian goldenrod are fully mixed with the biogas residue and buried in the soil for anaerobic fermentation for 6 months. Deep tillage is carried out once after 3 months of anaerobic fermentation.

[0070] S7. After the anaerobic fermentation in step S6 is completed, earthwork excavation is carried out, digging to a depth of 50 cm below the ground.

[0071] S8. Because the soil changes from a compacted state to a loose state after excavation and its volume increases, only 20 cm thick biogas residue is laid in the area excavated in step S7.

[0072] S9. Backfill all the unfilled soil excavated in step S1 onto the top of the biogas residue in step S8, keeping it level with the surrounding ground.

[0073] S10. Plant Canadian goldenrod in the area treated in step S9.

[0074] S11. Before the goldenrod planted in step S10 blooms, the goldenrod is cut and crushed. The crushed goldenrod stems are scattered in the goldenrod planting area. Biogas residue is used to cover the goldenrod so that it is completely covered. Aerobic fermentation is carried out for 3 months.

[0075] S12. Deeply till the area after aerobic fermentation in step S11 to fully mix the platycodon and / or rhizomes of Canadian goldenrod with the biogas residue and carry out anaerobic fermentation for 6 months. Deep tillage is carried out once after 3 months of anaerobic fermentation.

[0076] After the aerobic fermentation in steps S13 and S12 is completed, the soil excavated in step S7 is laid in the relocation area, thus completing the soil fertilization treatment at the relocation site.

[0077] Soil samples were taken before and after fertilization for testing, as shown in Table 3. After fertilization using the biogas residue method provided by this invention, the soil in the relocation site changed from alkaline to neutral, and the EC value, organic matter, available nitrogen, and available phosphorus were effectively improved, significantly enhancing the fertility of the soil in the relocation site.

[0078] Table 3. Test data of soil before and after fertilization in Example 3.

[0079]

[0080] It should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for using biogas residue to fertilize soil in relocation sites, characterized in that, Specifically, the following steps are included: S1. Excavate the relocation area to a depth of 30-70 cm; S2. Lay a 10-20 cm thick layer of biogas residue in the area excavated in step S1; S3. Backfill the soil excavated in step S1 onto the biogas residue in step S2; S4. Plant Canadian goldenrod in the area treated in step S3, and harvest the Canadian goldenrod before it blooms. S5. After harvesting and crushing the goldenrod from step S4, completely cover the goldenrod stems with biogas residue and carry out aerobic fermentation for 2-4 months. S6. Deeply till the area after aerobic fermentation in step S5, so that the platycodon and / or rhizomes of Canadian goldenrod are fully mixed with the biogas residue and buried in the soil for anaerobic fermentation for 5 to 7 months. After the anaerobic fermentation is completed, repeat steps S1 to S6 until all the soil of the relocation site dug out in step S1 is fertilized.

2. The method for using biogas residue to fertilize the soil of a relocation site according to claim 1, characterized in that, In steps S2 and S5, the biogas residue includes biogas residue produced by large-scale biogas production plants after anaerobic fermentation and solid-liquid separation.

3. The method for using biogas residue to fertilize the soil of a relocation site according to claim 1, characterized in that, In step S6, deep tillage is carried out 1-2 times during anaerobic fermentation.

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