Soil conditioner with passivated fluorine ion biological activity as well as preparation method and application of soil conditioner

Abstract

The invention discloses a soil conditioner with passivated fluorine ion biological activity and a preparation method and application thereof, and the soil conditioner comprises the following components in percentage by mass: 20-60% of celestite powder, 15-30% of spodumene powder, 20-60% of barite powder and 5-15% of manganese ore powder. The designed soil conditioner is applied to tea garden soil in winter or spring, and the fluorine content in tea tree leaves can be remarkably reduced. The soil conditioner disclosed by the invention contains strontium (Sr), lithium (Li), barium (Ba), manganese (Mn), calcium (Ca), magnesium (Mg) and other heavy metals, has very strong reducibility, and can form indissolvable compounds, such as SrF2, LiF, BaF2, MnF2, CaF2, MgF2 and the like, with fluorine ions, so that the content of soluble fluorine in plough layer soil can be effectively reduced, absorption of the fluorine ions in the soil by tea trees can be inhibited, and the content of fluorine in tea tree leaves can be remarkably reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fluorine reduction, and relates to the field of fluorine reduction of tea garden fresh leaf raw materials, and more particularly to a soil conditioner for passivating fluorine ion biological activity and a preparation method thereof, and application of the soil conditioner. BACKGROUND

[0002] Fluorine (F) is one of the elements widely distributed in nature. In some tea producing areas in China, such as Guizhou, Sichuan, Yunnan and Hunan, because the soil and groundwater contain high concentrations of fluorides, part of the tea tree branches and leaves accumulate high concentrations of fluorine, which exceeds the national limit standard (300 mg / kg). Long-term consumption of fluorine-contaminated tea will have a certain impact on human health. The removal of fluorine in tea mainly relies on processing technology and process, while the method of reducing the fluorine content in tea through fertilization and other cultivation measures is still in the exploratory stage.

[0003] Fluorine is the most active non-metallic element and the strongest single oxidizing agent. At room temperature, fluorine can react with most element single substances, and only a few heavy metals can form compounds that are difficult to dissolve in water.

[0004] Therefore, how to provide a soil conditioner capable of passivating the biological activity of fluorine ions to reduce the fluorine content in crops is a technical problem that those skilled in the art urgently need to solve. SUMMARY

[0005] The application provides a soil conditioner for passivating the biological activity of fluorine ions and a preparation method and application thereof. The total fluorine content in soil has weak correlation with the fluorine content in tea, while the soluble fluorine (including water-soluble and salt-soluble two categories) in soil has high positive correlation with the fluorine content in tea. The application utilizes the reducing properties of strontium (Sr) in celestite, lithium (Li) in spodumene, barium (Ba) in barite, manganese (Mn) in manganese ore and calcium (Ca), magnesium (Mg) in these ores to form compounds with fluorine ions, such as SrF2, LiF, BaF2, MnF2, CaF2, MgF2 and the like, wherein the binding force of Sr and Ba with fluorine ions is obviously greater than that of other metal ions. Therefore, after the four kinds of ore powders are mixed in a specific proportion, not only the reaction surface area and active sites can be increased, but also a microenvironment more conducive to capturing fluorine ions can be formed through synergistic effect, solubility product effect and pH buffering effect, so that fluorine ions have more opportunities to contact and react with metal ions, thereby significantly improving the overall efficiency of the conversion of fluorine ions to insoluble state, achieving the purpose of efficiently passivating soil fluorine ions, and effectively reducing the content of soluble fluorine in rhizosphere soil, inhibiting the process of fluorine ion transport from soil to tea tree roots, and significantly reducing the fluorine content in tea.

[0006] In order to achieve the above-mentioned purpose, one of the purposes of the present application provides a soil conditioner for passivating the biological activity of fluoride ions, comprising the following raw materials in mass percentage: celestite powder 20-60%, spodumene powder 15-30%, barite powder 20-60%, and manganese ore powder 5-15%.

[0007] Preferably, the soil conditioner comprises the following raw materials in mass percentage: celestite powder 30%, spodumene powder 20%, barite powder 40%, and manganese ore powder 10%.

[0008] Preferably, the celestite powder, the spodumene powder, the barite powder, and the manganese ore powder are all passed through a 100-mesh sieve.

[0009] The second purpose of the present application provides a preparation method of the above-mentioned soil conditioner, which comprises the following steps: taking each raw material in mass percentage, mixing and stirring uniformly to obtain the soil conditioner.

[0010] The third purpose of the present application provides an application of the above-mentioned soil conditioner or the soil conditioner obtained by the above-mentioned preparation method in reducing the soluble fluoride content in soil.

[0011] The fourth purpose of the present application provides an application of the above-mentioned soil conditioner or the soil conditioner obtained by the above-mentioned preparation method in reducing the soluble fluoride content in the plough layer soil of tea trees.

[0012] The fifth purpose of the present application provides an application of the above-mentioned soil conditioner or the soil conditioner obtained by the above-mentioned preparation method in reducing the fluoride content in tea leaves.

[0013] The sixth purpose of the present application provides an application method of the soil conditioner for passivating the biological activity of fluoride ions, which comprises the following steps: opening a deep trench in a tea tree plot, applying the above-mentioned soil conditioner or the soil conditioner obtained by the above-mentioned preparation method into the trench, and covering the trench with soil, and the application amount is 750-1500 kg per hectare.

[0014] Preferably, the soil conditioner is applied in winter before the branches and leaves of tea trees sprout, and the optimal application time is from January 1 to February 25.

[0015] Preferably, the soil conditioner is applied in early spring after the tender buds of tea trees are picked, and the optimal application time is from March 20 to April 30.

[0016] In summary, the present application at least has the following technical effects: 1) The present application can form compounds with strong reducibility, such as SrF2, LiF, BaF2, MnF2, CaF2, and MgF2, by adding trace elements such as strontium, lithium, barium, manganese, calcium, and magnesium, so as to reduce the mobility of fluoride ions in soil and the biological activity thereof, and significantly reduce the fluoride content in tea leaves. 2) The soil conditioner designed by the application has simple and easy-to-operate formula and preparation method and is environment-friendly; 3) The soil conditioner designed by the application forms an isolation layer in the rhizosphere of tea trees, can convert soluble fluoride ions into insoluble fluorides on site, thereby inhibiting the process of fluoride ions in the soil into the root system of tea trees; before the sprouting of tea tree branches and leaves or after the picking of tea tree sprouts, deep application by trenching in the tea tree ridge can effectively promote the growth of new roots and is not affected by the characteristics of varieties and growth seasons, and has the advantages of simple operation, easy popularization and low cost. DETAILED DESCRIPTION

[0017] The preferred embodiments of the application will be described in detail below with reference to the examples. It should be understood that the following examples are given only for the purpose of illustration and are not intended to limit the scope of the application. Those skilled in the art can make various modifications and replacements to the application without departing from the spirit and principles of the application.

[0018] In the following examples, the experimental methods used are conventional methods unless otherwise specified.

[0019] In the following examples, the materials, reagents, etc. used are commercially available unless otherwise specified. Example 1

[0020] The embodiment discloses a soil conditioner for passivating fluoride ion activity in tea gardens, wherein the percentages are by mass: lapis lazuli powder 20-60%, spodumene powder 15-30%, barite powder 20-60%, and manganese ore powder 5-15%.

[0021] To further optimize the above technical solution, the percentages are by mass: lapis lazuli powder 30%, spodumene powder 20%, barite powder 40%, and manganese ore powder 10%.

[0022] The application method of the above soil conditioner is also disclosed, comprising the following steps: S1: lapis lazuli powder, spodumene powder, barite powder, and manganese ore powder that have passed through a 100-mesh sieve are prepared according to the above mass percentages, mixed and stirred uniformly, and then a soil conditioner is prepared; S2: a 20-40 cm deep trench is opened in the tea tree ridge, the fluoride reduction special fertilizer is applied into the trench, and then covered with soil, with a dosage of 750-1500 kg per hectare each time.

[0023] To further optimize the above technical solution, in step S2, when it is winter before the sprouting of tea tree branches and leaves, a 20-40 cm deep trench is opened in the tea tree ridge, the fluoride reduction special fertilizer is applied into the trench, and then covered with soil, with a dosage of 750-1500 kg per hectare each time.

[0024] In order to further optimize the above technical scheme, in step S2, when it is early spring after the tea bud picking, a deep ditch of 20-40 cm is opened in the tea row, the fluorine reduction special fertilizer is applied into the ditch and covered with soil, and the dosage is 750-1500 kg per hectare each time. Example 2

[0025] Winter fluorine reduction test: In early January 2024, in the black tea production base of Hunan Province, a mountain tea garden with soil fluorine content of 420 mg / kg was selected for the test. The test field was divided into 36 plots, of which 32 plots were applied with soil conditioner, and 4 plots were blank controls without soil conditioner. Each plot area is 40 m 2 , which is composed of 2 rows of tea trees, the tea row width is 1.5 meters, and the row spacing is 0.5 meters. The control area and the treatment area are randomly arranged, with 4 repetitions. The soil conditioner applied in the treatment plot is divided into four types, the composition of soil conditioner A is: 30% celestite powder, 20% spodumene powder, 40% barite powder and 10% manganese ore powder; The composition of soil conditioner B is: 20% celestite powder, 15% spodumene powder, 60% barite powder and 5% manganese ore powder; The composition of soil conditioner C is: 60% celestite powder, 15% spodumene powder, 20% barite powder and 5% manganese ore powder; The composition of soil conditioner D is: 25% celestite powder, 30% spodumene powder, 30% barite powder and 15% manganese ore powder.

[0026] The dosage of the same soil conditioner is divided into two gradients of 750 kg / ha and 1500 kg / ha.

[0027] A deep ditch of 20-40 cm is opened on both sides of the tea row, and the soil conditioner is applied into the ditch and covered with soil. By the middle and late of June, when 6-9 leaves grow on the new branches of tea trees, mixed harvesting is carried out, and after drying, the tea leaves are ground into powder. The fluorine content in tea leaves is detected according to the national agricultural industry standard (NY / T838-2004). The results show that the fluorine content of tea leaves harvested in the 4 control plots without soil conditioner is 571.8 mg / kg on average, which is significantly higher than the national fluorine limit standard; the fluorine content of tea leaves harvested in the 32 treatment plots with soil conditioner in winter is 278.6 mg / kg on average, which is lower than the national fluorine limit standard. Compared with the control, after applying soil conditioners A, B, C and D in winter, the fluorine content in tea leaves harvested in summer decreases by 50.5%-54.1%, 51.2%-53.8%, 48.0%-51.5% and 49.8%-51.5% respectively (as shown in Table 1).

[0028] High-dose soil conditioner (1500 kg / ha) reduced fluoride content in tea leaves by approximately 2%–4% compared to low-dose soil conditioner (750 kg / ha). Treatment A2 (1500 kg / ha) reduced fluoride content in tea leaves to 262.5 mg / kg, representing the largest reduction.

[0029] While harvesting tea leaves, soil samples were taken from the 0-25 cm topsoil layer between tea bushes in each plot. Five samples were taken from each plot. The samples were mixed, air-dried, and after removing plant roots and stones, they were ground and passed through a 2 mm sieve. Then, the fluoride content of various forms in the soil was determined according to the following steps: Accurately weigh 0.2000 g of soil sample and melt it with sodium hydroxide. Dissolve the melt in water, adjust the pH of the test solution with bromocresol purple indicator to make the cations insoluble, and determine the fluoride content in the soil using a fluoride ion selective electrode. Accurately weigh 0.2000 g of soil sample and extract water-soluble fluoride (Ws-F) using hot water at 70℃; Accurately weigh 0.2000 g of soil sample and extract exchangeable fluorine (Ex-F) using 1M MgCl2. (4) Accurately weigh 0.2000 g of soil sample and extract organically bound fluorine (OM-F) with 0.04 M NH2OH·HCl and 20.0% CH3COOH; Accurately weigh 0.2000 g of soil sample and extract Fe / Mn oxide-bound fluorine (Fe / Mn-F) using 0.02 M HNO3, 30.0% hydrogen peroxide, and 3.2 M NH4AC.

[0030] The sum of water-soluble (Ws-F) and exchangeable (Ex-F) fluoride contents in soil constitutes the soluble fluoride content, while the sum of organically bound (OM-F), Fe / Mn oxide-bound (Fe / Mn-F), and residual fluoride contents constitutes the insoluble fluoride content. The results showed that in the four control plots without soil conditioner application, the average soluble fluoride content in the topsoil was 2.67 mg / kg, while in the 32 treatment plots with winter soil conditioner application, the soluble fluoride content in the topsoil decreased to 2.05 mg / kg. Compared to the control, winter application of soil conditioner resulted in a 23.2% decrease in fluoride content in the topsoil during the rapid growth period of tea plants in summer. This indicates that soil conditioner effectively reduced the biological activity of fluoride ions, thereby inhibiting the process of fluoride entering the root system from the soil. Example 3

[0031] Winter Fluoride Reduction Experiment: In early January 2024, an experiment was conducted in a hilly tea garden with a soil fluoride content of 610 mg / kg in a dark tea production base in Hunan Province. The field experiment design was identical to that of Example 2, with 32 plots treated with soil conditioner and 4 plots serving as blank controls without soil conditioner application. The control and experimental plots were randomly arranged and replicated four times. Tea shoots were harvested in mid-to-late June when they had 6-9 leaves on their new branches. After air-drying, the tea leaves were ground into powder, and the fluoride content was tested according to the Chinese agricultural industry standard (NY / T838-2004). The results showed that the average fluoride content of the tea harvested from the four control plots without soil conditioner application was 620.3 mg / kg, more than twice the national fluoride limit. The average fluoride content of the tea harvested from the 32 treatment plots with winter soil conditioner application was 294.4 mg / kg, lower than the national fluoride limit. Compared with the control, the fluoride content in tea leaves harvested in summer decreased by 51.9%~52.6%, 51.7%~52.0%, 52.1%~53.7%, and 52.1%~54.1% respectively after applying soil conditioners A, B, C, and D in winter (as shown in Table 1).

[0032] The difference in fluoride reduction in tea leaves between high-dose soil conditioner (1500 kg / ha) and low-dose soil conditioner (750 kg / ha) was not significant.

[0033] Applying 1500 kg / ha of soil conditioner D (treatment D2) reduced the fluoride content in tea leaves to 284.9 mg / kg, making it the treatment with the most significant fluoride reduction effect.

[0034] During tea harvesting, soil samples were taken from the 0-25 cm topsoil layer between tea plantation beds in each plot, with five samples taken from each plot. The samples were mixed, air-dried, and after removing plant roots and stones, ground finely and passed through a 2 mm sieve. The soluble and insoluble fluoride contents in the soil were then determined according to the steps described in Example 2. The results showed that in the four control plots without soil conditioner application, the average soluble fluoride content in the topsoil was 2.93 mg / kg, while in the 32 treatment plots with winter soil conditioner application, the soluble fluoride content in the topsoil decreased to 2.17 mg / kg. Compared to the control, the fluoride content in the topsoil decreased by 25.9% during the rapid growth period of tea plants in summer after winter soil conditioner application. This indicates that the soil conditioner effectively reduced the biological activity of fluoride ions, thereby inhibiting the process of fluoride entering the root system from the soil. Example 4

[0035] Spring Fluoride Reduction Experiment: In early April 2024, an experiment was conducted in a mountain tea garden in a Hunan Province black tea production base where the soil fluoride content was 420 mg / kg. The experimental field was divided into 36 plots, each with an area of ​​40 m². 2The field trial design was identical to Example 2, with 32 plots treated with soil conditioner and 4 plots serving as blank controls without soil conditioner. The control and experimental plots were randomly arranged and replicated four times. Tea shoots were harvested in mid-to-late June when they had 6-9 leaves on their new branches. After air-drying, the tea leaves were ground into powder, and the fluoride content was tested according to the Chinese agricultural industry standard (NY / T838-2004). The results showed that the average fluoride content of the tea harvested from the four control plots without soil conditioner was 558.9 mg / kg, significantly higher than the national fluoride limit. The average fluoride content of the tea harvested from the 32 treatment plots with spring soil conditioner application was 282.7 mg / kg, lower than the national fluoride limit. Compared with the control, the fluoride content in tea leaves harvested in summer decreased by 48.3%~50.2%, 47.8%~51.0%, 48.4%~50.8%, and 48.2%~50.7% respectively after applying soil conditioners A, B, C, and D in spring (as shown in Table 2).

[0036] High-dose soil conditioner (1500 kg / ha) reduced fluoride levels in tea leaves by 2% to 3% compared to low-dose soil conditioner (750 kg / ha).

[0037] Applying 1500 kg / ha of soil conditioner B (treatment B2) reduced the fluoride content in tea leaves to 273.9 mg / kg, making it the treatment with the most significant fluoride reduction effect.

[0038] During tea harvesting, soil samples were taken from the 0-25 cm topsoil layer between tea plantation beds in each plot, with five samples taken from each plot. The samples were mixed, air-dried, and after removing plant roots and stones, ground finely and passed through a 2 mm sieve. The soluble and insoluble fluoride contents in the soil were then determined according to the steps described in Example 2. The results showed that in the four control plots without soil conditioner application, the average soluble fluoride content in the topsoil was 2.63 mg / kg, while in the 32 treatment plots with winter soil conditioner application, the soluble fluoride content in the topsoil decreased to 2.01 mg / kg. Compared to the control, the fluoride content in the topsoil decreased by 23.6% during the rapid growth period of tea plants in summer after winter soil conditioner application. This indicates that the soil conditioner effectively reduced the biological activity of fluoride ions, thereby inhibiting the process of fluoride entering the root system from the soil. Example 5

[0039] Spring Fluoride Reduction Experiment: In early April 2024, a field experiment was conducted in a mountain tea garden with a soil fluoride content of 610 mg / kg in a black tea production base in Hunan Province. The field experiment design was identical to that of Example 2, with 32 plots treated with soil conditioner and 4 plots serving as blank controls without soil conditioner application. The control and experimental plots were randomly arranged and replicated four times. Tea shoots were harvested in mid-to-late June when they had 6-9 leaves on their new branches. After air-drying, the tea leaves were ground into powder, and the fluoride content was tested according to the Chinese agricultural industry standard (NY / T838-2004). The results showed that the average fluoride content of the tea harvested from the four control plots without soil conditioner application was 616.4 mg / kg, significantly higher than the national fluoride limit. The average fluoride content of the tea harvested from the 32 treatment plots with spring soil conditioner application was 292.7 mg / kg, lower than the national fluoride limit. Compared with the control, the fluoride content in tea leaves harvested in summer decreased by 51.7%~52.7%, 51.4%~54.6%, 51.8%~53.3%, and 52.2%~52.5% respectively after applying soil conditioners A, B, C, and D in spring (as shown in Table 2).

[0040] Applying 1500 kg / ha of soil conditioner B (treatment B2) reduced the fluoride content in tea leaves to 279.8 mg / kg, making it the treatment with the most significant fluoride reduction effect.

[0041] During tea harvesting, soil samples were taken from the 0-25 cm topsoil layer between tea plantation beds in each plot. Five samples were collected from each plot, mixed, and air-dried. After removing plant roots and stones, the samples were ground and passed through a 2 mm sieve. The soluble and insoluble fluoride contents in the soil were then determined according to the steps in Example 2. The results showed that in the four control plots without soil conditioner application, the average soluble fluoride content in the topsoil was 2.98 mg / kg, while in the 32 treatment plots with winter soil conditioner application, the average soluble fluoride content in the topsoil was 2.13 mg / kg. Compared with the control, the fluoride content in the topsoil decreased by 28.5% during the rapid growth period of tea plants in summer after winter soil conditioner application. This indicates that the soil conditioner effectively reduced the biological activity of fluoride ions, thereby inhibiting the process of fluoride entering the root system from the soil.

[0042] Table 1. Effects of winter application of soil conditioner formulation and dosage on fluoride content in tea leaves.

[0043] Note: The formula for calculating the fluoride reduction rate (%) is: [(CK-A) / CK]×100%, where CK is the fluoride content of tea leaves in the control area and A is the fluoride content of tea leaves in the treatment area.

[0044] Table 2. Effects of Spring-Applied Soil Conditioner Formulation and Dosage on Fluorine Content in Tea Leaves

[0045] Note: The formula for calculating the fluoride reduction rate (%) is: [(CK-A) / CK]×100%, where CK is the fluoride content of tea leaves in the control area and A is the fluoride content of tea leaves in the treatment area.

[0046] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0047] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A soil conditioner that passivates fluoride ion activity, characterized in that, The raw materials include the following percentages by weight: celestite powder 20-60%, spodumene powder 15-30%, barite powder 20-60%, and manganese ore powder 5-15%.

2. The soil conditioner with passivated fluoride ion activity according to claim 1, characterized in that, The raw materials include the following percentages by weight: 30% celestite powder, 20% spodumene powder, 40% barite powder, and 10% manganese ore powder.

3. A soil conditioner with passivated fluoride ion activity according to claim 1 or 2, characterized in that, The celestite powder, spodumene powder, barite powder, and manganese ore powder all passed through a 100-mesh sieve.

4. A method for preparing a soil conditioner with passivated fluoride ion activity, characterized in that, Using the soil conditioner described in claim 3 as a raw material, each raw material is weighed by mass percentage, and the mixture is stirred evenly to obtain the soil conditioner.

5. The application of the soil conditioner according to claim 3 or the soil conditioner obtained by the preparation method according to claim 4 in reducing the soluble fluoride content in soil.

6. The application of the soil conditioner according to claim 3 or the soil conditioner obtained by the preparation method according to claim 4 in reducing the soluble fluoride content in the topsoil of tea trees.

7. The application of the soil conditioner according to claim 3 or the soil conditioner obtained by the preparation method according to claim 4 in reducing the fluoride content of tea.

8. A method for applying a soil conditioner with passivated fluoride ion activity, characterized in that, Dig deep trenches between tea tree beds, apply the soil conditioner described in claim 3 or the soil conditioner prepared by the method of claim 4 into the trenches, and then cover with soil. The application rate is 750-1500 kg per hectare.

9. The application method according to claim 8, characterized in that, The soil conditioner is applied during the winter before the tea tree branches and leaves sprout, with the optimal application time being from January 1st to February 25th.

10. The application method according to claim 8, characterized in that, The soil conditioner is to be applied in early spring after the tea buds are picked, with the optimal application time being from March 20 to April 30.

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