Preparation method and application of nitrogen modified humus

Abstract

The invention discloses a preparation method and application of nitrogen element modified humus, the preparation method of the nitrogen element modified humus comprises the following steps: S1: mixing humus with acid and an oxidizing agent for reaction to obtain carboxylated humus; s2, mixing and reacting the carboxylated humus obtained in the step S1 with an amine compound to obtain the nitrogen modified humus. According to the preparation method of the nitrogen modified humus provided by the invention, the humus is taken as a raw material, and the content of nitrogen in the humus is greatly increased through carboxylation reaction and amidation; meanwhile, the molecular weight of the modified humus is further reduced, the water solubility of the modified humus is improved, and absorption of plants is facilitated; the preparation method is simple and convenient in steps and suitable for being widely applied to actual production.

Description

Technical Field

[0001] The invention belongs to the technical field of plant cultivation, and in particular relates to a preparation method and application of nitrogen-modified humus. Background Art

[0002] Humus fertilizer is an organic fertilizer with humus as the main component. It has many functions such as promoting plant growth, increasing crop yields, and improving soil structure. Humus fertilizer can increase the content of soil organic matter and improve soil structure; the organic matter in it can improve the water retention and fertilizer retention of the soil, help increase soil fertility, improve soil texture, and promote root development; these organic substances can also serve as a nutrient source for plants, providing carbon, nitrogen, phosphorus, potassium and other elements required by plants. These elements can promote plant growth and development, enhance the resistance of plants to stress, and improve crop quality and yield. Humus fertilizer also contains rich organic acids and trace elements, which can promote the absorption and utilization of nutrients by plants. Organic acids can dissociate hydrogen ions, making mineral nutrients in the soil easier to be absorbed by plants, thereby improving nutrient utilization efficiency and reducing fertilization costs. Organic acids can also play a role in regulating soil pH. At the same time, organic acids can also promote the growth and metabolic activities of soil microorganisms, increase soil fertility, and improve the soil environment. At present, humus is basically used directly in soil fertilization. In order to increase soil fertility and promote plant growth, it is of great significance to develop modified fertilizers of humus. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a preparation method of nitrogen-modified humus, which uses humus as a raw material, and through carboxylation and amidation, greatly increases the nitrogen content in the humus; at the same time, the molecular weight of the modified humus is further reduced, and its water solubility is improved, which is more conducive to plant absorption; the steps of the preparation method are simple and convenient, and are suitable for wide application in actual production.

[0004] The present invention also provides nitrogen-modified humus prepared by the preparation method.

[0005] The invention also provides a method for increasing tobacco yield.

[0006] According to a first aspect of the present invention, a method for preparing nitrogen-modified humus is provided, the preparation method comprising the following steps:

[0007] S1: mixing humus with acid and oxidant to obtain carboxylated humus;

[0008] S2: The carboxylated humus obtained in step S1 is mixed with an amine compound for reaction to obtain nitrogen-modified humus.

[0009] In some embodiments of the present invention, the humus in step S1 includes at least one of humic acid, fulvic acid and humin.

[0010] In some embodiments of the present invention, the humus is pretreated before the mixing reaction; the pretreatment includes crushing and vacuum drying the humus.

[0011] In some embodiments of the present invention, the particle size of the humus is 200-300 meshes.

[0012] In some embodiments of the present invention, the temperature of the vacuum drying process is 70-90°C.

[0013] In some embodiments of the present invention, the vacuum drying treatment is performed for 3 to 5 hours.

[0014] In some embodiments of the present invention, the acid in step S1 includes sulfuric acid or nitric acid.

[0015] In some embodiments of the present invention, the concentration of the acid is 3% to 10%.

[0016] In some embodiments of the present invention, the concentration of the acid is 3% to 7%.

[0017] In some embodiments of the present invention, the mixing ratio of the humus to the acid is 0.5 to 2 L of acid per kg of humus.

[0018] In some embodiments of the present invention, the mixing ratio of the humus to the acid is 0.5 to 1.5 L of acid per kg of humus.

[0019] In some embodiments of the present invention, the oxidant in step S1 includes hydrogen peroxide.

[0020] In some embodiments of the present invention, the concentration of the hydrogen peroxide is 20-40 w / v%.

[0021] In some embodiments of the present invention, the concentration of the hydrogen peroxide is 25-35 w / v%.

[0022] In some embodiments of the present invention, the mass ratio of the oxidant to the humus is 1:(5-15).

[0023] In some embodiments of the present invention, the mass ratio of the oxidant to the humus is 1:(8-12).

[0024] In some embodiments of the present invention, the reaction temperature in step S1 is 60-120°C.

[0025] In some embodiments of the present invention, the reaction temperature in step S1 is 70-90°C.

[0026] In some embodiments of the present invention, the reaction time in step S1 is 6 to 12 hours.

[0027] In some embodiments of the present invention, the reaction time in step S1 is 9 to 11 hours.

[0028] In some embodiments of the present invention, the step S1 further comprises, after the reaction is completed, cooling the reaction system to room temperature and filtering, and vacuum drying the filter cake obtained by filtration.

[0029] In some embodiments of the present invention, the step S2 further comprises mixing a reaction solvent with the carboxylated humic acid before adding the organic amine.

[0030] In some embodiments of the present invention, the reaction solvent comprises N,N-dimethylformamide.

[0031] In some embodiments of the present invention, the volume of the N,N-dimethylformamide is consistent with the volume of the acid in step S1.

[0032] In some embodiments of the present invention, the amine compound in step S2 includes an organic amine.

[0033] In some embodiments of the present invention, the organic amine includes at least one of aliphatic amines, aromatic amines, heterocyclic amines and alcohol amines.

[0034] In some embodiments of the present invention, the fatty amine comprises diethylamine and / or triethylamine.

[0035] In some embodiments of the present invention, the mass ratio of the humus in step S1 to the amine compound in step S2 is (3-12):1.

[0036] In some embodiments of the present invention, the mass ratio of the humus in step S1 to the amine compound in step S2 is (5-10):1.

[0037] In some embodiments of the present invention, the reaction temperature in step S2 is 100-150°C.

[0038] In some embodiments of the present invention, the reaction temperature in step S2 is 110-130°C.

[0039] In some embodiments of the present invention, the reaction time in step S2 is 6 to 10 hours.

[0040] In some embodiments of the present invention, the reaction time in step S2 is 7 to 9 hours.

[0041] In some embodiments of the present invention, the step S2 further comprises filtering the reaction system after the reaction is completed, and washing the filter cake obtained by the filtering with water.

[0042] According to a second aspect of the present invention, a nitrogen-modified humus prepared by the preparation method described in the first aspect of the present invention is provided.

[0043] According to a third aspect of the present invention, a method for increasing tobacco yield is provided, the method comprising:

[0044] The nitrogen-modified humus prepared by the preparation method described in the first aspect of the present invention and the tobacco-specific fertilizer are mixed and applied.

[0045] In some embodiments of the present invention, the mixing mass ratio of the nitrogen-modified humus to the tobacco-specific fertilizer is 1:(5-10).

[0046] In some embodiments of the present invention, the mixing mass ratio of the nitrogen-modified humus to the tobacco-specific fertilizer is 3:10.

[0047] In some embodiments of the present invention, the nitrogen-modified humus and tobacco-specific fertilizer are mixed and applied in an amount of 50 to 80 kg / mu.

[0048] In some embodiments of the present invention, the nitrogen-modified humus and tobacco-specific fertilizer are mixed and applied in an amount of 60 to 70 kg / mu.

[0049] In some embodiments of the present invention, the fertilizer is applied at a distance of 15 to 20 cm from the tobacco root and at a depth of 20 to 30 cm.

[0050] The present invention has at least the following beneficial effects:

[0051] The present invention provides a preparation method of nitrogen-modified humus, which uses humus as a raw material and undergoes carboxylation modification and amidation reaction in sequence; wherein, carboxylation modification can increase the carboxyl groups on the surface of the humus to facilitate the introduction of subsequent nitrogen-containing groups, and the addition of hydrogen peroxide during carboxylation can oxidize the hydroxyl groups in the humus to carboxyl groups, thereby improving the carboxylation efficiency; and amidation reaction is to use an organic small molecule containing an amino group to react with the carboxyl-modified humus to obtain a modified humus rich in nitrogen content. At the same time, the preparation method is simple and easy to use, and will not introduce any components that are not conducive to plant growth, and is suitable for being widely used in the fields of plant cultivation, soil conservation, and the like.

[0052] The molecular weight of the nitrogen-modified humus provided by the present invention is greatly reduced after modification, so that its water solubility is further improved, which is more conducive to plant absorption; at the same time, a large amount of nitrogen elements required for plant growth are introduced during the modification process.

[0053] The present invention provides a method for increasing tobacco yield by applying the nitrogen-modified humus and conventional tobacco-specific fertilizer to tobacco roots, which can significantly improve the organic matter content in the soil, accelerate the absorption of essential elements for plant growth, and improve tobacco quality and tobacco yield. DETAILED DESCRIPTION

[0054] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0055] Example 1

[0056] This embodiment prepares a nitrogen-modified humus, and the preparation method thereof specifically comprises the following steps:

[0057] 1) Carboxylation of humic acid:

[0058] 5 kg of humic acid was crushed into 200-300 mesh powder and placed in a vacuum drying oven at 80° C. for 4 hours, and then allowed to cool to room temperature naturally after drying; the humic acid powder was poured into 5 L of 5 w / v% sulfuric acid solution, and 500 g of hydrogen peroxide (hydrogen peroxide concentration was 30 w / v%) was added and mixed evenly, and then heated to 80° C., stirred and reacted for 10 hours, and then naturally cooled to room temperature after the reaction was completed, and then filtered with a Buchner funnel, and the filter cake was vacuum dried at 80° C. to obtain carboxylated humic acid;

[0059] 2) Amidation reaction:

[0060] The carboxylated humic acid obtained in step 1) was added to 5L N,N-dimethylformamide, and then 500g diethylamine was added and mixed evenly, and the mixture was heated to 120°C and stirred for reaction for 8h. After the reaction was completed, the mixture was filtered with a Buchner funnel and the filter cake was washed with water to obtain 5.3kg nitrogen-modified humus.

[0061] Example 2

[0062] This embodiment prepares a nitrogen-modified humus. The preparation method thereof is different from that of embodiment 1 only in that the amount of hydrogen peroxide in step 1) is adjusted to 1000 g, and the other steps are consistent with those of embodiment 1.

[0063] Example 3

[0064] This embodiment prepares a nitrogen-modified humus. The preparation method thereof is different from that of embodiment 1 only in that the amount of diethylamine in step 2) is adjusted to 1000 g, and the other steps are consistent with those of embodiment 1.

[0065] Example 4

[0066] This embodiment provides a method for increasing tobacco yield, which comprises the following steps:

[0067] The nitrogen-modified humus prepared in Example 1 was evenly mixed with 50 kg of tobacco-specific fertilizer (purchased from Chenzhou Jintu Chemical Fertilizer Co., Ltd.) for use. When applied, a 20 cm deep pit was dug in 1 acre of tobacco field at a distance of 15 cm from the root of the tobacco with a shovel, and the mixed fertilizer (70 g per tobacco plant) was placed in the pit and covered with soil, and then the tobacco was maintained normally; the nitrogen-modified humus corresponding to each acre of tobacco field was 15 kg and the tobacco-specific fertilizer was 50 kg.

[0068] Example 5

[0069] This embodiment provides a method for increasing tobacco yield. The difference between this method and Example 4 is that the nitrogen-modified humus is replaced by the nitrogen-modified humus prepared in Example 2, and the other steps are consistent with Example 4.

[0070] Example 6

[0071] This embodiment provides a method for increasing tobacco yield. The difference between this method and Example 4 is that the nitrogen-modified humus is replaced by the nitrogen-modified humus prepared in Example 3, and the other steps are consistent with Example 4.

[0072] Comparative Example 1

[0073] In this comparative example, a modified humus is prepared. The preparation method thereof is different from that of Example 1 only in that 500 g of diethylamine in step 2) is omitted, and the other steps are consistent with those of Example 1.

[0074] Comparative Example 2

[0075] In this comparative example, a nitrogen-modified humus is prepared. The preparation method thereof is different from that of Example 1 only in that 500 g of hydrogen peroxide in step 1) is omitted, and the other steps are consistent with those of Example 1.

[0076] Comparative Example 3

[0077] In this comparative example, a nitrogen-modified humus is prepared. The preparation method thereof is different from that in Example 1 only in that the carboxylation treatment in step 1) is omitted, and the crushed humic acid is directly subjected to an amidation reaction. The other steps are consistent with those in Example 1.

[0078] Test example

[0079] This test example tests the effects of the humus prepared in Examples 1 to 3 and Comparative Examples 1 to 3 on tobacco growth. The specific test method is as follows:

[0080] 1) Application method: Referring to the tobacco yield increasing method described in Example 4, equal amounts of the modified humus prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were mixed with tobacco-specific fertilizers and applied.

[0081] 2) After applying the mixed fertilizer, the soil was maintained normally for 30 days, and the organic matter content, available nitrogen content, available phosphorus content, and microbial carbon content in the soil were tested. At the same time, the tobacco leaf yield of each group was counted. The results are shown in Table 1.

[0082] Table 1 Soil test results and tobacco leaf yield statistics

[0083]

[0084] From the results in Table 1, we can see that:

[0085] ① Compared with Example 1, Example 2 only increases the amount of hydrogen peroxide, and the increase of hydrogen peroxide will lead to a deeper degree of oxidation of humic acid, resulting in an increase in the content of available phosphorus, available nitrogen and organic matter in the soil; however, excessive oxidants will have a toxic effect on microorganisms in the soil, resulting in a decrease in the soil microbial carbon content. The slight decrease in tobacco yield compared with Example 1 may be due to the decrease in the content of soil microorganisms;

[0086] ② Compared with Example 1, Example 3 only increases the amount of diethylamine, and the increase in diethylamine leads to an increase in the content of available phosphorus, available nitrogen and organic matter in the soil; however, excessive diethylamine is not only toxic to microorganisms, but may also affect the physical and chemical properties of the soil, such as pH, air permeability, etc., ultimately leading to a decrease in the soil microbial carbon content. The slight decrease in its tobacco yield compared with Example 1 may be due to the decrease in the soil microbial content;

[0087] ③ Compared with Examples 1 to 3, the tobacco yield finally obtained in Comparative Example 1 is significantly lower, because Comparative Example 1 omits the amidation reaction step, resulting in the nitrogen content of the modified humus being much lower than that of Examples 1 to 3, and therefore the yield is lower than that of Examples 1 to 3;

[0088] ④ Compared with Examples 1 to 3, the tobacco yield finally obtained in Comparative Example 2 is significantly lower. This is because Comparative Example 2 omits the step of hydrogen peroxide oxidation, resulting in insufficient carboxylation reaction of the humus, and the subsequent amidation reaction is also affected. The nitrogen content of the nitrogen-modified humus finally obtained is reduced, so the yield is less than that of Examples 1 to 3;

[0089] ⑤ Compared with Examples 1 to 3, the tobacco yield finally obtained in Comparative Example 3 is significantly reduced. This is because Comparative Example 3 omits the step of carboxylation reaction, resulting in the humus not obtaining enough hydroxyl groups to react with hydrogen peroxide, and further unable to undergo sufficient amidation reaction. The nitrogen content of the nitrogen-modified humus finally obtained is reduced, and therefore the yield is less than that of Examples 1 to 3.

[0090] The embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for preparing nitrogen-modified humus, characterized in that: The preparation method comprises the following steps: S1: mixing humus with acid and oxidant to obtain carboxylated humus; S2: The carboxylated humus obtained in step S1 is mixed with an amine compound for reaction to obtain nitrogen-modified humus.

2. The preparation method according to claim 1, characterized in that: The humus in step S1 includes at least one of humic acid, fulvic acid and humin; Preferably, the particle size of the humus is 200-300 meshes.

3. The preparation method according to claim 1, characterized in that: The acid in step S1 includes sulfuric acid or nitric acid; Preferably, the concentration of the acid is 3% to 10%; Preferably, the mixing ratio of the humus to the acid is 0.5 to 2 L of acid per kg of humus.

4. The preparation method according to claim 1, characterized in that: The oxidant in step S1 includes hydrogen peroxide; Preferably, the mass ratio of the oxidant to the humus is 1:(5-15).

5. The preparation method according to claim 1, characterized in that: The reaction temperature in step S1 is 60-120°C; Preferably, the reaction time in step S1 is 6 to 12 hours.

6. The preparation method according to claim 1, characterized in that: The amine compound in step S2 includes an organic amine; Preferably, the organic amine includes at least one of aliphatic amines, aromatic amines, heterocyclic amines and alcohol amines; More preferably, the fatty amine comprises diethylamine and / or triethylamine.

7. The preparation method according to claim 1, characterized in that: The mass ratio of the humus in step S1 to the amine compound in step S2 is (3-12):

1.

8. The preparation method according to claim 1, characterized in that: The reaction temperature in step S2 is 100-150°C; Preferably, the reaction time in step S2 is 6 to 10 hours.

9. Nitrogen-modified humus prepared by the preparation method as claimed in any one of claims 1 to 8.

10. A method for increasing tobacco yield, characterized in that: The tobacco leaf yield increasing method comprises: Mixing the nitrogen-modified humus prepared by the preparation method according to any one of claims 1 to 8 with a tobacco-specific fertilizer and applying the mixture; Preferably, the mixing mass ratio of the nitrogen-modified humus to the tobacco-specific fertilizer is 1:(5-10).

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