Composite nitrogen fertilizer synergist and application thereof in improving nitrogen utilization rate of crops

Abstract

The invention discloses a composite nitrogen fertilizer synergist and application thereof in improving the nitrogen utilization rate of crops. The composite nitrogen fertilizer synergist comprises the following components: 5-15g / mu of gamma-polyglutamic acid, 50-100kg / mu of wormcast and 0.02-0.06 g / mu of hemin. The composite nitrogen fertilizer synergist is uniformly mixed in a nitrogen fertilizer such as urea, and the nitrogen fertilizer is applied according to the conventional dosage and period in the whole planting process; the nitrogen utilization rate is synergistically increased through a physical, biological and physiological trinity mechanism by utilizing the synergistic effect of gamma-polyglutamic acid, wormcast and hemin in soil; the crop nitrogen fertilizer utilization rate is increased to about 50%; the operation is simple, the cost is extremely low, and the popularization and application prospects are extremely good.

Description

Technical Field

[0001] This invention relates to the field of improving agricultural nitrogen fertilizer utilization efficiency, specifically to a compound nitrogen fertilizer synergist and its application in improving crop nitrogen utilization efficiency. Background Technology

[0002] In traditional agricultural production, according to data from the Chinese Academy of Agricultural Sciences in 2024, the utilization rate of chemical nitrogen fertilizers such as urea and ammonium nitrogen in the current season is generally less than 40%. Unabsorbed nitrogen is lost through volatilization, leaching, and other forms, which not only wastes resources but also leads to environmental problems such as soil acidification and eutrophication of water bodies. In recent years, the global implementation of the "nitrogen reduction and efficiency improvement" policy has urgently required breakthroughs in existing technological bottlenecks.

[0003] Current technologies for improving nitrogen use efficiency have the following drawbacks: For example, slow-release fertilizers achieve physical regulation of nitrogen release, but have high production costs, release rates are greatly affected by temperature and humidity, and membrane residues pose environmental risks; for example, nitrification inhibitors delay the conversion of ammonium nitrogen, but their effects are unstable and may inhibit crop growth; for example, microbial agents biologically activate the soil, but single species (such as nitrogen-fixing bacteria) have limited functions, are difficult to store, have poor environmental adaptability, and unstable field effects.

[0004] While existing technologies involve nitrogen fertilizer synergists, they mostly focus on a single mechanism of action. This invention fills the technological gap in low-cost, highly stable, and environmentally friendly compound formulations by utilizing the synergistic effect of component combination and soil-crop system regulation. This invention leverages the synergistic effect of γ-polyglutamic acid, heme chloride, and earthworm castings in the soil to synergistically enhance nitrogen use efficiency through a three-pronged physical, biological, and physiological mechanism; increasing crop nitrogen fertilizer utilization efficiency to approximately 50%; it is simple to operate, extremely low in cost, and has excellent prospects for widespread application. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a compound nitrogen fertilizer synergist and its application in improving crop nitrogen utilization. The application amounts of each component in this compound nitrogen fertilizer synergist are: 5-15 g / mu of γ-polyglutamic acid, 50-100 kg / mu of earthworm castings, and 0.02-0.06 g / mu of heme chloride. The above compound nitrogen fertilizer synergist is mixed evenly with nitrogen fertilizer such as urea. Nitrogen fertilizer is applied according to conventional dosage and timing throughout the planting process. This invention utilizes the synergistic effect of γ-polyglutamic acid, earthworm castings, and heme chloride in the soil to synergistically improve nitrogen utilization through a three-pronged mechanism of physical, biological, and physiological processes. It increases crop nitrogen fertilizer utilization to about 50%. The operation is simple, the cost is extremely low, and it has excellent prospects for widespread application.

[0006] To achieve the above technical effects, the following technical solution is adopted: A compound nitrogen fertilizer synergist, with the following components: γ-polyglutamic acid, earthworm castings, and heme chloride; The dosage of each component is as follows: γ-polyglutamic acid 5-15g / mu, earthworm castings 50-100kg / mu and heme chloride 0.02-0.06g / mu.

[0007] Furthermore, the amount of γ-polyglutamic acid is 10g / mu, earthworm castings are 100kg / mu, and heme chloride is 0.04g / mu.

[0008] Furthermore, the heme chloride is a wettable powder with an active ingredient content of 0.3%.

[0009] Furthermore, the heme chloride is dissolved and diluted with a surfactant solution with a concentration of 1-3 mmol / L, wherein the concentration of the heme chloride in the surfactant solution is 0.02-0.06 g / L.

[0010] Furthermore, the surfactant is one or more of sodium dodecyl sulfate (SDS), Tween 80, and Span S80.

[0011] The specific method for using a compound nitrogen fertilizer synergist is as follows: Mix the compound nitrogen fertilizer enhancer evenly with the nitrogen fertilizer, and apply the nitrogen fertilizer according to the conventional dosage and timing throughout the entire crop planting process.

[0012] Furthermore, the specific method for uniformly mixing the compound nitrogen fertilizer synergist into the nitrogen fertilizer is as follows: First, weigh out the required amounts of γ-polyglutamic acid, earthworm castings, and heme chloride according to the crop area. Dissolve the heme chloride in a surfactant solution with a concentration of 1-3 mmol / L to obtain a concentration of 0.02-0.06 g / L, thus obtaining a heme chloride solution. Dissolve the γ-polyglutamic acid in the heme chloride solution to obtain a mixed solution. Spray the mixed solution evenly onto the continuously stirred earthworm castings, ensuring all three components are thoroughly mixed. After drying at room temperature, add nitrogen fertilizer to the prepared earthworm castings and mix well before use.

[0013] Furthermore, the nitrogen fertilizer includes, but is not limited to, urea.

[0014] Furthermore, the crops mentioned include, but are not limited to, rice.

[0015] The beneficial effects of this invention are as follows: This invention discloses a compound nitrogen fertilizer synergist and its application in improving crop nitrogen utilization. The application amounts of each component in the compound nitrogen fertilizer synergist are: 5-15 g / mu of γ-polyglutamic acid, 50-100 kg / mu of earthworm castings, and 0.02-0.06 g / mu of heme chloride. The above compound nitrogen fertilizer synergist is mixed evenly with nitrogen fertilizer such as urea. Nitrogen fertilizer is applied according to conventional dosage and timing throughout the planting process. This invention utilizes the synergistic effect of γ-polyglutamic acid, earthworm castings, and heme chloride in the soil to synergistically improve nitrogen utilization through a three-pronged mechanism of physical, biological, and physiological processes. It increases crop nitrogen fertilizer utilization to about 50%. The operation is simple, the cost is extremely low, and it has excellent prospects for widespread application. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0017] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0018] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0019] The heme chloride used in the following examples and comparative examples was purchased from Shanghai Changde Technology Co., Ltd., as a 0.3% wettable powder with pesticide registration certificate number PD20161264. Earthworm castings and γ-polyglutamic acid were commercially available.

[0020] Example 1: Compound nitrogen fertilizer synergist 1 has the following components and dosages: γ-polyglutamic acid 5g / mu, earthworm castings 50kg / mu, and heme chloride 0.02g / mu.

[0021] First, weigh out the required amounts of γ-polyglutamic acid, earthworm castings, and heme chloride according to the crop area. Dissolve the heme chloride in a 2 mmol / L SDS surfactant solution to obtain a heme chloride solution with a concentration of 0.02 g / L. Dissolve the γ-polyglutamic acid in the heme chloride solution to obtain a mixed solution. Spray the mixed solution evenly onto the continuously turned earthworm castings, mixing the three components thoroughly. After drying at room temperature, add nitrogen fertilizer to the prepared earthworm castings and mix well before use. The application time and method are described below.

[0022] Example 2: Compound nitrogen fertilizer synergist 2 has the following components and dosages: γ-polyglutamic acid 15g / mu, earthworm castings 100kg / mu, and heme chloride 0.06g / mu.

[0023] First, weigh out the required amounts of γ-polyglutamic acid, earthworm castings, and heme chloride according to the crop area. Dissolve the heme chloride in a 2 mmol / L SDS surfactant solution to obtain a heme chloride solution with a concentration of 0.06 g / L. Dissolve the γ-polyglutamic acid in the heme chloride solution to obtain a mixed solution. Spray the mixed solution evenly onto the continuously turned earthworm castings, mixing the three components thoroughly. After drying at room temperature, add the crop nitrogen fertilizer to the prepared earthworm castings and mix well before use. The application time and method are described below.

[0024] Example 3: Compound nitrogen fertilizer synergist 3 has the following components and dosages: γ-polyglutamic acid 10g / mu, earthworm castings 100kg / mu, and heme chloride 0.04g / mu.

[0025] First, weigh out the required amounts of γ-polyglutamic acid, earthworm castings, and heme chloride according to the crop area. Dissolve the heme chloride in a 2 mmol / L SDS surfactant solution to obtain a heme chloride solution with a concentration of 0.04 g / L. Dissolve the γ-polyglutamic acid in the heme chloride solution to obtain a mixed solution. Spray the mixed solution evenly onto the continuously turned earthworm castings, mixing the three components thoroughly. After drying at room temperature, add the crop nitrogen fertilizer to the prepared earthworm castings and mix well before use. The application time and method are described below.

[0026] All comparative examples are based on Example 3.

[0027] Comparative Example 1: Nitrogen fertilizer enhancer 4 has the following components and dosages: 100 kg of earthworm castings + 10 g / mu and 0.04 g / mu of heme chloride. Other aspects remain the same as in Example 3.

[0028] Comparative Example 2: Nitrogen fertilizer synergist 5 has the following components and dosages: γ-polyglutamic acid 10g / mu and heme chloride 0.04g / mu. Other aspects remain the same as in Example 3.

[0029] Comparative Example 3: Nitrogen fertilizer enhancer 6 has the following components and dosages: γ-polyglutamic acid 10+ 0.04 g / mu and earthworm castings 100 kg / mu. Other components remain the same as in Example 3.

[0030] Comparative Example 4: Nitrogen fertilizer synergist 7 has the following component dosage: γ-polyglutamic acid 10+ 0.04 g / mu. Other components remain consistent with Example 3.

[0031] Comparative Example 5: Nitrogen fertilizer enhancer 8 has the following components and dosages: 100kg + 10g + 0.04g / mu of earthworm castings. All other components remain the same as in Example 3.

[0032] Comparative Example 6: Nitrogen fertilizer enhancer 9 has the following component dosage: heme chloride 0.04 g / mu. All other components remain the same as in Example 3.

[0033] Comparative Example 7: No nitrogen fertilizer enhancer was applied; only nitrogen fertilizer was applied, and the amount of nitrogen fertilizer applied was the same as in Example 3.

[0034] Comparative Example 8: Do not apply any nitrogen fertilizer enhancers or nitrogen fertilizer.

[0035] The nitrogen fertilizer synergists in Examples 1-3 and Comparative Examples 1-8 are evaluated below: A field plot experiment was conducted for two consecutive years, 2022 and 2023, in Dayuan Village, Luzhou Township, Shanggao County. The soil in the experimental field had a pH of 5.44, an organic matter content of 28.1 g / kg, a total nitrogen content of 1.67 mg / kg, and moderate soil fertility. The soil type was nutrient-deficient paddy soil, and the rice variety planted was Weiliangyou 7713. The entire field was divided into 33 plots, each with an area of ​​30 m². 2 Field ridges were constructed between the plots and covered with plastic film. There were 11 treatment plots in total, with three replicates for each. Treatment plots 1-9 were the nitrogen fertilizer synergist treatments used in Examples 1-3 and Comparative Examples 1-6, respectively. Treatment 10 was the conventional fertilization treatment (without compound nitrogen fertilizer synergist, i.e., Comparative Example 7). Treatment 11 was the no-nitrogen treatment (without compound nitrogen fertilizer synergist and no nitrogen fertilizer, i.e., Comparative Example 8). Except for the plot without nitrogen, all other plots were treated with 12 kg / mu of pure N; all plots were treated with 5 kg / mu of P2O5 and 10 kg / mu of K2O. The nitrogen fertilizer used was urea (46% N content), the phosphate fertilizer was calcium magnesium phosphate (16% P2O5 content), and the potassium fertilizer was potassium chloride (60% K2O content).

[0036] The specific usage method is as follows: Rice seedlings were raised in the field. One day before transplanting, each plot was treated according to the requirements, with enhanced nitrogen fertilizer containing compound nitrogen fertilizer synergist mixed thoroughly with calcium magnesium phosphate fertilizer and potassium chloride fertilizer, and then applied to the paddy field. Other field management methods and pest and disease control methods remained consistent with traditional methods. After the rice matured, the actual harvest was conducted in each plot for yield measurement. Samples of grains and straw were taken, weighed, crushed, and digested using H2O2-H2SO4. The nitrogen content was determined using a Kjeldahl nitrogen analyzer, and the nitrogen fertilizer utilization rate was calculated. Nitrogen uptake by rice plants = nitrogen uptake by rice grains + nitrogen uptake by rice straw; nitrogen uptake by rice grains = rice grain yield × grain nitrogen content; nitrogen uptake by rice straw = rice straw yield × straw nitrogen content; nitrogen fertilizer utilization rate = (nitrogen uptake by plants in nitrogen-treated areas - nitrogen uptake by plants in non-nitrogen-treated areas) / nitrogen application rate × 100%.

[0037] Table 1 shows that the average yield of each treatment after two years differed significantly after applying nitrogen fertilizer synergists. The lowest yield was observed in the no-nitrogen-application treatment (Comparative Example 8), followed by the conventional fertilization treatment (Comparative Example 7). The yields of the nitrogen fertilizer synergists were all higher than those of conventional fertilization. Examples 1-3 showed yield increases of 14.3-18.8% compared to conventional fertilization; Comparative Examples 1-3 showed increases of 6.6-7.9%; and Comparative Examples 4-6 showed increases of 3.2-4.6%. This indicates that the application of compound nitrogen fertilizer synergists yielded the best results, significantly superior to single synergists or combinations of two synergists.

[0038] Table 1 Rice yield of each treatment

[0039] Note 1: Except for the fertilization method, all other conventional cultivation methods are the same for the groups in the table.

[0040] Table 2 shows that after applying nitrogen fertilizer synergists, there were significant differences in nitrogen fertilizer utilization rates among the treatments, with the conventional fertilization treatment (Comparative Example 7) showing the lowest rate, averaging 33.3% over two years. The nitrogen fertilizer utilization rates of the treatments using nitrogen fertilizer synergists were all higher than those of conventional fertilization. Examples 1-3 showed an increase of 15.0-16.2 percentage points compared to conventional fertilization; Comparative Examples 1-3 showed an increase of 4.0-5.7 percentage points; and Comparative Examples 4-6 showed an increase of 2.1-3.7 percentage points. This indicates that applying compound nitrogen fertilizer synergists can significantly improve nitrogen fertilizer utilization rates, with effects exceeding those of single synergists or combinations of two synergists.

[0041] Table 2 Nitrogen fertilizer utilization rate of rice in each treatment

[0042] A pot experiment was conducted in a glass mesh room. The soil used was paddy soil of the rice variety Weiliangyou 7713. The experiment included eight treatments, replicated three times. Soil was placed in plastic buckets, each containing 6 kg of soil. Treatments 1-7 were the nitrogen fertilizer synergist treatments used in Example 3 and Comparative Examples 1-6, respectively. Treatment 8 was the conventional fertilization treatment (without the compound nitrogen fertilizer synergist, using conventional nitrogen fertilizer, i.e., Comparative Example 7). All pots were treated with a single application of pure N 120 mg / kg, P2O5 60 mg / kg, and K2O 100 mg / kg soil. Nitrogen fertilizer was applied using… 15 Nitrogen-labeled urea, with an abundance of 20.16%, was purchased from the Shanghai Chemical Industry Research Institute. The phosphate fertilizer was calcium magnesium phosphate (P2O5 content 16%), and the potash fertilizer was potassium chloride (K2O content 60%). The dosage of nitrogen fertilizer synergist was calculated based on the nitrogen fertilizer dosage.

[0043] The specific usage method is as follows: One day before rice transplanting, the fertilizers and nitrogen fertilizer enhancers used in each treatment were thoroughly mixed with the soil, and the soil was soaked with water. Rice was transplanted in 3 holes per pot, with 2 seedlings per hole. During the rice growing season, a 3-5 cm water layer was maintained. The treatments were randomly arranged, and the positions of the plastic containers were changed periodically. After the pot experiment was harvested, rice plant samples were separated into grain and straw samples for yield calculation, and the total nitrogen in the soil was measured. 15 N abundance. After rice harvest, all soil samples in the container were mixed and then sampled again to determine total soil nitrogen and its abundance. 15 Nitrogen abundance. Total nitrogen in the sample was determined using the Kjeldahl method. 15 Nitrogen abundance was determined using isotope ratio mass spectrometry. Rice plants 15 N absorption = grain 15 N absorption capacity + straw 15 N uptake, grain / straw 15 N absorption = nitrogen absorption of grains / straw × ( 15 N 籽粒 / 秸秆丰度 - 15 N 自然丰度 ) / ( 15 N 肥料丰度 - 15 N 自然丰度 ); 15 N residue = Soil nitrogen accumulation × ( 15 N 土壤丰度 - 15 N 自然丰度 ) / ( 15 N 肥料丰度 - 15 N 自然丰度 ); 15 N loss amount = 15 N Fertilizer application rate - 15 N absorption capacity - 15N residual amount. 15 N utilization rate (%) = 15 N plant absorption (g / pot) / 15 N Fertilizer application rate (g / pot) ×100; 15 N Residual Rate (%) = 15 N residue (g / pot) / 15 N Fertilizer application rate (g / pot) ×100; 15 N loss rate (%) = 100- 15 N utilization rate - 15 N residual rate. (Among them) 15 The natural abundance of N was calculated as 0.366%.

[0044] Table 3 shows that after applying nitrogen fertilizer synergist, there were significant differences in plant height and yield among the different treatments in the pot experiment. The conventional fertilization treatment (Comparative Example 7) had the lowest plant height, grain yield, and straw yield. Example 3, which used compound nitrogen fertilizer synergist, showed the best results, with plant height, grain yield, straw yield, and total biomass increasing by 8.0%, 45.1%, 10.8%, and 27.9%, respectively, compared to conventional fertilization. The increases in plant height and yield in Comparative Examples 1-6 compared to conventional fertilization were far less significant than those in Example 3. This indicates that applying compound nitrogen fertilizer synergist can significantly promote rice growth and increase rice yield.

[0045] Table 3 Effects of different treatments on rice plant growth and yield

[0046] Note: Biomass is the sum of grain yield and straw yield in the pot experiment. Table 4 shows that after applying nitrogen fertilizer synergist, the effects of different treatments were observed. 15 The fate of nitrogen fertilizers differs significantly depending on whether conventional fertilization (comparative example 7) is applied. 15 nitrogen uptake and 15 Nitrogen utilization rates were lowest in all cases. Nitrogen fertilizer utilization rates were higher in treatments using nitrogen fertilizer enhancers than in conventional fertilization treatments, with Example 3 showing the highest utilization rate compared to conventional fertilization. 15 Nitrogen uptake increased by 49.2%. 15 N utilization rate increased by 14.5 percentage points; compared with conventional fertilization, comparisons 1-6 showed improvement. 15 Nitrogen uptake increased by 5.3-21.5%. 15 Nitrogen utilization rate only increased by 1.5-6.3 percentage points. This indicates that applying compound nitrogen fertilizer synergists can significantly improve nitrogen fertilizer utilization rate, and its effect is significantly better than that of a single synergist or a combination of two synergists, demonstrating a good synergistic effect. Meanwhile, Example 3 showed an improvement compared to conventional fertilization. 15 N residue and 15 The residual rate of N was significantly reduced. 15 N loss and15 The loss rate of nitrogen indicates that the application of compound nitrogen fertilizer synergists is effective in improving soil nitrogen retention and reducing nitrogen loss.

[0047] Table 4 Different treatments 15 The impact of N's destination

[0048] Based on the experimental results of the above embodiments, the present invention utilizes the synergistic effect of γ-polyglutamic acid, earthworm castings and heme chloride in the soil to synergistically improve nitrogen utilization through a three-in-one mechanism of physical, biological and physiological processes; it increases crop nitrogen fertilizer utilization to about 50%; the technical effect is excellent, and it solves the major technical problem of low nitrogen fertilizer utilization (only about 30%).

[0049] In summary, this invention discloses a compound nitrogen fertilizer synergist and its application in improving crop nitrogen utilization efficiency. The application amounts of each component in the compound nitrogen fertilizer synergist are: 5-15 g / mu of γ-polyglutamic acid, 50-100 kg / mu of earthworm castings, and 0.02-0.06 g / mu of heme chloride. The above compound nitrogen fertilizer synergist is mixed evenly with nitrogen fertilizer such as urea. Nitrogen fertilizer is applied according to conventional dosage and timing throughout the planting process. This invention utilizes the synergistic effect of γ-polyglutamic acid, earthworm castings, and heme chloride in the soil to synergistically improve nitrogen utilization efficiency through a three-pronged mechanism of physical, biological, and physiological processes. It increases crop nitrogen fertilizer utilization efficiency to about 50%. The operation is simple, the cost is extremely low, and it has excellent prospects for widespread application.

[0050] Therefore, those skilled in the art will recognize that although embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A compound nitrogen fertilizer synergist, characterized in that, The components of the synergist are: γ-polyglutamic acid, earthworm castings, and heme chloride; The dosage of each component is as follows: γ-polyglutamic acid 5-15g / mu, earthworm castings 50-100kg / mu and heme chloride 0.02-0.06g / mu.

2. The compound nitrogen fertilizer synergist as described in claim 1, characterized in that, The ingredients are γ-polyglutamic acid 10g / mu, earthworm castings 100kg / mu, and heme chloride 0.04g / mu.

3. The compound nitrogen fertilizer synergist as described in claim 1, characterized in that, The heme chloride is a wettable powder with an active ingredient content of 0.3%.

4. A compound nitrogen fertilizer synergist as described in claim 1, characterized in that, The heme chloride is dissolved and diluted with a surfactant solution with a concentration of 1-3 mmol / L, wherein the concentration of the heme chloride in the surfactant solution is 0.02-0.06 g / L.

5. A compound nitrogen fertilizer synergist as described in claim 4, characterized in that, The surfactant is one or more of sodium dodecyl sulfate (SDS), Tween 80, and Span S80.

6. The method of using a compound nitrogen fertilizer synergist as described in claim 1, characterized in that, The specific usage method is as follows: Mix the compound nitrogen fertilizer enhancer evenly with the nitrogen fertilizer, and apply the nitrogen fertilizer according to the conventional dosage and timing throughout the entire crop planting process.

7. The method of using a compound nitrogen fertilizer synergist as described in claim 6, characterized in that, The specific method for uniformly mixing the compound nitrogen fertilizer synergist into the nitrogen fertilizer is as follows: First, weigh out the required amounts of γ-polyglutamic acid, earthworm castings, and heme chloride according to the crop area. Dissolve the heme chloride in a surfactant solution with a concentration of 1-3 mmol / L to obtain a concentration of 0.02-0.06 g / L, thus obtaining a heme chloride solution. Dissolve the γ-polyglutamic acid in the heme chloride solution to obtain a mixed solution. Spray the mixed solution evenly onto the continuously stirred earthworm castings, ensuring all three components are thoroughly mixed. After drying at room temperature, add nitrogen fertilizer to the prepared earthworm castings and mix well before use.

8. The method of using a compound nitrogen fertilizer synergist as described in claim 6, characterized in that, The nitrogen fertilizer includes, but is not limited to, urea.

9. The method of using a compound nitrogen fertilizer synergist as described in claim 6, characterized in that, The crops mentioned include, but are not limited to, rice.

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