Biomass fertilizer for improving soil environment and preparation method thereof

Abstract

The invention relates to the technical field of fertilizers, and discloses a biomass fertilizer for improving a soil environment and a preparation method thereof. A lignin grafted copolymer and modified sodium alginate are used as raw materials, a calcium ion in-situ gel method is used for preparing composite hydrogel, and biomass charcoal, urea and monopotassium phosphate are added into the hydrogel, so that the biomass fertilizer for improving the soil environment is obtained. Pyrrole groups in the lignin grafted copolymer and nitrogen atoms in a Mannich base structure are used as hydrogen bond receptors, so that the hydrogen bond interaction with a hydrogel molecular chain is enhanced, and the water retention capacity of the fertilizer is improved; a rigid structure of the lignin also plays a role in a gel network, collapse of a cross-linked network is reduced, so that a richer three-dimensional pore structure is formed, and the water retention effect of the fertilizer is enhanced; the quaternary ammonium salt group can cause exosmosis of bacterial substances by destroying a bacterial cell membrane structure, so that the antibacterial effect of the fertilizer is enhanced; thioureido can be combined with enzyme in bacterial cells to achieve an antibacterial effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fertilizers, in particular to a biomass fertilizer for improving soil environment and a preparation method thereof. BACKGROUND

[0002] Agricultural soil is the core resource supporting food production and ecological balance. However, in recent years, soil degradation has continued to worsen, which has become a key bottleneck restricting the sustainable development of agriculture. Biomass charcoal refers to carbon-rich substances generated by the thermal decomposition of biomass organic raw materials under anaerobic or anoxic conditions. Various biomass materials such as straw, sawdust, rice husk, and sludge are applied in the preparation of biomass charcoal. Biomass charcoal is usually alkaline and has a rich pore structure, which can provide and promote the release of soluble organic matter in soil. When added to fertilizers as an improver, biomass fertilizer can change the physical and chemical properties of soil and has been widely concerned and applied in the field of agriculture. However, its function still has limitations: existing technologies mainly focus on nutrient release and soil fertility improvement, and the optimization of water retention performance of fertilizers is insufficient. Traditional biomass fertilizers mainly rely on the pore adsorption of organic matter to retain water, and water is easily lost. In terms of antibacterial function, many technologies indirectly inhibit bacteria by adjusting soil pH or increasing the number of beneficial microorganisms, which has poor antibacterial performance. Patent CN119661276A discloses a carbohydrate biomass fertilizer and a preparation method thereof. The biomass fertilizer prepared by the invention helps to improve soil structure and increase soil fertility, promotes plant growth, and has the characteristics of environmental protection and sustainability. However, its water retention and antibacterial effects on soil need to be improved. SUMMARY

[0003] (I) Technical problems to be solved

[0004] In view of the deficiencies of the prior art, the present application provides a biomass fertilizer for improving soil environment and a preparation method thereof. The biomass fertilizer prepared by the present application has good water retention and antibacterial effects on soil.

[0005] (II) Technical solutions

[0006] In order to achieve the above object, the present application provides the following technical scheme: a preparation method of a biomass fertilizer for improving soil environment, the preparation method of the biomass fertilizer for improving soil environment is as follows: 2.8-3.2 mL of calcium ion crosslinking agent is added into 15-20 mL of deionized water, 0.3-0.5 g of lignin graft copolymer, 0.25-0.35 g of biomass charcoal, 0.1-0.2 g of urea and 0.08-0.12 g of potassium dihydrogen phosphate are added into the deionized water, and then stirred and dissolved, 0.46-0.5 g of modified sodium alginate is further added into the deionized water, and then stirred for 3.5-4.5 h, 1.7-2.3 mL of gluconolactone solution with a mass fraction of 7.6%-8% is added dropwise into the deionized water, and then continuously stirred for 0.5-2 min, the sol is poured into a mold, and then placed for 16-20 h, and then placed in an oven at 40-45 DEG C for drying, so as to obtain the biomass fertilizer for improving soil environment.

[0007] Preferably, the preparation method of the calcium ion crosslinking agent is as follows: 3.36-3.364 g of disodium ethylenediaminetetraacetate and 1.1-1.12 g of calcium chloride are added into 35-45 mL of deionized water, and then dissolved under ultrasonic, the pH value is adjusted to 5-6, and then deionized water is added to 50 mL, so as to obtain the calcium ion crosslinking agent.

[0008] Preferably, the preparation method of the lignin graft copolymer comprises the following steps:

[0009] (1) 1.4-1.46 g of trimethyl-1,3-propanediamine is added into 30-40 mL of anhydrous ethanol solvent, and then stirred and dissolved, 2.55-2.65 g of 3-chloropropyltrimethoxysilane is added dropwise into the anhydrous ethanol solvent, the dropwise adding time is 30-50 min, after the dropwise adding is completed, the reaction temperature is increased to reflux reaction for 12-15 h, after the reaction is completed, the solvent is removed by rotary evaporation, so as to obtain a silane quaternary ammonium salt intermediate;

[0010] (2) 2.74-2.77 g of the silane quaternary ammonium salt intermediate is added into 40-60 mL of anhydrous ethanol solvent, and then stirred and dissolved, 0.13-0.23 mL of concentrated hydrochloric acid is added to adjust the pH value to 2.4-2.6, nitrogen is introduced for protection, the temperature is increased to 98-102 DEG C, 0.64-0.68 mL of formaldehyde solution and 1.45-1.5 g of 1-(2-chloro-ethyl)-pyrrolidin-2-one are added into the anhydrous ethanol solvent, the reaction is carried out for 4-8 h, after the reaction is completed, the solvent is removed by rotary evaporation, and then washed and vacuum dried, so as to obtain a mannich base modified silane quaternary ammonium salt;

[0011] (3) adding 2.4-2.6 g of lignin, 10-15 mL of 3.5%-4% sodium hydroxide solution to adjust the pH value to 10.5-11.1, stirring and dissolving, and then stirring at 60-80 ℃ for 25-35 min, and then introducing nitrogen protection, and then adding 0.075-0.125 g of potassium persulfate initiator, 4.43-4.47 g of Mannich base modified silane quaternary ammonium salt and 2.95-3.05 g of acrylic acid, and then reacting for 2-3 h, and then filtering, dialyzing and removing the solvent by rotary evaporation, and then freeze-drying to obtain the lignin graft copolymer.

[0012] Preferably, the reaction temperature in the step (1) is 78-84 ℃.

[0013] Preferably, the mass fraction of the formaldehyde solution in the step (2) is 36%-38%.

[0014] Preferably, the preparation method of the modified sodium alginate comprises the following steps:

[0015] S1. adding 2.4-2.6 g of sodium alginate and 2.2-2.8 mL of sodium hydroxide solution to 80-120 mL of deionized water, stirring and dissolving to obtain a sodium alginate solution, adding 3.92-3.98 g of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride to 8-12 mL of sodium hydroxide solution, stirring and mixing, and then adding the mixture to the sodium alginate solution dropwise at 42-48 ℃, and then raising the temperature to 66-74 ℃ to react for 7-10 h, and then adding anhydrous ethanol to precipitate, washing the precipitate and freeze-drying to obtain the amphoteric sodium alginate intermediate;

[0016] S2. adding 2.6-2.8 g of the amphoteric sodium alginate intermediate and 165-185 mL of phosphate buffer solution with a pH value of 5.8-6.2 to a flask, stirring and dissolving, and then adding 1.18-1.22 g of 1-ethyl-(3-dimethylaminopropyl) carbonyl diimide hydrochloride to the flask, and then reacting for 2.5-4.5 h, and then continuously adding 0.7-0.75 g of N-hydroxysuccinimide and 2.26-2.3 g of aminothiourea, and then reacting for 12-15 h, and then adding anhydrous ethanol to precipitate, washing the precipitate and freeze-drying to obtain the modified sodium alginate.

[0017] Preferably, the mass fraction of the sodium hydroxide solution in the step S1 is 3.8%-4.2%.

[0018] The application provides a biomass fertilizer for improving soil environment, which is prepared by the preparation method.

[0019] (Three) beneficial technical effects

[0020] The present application uses lignin graft copolymerization and modification of sodium alginate as raw materials, and uses calcium ion in-situ gelation to prepare composite hydrogel, and directly adds biomass charcoal, urea and potassium dihydrogen phosphate into the hydrogel during preparation, so as to obtain a biomass fertilizer for improving soil environment.

[0021] The pyrrole groups in the lignin graft copolymer and the nitrogen atoms in the Mannich base structure act as hydrogen bond acceptors, enhancing the hydrogen bond interaction with the molecular chains of the hydrogel, forming a stable physical crosslinking network structure, and improving the water retention performance of the fertilizer; the introduction of silane groups further increases the crosslinking sites, improving the stability of the hydrogel network structure; at the same time, the rigid structure of lignin itself also plays a role in the gel network, acting as a physical filler to fill in the network gaps, reducing the collapse of the crosslinking network, thereby forming a more abundant three-dimensional pore structure, increasing the water storage space, and further enhancing the water retention of the fertilizer; the quaternary ammonium salt groups introduced into the lignin graft copolymer and the modified sodium alginate can bind to the phospholipid bilayer of the bacterial cell membrane, destroy the membrane structure, cause bacterial material exosmosis and cell rupture, and cause the death of bacteria, thereby enhancing the bacteriostatic effect of the fertilizer; at the same time, the thiourea groups in the modified sodium alginate have reducing properties, can combine with enzymes in the bacterial cells involved in redox reactions, cause the enzyme activity to decrease or be lost, affect key physiological processes such as energy metabolism, and have a bacteriostatic effect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the synthetic reaction formula of the lignin graft copolymer.

[0023] Figure 2 is the synthetic reaction formula of the modified sodium alginate. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application is described clearly and completely, obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0025] In order to better understand the above technical scheme, the above technical scheme will be described in detail below in combination with the drawings in the specification and specific embodiments.

[0026] Embodiment 1

[0027] (1) 1.4 g of trimethyl-1,3-propanediamine was added to 30 mL of anhydrous ethanol solvent, stirred and dissolved, 2.55 g of 3-chloropropyl trimethoxysilane was added dropwise, the dropwise time was 30 min, after the dropwise addition was completed, the temperature was raised to 78°C and refluxed for 12 h, after the reaction was completed, the solvent was removed by rotary evaporation, and a silane quaternary ammonium salt intermediate was obtained;

[0028] (2) 2.74 g of the silane quaternary ammonium salt intermediate was added to 40 mL of anhydrous ethanol solvent, stirred and dissolved, 0.13 mL of concentrated hydrochloric acid was added to adjust the pH value to 2.4, nitrogen was introduced for protection, the temperature was raised to 98°C, 0.64 mL of a 36% mass fraction formaldehyde solution and 1.45 g of 1-(2-chloro-ethyl)-pyrrolidin-2-one were added, and reacted for 4 h, after the reaction was completed, the solvent was removed by rotary evaporation, washed and vacuum dried, and a Mannich base modified silane quaternary ammonium salt was obtained;

[0029] (3) 2.4 g of lignin, 10 mL of a 3.5% mass fraction sodium hydroxide solution were added to a flask to adjust the pH value to 10.5, stirred and dissolved, after stirring at 60°C for 25 min, nitrogen was introduced for protection, 0.075 g of potassium persulfate initiator, 4.43 g of the Mannich base modified silane quaternary ammonium salt and 2.95 g of acrylic acid were added, and reacted for 2 h, after the reaction was completed, filtration and dialysis were performed, the solvent was removed by rotary evaporation, and freeze-drying was performed, and a lignin graft copolymer was obtained;

[0030] (4) 2.4 g of sodium alginate and 2.2 mL of a 3.8% mass fraction sodium hydroxide solution were added to 80 mL of deionized water, stirred and dissolved, and a sodium alginate solution was obtained, 3.92 g of 3-chloro-2-hydroxypropyl trimethylammonium chloride was added to 8 mL of a sodium hydroxide solution, stirred and mixed, and at 42°C, it was added dropwise to the sodium alginate solution, after the dropwise addition was completed, the temperature was raised to 66°C and reacted for 7 h, after the reaction was completed, anhydrous ethanol was added and precipitated, the precipitate was washed and freeze-dried, and a zwitterionic sodium alginate intermediate was obtained;

[0031] (5) 2.6 g of the zwitterionic sodium alginate intermediate and 165 mL of a phosphate buffer solution with a pH value of 5.8 were added to a flask, stirred and dissolved, 1.18 g of 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole hydrochloride was added, reacted for 2.5 h, 0.7 g of N-hydroxysuccinimide and 2.26 g of aminothiourea were further added, reacted for 12 h, after the reaction was completed, anhydrous ethanol was added and precipitated, the precipitate was washed and freeze-dried, and a modified sodium alginate was obtained;

[0032] (6) 3.36 g of ethylenediaminetetraacetic acid disodium salt and 1.1 g of calcium chloride were added to 35 mL of deionized water, dissolved under ultrasonic, the pH value was adjusted to 5, and deionized water was added to 50 mL, and a calcium ion crosslinking agent was obtained;

[0033] (7) To 15 mL of deionized water, 2.8 mL of calcium ion crosslinking agent was added, 0.3 g of lignin graft copolymer, 0.25 g of biomass charcoal, 0.1 g of urea, 0.08 g of potassium dihydrogen phosphate were added, stirred and dissolved, then 0.46 g of modified sodium alginate was added, stirred for 3.5 h, then 1.7 mL of 7.6% mass fraction of gluconolactone solution was added dropwise, and stirred for 0.5 min. The sol was poured into a mold and placed in a 40°C oven for 16 h to dry. A biomass fertilizer for improving soil environment was obtained.

[0034] Example 2

[0035] (1) To 40 mL of anhydrous ethanol solvent, 1.46 g of trimethyl-1,3-propanediamine was added and stirred and dissolved. 2.65 g of 3-chloropropyltrimethoxysilane was added dropwise, the dropwise addition time was 50 min, after the dropwise addition was completed, the temperature was raised to 84°C and refluxed for 15 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a silane quaternary ammonium salt intermediate;

[0036] (2) To 60 mL of anhydrous ethanol solvent, 2.77 g of silane quaternary ammonium salt intermediate was added and stirred and dissolved. 0.23 mL of concentrated hydrochloric acid was added to adjust the pH to 2.6. Nitrogen was introduced for protection. The temperature was raised to 102°C, and 0.68 mL of 38% mass fraction of formaldehyde solution, 1.5 g of 1-(2-chloro-ethyl)-pyrrolidin-2-one was added. The reaction was carried out for 8 h. After the reaction was completed, the solvent was removed by rotary evaporation, washed and vacuum dried to obtain a Mannich base modified silane quaternary ammonium salt.

[0037] (3) To the flask, 2.6 g of lignin, 15 mL of 4% mass fraction of sodium hydroxide solution was added to adjust the pH to 11.1, and stirred and dissolved. After stirring at 80°C for 35 min, nitrogen was introduced for protection. 0.125 g of potassium persulfate initiator, 4.47 g of Mannich base modified silane quaternary ammonium salt, 3.05 g of acrylic acid were added. The reaction was carried out for 3 h. After the reaction was completed, it was filtered, dialyzed, and the solvent was removed by rotary evaporation. Freeze-drying was carried out to obtain a lignin graft copolymer.

[0038] (4) To 120 mL of deionized water, 2.6 g of sodium alginate and 2.8 mL of 4.2% mass fraction of sodium hydroxide solution were added and stirred and dissolved to obtain a sodium alginate solution. 3.98 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride was added to 12 mL of sodium hydroxide solution, stirred and mixed, and then added dropwise to the sodium alginate solution at 48°C. After the dropwise addition was completed, the temperature was raised to 74°C and the reaction was carried out for 10 h. After the reaction was completed, anhydrous ethanol was added and the precipitate was washed and freeze-dried to obtain an amphoteric sodium alginate intermediate.

[0039] (5) 2.8 g of the amphoteric sodium alginate intermediate, 185 mL of a phosphate buffer solution with a pH value of 6.2 were added to a flask and stirred and dissolved, 1.22 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride was added thereto, after 4.5 h of reaction, 0.75 g of N-hydroxysuccinimide, 2.3 g of aminothiourea were continuously added, after 15 h of reaction, the reaction was completed, anhydrous ethanol was added for precipitation, the precipitate was washed and freeze-dried to obtain the modified sodium alginate;

[0040] (6) 3.364 g of disodium ethylenediaminetetraacetate, 1.12 g of calcium chloride were added to 45 mL of deionized water and dissolved under ultrasonic, the pH value was adjusted to 6, and deionized water was added to 50 mL to obtain a calcium ion crosslinking agent;

[0041] (7) 3.2 mL of the calcium ion crosslinking agent was added to 20 mL of deionized water, 0.5 g of the lignin graft copolymer, 0.35 g of the biomass charcoal, 0.2 g of urea, 0.12 g of potassium dihydrogen phosphate were added and stirred and dissolved, 0.5 g of the modified sodium alginate was further added thereto, after 4.5 h of stirring, 2.3 mL of a 8% mass fraction of gluconolactone solution was added dropwise, and the stirring was continued for 2 min, the sol was poured into a mold, and after 20 h of standing, it was placed in an oven at 45℃ for drying to obtain the biomass fertilizer for improving the soil environment.

[0042] Example 3

[0043] (1) 1.43 g of trimethyl-1,3-propanediamine was added to 35 mL of anhydrous ethanol solvent and stirred and dissolved, 2.6 g of 3-chloropropyltrimethoxysilane was added dropwise thereto, the dropwise addition was completed in 40 min, and the temperature was raised to 81℃ for reflux reaction for 13.5 h, after the reaction was completed, the solvent was removed by rotary evaporation to obtain a silane quaternary ammonium salt intermediate;

[0044] (2) 2.755 g of the silane quaternary ammonium salt intermediate was added to 50 mL of anhydrous ethanol solvent and stirred and dissolved, 0.18 mL of concentrated hydrochloric acid was added to adjust the pH value to 2.5, nitrogen was introduced for protection, the temperature was raised to 100℃, 0.66 mL of a 37% mass fraction of formaldehyde solution, 1.475 g of 1-(2-chloro-ethyl)-pyrrolidin-2-one were added thereto, the reaction was carried out for 6 h, after the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and vacuum dried to obtain a Mannich base modified silane quaternary ammonium salt;

[0045] (3) 2.5 g of lignin, 12.5 mL of 3.75% by mass sodium hydroxide solution to adjust pH to 10.8, stirring and dissolving, after stirring at 70°C for 30 min, nitrogen protection, 0.1 g of potassium persulfate initiator, 4.45 g of Mannich base modified silane quaternary ammonium salt, 3 g of acrylic acid, reaction for 2.5 h, after reaction, filtration, dialysis, rotary evaporation to remove solvent, freeze-drying, to obtain lignin graft copolymer;

[0046] (4) 2.5 g of sodium alginate, 2.5 mL of 4% by mass sodium hydroxide solution, stirring and dissolving, to obtain sodium alginate solution, 3.95 g of 3-chloro-2-hydroxypropyl trimethylammonium chloride was added to 10 mL of sodium hydroxide solution, stirring and mixing, at 45°C, it was added dropwise to the sodium alginate solution, after dropwise addition, the temperature was raised to 70°C and reacted for 8.5 h, after reaction, anhydrous ethanol was added to precipitate, the precipitate was washed and freeze-dried to obtain the amphoteric sodium alginate intermediate;

[0047] (5) 2.7 g of amphoteric sodium alginate intermediate, 175 mL of pH 6 phosphate buffer solution, stirring and dissolving, 1.2 g of 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole hydrochloride was added, after reaction for 3.5 h, 0.725 g of N-hydroxysuccinimide, 2.28 g of aminothiourea was continuously added, reaction for 13.5 h, after reaction, anhydrous ethanol was added to precipitate, the precipitate was washed and freeze-dried to obtain modified sodium alginate;

[0048] (6) 3.362 g of disodium ethylenediaminetetraacetate, 1.11 g of calcium chloride was added to 40 mL of deionized water, dissolved under ultrasonic, pH was adjusted to 5.5, deionized water was added to 50 mL to obtain calcium ion crosslinking agent;

[0049] (7) 3 mL of calcium ion crosslinking agent was added to 17.5 mL of deionized water, 0.4 g of lignin graft copolymer, 0.3 g of biomass charcoal, 0.15 g of urea, 0.1 g of potassium dihydrogen phosphate was added, stirring and dissolving, 0.48 g of modified sodium alginate was added, stirring for 4 h, 2 mL of 7.8% by mass gluconolactone solution was added dropwise, stirring for 1.2 min, the sol was poured into a mold, after standing for 18 h, it was placed in an oven at 42°C to dry, to obtain biomass fertilizer for improving soil environment.

[0050] Example 4

[0051] (1) 1.4 g of trimethyl-1,3-propanediamine was added to 30 mL of anhydrous ethanol solvent, stirred and dissolved, 2.55 g of 3-chloropropyl trimethoxysilane was added dropwise, the dropwise time was 30 min, after the dropwise addition was completed, the temperature was raised to 78°C and refluxed for 12 h, after the reaction was completed, the solvent was removed by rotary evaporation, and a silane quaternary ammonium salt intermediate was obtained;

[0052] (2) 2.74 g of the silane quaternary ammonium salt intermediate was added to 40 mL of anhydrous ethanol solvent, stirred and dissolved, 0.13 mL of concentrated hydrochloric acid was added to adjust the pH value to 2.4, nitrogen was introduced for protection, the temperature was raised to 98°C, 0.64 mL of a 36% mass fraction formaldehyde solution and 1.45 g of 1-(2-chloro-ethyl)-pyrrolidin-2-one were added, and the reaction was carried out for 4 h, after the reaction was completed, the solvent was removed by rotary evaporation, washed and vacuum dried, and a Mannich base modified silane quaternary ammonium salt was obtained;

[0053] (3) 2.6 g of lignin, 15 mL of a 4% mass fraction sodium hydroxide solution were added to a flask to adjust the pH value to 11.1, stirred and dissolved, after stirring at 80°C for 35 min, nitrogen was introduced for protection, 0.125 g of potassium persulfate initiator, 4.47 g of the Mannich base modified silane quaternary ammonium salt and 3.05 g of acrylic acid were added, and the reaction was carried out for 3 h, after the reaction was completed, filtration, dialysis and removal of the solvent by rotary evaporation were carried out, and freeze-drying was performed, and a lignin graft copolymer was obtained;

[0054] (4) 2.6 g of sodium alginate and 2.8 mL of a 4.2% mass fraction sodium hydroxide solution were added to 120 mL of deionized water, stirred and dissolved, and a sodium alginate solution was obtained, 3.98 g of 3-chloro-2-hydroxypropyl trimethylammonium chloride was added to 12 mL of a sodium hydroxide solution, stirred and mixed, and at 48°C, it was added dropwise to the sodium alginate solution, after the dropwise addition was completed, the temperature was raised to 74°C and the reaction was carried out for 10 h, after the reaction was completed, anhydrous ethanol was added and precipitated, the precipitate was washed and freeze-dried, and a zwitterionic sodium alginate intermediate was obtained;

[0055] (5) 2.7 g of the zwitterionic sodium alginate intermediate and 175 mL of a phosphate buffer solution with a pH value of 6 were added to a flask, stirred and dissolved, 1.2 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride was added, the reaction was carried out for 3.5 h, then 0.725 g of N-hydroxysuccinimide and 2.28 g of aminothiourea were continuously added, the reaction was carried out for 13.5 h, after the reaction was completed, anhydrous ethanol was added and precipitated, the precipitate was washed and freeze-dried, and a modified sodium alginate was obtained;

[0056] (6) adding 3.362 g of disodium ethylenediaminetetraacetate, 1.11 g of calcium chloride into 40 mL of deionized water, dissolving under ultrasonic, adjusting pH value to 5.5, and constant volume to 50 mL with deionized water to obtain a calcium ion crosslinking agent;

[0057] (7) adding 3 mL of the calcium ion crosslinking agent into 17.5 mL of deionized water, adding 0.4 g of the lignin graft copolymer, 0.3 g of the biomass charcoal, 0.15 g of urea, 0.1 g of potassium dihydrogen phosphate into the solution, stirring and dissolving, then adding 0.48 g of the modified sodium alginate into the solution, stirring for 4 h, then adding 2 mL of a 7.8% by mass gluconolactone solution dropwise into the solution, continuing to stir for 1.2 min, pouring the sol into a mold, and placing the mold in an oven at 42°C for drying after standing for 18 h to obtain a biomass fertilizer for improving soil environment.

[0058] Example 5

[0059] (1) adding 1.43 g of trimethyl-1,3-propanediamine into 35 mL of anhydrous ethanol solvent, stirring and dissolving, then adding 2.6 g of 3-chloropropyltrimethoxysilane dropwise into the solution, the dropping time being 40 min, after the dropping was completed, the temperature was raised to 81°C for refluxing reaction for 13.5 h, after the reaction was completed, the solvent was removed by rotary evaporation to obtain a silane quaternary ammonium salt intermediate;

[0060] (2) adding 2.755 g of the silane quaternary ammonium salt intermediate into 50 mL of anhydrous ethanol solvent, stirring and dissolving, adding 0.18 mL of concentrated hydrochloric acid to adjust the pH value to 2.5, and then introducing nitrogen protection, and then adding 0.66 mL of a 37% by mass formaldehyde solution and 1.475 g of 1-(2-chloro-ethyl)-pyrrolidin-2-one into the solution, and then reacting for 6 h, after the reaction was completed, the solvent was removed by rotary evaporation, and then the product was washed and vacuum dried to obtain a Mannich base modified silane quaternary ammonium salt;

[0061] (3) adding 2.4 g of lignin and 10 mL of a 3.5% by mass sodium hydroxide solution into a flask to adjust the pH value to 10.5, stirring and dissolving, and then introducing nitrogen protection after stirring at 60°C for 25 min, and then adding 0.075 g of potassium persulfate initiator, 4.43 g of the Mannich base modified silane quaternary ammonium salt, and 2.95 g of acrylic acid into the solution, and then reacting for 2 h, after the reaction was completed, the product was filtered, dialyzed, and then the solvent was removed by rotary evaporation, and then the product was freeze-dried to obtain a lignin graft copolymer;

[0062] (4) 2.4 g of sodium alginate, 2.2 mL of a 3.8% by mass sodium hydroxide solution were added to 80 mL of deionized water, and dissolved by stirring to obtain a sodium alginate solution. 3.92 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride was added to 8 mL of a sodium hydroxide solution, and mixed by stirring. The mixture was added dropwise to the sodium alginate solution at 42°C, and after the dropwise addition was completed, the temperature was raised to 66°C, and the reaction was allowed to proceed for 7 h. After the reaction was completed, anhydrous ethanol was added, and the precipitate was washed and freeze-dried to obtain an amphoteric sodium alginate intermediate;

[0063] (5) 2.8 g of the amphoteric sodium alginate intermediate, 185 mL of a phosphate buffer solution having a pH of 6.2 were added to a flask, and dissolved by stirring. 1.22 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride was added thereto, and the reaction was allowed to proceed for 4.5 h. After the reaction was completed, 0.75 g of N-hydroxysuccinimide, 2.3 g of aminothiourea were further added, and the reaction was allowed to proceed for 15 h. After the reaction was completed, anhydrous ethanol was added, and the precipitate was washed and freeze-dried to obtain a modified sodium alginate.

[0064] (6) 3.364 g of disodium ethylenediaminetetraacetate, 1.12 g of calcium chloride were added to 45 mL of deionized water, and dissolved under ultrasonication. The pH was adjusted to 6, and the volume was made up to 50 mL with deionized water to obtain a calcium ion crosslinking agent.

[0065] (7) 3.2 mL of the calcium ion crosslinking agent was added to 20 mL of deionized water, and 0.5 g of the lignin graft copolymer, 0.35 g of the biomass charcoal, 0.2 g of urea, 0.12 g of potassium dihydrogen phosphate were added thereto, and dissolved by stirring. 0.5 g of the modified sodium alginate was further added thereto, and the mixture was stirred for 4.5 h. 2.3 mL of a 8% by mass gluconolactone solution was added dropwise thereto, and the stirring was continued for 2 min. The sol was poured into a mold, and after standing for 20 h, the mold was dried in an oven at 45°C to obtain a biomass fertilizer for improving the soil environment.

[0066] Comparative Example 1

[0067] This comparative example differs from Example 5 in that the lignin graft copolymer was not contained in step (7).

[0068] Comparative Example 2

[0069] This comparative example differs from Example 5 in that the modified sodium alginate was not contained in step (7).

[0070] The biomass fertilizers in Examples 1-5 and Comparative Examples 1-2 were mixed with dry soil at a ratio of 0.8 wt%, placed in a PVC tube with a diameter of 4.5 cm and a length of 15 cm, the bottom of the tube was sealed with a 300-mesh nylon net and weighed, then the PVC tube was hung in deionized water for 12 h, the tube was taken out and hung vertically on a shelf, allowing the water to flow freely, and the weight of the tube was measured. The maximum water holding capacity was calculated, the maximum water holding capacity = (the total weight of the tube after wetting without water seepage - the weight of the dry soil and the PVC tube before wetting) / (the weight of the dry soil and the PVC tube before weting - the weight of the PVC tube) x 100%. The test results are shown in Table 1.

[0071] Table 1: Water retention performance test.

[0072] Item Maximum water holding capacity (%) Example 1 55.7 Example 2 56.3 Example 3 56.6 Example 4 55.5 Example 5 56.1 Comparative Example 1 44.7 Comparative Example 2 40.8

[0073] As can be seen from Table 1, the biomass fertilizers in Examples 1-5 increase the moisture content of the soil and improve the soil's ability to retain water compared to the biomass fertilizers in Comparative Examples 1-2, and have good water retention performance.

[0074] The antibacterial experiment was set up with 8 treatments, 7 treatment groups took 2.0 kg of sterilized soil, 40 g of biomass fertilizer in Examples 1-5 and Comparative Examples 1-2 was added to the sterilized soil, sterile water was added to make the soil moisture content reach 60%, 20 mL of bacterial suspension (10 8 CFU / mL) containing Pseudomonas solanacearum, Rhizoctonia solani, Fusarium oxysporum, and Sclerotinia sclerotiorum was evenly sprayed onto the soil, and incubated at 25°C in the dark for 14 days; the control group did not add biomass fertilizer, and the others were the same as the treatment group. The antibacterial rate was calculated, the antibacterial rate = (control group bacteria - treatment group bacteria) / control group bacteria x 100%. The test results are shown in Table 2.

[0075] Table 2: Antibacterial performance test.

[0076] Item Bacteriostatic rate (%) Example 1 96.2 Example 2 95.5 Example 3 95.8 Example 4 96.0 Example 5 95.8 Comparative Example 1 78.3 Comparative Example 2 72.4

[0077] As can be seen from Table 2, the biomass fertilizers in Examples 1-5 have better antibacterial effect on soil compared to the biomass fertilizers in Comparative Examples 1-2.

[0078] It should be noted that, in the present document, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0079] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

[0080] Those skilled in the art should understand that the above only describes some specific embodiments of the present application, rather than all embodiments. It should be noted that many modifications and improvements can be made by those of ordinary skill in the art, and all modifications or improvements that do not exceed the scope of the claims should be considered as the protection scope of the present application.

Claims

1. A method for preparing a biomass fertilizer for improving the soil environment, characterized in that, The preparation method of the biomass fertilizer for improving the soil environment is as follows: Add 2.8-3.2 mL of calcium ion crosslinking agent to 15-20 mL of deionized water, then add 0.3-0.5 g of lignin graft copolymer, 0.25-0.35 g of biochar, 0.1-0.2 g of urea, and 0.08-0.12 g of potassium dihydrogen phosphate. Stir and dissolve, then add 0.46-0.5 g of modified sodium alginate. Stir for 3.5-4.5 h, then add 1.7-2.3 mL of glucono-delta-lactone solution with a mass fraction of 7.6%-8%. Continue stirring for 0.5-2 min, pour the sol into a mold, let it stand for 16-20 h, and then dry it in an oven at 40-45℃ to obtain the biomass fertilizer for improving the soil environment.

2. The method for preparing biomass fertilizer for improving soil environment according to claim 1, characterized in that, The calcium ion crosslinking agent is prepared by adding 3.36-3.364g of disodium ethylenediaminetetraacetate and 1.1-1.12g of calcium chloride to 35-45mL of deionized water, dissolving under ultrasound, adjusting the pH to 5-6, and then bringing the volume to 50mL with deionized water to obtain the calcium ion crosslinking agent.

3. The method for preparing biomass fertilizer for improving the soil environment according to claim 1, characterized in that, The method for preparing the lignin graft copolymer includes the following steps: (1) Add 1.4-1.46 g of trimethyl-1,3-propanediamine to 30-40 mL of anhydrous ethanol solvent, stir to dissolve, and add 2.55-2.65 g of 3-chloropropyltrimethoxysilane dropwise over 30-50 min. After the addition is complete, heat to the reaction temperature and reflux for 12-15 h. After the reaction is complete, remove the solvent by rotary evaporation to obtain the silane quaternary ammonium salt intermediate. (2) Add 2.74-2.77 g of silane quaternary ammonium salt intermediate to 40-60 mL of anhydrous ethanol solvent, stir to dissolve, add 0.13-0.23 mL of concentrated hydrochloric acid to adjust the pH to 2.4-2.6, purge with nitrogen for protection, heat to 98-102℃, add 0.64-0.68 mL of formaldehyde solution and 1.45-1.5 g of 1-(2-chloro-ethyl)-pyrrolidine-2-one, react for 4-8 h, after the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain Mannich base modified silane quaternary ammonium salt; (3) Add 2.4-2.6g of lignin and 10-15mL of 3.5%-4% sodium hydroxide solution to the flask to adjust the pH to 10.5-11.

1. Stir to dissolve and stir at 60-80℃ for 25-35min. Then, purge with nitrogen for protection. Add 0.075-0.125g of potassium persulfate initiator, 4.43-4.47g of Mannich base-modified silane quaternary ammonium salt, and 2.95-3.05g of acrylic acid. React for 2-3h. After the reaction is complete, filter, dialyze, remove solvent by rotary evaporation, and freeze dry to obtain lignin graft copolymer.

4. The method for preparing biomass fertilizer for improving soil environment according to claim 3, characterized in that, The reaction temperature in step (1) is 78-84℃.

5. The method for preparing biomass fertilizer for improving the soil environment according to claim 3, characterized in that, The formaldehyde solution in step (2) has a mass fraction of 36%-38%.

6. The method for preparing biomass fertilizer for improving soil environment according to claim 1, characterized in that, The method for preparing the modified sodium alginate includes the following steps: S1. Add 2.4-2.6 g of sodium alginate and 2.2-2.8 mL of sodium hydroxide solution to 80-120 mL of deionized water, stir to dissolve, and obtain sodium alginate solution. Add 3.92-3.98 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride to 8-12 mL of sodium hydroxide solution, stir to mix, and add it dropwise to sodium alginate solution at 42-48℃. After the addition is complete, raise the temperature to 66-74℃ and react for 7-10 h. After the reaction is complete, add anhydrous ethanol and let it stand to precipitate. Wash the precipitate and freeze dry to obtain amphoteric sodium alginate intermediate. S2. Add 2.6-2.8 g of amphoteric sodium alginate intermediate and 165-185 mL of phosphate buffer solution with a pH of 5.8-6.2 to a flask, stir to dissolve, add 1.18-1.22 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, react for 2.5-4.5 h, then add 0.7-0.75 g of N-hydroxysuccinimide and 2.26-2.3 g of aminothiourea, react for 12-15 h, after which add anhydrous ethanol to allow precipitation, wash the precipitate and freeze dry to obtain modified sodium alginate.

7. The method for preparing biomass fertilizer for improving soil environment according to claim 6, characterized in that, The mass fraction of sodium hydroxide solution in step S1 is 3.8%-4.2%.

8. A biomass fertilizer for improving the soil environment, prepared by any one of claims 1-8.

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