Plant nutrient solution for improving saline-alkali soil and preparation method of plant nutrient solution

Abstract

The invention relates to the technical field of agriculture, in particular to a plant nutrient solution for saline-alkali soil improvement and a preparation method thereof. The invention relates to a preparation method of a plant nutrient solution for improving saline-alkali soil. The preparation method comprises the following steps: preparing NO3-intercalated layered double hydroxides and acid modified calcium-based montmorillonite; preparing humic acid chelated calcium magnesium powder; preparing a binary compound; and preparing the plant nutrient solution. The preparation method comprises the following steps: preparing NO3-intercalated layered double hydroxides from calcium nitrate tetrahydrate and aluminum nitrate nonahydrate, carrying out acid modification on calcium-based montmorillonite by using dilute sulphuric acid, purifying humic acid, and mixing with calcium chloride and magnesium chloride hexahydrate to prepare humic acid chelated calcium magnesium powder. Finally, the three components are added into pig excrement fermentation liquor to prepare a plant nutrient solution, an adsorption-replacement-leaching closed loop can be formed, the desalination and alkali reduction efficiency is remarkably improved, the soil structure is improved, the effect of synergistically improving the saline-alkali soil is achieved, and therefore plant growth is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural technology, in particular to a plant nutrient solution for saline-alkali soil improvement and a preparation method thereof. BACKGROUND

[0002] As an important global reserve arable land resource, saline-alkali soil is widely distributed in China, mainly in the northwest, north China and coastal areas. However, there are core problems such as high salt stress, high pH barrier, soil structure hardening and low nutrient availability, which seriously restrict agricultural production: high concentration of Na + , Cl - can destroy the osmotic balance of plant cells, leading to difficulty in root water and fertilizer absorption, causing physiological drought; high soil pH can easily cause the formation of insoluble precipitates of trace elements such as phosphorus, iron and zinc, reducing nutrient utilization rate; at the same time, soil granular structure is destroyed due to salinization, resulting in poor air permeability and water retention, further aggravating plant growth stress, resulting in low crop yield and weak stress resistance, and even large-scale crop failure.

[0003] At present, traditional saline-alkali soil improvement methods such as water conservancy engineering salt washing, replacement of guest soil, etc. have certain effect, but have problems such as large amount of engineering, high cost, easy to repeat, etc.; the use of chemical modifiers such as gypsum and phosphogypsum can neutralize alkalinity, but long-term use can easily lead to soil compaction or secondary pollution.

[0004] In the direction of organic improvement, the use of agricultural waste resources such as livestock and poultry manure has attracted attention, because it can not only provide organic matter to improve soil structure, but also recycle waste, which is in line with the development direction of green agriculture. Taking pig excrement as an example, pig excrement produced by breeding industry is rich in organic matter, nitrogen, phosphorus and other elements, which can be converted into plant nutrient solution through fermentation, composting and sterilization processes, and can exist in a form that is more easily absorbed by plants. With the slow decomposition of organic matter, the nutrient release rate is more matched with the growth demand of plants, which can not only avoid the problem of "root burning" or rapid loss of nutrients of chemical fertilizers, but also can provide long-term basic nutrients and trace elements required for plant growth, and improve crop quality and yield. However, the content of potassium and stress resistance nutrients in pig excrement is low, and the nutrient solution directly prepared from pig excrement is easy to cause "excess nitrogen and phosphorus, and insufficient potassium", which affects the salt resistance of crops. At the same time, the decomposition products of organic matter are mainly conventional nutrients, and lack of functional ingredients that can directly adjust the soil pH and complex excessive Na + in saline-alkali soil, making it difficult to simultaneously realize the synergy of "nutrient supply" and "saline-alkali improvement", and cannot meet the special needs of plants in saline-alkali soil.

[0005] Therefore, it is necessary to provide a plant nutrient solution for saline-alkali soil improvement and a preparation method thereof to overcome the above defects. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application aims to provide a plant nutrient solution for saline-alkali soil improvement and a preparation method thereof.

[0007] The present application provides a preparation method of a plant nutrient solution for saline-alkali soil improvement, comprising the following steps: S1: preparing NO3 - Interlayered layered double hydroxide and acid modified calcium-based montmorillonite Preparation of NO3 from calcium nitrate tetrahydrate and aluminum nitrate nonahydrate - Interlayered layered double hydroxide, acid modified calcium-based montmorillonite, humic acid chelated calcium magnesium powder, binary compound, proline, alginate oligosaccharide, surfactant and water are uniformly mixed to obtain the plant nutrient solution. S2: preparing humic acid chelated calcium magnesium powder After preparing a purified humic acid solution by purifying humic acid, a mixed solution of calcium chloride and magnesium chloride hexahydrate is added, stirred and mixed, concentrated, dried, and crushed to obtain humic acid chelated calcium magnesium powder. S3: preparing a binary compound S3.1: After cleaning and drying the spirulina, grinding into powder, adding deionized water at a ratio of 1g: (50-60)mL, stirring for 10-20min, and then ultrasonic dispersion for 20-30min, the spirulina carbon dots are obtained by transferring to a high-pressure reaction kettle for hydrothermal reaction at 160-180℃ for 6-8h, cooling, centrifuging to obtain supernatant, and then filtering, dialysis and freeze-drying. S3.2: After cleaning and softening the dried silkworm sand, adding a mixed solvent, and then adding zeolite and heating to reflux at 70-80℃ for 1-2h, the filtrate is obtained by filtering after the temperature drops to 50℃, and then repeating the extraction of the filter residue for 1-2 times, and then concentrating the combined filtrate by rotary evaporation to 1 / 4 of the original volume. S3.3: The spirulina carbon dots are added to deionized water, stirred for 10-20min, and then ultrasonic dispersed for 10-20min to obtain a spirulina carbon dot dispersion liquid, and then heated to 30-40℃, while stirring, the silkworm sand extract solution is added, and then stirred for 1-2h, and then ultrasonic treated for 5-10min, and then the precipitate is collected by centrifugation, washed and vacuum freeze-dried to obtain the binary compound. S4: preparing a plant nutrient solution After treating the pig excrement, adding a compound microbial agent for fermentation, and then adding NO3 - Interlayered layered double hydroxide, acid modified calcium-based montmorillonite, humic acid chelated calcium magnesium powder, binary compound, proline, alginate oligosaccharide, surfactant and water are uniformly mixed to obtain the plant nutrient solution.

[0008] Further, S1 specifically comprises the following steps: S1.1: Add calcium nitrate tetrahydrate and aluminum nitrate nonahydrate into deionized water according to (1.2-1.3) g: 1 g: (80-90) mL, fully stir to dissolve, and obtain a mixed salt solution; S1.2: Pour the mixed salt solution and sodium hydroxide solution into a colloid mill, react for 3-5 min at 3000-4000 rpm, collect the precipitate by centrifugation, wash with deionized water until neutral, and dry to obtain NO3 - intercalated layered double hydroxide; S1.3: Add calcium-based montmorillonite into dilute sulfuric acid according to 1 g: (10-20) mL, stir at 40-50°C for 6-8 h, cool, separate by centrifugation, wash, dry, and grind to obtain acid-modified calcium-based montmorillonite.

[0009] Further, S2 specifically comprises the following steps: S2.1: Add humic acid into dilute hydrochloric acid with a concentration of 1 mol / L according to 1 g: (10-20) mL, stir at 40-50°C for 30-40 min, collect the precipitate by filtration, wash, and drain, then add sodium hydroxide solution with a concentration of 5% according to 1 g: (8-10) mL, stir at 50-60°C for 50-60 min, centrifuge at 4000-5000 rpm for 10-20 min, and collect the supernatant to obtain a purified humic acid solution; S2.2: Add calcium chloride and magnesium chloride hexahydrate into deionized water according to 1 g: (1.8-2) g: (85-95) mL, fully stir to dissolve, then add the purified humic acid solution, stir at 50-60°C for 1-2 h, transfer to a rotary evaporator, concentrate under vacuum to 1 / 5 of the original volume, dry to constant weight, and grind to obtain humic acid chelated calcium-magnesium powder.

[0010] Further, S4 specifically comprises the following steps: S4.1: Heat the pig excrement at 220-230°C for 1-2 h to kill harmful bacteria and insect eggs in the pig excrement, and then perform solid-liquid separation to obtain a pig excrement treatment liquid; S4.2: Mix the pig excrement treatment liquid and the compound microbial agent, and perform aerobic fermentation at 32-35°C for 68-72 h to obtain a fermentation liquid, then add NO3 - intercalated layered double hydroxide, acid-modified calcium-based montmorillonite prepared in step S1.3, humic acid chelated calcium-magnesium powder prepared in step S2.2, binary compound prepared in step S3.3, proline, alginate oligosaccharide, surfactant, and water, and stir to mix uniformly to obtain a plant nutrient solution.

[0011] Further, the volume ratio of the mixed salt solution to the sodium hydroxide solution is 1:1, and the concentration of the sodium hydroxide solution is 2 mol / L.

[0012] Further, the mass ratio of pure humic acid to calcium chloride in the purified humic acid solution is (3.5-3.8):1.

[0013] Further, the addition amount of the zeolite is 0.08%-0.1% of the dry silkworm sand, the addition amount of the mixed solvent is 4-5 times of the dry silkworm sand, and the mixed solvent is prepared by mixing acetone and ethanol at a volume ratio of 1:2.

[0014] Further, the water content of the softened dry silkworm sand is 25%-30%, and the volume ratio of the spirulina carbon point dispersion liquid to the silkworm sand extraction liquid is (1-2):1.

[0015] Further, according to the mass fraction, the raw material composition of the plant nutrient solution is: 90-100 parts of pig excrement treatment liquid, 0.2-0.3 parts of compound microbial agent, 6-8 parts of NO3 - The intercalated layered double hydroxide, 1-3 parts of acid-modified calcium-based montmorillonite, 3-5 parts of humic acid chelated calcium and magnesium powder, 8-10 parts of binary compound, 6-8 parts of proline, 2-3 parts of alginate oligosaccharide, 3-5 parts of surfactant and 30-40 parts of water; wherein the compound microbial agent is mixed by Bacillus subtilis, Trichoderma harzianum and Bacillus mucilaginosus at a mass ratio of (2-3):(1-3):1, and the surfactant is rhamnolipid.

[0016] A plant nutrient solution for saline-alkali soil improvement is prepared by the preparation method of any one of the above plant nutrient solutions.

[0017] The present application has the following advantages: 1、In the present application, first, calcium nitrate tetrahydrate and aluminum nitrate nonahydrate are used as raw materials to prepare NO3 - The intercalated layered double hydroxide, then the acid modification of calcium-based montmorillonite is carried out by dilute sulfuric acid, then the humic acid chelated calcium and magnesium powder is prepared by mixing the purified humic acid solution with calcium chloride and magnesium chloride hexahydrate solution, and finally the plant nutrient solution is prepared by adding the three to the pig excrement fermentation liquid, so that NO3 - The intercalated layered double hydroxide can exchange and adsorb Cl - and strong alkaline anions through anion exchange, and the acid-modified montmorillonite can exchange and adsorb Na + and dissociate H + through cation exchange, which can combine with alkaline anions in the soil, and the calcium and magnesium ions released by the humic acid chelated calcium and magnesium can further exchange with Na + on the soil colloid, supplement the cation exchange capacity of the montmorillonite, and dissociate H +Can directly consume alkaline anions in soil, and avoid exchange Na + Re-adsorb to soil particles, significantly improve the desalination and alkali reduction efficiency of saline-alkali soil, so as to effectively improve the effect of saline-alkali soil, and promote plant growth.

[0018] 2、The present application first uses spirulina as raw material, synthesizes spirulina carbon dots by hydrothermal method, then extracts dried silkworm sand to prepare silkworm sand extract, then uniformly loads the spirulina carbon dots on the silkworm sand extract to prepare a binary compound, and then adds the binary compound into pig excrement fermentation liquor to prepare plant nutrient solution, the surface functional groups of the spirulina carbon dots can form hydrogen bonds or electrostatic interactions with the silkworm sand extract, reducing the oxidation and hydrolysis of active substances in the silkworm sand extract in the nutrient solution, and at the same time, the spirulina carbon dots can 'target' transport the silkworm sand extract to the plant demand site, effectively improving the utilization rate of the silkworm sand extract, and effectively promoting plant growth and increasing yield, in addition, the spirulina carbon dots can directly scavenge active oxygen, the silkworm sand extract can induce the generation of antioxidant enzymes in plants and enhance the stability of plant cell membranes, the two can form a 'double defense', enhance the long-term stress resistance of plants, and the chelating ability of carbon dots to heavy metals and the antibacterial effect of silkworm sand alkaloids can resist 'abiotic stress' and 'biotic stress' at the same time, the stress resistance range is significantly expanded, and the plant stress resistance is significantly improved.

[0019] 3、In the present application, after proline and alginate oligosaccharide are added into pig excrement fermentation liquor to prepare plant nutrient solution, on the one hand, proline directly maintains osmotic pressure through intracellular solute accumulation, forms 'osmotic pressure gradient', promotes root system to absorb water from saline-alkali soil, and at the same time reduces cell water loss, and alginate oligosaccharide can induce plants to regulate stomatal opening and closing, reduce transpiration water loss, promote root elongation and increase root hair quantity, expand root water absorption area, and at the same time enhance root cell membrane permeability, improve water absorption rate, and the combination of the two can form a water management closed loop of 'absorption-retention-utilization', effectively alleviate the 'physiological drought' of saline-alkali soil, maintain normal transpiration and photosynthesis of plants, and effectively promote plant growth, on the other hand, proline maintains normal metabolic function of plants by relieving stress, ensures that nutrients in liquid fertilizer can be used to synthesize growth essential substances such as proteins, chlorophyll and nucleic acids, avoids 'idling' of nutrients, and alginate oligosaccharide can activate stress resistance, promote photosynthesis efficiency of plants, accelerate synthesis and transport of photosynthetic products, provide energy for root growth and nutrient absorption, and the combination of the two can further enhance the stress resistance of plants. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The preparation method flow chart of the plant nutrient solution for improving saline-alkali soil adopted in the embodiments of the present application. DETAILED DESCRIPTION

[0021] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0022] Example 1: A method for preparing a plant nutrient solution for saline-alkali land improvement, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of NO3 - Intercalated layered bimetallic hydroxides and acid-modified calcium-based montmorillonite S1.1: Add calcium nitrate tetrahydrate and aluminum nitrate nonahydrate to deionized water at a ratio of 1.2g:1g:80mL, stir thoroughly to dissolve, and obtain a mixed salt solution; S1.2: Pour the above mixed salt solution and sodium hydroxide solution into a colloid mill, react at 3000 rpm for 3 min, centrifuge to collect the precipitate, wash with decarbonated water until neutral, and dry to obtain NO3. - Intercalated layered bimetallic hydroxides, wherein the volume ratio of the mixed salt solution to the sodium hydroxide solution is 1:1, and the concentration of the sodium hydroxide solution is 2 mol / L; S1.3: Add calcium-based montmorillonite to dilute sulfuric acid at a ratio of 1g:10mL, stir at 40℃ for 6h, cool, and then centrifuge, wash, dry and grind to obtain acid-modified calcium-based montmorillonite; S2: Preparation of humic acid chelated calcium-magnesium powder S2.1: Add humic acid to 1 mol / L dilute hydrochloric acid at a ratio of 1 g: 10 mL, stir at 40 °C for 30 min, collect the precipitate by filtration, wash and drain, add it to 5% sodium hydroxide solution at a ratio of 1 g: 8 mL, stir at 50 °C for 50 min, centrifuge at 4000 rpm for 10 min, collect the supernatant to obtain purified humic acid solution; S2.2: Add calcium chloride and magnesium chloride hexahydrate to deionized water at a ratio of 1g:1.8g:85mL, stir thoroughly to dissolve, then add to the above purified humic acid solution, keep warm at 50℃ and stir for 1h, then transfer to a rotary evaporator, vacuum concentrate to 1 / 5 of the original volume, dry to constant weight, and pulverize to obtain humic acid chelated calcium magnesium powder, wherein the mass ratio of pure humic acid to calcium chloride in the purified humic acid solution is 3.5:1; S3: Preparation of binary complexes S3.1: Spirulina is washed, dried, ground into powder, and then added to deionized water at a ratio of 1g:50mL. The mixture is stirred for 10min, then ultrasonically dispersed for 20min. The mixture is then transferred to a high-pressure reactor and hydrothermally reacted at 160℃ for 6h. After cooling, the supernatant is centrifuged, filtered, dialyzed, and freeze-dried to obtain spirulina carbon dots. S3.2: After washing and softening the dry silkworm excrement to a water content of 25%, adding a mixed solvent, then adding zeolite, and heating to reflux at 70°C for 1h, when the temperature drops to 50°C, filter, then repeat the extraction of the residue once, combine the filtrate, and rotary evaporate to concentrate to 1 / 4 of the original volume, to obtain silkworm excrement extract, wherein the amount of zeolite added is 0.08% of the mass of dry silkworm excrement, the amount of mixed solvent added is 4 times the mass of dry silkworm excrement, and the mixed solvent is prepared by mixing acetone and ethanol at a volume ratio of 1:2; S3.3: The above spirulina carbon dots are added to deionized water, stirred for 10 min, then ultrasonic dispersed for 10 min, to obtain spirulina carbon dot dispersion, then heated to 30°C, while stirring, add the above silkworm excrement extract, continue stirring for 1h, then ultrasonic treatment for 5 min, then collect the precipitate by centrifugation, wash and vacuum freeze-dry, to obtain a binary compound, wherein the volume ratio of spirulina carbon dot dispersion to silkworm excrement extract is 1:1; S4: Preparation of plant nutrient solution S4.1: The pig excrement is heat treated at 220°C for 1h, then solid-liquid separation is performed, to obtain pig excrement treatment liquid; S4.2: 90 parts by mass of the above pig excrement treatment liquid and 0.2 parts by mass of a compound microbial agent are mixed, aerobic fermentation is carried out at 32°C for 68h, to obtain fermentation liquor, then 6 parts by mass of NO3 - The intercalated layered double hydroxide, 1 part by mass of the acid modified calcium based montmorillonite prepared in step S1.3, 3 parts by mass of the humic acid chelated calcium magnesium powder prepared in step S2.2, 8 parts by mass of the binary compound prepared in step S3.3, 6 parts by mass of proline, 2 parts by mass of alginate oligosaccharide, 3 parts by mass of rhamnolipid and 30 parts by mass of water are stirred and mixed uniformly, to obtain the plant nutrient solution, wherein the compound microbial agent is prepared by mixing Bacillus subtilis, Trichoderma harzianum and Bacillus mucilaginosus at a mass ratio of 2:1:1, and the effective viable count of Bacillus subtilis, Trichoderma harzianum and Bacillus mucilaginosus is 10 10 CFU / g.

[0023] Example 2, a preparation method of a plant nutrient solution for saline-alkali land improvement, as shown in Figure 1 , comprising the following steps: S1: Preparation of NO3 - intercalated layered double hydroxide and acid modified calcium based montmorillonite S1.1: Calcium nitrate tetrahydrate and aluminum nitrate nonahydrate are added to deionized water at a ratio of 1.25g:1g:85mL, fully stirred and dissolved, to obtain a mixed salt solution; S1.2: The above mixed salt solution and sodium hydroxide solution are poured into a colloid mill, reacted at 3500rpm for 4min, then the precipitate is collected by centrifugation, washed with deionized water until neutral and dried, to obtain NO3- Intercalation layered double hydroxide, wherein the volume ratio of the mixed salt solution to the sodium hydroxide solution is 1:1, and the concentration of the sodium hydroxide solution is 2 mol / L; S1.3: Put the calcium-based montmorillonite into dilute sulfuric acid at a ratio of 1 g:15 mL, stir at 45°C for 7 h, after cooling, separate by centrifugation, wash, dry and grind to obtain acid-modified calcium-based montmorillonite; S2: Preparation of humic acid chelated calcium-magnesium powder S2.1: Put the humic acid into dilute hydrochloric acid with a concentration of 1 mol / L at a ratio of 1 g:15 mL, stir at 45°C for 35 min, collect the precipitate by filtration, wash, and drain, then add sodium hydroxide solution with a concentration of 5% at a ratio of 1 g:9 mL, stir at 55°C for 55 min, centrifuge at 4500 rpm for 15 min, collect the supernatant to obtain a purified humic acid solution; S2.2: Put calcium chloride and magnesium chloride hexahydrate into deionized water at a ratio of 1 g:1.9 g:90 mL, stir to dissolve, then add the above purified humic acid solution, stir at 55°C for 1.5 h, then transfer to a rotary evaporator, concentrate under vacuum to 1 / 5 of the original volume, dry to constant weight, and then crush to obtain humic acid chelated calcium-magnesium powder, wherein the mass ratio of pure humic acid in the purified humic acid solution to calcium chloride is 3.6:1; S3: Preparation of binary composite S3.1: After washing and drying, grind the spirulina into powder, then add deionized water at a ratio of 1 g:55 mL, stir for 15 min, then ultrasonic disperse for 25 min, then transfer to a high-pressure reaction kettle, hydrothermal reaction at 170°C for 7 h, after cooling, centrifuge to collect the supernatant, then filter, dialysis and freeze-drying to obtain spirulina carbon dots; S3.2: After washing and softening to a water content of 28%, add the dry silkworm sand into the mixed solvent, then add zeolite and heat to reflux at 75°C for 1.5 h, then filter after the temperature drops to 50°C, repeat the extraction once more, combine the filtrate, and concentrate by rotary evaporation to 1 / 4 of the original volume to obtain silkworm sand extract, wherein the addition amount of zeolite is 0.09% of the mass of dry silkworm sand, the addition amount of mixed solvent is 4.5 times the mass of dry silkworm sand, and the mixed solvent is prepared by mixing acetone and ethanol at a volume ratio of 1:2; S3.3: Add the above spirulina carbon dots into deionized water, stir for 15 min, then ultrasonic disperse for 15 min to obtain spirulina carbon dot dispersion, then heat to 35°C, add the above silkworm sand extract while stirring, continue to stir for 1.5 h, then ultrasonic treat for 7.5 min, then collect the precipitate by centrifugation, wash and vacuum freeze-dry to obtain a binary composite, wherein the volume ratio of spirulina carbon dot dispersion to silkworm sand extract is 1.5:1; S4: Preparation of plant nutrient solution S4.1: The pig excrement is heat treated at 225℃ for 1.5h, and then solid-liquid separation is performed to obtain a pig excrement treatment liquid; S4.2: 95 parts by mass of the pig excrement treatment liquid and 0.25 parts by mass of a compound microbial agent are mixed, and aerobic fermentation is performed at 33℃ for 70h to obtain a fermentation liquid, and then 7 parts by mass of the NO3 - The intercalated layered double hydroxide, 2 parts by mass of the acid-modified calcium-based montmorillonite prepared in step S1.3, 4 parts by mass of the humic acid chelated calcium-magnesium powder prepared in step S2.2, 9 parts by mass of the binary compound prepared in step S3.3, 7 parts by mass of proline, 2.5 parts by mass of alginate oligosaccharide, 4 parts by mass of rhamnolipid, and 35 parts by mass of water are stirred and mixed uniformly to obtain a plant nutrient liquid, wherein the compound microbial agent is composed of Bacillus subtilis, Trichoderma harzianum, and Bacillus mucilaginosus at a mass ratio of 2.5:2:1, and the effective viable bacterial count of the Bacillus subtilis, Trichoderma harzianum, and Bacillus mucilaginosus is 10 10 CFU / g.

[0024] Example 3, a preparation method of a plant nutrient liquid for saline-alkali soil improvement, as shown in Figure 1 , comprises the following steps: S1: preparing NO3 - intercalated layered double hydroxide and acid-modified calcium-based montmorillonite S1.1: calcium nitrate tetrahydrate and aluminum nitrate nonahydrate are added to deionized water at a ratio of 1.3g:1g:90mL, and fully stirred and dissolved to obtain a mixed salt solution; S1.2: the mixed salt solution and sodium hydroxide solution are poured into a colloid mill, reacted at 4000rpm for 5min, and then the precipitate is collected by centrifugation, washed with deionized water until neutral, and dried to obtain NO3 - intercalated layered double hydroxide, wherein the volume ratio of the mixed salt solution to the sodium hydroxide solution is 1:1, and the concentration of the sodium hydroxide solution is 2mol / L; S1.3: calcium-based montmorillonite is added to dilute sulfuric acid at a ratio of 1g:20mL, stirred at 50℃ for 8h, and after cooling, centrifuged, washed, dried, and ground to obtain acid-modified calcium-based montmorillonite; S2: preparing humic acid chelated calcium-magnesium powder S2.1: humic acid is added to dilute hydrochloric acid with a concentration of 1mol / L at a ratio of 1g:20mL, and stirred at 50℃ for 40min, and then the precipitate is collected by filtration, washed, and drained, and then 1g:10mL of 5% sodium hydroxide solution is added, stirred at 60℃ for 60min, and then centrifuged at 5000rpm for 20min to collect the supernatant to obtain a purified humic acid solution; S2.2: Add calcium chloride and magnesium chloride hexahydrate into deionized water at a ratio of 1 g:2 g:95 mL, fully stir and dissolve, then add the purified humic acid solution described above, keep stirring at 60°C for 2 h, then transfer to a rotary evaporator, concentrate under vacuum to 1 / 5 of the original volume, then dry to constant weight, crush, and obtain humic acid chelated calcium-magnesium powder, wherein the mass ratio of pure humic acid in the purified humic acid solution to calcium chloride is 3.8:1; S3: Preparation of binary compound S3.1: After cleaning and drying the spirulina, grind it into powder, then add deionized water at a ratio of 1 g:60 mL, stir for 20 min, then ultrasonic dispersion for 30 min, then transfer to a high-pressure reaction kettle, hydrothermal reaction at 180°C for 8 h, after cooling, centrifugal separation to obtain supernatant, then filtration, dialysis and freeze-drying to obtain spirulina carbon dots; S3.2: After cleaning and softening the dried silkworm sand to a moisture content of 30%, add mixed solvent, then add zeolite, heat to reflux at 80°C for 2 h, then filter after the temperature drops to 50°C, then repeat the extraction of the residue for 2 more times, combine the filtrate, and rotary evaporate to concentrate to 1 / 4 of the original volume to obtain silkworm sand extract, wherein the amount of zeolite added is 0.1% of the mass of dried silkworm sand, the amount of mixed solvent added is 5 times the mass of dried silkworm sand, and the mixed solvent is prepared by mixing acetone and ethanol at a volume ratio of 1:2; S3.3: Add the spirulina carbon dots described above into deionized water, stir for 20 min, then ultrasonic dispersion for 20 min to obtain spirulina carbon dot dispersion, then heat to 40°C, while stirring, add the silkworm sand extract described above, continue stirring for 2 h, then ultrasonic treatment for 10 min, then collect the precipitate by centrifugation, wash and vacuum freeze-dry to obtain a binary compound, wherein the volume ratio of spirulina carbon dot dispersion to silkworm sand extract is 2:1; S4: Preparation of plant nutrient solution S4.1: Heat the pig excrement at 230°C for 2 h, then perform solid-liquid separation to obtain pig excrement treatment solution; S4.2: Mix 100 parts by mass of the pig excrement treatment solution described above with 0.3 parts by mass of compound microbial agent, aerobic fermentation at 35°C for 72 h to obtain fermentation liquor, then add 8 parts by mass of NO3 - intercalated layered double hydroxide, 3 parts by mass of acid-modified calcium-based montmorillonite prepared in step S1.3, 5 parts by mass of humic acid chelated calcium-magnesium powder prepared in step S2.2, 10 parts by mass of binary compound prepared in step S3.3, 8 parts by mass of proline, 3 parts by mass of alginate oligosaccharide, 5 parts by mass of rhamnolipid, and 40 parts by mass of water, to obtain plant nutrient solution, wherein the compound microbial agent is prepared by mixing Bacillus subtilis, Trichoderma harzianum and Bacillus mucilaginosus at a mass ratio of 3:3:1, and the effective viable count of Bacillus subtilis, Trichoderma harzianum and Bacillus mucilaginosus is 1010 CFU / g.

[0025] Comparative Example 1, the difference between Comparative Example 1 and Example 1 is that the acid-modified calcium-based montmorillonite and humic acid chelated calcium-magnesium powder in step S4.2 are replaced by an equal amount of NO3 - intercalated layered double hydroxide.

[0026] Comparative Example 2, the difference between Comparative Example 2 and Example 1 is that the humic acid chelated calcium-magnesium powder and NO3 - intercalated layered double hydroxide in step S4.2 are replaced by an equal amount of acid-modified calcium-based montmorillonite.

[0027] Comparative Example 3, the difference between Comparative Example 3 and Example 1 is that the NO3 - intercalated layered double hydroxide and acid-modified calcium-based montmorillonite in step S4.2 are replaced by an equal amount of humic acid chelated calcium-magnesium powder.

[0028] Comparative Example 4, the difference between Comparative Example 4 and Example 1 is that the NO3 - intercalated layered double hydroxide, acid-modified calcium-based montmorillonite and humic acid chelated calcium-magnesium powder in step S4.2 are removed.

[0029] Comparative Example 5, the difference between Comparative Example 5 and Example 1 is that the binary compound in step S4.2 is removed.

[0030] Comparative Example 6, the difference between Comparative Example 6 and Example 1 is that the proline in step S4.2 is replaced by an equal amount of alginate oligosaccharide.

[0031] Comparative Example 7, the difference between Comparative Example 7 and Example 1 is that the alginate oligosaccharide in step S4.2 is replaced by an equal amount of proline.

[0032] Test Example: Test 1: The salt concentration value and pH value of the soil at a depth of 35 cm in the saline-alkali soil 30 days after applying the plant nutrient solution prepared in Examples 1-3 and Comparative Examples 1-4, respectively, were detected, and the results are shown in Table 1.

[0033] Table 1: Saline-alkali soil improvement effect of plant nutrient solution

[0034] From Table 1 above, it can be seen that in Comparative Example 1, Comparative Example 2 and Comparative Example 3, only NO3 -When one of the intercalation layered double hydroxide, the acid-modified calcium-based montmorillonite, and the humic acid chelated calcium-magnesium powder is used to prepare a plant nutrient solution, the salt concentration value and the pH value of the improved saline-alkali soil are both lower than those of Comparative Example 4, but both are higher than those of Example 1. Therefore, it can be seen that when the NO3 - When the intercalation layered double hydroxide, the acid-modified calcium-based montmorillonite, and the humic acid chelated calcium-magnesium powder are added into the pig excrement fermentation liquid to prepare the plant nutrient solution, the saline-alkali soil can be effectively improved.

[0035] Test 2: The saline-alkali soil was used as the test soil, and corn was used as the test crop. The saline-alkali soil was divided into 7 groups, which were Example 1-3 groups, Comparative Example 5-7 groups, and a blank group. Each group had 3 repeated groups, and each repeated group had 100 m 2 Among them, the plant nutrient solution prepared in Example 1-3 and Comparative Example 5-7 was applied to Example 1-3 and Comparative Example 5-7 groups, respectively, and no plant nutrient solution was applied to the blank group. After planting corn, during the planting period, the seedling survival rate, plant height (tasseling stage), and chlorophyll SPAD value (grain filling stage) were detected, and the corn yield (grain dry weight) was counted after harvesting the corn. The average values are shown in Table 2.

[0036] Table 2: Test results of corn growth indicators

[0037] Table 3: Corn harvesting conditions

[0038] From Table 2 and Table 3, it can be seen that when no binary compound is added in Comparative Example 5, the seedling survival rate, plant height, chlorophyll SPAD value, and grain dry weight of corn after applying the prepared plant nutrient solution are all lower than those of Example 1. Therefore, it can be seen that when the binary compound is prepared by using spirulina as raw material, synthesizing spirulina carbon dots by hydrothermal method, extracting dry silkworm sand to prepare silkworm sand extract, and then loading the silkworm sand extract with spirulina carbon dots, the plant nutrient solution prepared by adding the binary compound into the pig excrement fermentation liquid can effectively promote plant growth, improve yield, and significantly improve plant stress resistance.

[0039] In addition, when only one of brown algal oligosaccharide or proline is added in the plant nutrient solution in Comparative Example 6 and Comparative Example 7, the seedling survival rate, plant height, chlorophyll SPAD value, and grain dry weight of corn after applying the prepared plant nutrient solution are all lower than those of Example 1. Therefore, it can be seen that when proline and brown algal oligosaccharide are added together into the pig excrement fermentation liquid to prepare the plant nutrient solution, the combination of the two can effectively promote plant growth and further enhance the stress resistance of plants.

[0040] It is to be understood that all of the above modifications and alterations can be made to the above-described arrangements and that all such modifications and alterations are intended to be included within the scope of the present application. Those skilled in the art will readily appreciate that other modifications and alterations can be made to the present application without departing from the scope of the application.

Claims

1. A method for preparing a plant nutrient solution for salinity improvement, characterized by, It comprises the following steps: S1: Preparation of NO3 - Intercalated layered double hydroxides and acid-modified calcium-based montmorillonite Preparation of NO3 - The calcium-based montmorillonite is modified by intercalation of layered double hydroxide and acidification with dilute sulfuric acid. S2: preparation of humic acid chelated calcium magnesium powder After preparing the purified humic acid solution by purifying humic acid, a mixed solution of calcium chloride and magnesium chloride hexahydrate is added, and stirring, mixing, concentration, drying and crushing are carried out to obtain humic acid chelated calcium magnesium powder; S3: preparation of binary compound S3.1: After cleaning and drying the spirulina, it is ground into powder, then 1g of the powder is added to 50-60mL of deionized water, stirred for 10-20min, and then ultrasonically dispersed for 20-30min, and then transferred to a high-pressure reaction kettle for hydrothermal reaction at 160-180℃ for 6-8h. After cooling, the supernatant is collected by centrifugation, and then filtered, dialyzed and freeze-dried to obtain spirulina carbon dots; S3.2: After cleaning and softening the dried silkworm sand, it is added to a mixed solvent, and then zeolite is added and heated to reflux at 70-80℃ for 1-2h. After the temperature drops to 50℃, the filtrate is collected by filtration, and then the filtrate is repeatedly extracted for 1-2 times. The combined filtrate is concentrated by rotary evaporation to 1 / 4 of the original volume, and then silkworm sand extract is obtained; S3.3: The spirulina carbon dots are added to deionized water, stirred for 10-20min, and then ultrasonically dispersed for 10-20min to obtain a spirulina carbon dot dispersion. Then the temperature is heated to 30-40℃, and the silkworm sand extract is added while stirring. After stirring for 1-2h, ultrasonic treatment is carried out for 5-10min. The precipitate is collected by centrifugation, washed and vacuum freeze-dried to obtain a binary compound; S4: preparation of plant nutrient solution After the pig excrement is treated, the composite microbial inoculant is added for fermentation, and NO3 - Intercalation layered double hydroxide, acid modified calcium based montmorillonite, humic acid chelated calcium magnesium powder, binary compound, proline, alginate oligosaccharide, surfactant and water are uniformly mixed to obtain a plant nutrient solution.

2. The method for preparing a plant nutrient solution for saline-alkali land improvement according to claim 1, characterized in that, S1 specifically comprises the following steps: S1.1: 1.2-1.3g of calcium nitrate tetrahydrate and 1g of aluminum nitrate nonahydrate are added to 80-90mL of deionized water, and stirred to dissolve to obtain a mixed salt solution; S1.2: Pour the mixed salt solution and sodium hydroxide solution into a colloid mill, react for 3-5 min at 3000-4000 rpm, centrifuge to collect the precipitate, wash with carbon dioxide-free water until neutral, and dry to obtain NO3 - intercalated layered double hydroxide; S1.3: 1g of calcium-based montmorillonite is added to dilute sulfuric acid, and stirred at 40-50℃ for 6-8h. After cooling, the mixture is separated by centrifugation, washed, dried and ground to obtain acid-modified calcium-based montmorillonite.

3. The method for preparing a plant nutrient solution for saline-alkali land improvement according to claim 2, characterized in that, S2 specifically comprises the following steps: S2.1: 1g of humic acid is added to 10-20mL of 1mol / L dilute hydrochloric acid, and stirred at 40-50℃ for 30-40min. The precipitate is collected by filtration, washed, drained, and then added to 8-10mL of 5% sodium hydroxide solution, and stirred at 50-60℃ for 50-60min. The mixture is centrifuged at 4000-5000rpm for 10-20min, and the supernatant is collected to obtain a purified humic acid solution; S2.2: 1g of calcium chloride and 1.8-2g of magnesium chloride hexahydrate are added to 85-95mL of deionized water, and stirred to dissolve. The purified humic acid solution is added, and stirred at 50-60℃ for 1-2h. The mixture is then transferred to a rotary evaporator, and concentrated under vacuum to 1 / 5 of the original volume. After drying to a constant weight, the mixture is crushed to obtain humic acid chelated calcium magnesium powder.

4. The method of claim 1, wherein the plant nutrient solution for improving saline-alkali soil is prepared by adding 0.1 to 0.5 wt% of the composition of claim 1 to 100 wt% of water. S4 specifically comprises the following steps: S4.1: Pig excrement is heat-treated at 220-230℃ for 1-2h, and then subjected to solid-liquid separation to obtain a pig excrement treatment solution; S4.2: The pig excrement treatment liquid and the compound microbial agent are mixed, aerobic fermentation is carried out at 32-35℃ for 68-72h, a fermentation liquid is obtained, and the NO3 - The intercalation layered double hydroxide, the acid-modified calcium-based montmorillonite prepared in step S1.3, the humic acid chelated calcium-magnesium powder prepared in step S2.2, the binary compound prepared in step S3.3, proline, alginate oligosaccharide, a surfactant and water are stirred and mixed uniformly to obtain a plant nutrient liquid.

5. The method of claim 2, wherein the plant nutrient solution for improving saline-alkali soil is prepared by adding 0.1 to 0.5 wt% of the composition of claim 1 to 1000 parts by weight of water. The volume ratio of the mixed salt solution to the sodium hydroxide solution is 1:1, and the concentration of the sodium hydroxide solution is 2mol / L.

6. The method of claim 3, wherein the plant nutrient solution for improving saline-alkali soil is prepared by adding 0.1 to 0.5 wt% of the composition of claim 1 to 1000 parts by weight of water. The mass ratio of pure humic acid to calcium chloride in the purified humic acid solution is 3.5-3.8:

1.

7. The method of claim 1, wherein the plant nutrient solution for improving saline-alkali soil is prepared by adding 0.1 to 0.5 wt% of the composition of claim 1 to 100 wt% of water. The zeolite is added in an amount of 0.08%-0.1% of the dry silkworm sand, and the mixed solvent is added in an amount of 4-5 times of the dry silkworm sand, and the mixed solvent is prepared by mixing acetone and ethanol at a volume ratio of 1:

2.

8. The method of claim 1, wherein the plant nutrient solution for improving saline-alkali soil is prepared by adding 0.1 to 0.5 wt% of the composition of claim 1 to 100 wt% of water. The moisture content of the softened dry silkworm sand is 25%-30%, and the volume ratio of the spirulina carbon point dispersion liquid to the silkworm sand extraction liquid is 1-2:

1.

9. The method of claim 4, wherein the plant nutrient solution for improving saline-alkali soil is prepared by adding 0.1 to 0.5 wt% of the composition of claim 1 to 1000 parts by weight of water. The raw material composition of the plant nutrient solution is 90-100 parts of pig excrement treatment liquid, 0.2-0.3 parts of compound microbial agent, 6-8 parts of NO3 - The raw material composition of the plant nutrient solution is 90-100 parts of pig excrement treatment liquid, 0.2-0.3 parts of compound microbial agent, 6-8 parts of NO3 - The raw material composition of the plant nutrient solution is 90-100 parts of pig excrement treatment liquid, 0.2-0.3 parts of compound microbial agent, 6-8 parts of NO3 - The raw material composition of the plant nutrient solution is 90-100 parts of pig excrement treatment liquid, 0.2-0.3 parts of compound microbial agent, 6-8 parts of NO3 - The raw material composition of the plant nutrient solution is 90-100 parts of pig excrement treatment liquid, 0.2-0.3 parts of compound microbial agent, 6-8 parts of NO3 - The raw material composition of the plant nutrient solution is 90-100 parts of pig excrement treatment liquid, 0.2-0.3 parts of compound microbial agent, 6-8 parts of NO3 - The raw material composition of the plant nutrient solution is 90-100 parts of pig excrement treatment liquid, 0.2-0.3 parts of compound microbial agent, 6-8 parts of NO3 - The raw material composition of the plant nutrient solution is 90-100 parts of pig excrement treatment liquid, 0.2-0.3 parts of compound microbial agent, 6-8 parts of NO3 - The raw material composition of the plant nutrient solution is 10. A plant nutrient solution for salinity improvement, characterized by, The plant nutrient solution is prepared by the method of any one of claims 1-9.

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