Method for promoting plant growth and improving soil based on fly ash

Abstract

The invention relates to the technical field of soil improvement, and discloses a method for promoting plant growth and improving soil based on fly ash. The method comprises the following steps: adding 5-50% by mass of fly ash into plant soil, selecting different plants as research objects, observing the growth conditions of the plants, and screening out the optimal adding proportion of the fly ash. Wherein the fly ash is spherical particles, and the particle size is 1-10 [mu] m. According to the method for promoting plant growth and improving soil based on fly ash, a proper amount of fly ash is added into soil to adjust the pH of acid soil and improve the physical and chemical properties and the structure of the soil, meanwhile, nutrient substances are provided for plants, growth of the plants is promoted, and resource utilization of waste is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and particularly relates to a method for promoting plant growth and soil improvement based on fly ash. Background Art

[0002] Fly ash is a solid by-product generated during the combustion of coal in coal-fired power plants. The main components of fly ash include silicon dioxide (SiO2), aluminum oxide (Al2O3), calcium oxide (CaO), and iron oxide (Fe2O3). In addition, it also contains some trace elements such as magnesium (Mg), potassium (K), sodium (Na), and phosphorus (P), and these components have certain mineral fertilizer effects. However, due to its complex composition, fly ash is regarded as a kind of waste. Nevertheless, the unique chemical properties and mineral composition of fly ash also provide the possibility for its application in multiple fields. The application fields of fly ash mainly include building materials, environmental governance, soil improvement, etc.

[0003] The application of fly ash in agriculture mainly focuses on soil improvement and plant growth. By applying an appropriate amount of fly ash, the physical and chemical properties of the soil can be improved, which is helpful for plant growth. Due to the high porosity and small particle size of fly ash, it can increase the air permeability and drainage of the soil. Especially in soils with high viscosity, fly ash can help loosen the soil and reduce soil compaction. At the same time, the minerals contained in fly ash can slowly release and provide trace elements required for plant growth, such as Ca, Mg, K, etc., which is beneficial to the healthy growth of the roots of certain plants and has certain value in soil improvement. In addition, elements such as Ca, Mg, K play an important role in the formation of plant cell walls, photosynthesis, and metabolic regulation, thus having a positive impact on plant growth. In addition, fly ash contains a certain amount of essential elements for plants, which can supplement the nutrients in the soil during the application process and improve soil fertility, especially having a good improvement effect on some barren soils and acidic soils. The nutrient elements rich in fly ash have the effects of enhancing the stress resistance and promoting the growth of plants. Some studies show that applying an appropriate amount of fly ash can enhance the drought resistance and pest resistance of certain crops, improve the photosynthesis efficiency and biomass accumulation of crops, and thus increase the yield.

[0004] Although fly ash has the potential to improve soil and promote plant growth, its application also poses certain risks. Fly ash may contain a certain amount of heavy metals (such as Pb, Cd, As, etc.) and harmful substances. If not properly treated, long-term or large-scale application of fly ash may lead to heavy metal accumulation, which in turn affects plant health and even endangers the health of humans and animals through the food chain. In addition, fly ash has a strong alkalinity, and excessive application may cause soil salinization or alkalization, affecting the normal water and nutrient absorption of crops. Therefore, it is unknown whether the addition ratio of fly ash in the soil will have beneficial or harmful effects on plant growth, and more experiments are needed to verify it in order to achieve the waste utilization of fly ash and improve the soil and environmental conditions. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for promoting plant growth and soil improvement based on fly ash, adding an appropriate amount of fly ash to the soil to adjust the pH of acidic soil, improve the physical and chemical properties and soil structure of the soil (enhance the aeration and water retention of the soil), and at the same time provide nutrients for plants to promote plant growth and achieve the resource utilization of waste.

[0006] To achieve the above purpose, the present invention provides a method for promoting plant growth and soil improvement based on fly ash, adding 5 - 50% by mass ratio of fly ash to the plant soil, selecting different plants as research objects, observing the plant growth situation, and screening out the optimal addition ratio of fly ash.

[0007] Further, the fly ash is spherical particles with a particle size of 1 - 10 μm.

[0008] Further, the addition amount of fly ash is 5 - 10% of the total mass of the plant soil and fly ash, and the plant soil is soil mixture Ⅰ or soil mixture Ⅱ; soil mixture Ⅰ is vermiculite and nutrient soil, and the ratio of vermiculite to nutrient soil is 3:1, and soil mixture Ⅱ is perlite and soil, and the ratio of perlite to soil is 1:1.

[0009] Further, the elements in the fly ash include CaO, Fe2O3, MgO, Na2O, K2O, TiO2, P2O5, BaO, MnO2, and SrO.

[0010] Further, after adding fly ash, the pH of the plant soil is 6.0 - 7.5.

[0011] Further, the research objects include tomatoes, Arabidopsis thaliana, fruit radishes, spinach, and corn.

[0012] The model plant tomato (Solanum lycopersicum) has a short planting cycle, strong adaptability, is easy to plant and manage, and is an important cash crop.

[0013] Preferably, tomato seeds need to be sterilized during planting.

[0014] The model plant Arabidopsis thaliana has a small genome and a short life cycle, is easy to plant and cultivate, and is a representative angiosperm.

[0015] Preferably, Arabidopsis thaliana seeds need to be sterilized during planting.

[0016] Spinacia oleracea, a classic plant in photosynthesis research, has certain advantages in research on photosynthesis, heavy metal absorption, nutrient metabolism, etc., and is highly adaptable and easy to plant and cultivate.

[0017] Preferably, Spinacia oleracea seeds need to be sterilized during planting.

[0018] Raphanus sativus has a short growth cycle and can complete the entire growth process in about 30 days, and the growth and development of the plant can be evaluated according to the shape, color, and size of its roots.

[0019] Preferably, Raphanus sativus seeds need to be sterilized during planting.

[0020] The food crop Zea mays is a typical C4 photosynthesis plant and is often used to study photosynthesis.

[0021] Preferably, Zea mays seeds need to be sterilized during planting.

[0022] Furthermore, Soil Mixture I is suitable for the planting of tomatoes, Arabidopsis thaliana, Spinacia oleracea, and Raphanus sativus, and Soil Mixture II is suitable for the planting of Zea mays.

[0023] Furthermore, when observing the growth of plants, the observation indicators include germination rate, stem length, plant height, leaf size, and photosynthesis indicators.

[0024] The present invention provides the application of the above method for promoting plant growth and soil improvement based on fly ash in promoting the seed germination and plant growth of tomatoes, Raphanus sativus, Spinacia oleracea, and Zea mays.

[0025] The advantages and positive effects of the method for promoting plant growth and soil improvement based on fly ash according to the present invention are:

[0026] 1. By observing the morphology of fly ash, the present invention determines its main elemental composition and oxide types, and further evaluates the solubility of fly ash and its effect on soil pH at different addition ratios. The results show that the addition of fly ash has a significant regulatory effect on soil pH. Within a reasonable application ratio range, it promotes the germination, growth, and photosynthesis of some plants. However, excessive application of fly ash may inhibit plant growth, reduce plant photosynthesis, and even cause death. Therefore, when fly ash is used as a soil conditioner, the addition ratio should be determined according to the plant type and growth requirements.

[0027] 2. The fly ash in the present invention contains various minerals and elements, especially nutrient elements such as K, Ca, Mg, P, etc. that are beneficial to plant growth. However, fly ash also contains some heavy metal elements, such as Hg, Cd, Cr, etc. When fly ash is applied in excess, these heavy metals may have a negative impact on plants and soil, and even threaten human health. Therefore, in agriculture or plant cultivation, the application rate and usage conditions of fly ash should be scientifically and reasonably adjusted according to soil characteristics and plant needs. This can not only improve soil structure, provide nutrient elements, and promote plant growth, but also give full play to its advantages, improve its benefits in the environment, and realize the resource utilization of waste.

[0028] 3. The fly ash in the present invention is alkaline, and elements such as Ca, Mg, K, etc. contained in it can effectively adjust the soil pH value. During the process of plant cultivation, appropriate addition of fly ash can not only neutralize acidic soil, increase the soil pH value, but also improve the physical and chemical properties of the soil and promote the healthy growth of plants.

[0029] 4. The fly ash in the present invention is composed of spherical particles with a diameter of 1 - 10 μm. The moderate solubility of fly ash promotes the release of these elements in the soil, and the sedimentation of fly ash ensures its water preservation ability in the soil, improving soil aeration and water retention.

[0030] 5. Recycling the waste fly ash as a soil conditioner in the present invention not only effectively reduces environmental pollution but also realizes the resource utilization of waste.

[0031] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0032] Figure 1 It is the scanning electron microscope images of fly ash under different magnifications in Example 1 of the present invention, where (a) is at 160× magnification, (b) is at 1,000× magnification, (c) is at 10,000× magnification, and (d) is at 16,000× magnification;

[0033] Figure 2X-ray diffraction pattern of fly ash in Example 2 of the present invention;

[0034] Figure 3 Elemental analysis diagram of fly ash in Example 3 of the present invention, (a) is the type of oxides in the top ten contents (normalized statistics), and (b) is the type of heavy metal oxides (normalized statistics);

[0035] Figure 4 Solubility diagram of fly ash in Example 4 of the present invention, (a) is the visual diagram of sedimentation of fly ash at different concentrations at different times. In (a), ① is 0 minute, ② is 5 minutes, ③ is 15 minutes, ④ is 30 minutes, ⑤ is 60 minutes, ⑥ is 120 minutes, and (b) is the absorbance value of fly ash at different concentrations at different times at OD 660 ;

[0036] Figure 5 Diagram of the regulation of soil pH by different addition ratios of fly ash in Example 5 of the present invention, (a) is the pH of fly ash, (b) is the regulation of the pH of soil mixture Ⅰ by different addition ratios of fly ash, and (c) is the regulation of the pH of soil mixture Ⅱ by different addition ratios of fly ash;

[0037] Figure 6 Analysis results of tomatoes at different addition ratios of fly ash in Example 6 of the present invention, (a) is the seed germination rate at the same position, (b) is the phenotype, (c) is the leaf size, (d) is the stem length, and (e) is F V / F M ;

[0038] Figure 7 Analysis results of Arabidopsis thaliana at different addition ratios of fly ash in Example 7 of the present invention, (a) is the seed germination rate, (b) is the rosette diameter, (c) is the leaf width, and (d) is F V / F M , and (e) is the phenotype;

[0039] Figure 8 Analysis results of fruit radishes at different addition ratios of fly ash in Example 8 of the present invention, (a) is the seed germination rate, (b) is the stem length, and (c) is F V / F M , (d) is the fruit weight, (e) is the fruit, and (f) is the phenotype;

[0040] Figure 9 Analysis results of spinach at different addition ratios of fly ash in Example 9 of the present invention, (a) is the seed germination rate at the same position, (b) is the stem length, and (c) is F V / F M , (d) is the phenotype, and (e) is the leaf size;

[0041] Figure 10 This is the analysis result of corn under different addition ratios of fly ash in Example 10 of the present invention. (a) is the seed germination rate, (b) is the stem length, (c) is F V / F M , (d) is the phenotype;

[0042] Figure 11 This is the water retention result of Soil Mixture Ⅰ + fly ash in Example 11 of the present invention;

[0043] Figure 12 This is the water retention result of Soil Mixture Ⅱ + fly ash in Example 11 of the present invention. Detailed implementation manners

[0044] The technical solutions of the present invention will be further described below with reference to the drawings and examples.

[0045] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs.

[0046] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention. The experimental methods without specific conditions indicated in the following examples are usually determined according to national standards. The experimental instruments, equipment and reagents not indicated the sources in the following examples are all commercially available raw materials.

[0047] The equipment used in each step of the following examples is all conventional equipment. If there is no corresponding national standard, it shall be carried out according to the general international standard, conventional conditions, or the conditions recommended by the manufacturer.

[0048] Unless otherwise defined or explained, all the professional and scientific terms used in the present invention have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the method of the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0049] Example 1 Fly ash sample treatment and morphological analysis

[0050] Weigh a certain amount of fly ash and place it in an oven at 100 °C for drying for several hours until the sample is completely dry. Pass the dried fly ash through a 200-mesh sieve, and try to avoid excessive force to ensure the natural form of fly ash particles. Conduct electrical conductivity treatment on the treated sample, select appropriate acceleration voltage and magnification, and take pictures. As Figure 1 shown, Figure 1As can be seen from (a) and (b) in the figure, fly ash as a whole presents spherical particles of different sizes, and the size is mainly concentrated in the range of 1-10 μm. From Figure 1 As can be seen from (c) and (d) in the figure, the surface of fly ash particles is relatively rough. This may be because fly ash particles coagulate with each other in the air, resulting in smaller particles adsorbed on the surface of large particles; some metal oxides existing in fly ash may cause the roughness of their surface due to secondary crystallization; in addition, incomplete combustion during the production process of fly ash may also lead to residues adhering to the particle surface, which has a certain impact on the solubility of fly ash in the solution.

[0051] XRD Characterization of Fly Ash in Example 2

[0052] Same as Example 1, the fly ash particles were dried and sieved. The results are as Figure 2 shown. According to Figure 2 the analysis results, it can be seen that fly ash shows the existence of multiple crystal phases, among which there are mainly five crystal phases, namely mullite, quartz, hematite, analcime and sillimanite. Mullite is a refractory aluminosilicate mineral and is a common phase in fly ash. The high-temperature combustion process of fly ash promotes the formation of this crystal structure; quartz comes from the silicate components in the original fuel; hematite is an iron oxide mineral; analcime is a silicate product; sillimanite is a calcium-containing mineral phase. The distribution of the characteristic peaks of these crystal phases at 2θ values reveals the mineral composition and source of fly ash, and reflects the complex physical and chemical changes it has experienced during the coal combustion process.

[0053] Elemental Composition Analysis of Fly Ash in Example 3

[0054] Analyzing the elemental composition in fly ash is beneficial to further evaluate its impact on plant growth in plant cultivation, give full play to its potential as a soil conditioner in agriculture, and avoid the negative effects of its heavy metal compounds on plants.

[0055] Fly ash contains various nutrient elements required for plant growth and can be used as a potential fertilizer in agriculture. Figure 3 This is the main elemental composition of fly ash in the present invention. Figure 3 Among the top ten oxides in terms of content in (a), there are common nutrient elements required for plant growth such as Ca, Mg, K, P, etc.; at the same time, there are certain trace elements, which are crucial for plant growth, such as Fe, Mn, etc. The elements such as Ca and Mg contained in it can adjust the soil pH value, but excessive amounts will cause soil alkalization and be unfavorable for plant growth. In addition, Figure 3In (b), there are certain harmful heavy metals in fly ash, such as Pb, Cd, Hg, etc. However, as can be seen from Table 1, the content of the harmful heavy metals in the overall elements of fly ash is relatively low. Long-term and excessive use of fly ash containing harmful heavy metals will lead to the accumulation of heavy metals in the soil, which is harmful to plant growth and may endanger the ecosystem and human health through the food chain. Therefore, the addition amount of fly ash in plants is crucial for plant growth.

[0056] Table 1 Element Content

[0057] Type Content Type Content <![CDATA[Na2O]]> 6.2827 <![CDATA[Cr2O3]]> 0.0714 MgO 8.1350 <![CDATA[La2O3]]> 0.0702 <![CDATA[Al2O3]]> 0 <![CDATA[Ce2O3]]> 0.1397 <![CDATA[SiO2]]> 0 <![CDATA[Pr2O3]]> 0.0163 <![CDATA[P2O5]]> 4.1101 <![CDATA[Nd2O3]]> 0.0533 <![CDATA[K2O]]> 5.7562 <![CDATA[Sm2O3]]> 0.0132 CaO 33.9805 <![CDATA[Eu2O3]]> 0.0026 <![CDATA[TiO2]]> 5.3156 <![CDATA[Gd2O3]]> 0.0113 <![CDATA[MnO2]]> 0.8137 <![CDATA[Tb2O3]]> 0.0017 <![CDATA[Fe2O3]]> 31.4043 <![CDATA[Dy2O3]]> 0.0101 SrO 0.6636 <![CDATA[Y2O3]]> 0.0695 BaO 3.0012 <![CDATA[Ho2O3]]> 0.0019 HgO 0.0003 <![CDATA[Er2O3]]> 0.0059 <![CDATA[As2O3]]> 0.0127 <![CDATA[Tm2O3]]> 0.0008 <![CDATA[SeO2]]> 0.0105 <![CDATA[Yb2O3]]> 0.0054 PbO 0.0394 <![CDATA[Lu2O3]]> 0.0009 CdO 0.0002 - -

[0058] Example 4 Solubility of Fly Ash

[0059] Evaluating the solubility of fly ash is very important for its dissolution in the soil, the release of elements, the impact on the soil structure, and the regulation of the soil pH.

[0060] Weigh 0, 0.5, 2.5, 5, 50, 500 mg of dried and sieved fly ash, dissolve it in 5 mL of 1×PBS (pH 7.4), and let it stand after sufficient ultrasonic treatment. Take 200 μL of the supernatant every 0, 5, 15, 30, 60, 120 min and place it in a 96-well plate. Preheat the microplate reader and read the absorbance value of the supernatant at 600 nm to judge the sedimentation and dissolution properties of fly ash at different concentrations at different times. The results are as Figure 4 shown. As Figure 4 can be seen, the higher the concentration of the fly ash solution, the higher the color and absorbance value of the supernatant. However, the higher the concentration, the faster the sedimentation rate and the lower the solubility, and almost all of it sediments in about 60 min. For fly ash solutions with lower concentrations, their sedimentation rates are relatively slower, and there is a greater possibility of element release in the environment.

[0061] Example 5 pH Regulation by Fly Ash

[0062] The regulation effect of different addition ratios of fly ash on the pH of the soil mixture. Weigh 0, 2, 4, 10, 20 g of dried and sieved fly ash, mix it with 40, 38, 36, 30, 20 g of soil mixture respectively, add 40 mL of deionized water to the prepared fly ash-soil mixture, vortex it sufficiently and then let it stand for 1 h. Centrifuge at 5000 rpm for 10 min, and take the supernatant for pH detection. The results are as Figure 5 shown. As Figure 5It can be seen that due to the presence of relatively more compounds such as CaO in fly ash, fly ash itself is in an alkaline state (10.22). Soil mixture I is weakly acidic, and the acidic soil limits the nutrient absorption of plants. As the addition amount of fly ash increases, the soil pH value rises. At the addition ratio of 5%-10%, the soil pH value (5.90 - 6.30) is closest to the optimal pH (5.5 - 7.50) for plant growth. Soil mixture II itself is neutral or weakly alkaline (7.54), and with the participation of fly ash, the pH value increases significantly, making it more suitable for the growth of plants that prefer alkaline environments. Therefore, by adding an appropriate amount of fly ash, the growth of different types of plants can be regulated. When applying, select the appropriate amount of fly ash and soil according to the type of plants.

[0063] Example 6 Effect of Fly Ash on the Growth of Tomatoes

[0064] A method for tomato growth and soil improvement based on fly ash. The specific operation steps are as follows:

[0065] Prepare a certain amount of soil mixture I (vermiculite: nutrient soil = 3:1), and weigh 0, 2, 4, 10, 20 g of fly ash after drying and sieving, and mix them thoroughly with 40, 38, 36, 30, 20 g of soil mixture I respectively (40 g is the weight of soil required for each pot of plants). Fully absorb water in the soil in the pot, shallowly bury the sterilized tomato seeds in the soil, cover with a film, and wait for germination. Plant two seeds in each pot, and three pots are used as a parallel group.

[0066] The specific characterization methods are as follows:

[0067] 1. Seed germination rate: Record the germination situation of tomato seeds on the 3rd, 4th, 5th, 6th, and 7th days after planting.

[0068] 2. Phenotype: After the tomatoes grow for 4 weeks, record their phenotypes.

[0069] 3. Leaf width: After the tomatoes grow for 4 weeks, pick leaves at the same position of each tomato plant for recording and comparison.

[0070] 4. Stem length: After the tomatoes grow for 4 weeks, record their stem lengths.

[0071] 5. Chlorophyll fluorescence parameters: After the tomatoes grow for 4 weeks, pick leaves at the same position of each tomato plant. At the same position on the same side of the leaf (avoiding the veins), use a 1 cm punch to take leaves of the same size, place them in a leaf clip for dark treatment for 15 - 30 min, and use a Yaxin-1161G portable fluorescence meter (Beijing Yaxin Liyi Technology Co., Ltd.) to measure the chlorophyll fluorescence kinetic parameters.

[0072] The results are as Figure 6 shown, from Figure 6It can be seen that fly ash has different effects on the growth of tomatoes at different addition ratios. Figure 6 As can be seen from (a) in the figure, appropriate application of fly ash promotes germination at the initial stage of tomato seed germination (3 - 5 days). At an application ratio of 25% of fly ash, the seeds can fully germinate in the later stage of germination (6 - 7 days). While at an application ratio of 50%, tomato seeds do not germinate within 7 days and germinate and then stagnate in growth within 4 weeks of cultivation. Figure 6 In (b) and (c) in the figure, the leaf size at the same position of the tomato and the phenotype of the whole tomato plant are directly compared respectively. It can be seen that fly ash has an obvious promoting effect on the leaves and phenotype of tomatoes at an addition ratio of 5% - 10%. Research shows that the suitable pH range for tomato growth is between 6.0 - 7.0. Appropriate addition of fly ash changes the soil pH. While excessive application of fly ash leads to soil alkalization, and the accumulation of excessive elements and certain metal elements may inhibit the growth of tomatoes. Figure 6 In (d) in the figure, for Figure 6 In (b) in the figure, the stem height of the whole tomato plant is statistically analyzed. It can be seen that there is a significant difference in stem height between the group with a fly ash addition ratio of 10% and the control group. Further, the F in the chlorophyll fluorescence parameters is used V / F M to evaluate whether the application of fly ash will have a negative impact on the photosynthesis of tomatoes. Figure 6 As can be seen from (e) in the figure, the F of fly ash at an addition ratio of 5 - 25% V / F M has no significant difference from the control group, while at an addition ratio of 50%, it significantly inhibits the photosynthesis of plants.

[0073] Example 7: Effect of Fly Ash on the Growth of Arabidopsis thaliana

[0074] A method for the growth of Arabidopsis thaliana and soil improvement based on fly ash. The specific operation steps are as follows:

[0075] The specific operation is the same as that in Example 6. Three seeds are planted in each pot, and three pots are used as a parallel group. The specific characterization means are as follows:

[0076] 1. Seed germination rate: Record the germination situation of Arabidopsis thaliana seeds on the 3rd, 4th, 5th, 6th, and 7th days after planting.

[0077] 2. Rosette diameter: After Arabidopsis thaliana grows for 4 weeks, take a top-down photo to record the rosette diameter of Arabidopsis thaliana, and use Image J for data statistics.

[0078] 3. Leaf width: After Arabidopsis thaliana grows for 4 weeks, take a top-down photo to record the leaf width of Arabidopsis thaliana, and use Image J for data statistics.

[0079] 4. Chlorophyll fluorescence parameters: Arabidopsis thaliana seedlings with similar growth states were selected, and 5 intact leaves of uniform size were cut and dark-treated for 20 min. The chlorophyll fluorescence kinetic parameters were measured using a Yaxin-1161G portable fluorometer (Beijing Yaxin Liyi Technology Co., Ltd.).

[0080] 5. Phenotype: After 4 weeks of growth of Arabidopsis thaliana, the phenotype of Arabidopsis thaliana was photographed from above and recorded.

[0081] The results are as Figure 7 shown. It can be Figure 7 seen that fly ash has different effects on the growth of Arabidopsis thaliana at different addition ratios. Figure 7 As can be seen from (a) in [reference], the addition of fly ash had a negative impact on germination at the initial stage of seed germination. Within 7 days of germination, the germination rate was considerable at the addition ratio of 5%-10%, while at the addition ratio of 25%-50%, the seeds basically did not germinate. In addition, some germinated seedlings stagnated in the growth cycle. Figure 7 As can be seen from (b), (c), (d), and (e) in [reference], the addition of fly ash inhibited the growth of Arabidopsis thaliana. Some studies have shown that the optimal soil pH range for Arabidopsis thaliana is 5.50 - 6.50. The application of fly ash led to an increase in soil pH, which was not conducive to the germination and growth of Arabidopsis thaliana. In addition, the roots of Arabidopsis thaliana are sensitive to the environment and have poor adaptability. Therefore, fly ash cannot be used as a soil conditioner for the model plant Arabidopsis thaliana.

[0082] Example 8 Effect of Fly Ash on the Growth of Fruit Radish

[0083] A method for the growth of fruit radish and soil improvement based on fly ash. The specific operation steps are as follows:

[0084] The specific operation is the same as that in Example 6. The specific characterization methods are as follows:

[0085] 1. Seed germination rate: Record the germination of fruit radish seeds on the 3rd, 4th, 5th, 6th, and 7th days after planting.

[0086] 2. Stem length: After 4 weeks of growth of fruit radish, record its stem length and perform data statistics using Image J.

[0087] 3. Chlorophyll fluorescence parameters: The same as in Example 6.

[0088] 4. Fruit weight: After 4 weeks of growth of fruit radish, record the weight of each group of fruits.

[0089] 5. Fruit record: After 4 weeks of growth of fruit radish, record the fruit setting situation of each group.

[0090] 6. Phenotype: After 4 weeks of growth of fruit radish, record the phenotype of fruit radish.

[0091] The results are as Figure 8 shown. It can be seen from Figure 8 that fly ash has different effects on the growth of fruit radish at different addition ratios. Figure 8 As can be seen from (a) in Figure 8 Figure 8 Figure 8 V / F M Figure 8 that the appropriate addition of fly ash does not affect the germination rate of fruit radish, and a germination level similar to that of the control group can be achieved within 7 days. However, a 50% addition ratio significantly inhibits the germination of fruit radish.

[0092] Example 9 Effect of fly ash on the growth of spinach

[0093] A method for growing spinach and amending soil based on fly ash. The specific operation steps are as follows:

[0094] The specific operation is the same as that in Example 6. The specific characterization means are as follows:

[0095] 1. Seed germination rate: Record the germination situation of spinach seeds on the 3rd, 4th, 5th, 6th, and 7th days after planting.

[0096] 2. Stem length: After spinach grows for 4 weeks, record its stem length.

[0097] 3. Chlorophyll fluorescence parameters: The same as in Example 6.

[0098] 4. Phenotype: After spinach grows for 4 weeks, record the phenotype of spinach.

[0099] 5. Leaf width: After spinach grows for 4 weeks, pick leaves at the same position of each spinach plant for recording and comparison.

[0100] The results are as Figure 9 shown. It can be seen from Figure 9 that fly ash has different effects on the growth of spinach at different addition ratios. Figure 9 As can be seen from (a) in Figure 9 ​As can be seen from Fig. (b), when the addition ratio of fly ash is 5%, it has a promoting effect on the stem length of spinach. Figure 9 As can be seen from Fig. (c), when the addition ratio of fly ash is 5%, the F V / F M value of spinach leaves is close to that of the control group, indicating that the addition of fly ash does not cause stress to the photosynthesis of spinach. Figure 9 As can be seen from Figs. (d) and (e), as a soil conditioner, fly ash has a certain promoting effect on the whole spinach plant and the leaf size at the same position when the addition ratio is 5%.

[0101] Example 10 Effect of Fly Ash on Maize Growth

[0102] A method for maize growth and soil improvement based on fly ash. The specific operation steps are as follows:

[0103] Prepare a certain amount of soil mixture II (soil: perlite = 1:1). Weigh 0, 2, 4, 10, and 20 g of sieved and dried fly ash respectively, and mix them well with 40, 38, 36, 30, and 20 g of soil mixture II (40 g is the amount required for each pot of plants). Let the soil in the pot fully absorb water, and gently bury the sterilized maize seeds in the soil, cover with a film, and wait for germination. Plant two seeds in each pot, and three pots are used as a parallel group. The specific characterization methods are as follows:

[0104] 1. Seed germination rate: Record the germination of maize seeds on the 3rd, 4th, 5th, 6th, and 7th days after planting.

[0105] 2. Stem length: After maize grows for 4 weeks, record its stem length.

[0106] 3. Chlorophyll fluorescence parameters: The same as in Example 6.

[0107] 4. Phenotype: After maize grows for 4 weeks, record the phenotype of maize.

[0108] The results are as Figure 10 shown. It can be seen from Figure 10 that fly ash has different effects on the growth of maize at different addition ratios. It can be seen from Figure 10 Fig. (a) that when the addition ratio of fly ash is 5%, it has a promoting effect on the germination rate of maize seeds in the initial germination stage (3 - 5 d). When the addition ratio is 25%, although a certain germination starts in the later stage of the germination stage, the growth stage stagnates. While when the addition ratio is 50%, the seeds no longer germinate. Figure 10 As can be seen from Figs. (b), (c), and (d), as a soil conditioner, fly ash has a promoting effect on the stem height of maize and the F V / F MThere is no significant impact. The optimal soil pH range for corn growth is usually 6.00 - 7.50. Although the addition of fly ash increases the pH of Soil Mixture II, it also improves the soil structure and properties to a certain extent, enhances soil aeration and water retention, and provides various nutrient elements required by plants.

[0109] Example 11: Effects of Different Addition Amounts of Fly Ash on Soil Water Retention

[0110] 1. Water Retention of Soil Mixture I + Fly Ash:

[0111] Method: ① Saturated water content: Put 50 g of the mixture of vermiculite and fly ash into a beaker and soak it with deionized water for 12 h. Remove the excess water with filter paper to make the sample reach a state without excess free water. Weigh the weight of the saturated sample (wet weight, Ws). Dry the sample in an oven (105 °C, 24 h) and then weigh the dry weight (Wd).

[0112] Saturated water content (%) = [(Ws - Wd) / Wd] × 100;

[0113] ② Water holding capacity: After saturating the sample, place the sample in a permeation device (such as a sand column or filter paper funnel) and let it stand for 12 h to remove the water infiltrated by gravity. Weigh the wet weight Wf of the sample, and then dry the sample and weigh the dry weight Wd.

[0114] Water holding capacity (%) = [(Wf - Wd) / Wd] × 100;

[0115] ③ Water retention test: Record the residual water content corresponding to each suction and draw a water retention curve.

[0116] As Figure 11 shown, the porous structure and high specific surface area of fly ash enhance the binding ability of vermiculite - water. As the addition ratio of fly ash increases, the water retention ability is significantly enhanced.

[0117] However, due to the high proportion of fly ash filling the pores of vermiculite, the structure of the mixture becomes too dense, restricting water infiltration and storage. The water retention of the soil mixture decreases at a 50% addition ratio, and the parameters tend to be similar to those of pure vermiculite.

[0118] 2. Water Retention of Soil Mixture II + Fly Ash:

[0119] The method is the same as that of "Water Retention of Soil Mixture I + Fly Ash".

[0120] The results are as Figure 12As shown, within the range of fly ash addition ratio from 0% to 25%, the water retention of the soil gradually increases. When the addition ratio exceeds 25%, the improvement effect tends to level off and may even decline. The present invention discloses a method for promoting plant growth and soil improvement based on fly ash. Fly ash is used as a soil conditioner, and by virtue of the various elements, certain solubility, and the regulation effect on soil pH contained in fly ash, it is applied to the soil in different proportions to improve the soil and thereby promote plant growth.

[0121] Different plants show different effects under different addition ratios of fly ash. At the fly ash addition ratio of 5%-10%, there is a certain promoting effect on the seed germination rate, stem height, leaves, etc. of tomatoes, fruit radishes, spinach, and corn, and the F V / F M value basically remains between 0.75 and 0.80, showing no significant difference from the control group. This may be because the addition of fly ash improves the soil structure and properties, provides various nutrient elements required by plants, and appropriately adjusts the soil pH, etc. When the addition ratio of fly ash reaches 25% and above, the seed germination rate decreases and even no longer germinates, and there are inhibitions on the plant height, leaf size, and photosynthesis. This may be because the excessive addition of fly ash leads to soil pH alkalization and thus inhibits plant growth, or certain heavy metal elements in fly ash accumulate in the soil, threatening plant growth.

[0122] Fly ash cannot be a soil conditioner for the model plant Arabidopsis thaliana. The addition of fly ash inhibits the germination, growth, and photosynthesis of Arabidopsis thaliana, which may be related to the fact that the addition of fly ash changes the pH value required for the growth of Arabidopsis thaliana. Arabidopsis thaliana grows most stably between pH 5.50 and 6.00, while the application of fly ash significantly increases the soil pH of Arabidopsis thaliana; in addition, Arabidopsis thaliana belongs to plants sensitive to the root environment, and the application of fly ash increases the elements in the soil environment, inhibiting the growth of Arabidopsis thaliana, which is sensitive to environmental and heavy metal pollution. Therefore, there are crop variety differences in using fly ash as a soil conditioner.

[0123] Fly ash contains both various nutrient elements beneficial to plants and harmful heavy metal elements. By applying an appropriate amount of fly ash to suitable plant types, the waste fly ash can be converted into a plant growth improver, realizing waste utilization, hopefully improving environmental pollution, and supporting the sustainable development of agriculture.

[0124] Therefore, the present invention adopts the above-mentioned method for promoting plant growth and soil improvement based on fly ash, adding an appropriate amount of fly ash to the soil to adjust the pH of acidic soil, improve the physical and chemical properties and soil structure of the soil, and at the same time provide nutrients for plants to promote plant growth and realize the resource utilization of waste.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for promoting plant growth and soil improvement based on fly ash, characterized in that: Add 5-50% by mass of fly ash to plant soil, select different plants as research objects, observe the growth of plants, and screen out the optimal addition ratio of fly ash.

2. The method for promoting plant growth and soil improvement based on fly ash according to claim 1, characterized in that: The fly ash is spherical particles with a particle size of 1-10 μm.

3. The method for promoting plant growth and soil improvement based on fly ash according to claim 1, characterized in that: The addition amount of fly ash is 5-10% of the total mass of plant soil and fly ash. The plant soil is soil mixture Ⅰ or soil mixture Ⅱ; soil mixture Ⅰ is vermiculite and nutrient soil, with a ratio of vermiculite:nutrient soil = 3:1, and soil mixture Ⅱ is perlite and soil, with a ratio of perlite:soil = 1:

1.

4. A method for promoting plant growth and soil improvement based on fly ash according to claim 1, characterized in that: The elements in the fly ash include CaO, Fe2O3, MgO, Na2O, K2O, TiO2, P2O5, BaO, MnO2, and SrO.

5. A method for promoting plant growth and soil improvement based on fly ash according to claim 1, characterized in that: After adding fly ash, the pH of the plant soil is 6.0-7.

5.

6. The method for promoting plant growth and soil improvement based on fly ash according to claim 1, characterized in that: The research objects include tomatoes, Arabidopsis thaliana, fruit radishes, spinach, and corn.

7. A method for promoting plant growth and soil improvement based on fly ash according to claim 1, characterized in that: When observing the growth of plants, the observation indicators include germination rate, stem length, plant height, leaf size, and photosynthesis indicators.

8. Application of a method for promoting plant growth and soil improvement based on fly ash according to any one of claims 1-7 in promoting seed germination and plant growth of tomatoes, fruit radishes, spinach, and corn.

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