A soil cultivation method and its application in decomposing lignin

Abstract

This application provides a soil cultivation method and its application for lignin decomposition. Soil block A is selected from a broad-leaved forest area in a tropical or subtropical region with an undisturbed leaf decay layer of 5 cm or more. 10%-15% (by weight) of an ammonia absorption promoter is added to soil block A and mixed thoroughly. The soil is then cultivated for 2-6 weeks at a temperature of 25-33℃ and a humidity of 50%-70%. The soil prepared using this method can be used to decompose lignin. It is non-polluting to the soil, has low energy consumption, and decomposes lignin quickly. Compared to uncultivated soil, the cycle for lignin decomposition is shortened by approximately 10% after cultivation.

Description

Technical Field

[0001] This invention relates to the field of soil cultivation technology, and in particular to a soil cultivation method and its application in decomposing lignin. Background Technology

[0002] Lignocellulose is one of the most abundant, cheapest, and readily available renewable energy sources on Earth. It is primarily composed of cellulose, hemicellulose, and lignin. Hemicellulose is tightly bound to lignin molecules through covalent and hydrogen bonds, making the natural lignocellulose structure very robust. Lignin degradation is the rate-limiting step in the natural carbon cycle. During biomass biorefining, lignin binds tightly to other components, interfering with the pretreatment of lignocellulose. Lignin degradation products further inhibit subsequent fermentation processes and adsorb hydrolytic enzymes, posing a significant challenge to the efficient utilization of biomass.

[0003] In existing technologies, most methods for decomposing lignin involve physical, chemical, physical-chemical, and biological approaches. However, chemical methods require high concentrations of strong acids and alkalis, which result in rapid decomposition but cause irreversible environmental damage through waste liquid. Physical methods require stringent operating conditions, are energy-intensive, and costly. Biological methods decompose lignin slowly and are not suitable for large-scale industrial use. Summary of the Invention

[0004] In order to solve the technical problems of the existing technology of chemical methods causing great environmental damage, physical methods being costly, and biological methods being slow in the process of lignin treatment, the present invention provides a soil cultivation method for decomposing lignin that is pollution-free, low-energy-consumption, and fast.

[0005] A second objective of this invention is to provide an application of cultured soil-decomposed lignin.

[0006] To achieve the first objective mentioned above, the technical solution adopted by the present invention is as follows:

[0007] A soil cultivation method, comprising:

[0008] (1) Select broad-leaved forest areas in tropical or subtropical regions that are undisturbed by human activity;

[0009] (2) Select soil block A from (1) with a leaf decay layer of more than 5cm and excavate 0.8 to 1.2 square meters;

[0010] (3) Add an ammonia absorption promoter to soil block A, wherein the mass of the ammonia absorption promoter is 10%-15% of the mass of soil block A, and stir well;

[0011] (4) Cultivate at a temperature of 25-33℃ and a humidity of 50%-70% for 2-6 weeks to obtain cultivation soil A.

[0012] Tropical or subtropical broad-leaved forests have more complete ecosystems and a greater variety of species. The lignin content in broad-leaved woody plants is as high as 16-24%. Soil blocks A in this environment are rich in various genera of bacteria that can secrete enzymes that promote lignin decomposition, such as Toluenemonas, Trichomonas, Klebsiella, Methanogens, Enterobacteriaceae, and Rhodococcus. Adding 10%-15% by weight of ammonia absorbent stimulates the secretion of lignin-decomposing bacteria, increasing the content or activity of the secreted lignin-decomposing enzymes. When applied to decompose lignin, this can accelerate the decomposition process. Furthermore, since it is essentially a biological method of cultivating bacteria in the soil, it has a low energy consumption effect.

[0013] Furthermore, the ammonia absorption promoter is a mixture of yeast extract, glucose, and divalent manganese ion solution.

[0014] Adding yeast extract can increase the activity of lignin-degrading enzymes in the fungi. Divalent manganese ions can induce the secretion of lignin-degrading enzymes in the fungi. Adding glucose provides nutrients to the fungi and promotes the secretion of lignin-degrading enzymes.

[0015] Furthermore, the divalent manganese ion solution in step (3) is prepared from manganese dichloride, and the concentration of manganese in the divalent manganese ion solution is 1 μg / L to 9 μg / L.

[0016] The inventors' research shows that, in strains extracted from tropical or subtropical broad-leaved forest ecosystems, when the concentration of manganese in the divalent manganese ion solution falls within the aforementioned range, the effect of the strains secreting lignin-degrading enzymes increases with the increase of the concentration of dimethyl manganese ions.

[0017] Furthermore, the surface layer of the soil block A is 0.8–1.2 square meters and has a thickness of 8–1.2 cm.

[0018] Furthermore, in step (4), the pH value of soil A is 5-8. When the soil is in a neutral range, it is conducive to the reproduction of bacteria that secrete lignin-degrading enzymes.

[0019] Furthermore, in step (4), the oxygen content is 18% to 22%, and the carbon dioxide content is 0.3% to 4%. The oxygen and carbon dioxide content in the soil determines whether the main bacteria that reproduce there are aerobic or anaerobic. In the ecosystem of tropical or subtropical broad-leaved forests, most of the bacteria that secrete lignin-decomposing enzymes using lignin as a substrate are facultative anaerobic bacteria. Under these conditions, they mainly utilize the enzymes produced by their aerobic respiration. Therefore, the oxygen and carbon dioxide content needs to be controlled.

[0020] To achieve the second objective mentioned above, the technical solution adopted by the present invention includes the following steps:

[0021] (1) The lignin-containing leaf mold to be decomposed is cultivated for 2-3 days at a carbon-nitrogen ratio of 1:25-35 and a humidity of 50%-70% to obtain compost product A.

[0022] (2) Mix the compost product A obtained in (1) with the cultivation soil A and carry out composting treatment.

[0023] Microorganisms require carbon as an energy source during decomposition, while nitrogen is an essential element for synthesizing lignin-decomposing enzymes. By following the carbon-nitrogen ratio described above, the metabolism and decomposition efficiency of microorganisms can be optimized. According to the inventors' statistics, 1 volume of cultivation soil A can decompose 10-25 times its own volume of decaying leaves, and the cycle for soil A to decompose the lignin in the decaying leaves is approximately 25-30 days.

[0024] Furthermore, the composting process in step (2) includes the following steps:

[0025] (2.1) When the local temperature of the compost A reaches 26-35℃, the compost A will be turned over to make the temperature of each point inside the compost uniform, thus obtaining a stirred pile A.

[0026] (2.2) When the local temperature of the mixing pile A reaches 35-55℃, the compost A to be composted will be turned over to make the temperature of each point inside the pile uniform, thus obtaining the mixing pile B.

[0027] (2.3) When the temperature of the mixed pile B begins to drop, let it stand for 2-3 days.

[0028] Furthermore, the compostable product A is placed in a straight cylinder with a diameter of 0.8m to 1m for composting and decomposition.

[0029] Specifically, it also includes the step of: pretreatment, which involves cutting the lignin-containing leaf decaying material to be decomposed into pieces of 0.5-1 square centimeters.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. The soil cultivation method provided in this application involves selecting soil block A in a broad-leaved forest area in a tropical or subtropical region with an undisturbed leaf decay layer of more than 5 cm, adding 10%-15% by weight of an ammonia absorption promoter to the soil block A, mixing it evenly, and cultivating it at a temperature of 25-33℃ and a humidity of 50%-70% for 2-6 weeks. The soil prepared by this cultivation method can be used to decompose lignin, which is non-polluting to the soil, low in energy consumption, and has a fast lignin decomposition speed.

[0032] 2. The application of cultured soil for decomposing lignin provided in this application has the advantages of being pollution-free, low-energy, and fast-decomposing because the soil used is prepared by the above-mentioned soil cultivation method. Compared with uncultured soil, the cycle for decomposing lignin after cultivation is shortened by about 10%. Detailed Implementation

[0033] The specific technical solution of the present invention will be described below with reference to specific embodiments 1-4:

[0034] Example 1:

[0035] I. Cultivation Stage:

[0036] (1) Select broad-leaved forest areas in tropical or subtropical regions that are undisturbed by human activity;

[0037] (2) Select soil from (1) with a leaf decay layer of more than 5cm, and dig out a soil block A1 with a surface area of ​​0.8 square meters and a thickness of 8cm;

[0038] (3) Add 10% of ammonia absorption promoter to soil block A1, then add 2% yeast extract powder and 3% glucose by mass and stir well. Then add 5% manganese chloride solution with a concentration of 1 μg / L and stir well.

[0039] (4) Cultivate at 25℃ and 50% humidity for 6 weeks to obtain cultivation soil A1. During the period, turn the cultivation soil A1 to maintain its oxygen content of 18% and carbon dioxide content of 4%.

[0040] II. Application Phase:

[0041] Pretreatment: Cut the lignosulfonate-containing leaf material to be decomposed into 0.5 square centimeter pieces and soak them in ordinary tap water for 10 hours.

[0042] (1) The lignin-containing leaf mold to be decomposed is cultured for 3 days at a carbon-nitrogen ratio of 1:25 and a humidity of 50% to obtain compost product A1.

[0043] (2) Mix the compost A1 obtained in this stage (1) with the cultivation soil A1 and place it in a plastic cylinder with a diameter of 0.8m;

[0044] (2.1) When the local temperature of the compost A1 reaches 26-35℃, the compost A1 will be turned over to make the temperature of each point inside it uniform, thus obtaining a mixed pile A1.

[0045] (2.2) When the local temperature of the mixing pile A1 reaches 35-55℃, the composting product A1 is turned over to make the temperature of each point inside it uniform, thus obtaining the mixing pile B1.

[0046] (2.3) When the temperature of the mixed pile B1 begins to drop, let it stand for 2 days.

[0047] According to statistics, the decomposition of lignin in this stage takes about 28 days.

[0048] Example 2:

[0049] I. Cultivation Stage:

[0050] (1) Select broad-leaved forest areas in tropical or subtropical regions that are undisturbed by human activity;

[0051] (2) Select soil from (1) with a leaf decay layer of more than 5cm, and dig out a soil block A2 with a surface area of ​​1.2 square meters and a thickness of 1.2cm;

[0052] (3) Add 15% of ammonia absorption promoter to soil block A2, then add 4% of baker's yeast extract powder and 6% of glucose, stir well, then add 5% of manganese chloride solution with a concentration of 5 μg / L, and stir well.

[0053] (4) The soil was cultured for 2 weeks at a temperature of 33℃ and a humidity of 70% to obtain culture soil A2. During the period, the culture soil A2 was turned over to keep its oxygen content at 22% and carbon dioxide content at 2%.

[0054] II. Application Phase:

[0055] Pretreatment: Cut the lignosulfonate-containing leaf material to be decomposed into 1 square centimeter pieces and soak them in ordinary tap water for 15 hours.

[0056] (1) The lignin-containing leaf mold to be decomposed is cultured for 2 days at a carbon-nitrogen ratio of 1:35 and a humidity of 50% to obtain compost product A2.

[0057] (2) Mix the compost A2 obtained in this stage (1) with the cultivation soil A2 and place it in a plastic cylinder with a diameter of 1m;

[0058] (2.1) When the local temperature of the compost A2 reaches 26-35℃, the compost A2 will be turned over to make the temperature of each point inside it uniform, thus obtaining a mixed pile A2.

[0059] (2.2) When the local temperature of the mixing pile A2 reaches 35-55℃, the composting product A2 will be turned over to make the temperature of each point inside it uniform, thus obtaining the mixing pile B2.

[0060] (2.3) When the temperature of the mixed pile B2 begins to drop, let it stand for 2 days.

[0061] According to statistics, the decomposition of lignin in this stage took 33 days.

[0062] Example 3:

[0063] I. Cultivation Stage:

[0064] (1) Select broad-leaved forest areas in tropical or subtropical regions that are undisturbed by human activity;

[0065] (2) Select soil from (1) with a leaf decay layer of more than 5cm, and dig out a soil block A3 with a surface area of ​​1.2 square meters and a thickness of 1.2cm;

[0066] II. Application Phase:

[0067] Pretreatment: Cut the lignosulfonate-containing leaf material to be decomposed into 1 square centimeter pieces and soak them in ordinary tap water for 15 hours.

[0068] (1) The lignin-containing leaf mold to be decomposed is cultured for 2 days at a carbon-nitrogen ratio of 1:35 and a humidity of 50% to obtain compost product A3.

[0069] (2) Mix the compost A3 obtained in this stage (1) with the cultivation soil A3 and place it in a plastic cylinder with a diameter of 1m;

[0070] (2.1) When the local temperature of the compost A3 reaches 26-35℃, the compost A3 will be turned over to make the temperature of each point inside the compost uniform, thus obtaining a stirred pile A3.

[0071] (2.2) When the local temperature of the mixing pile A3 reaches 35-55℃, the composting product A3 is turned over to make the temperature of each point inside it uniform, thus obtaining the mixing pile B3.

[0072] (2.3) When the temperature of the mixed pile B3 begins to drop, let it stand for 2 days.

[0073] According to statistics, the decomposition of lignin in this stage takes 30 days.

[0074] Example 4:

[0075] I. Cultivation Stage:

[0076] (1) Select broad-leaved forest areas in tropical or subtropical regions that are undisturbed by human activity;

[0077] (2) Select soil from (1) with a leaf decay layer of more than 5cm, and dig out a soil block A4 with a surface area of ​​0.8 square meters and a thickness of 8cm;

[0078] II. Application Phase:

[0079] Pretreatment: Cut the lignosulfonate-containing leaf material to be decomposed into 0.5 square centimeter pieces and soak them in ordinary tap water for 10 hours.

[0080] (1) The lignin-containing leaf mold to be decomposed is cultured for 3 days at a carbon-nitrogen ratio of 1:25 and a humidity of 50% to obtain compost product A4.

[0081] (2) Mix the compost A4 obtained in this stage (1) with the cultivation soil A4 and place it in a plastic cylinder with a diameter of 0.8m;

[0082] (2.1) When the local temperature of the compost A4 reaches 26-35℃, the compost A4 will be turned over to make the temperature of each point inside the compost uniform, thus obtaining a mixed pile A4.

[0083] (2.2) When the local temperature of the mixing pile A4 reaches 35-55℃, the composting product A4 will be turned over to make the temperature of each point inside the pile uniform, thus obtaining the mixing pile B4.

[0084] (2.3) When the temperature of the mixed pile B1 begins to drop, let it stand for 2 days.

[0085] According to statistics, the decomposition of lignin in this stage takes about 38 days.

[0086] By comparing Example 2 with Example 3 and Example 1 with Example 4, it can be seen that the soil decomposes lignin for a longer time than the soil without cultivation treatment. Furthermore, the soil prepared by the cultivation method of the present invention is pollution-free, energy-efficient, and decomposes lignin quickly. Compared with the soil without cultivation, the cycle for decomposing lignin after cultivation is shortened by about 10%.

[0087] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of soil rearing, characterized by, The method comprises the following steps: (1) selecting a broad-leaved forest region in a tropical or subtropical region without human disturbance; (2) selecting a soil block A with a rotten leaf layer of more than 5 cm in the region selected in step (1) and digging 0.8-1.2 square meters; (3) adding an ammonia absorption promoter to the soil block A, wherein the mass of the ammonia absorption promoter is 10%-15% of the mass of the soil block A, and stirring uniformly; (31) the ammonia absorption promoter is a mixed solution of yeast extract, glucose and a divalent manganese ion solution; (32) the divalent manganese ion solution in step (3) is prepared from manganese dichloride, and the concentration of manganese in the divalent manganese ion solution is 1 μg / L-9 μg / L (4) culturing for 2-6 weeks at a temperature of 25-33 ℃ and a humidity of 50%-70% to obtain a cultivated soil A; (41) in step (4), the oxygen content is 18%-22%, and the carbon dioxide content is 0.3%-4%.

2. The soil cultivating method according to claim 1, characterized by: The thickness of the soil block A is 8-1.2 cm.

3. The soil cultivating method according to claim 1, characterized by: In step (4), the pH value of the soil A is 5-8.

4. Use of soil-decomposed lignin prepared according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: (1) decomposing rotten leaves containing lignin raw materials according to a carbon-nitrogen ratio of 1:25-35 and a humidity of 50%-70% for 2-3 days to obtain a compost product A; (2) mixing the compost product A obtained in step (1) with the cultivated soil A and performing composting and maturity treatment.

5. Use of soil-decomposed lignin according to claim 4, characterized in that: The maturity treatment in step (2) comprises the following steps: (2.1) when the local temperature of the compost product A reaches 26-35 ℃, the compost product A is turned over to balance the temperature at each point in the compost product A, and a stirred pile A is obtained; (2.2) when the local temperature of the stirred pile A reaches 35-55 ℃, the compost product A is turned over to balance the temperature at each point in the compost product A, and a stirred pile B is obtained; (2.3) when the temperature of the stirred pile B starts to drop, the stirred pile B is left to stand for 2-3 days.

6. Use of soil-decomposed lignin according to claim 4, characterized in that: The compost product A is placed in a straight cylinder with a diameter of 0.8-1 m for composting and maturity treatment.

7. Use of soil-decomposed lignin according to claim 4, characterized in that: The method further comprises a pretreatment step of cutting the rotten leaves containing lignin raw materials to be decomposed into pieces with a size of 0.5-1 square centimeters and soaking in clean water for 10-15 hours.