CN115109588A - A kind of rare earth doped hydrotalcite nano light fertilizer and its preparation method and application - Google Patents

Abstract

A rare earth doped hydrotalcite nanometer optical fertilizer and a preparation method and application thereof. The invention provides a rare earth doped hydrotalcite nanometer optical fertilizer, belonging to the technical field of pesticides and fertilizers. The rare earth doped hydrotalcite nano-optical fertilizer provided by the invention comprises hydrotalcite nanosheets and trivalent europium ions doped in the hydrotalcite nanosheet structure, wherein the mass content of the trivalent europium ions in the rare earth doped hydrotalcite nano-optical fertilizer is 2-30%. Through structural design and optimization, the europium element can show good light conversion performance, can convert ultraviolet light in a natural spectrum into red light which can be efficiently utilized by plants, and improves the crop yield; according to the invention, the hydrotalcite nanosheets are used as the trivalent europium ion structural elements, and the trivalent europium ions are doped in the hydrotalcite nanosheet structure, so that the structure is stable, photobleaching is not easy to occur, and the long-acting stability of the light conversion performance of the light fertilizer can be improved; the two-dimensional confinement effect of the hydrotalcite nanosheets contributes to the improvement of the quantum efficiency of the light conversion material. The invention achieves the aim of accurately matching the growth requirement of crops by controlling the doping proportion of europium.

Description

A kind of rare earth doped hydrotalcite nano light fertilizer and its preparation method and application

technical field

The invention relates to the technical field of pesticides and chemical fertilizers, in particular to a rare earth-doped hydrotalcite nano-light fertilizer and a preparation method and application thereof.

Background technique

With the continuous improvement of the level of farming, crop yields are approaching the limit. Simply increasing the supply of water and fertilizers will not only make it difficult to greatly increase crop yields, but will also face enormous challenges in environmental carrying capacity. Therefore, the development of new means of increasing crop yield that does not depend on the increased supply of water and fertilizer is not only of great significance to ensuring food security, but also helps to reduce non-point source pollution and achieve the goal of sustainable agricultural development.

Among the many methods of increasing yield, the photosynthesis of crops is promoted through the regulation of light environment, and the increase of yield has been widely concerned by scientific researchers. The light environment plays a crucial role in plant growth. Plants can accept different light qualities through photoreceptors, regulating plant growth and development, photosynthesis and material metabolism. The research results show that the blue-violet light region of 400-510nm and the red-orange light region of 610-720nm are the main wavelength ranges that plants absorb visible light. Therefore, through the use of light-converting materials, the spectrum with low crop utilization in the natural spectrum can be selectively converted into blue or red light that can be efficiently used by plants, and the light environment can be optimized. On the basis of increasing the environmental bearing pressure, it can promote crop photosynthesis, improve the utilization rate of water and fertilizer, and increase the amount of carbon sequestration, so as to achieve the purpose of increasing crop yield.

In recent years, widely studied agricultural light-converting materials include quantum dots and rare earth metal complexes. Among them, the materials represented by various quantum dots have the advantages of good monochromaticity and high quantum efficiency, but the quantum dot materials are expensive and difficult to prepare on a large scale; the light conversion materials of rare earth metal complexes are made of europium, samarium and terbium. and other rare earth ions as the center and salicylic acid and phenanthroline as ligands, the ternary complex of salicylic acid and phenanthroline was synthesized, and its composition is, Eu(Hsal) ₃ phen, Sm _1-x Tb _x (TTA) ₃ phen, etc., has a high matching red excitation light, but because its complexing ligands are mostly organic molecules with a cyclic structure, its photostability is poor, prone to photolysis, and it is difficult to achieve long-term growth. Efficient and stable spectral optimization.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a rare earth doped hydrotalcite nano light fertilizer, and the rare earth doped hydrotalcite nano light fertilizer provided by the present invention has long-term and stable light conversion performance.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The present invention provides a rare earth doped hydrotalcite nanometer light fertilizer, comprising hydrotalcite nanosheets and trivalent europium ions doped in the hydrotalcite nanosheet structure, wherein the trivalent europium ions are in the rare earth doped hydrotalcite The mass content of the nano light fertilizer is 2-30%.

Preferably, the chemical composition of the hydrotalcite nanosheets is (M ₁ ) _x (M ₂ ) _1-x (OH) ₂ K _y ·zH ₂ O, wherein M ₁ is Mg ^{2 +} , Ca ²⁺ , Zn ² one or more of ⁺ ;

M ₂ is one or more of Fe ³⁺ , Cr ³⁺ or Al ³⁺ ;

K is an acid ion;

x=0.2～0.5; the value of y keeps the charge of (M ₁ ) _x (M ₂ ) _1-x (OH) ₂ K _y ·zH ₂ O conserved; z=1～20.

Preferably, the chemical composition of the rare earth-doped hydrotalcite nano-photofertilizer is (M ₁ ) _x (EuM ₂ ) _1-x (OH) ₂ K _y ·zH ₂ O.

Preferably, the particle size of the rare earth-doped hydrotalcite nano-optical fertilizer is 20-200 nm.

The present invention provides a method for preparing the above rare earth-doped hydrotalcite nanometer light fertilizer, comprising the following steps:

A precursor solution for preparing hydrotalcite nanosheets is provided, the precursor solution includes a soluble metal salt solution and a strong alkali solution;

The soluble trivalent europium salt, the soluble metal salt solution and the strong alkali solution are mixed to carry out a co-precipitation reaction to obtain the rare earth doped hydrotalcite nanometer light fertilizer.

Preferably, the co-precipitation reaction is carried out under shearing conditions, the shearing rate is 3000-8000 r/min, and the time is 1-5 min.

Preferably, the concentration of the soluble metal salt solution is 0.005-0.5 mol/L, and the concentration of the strong alkali solution is 0.01-1.0 mol/L.

The present invention provides the application of the rare earth-doped hydrotalcite nanometer light fertilizer in promoting crop photosynthesis.

Preferably, the crop is one or more of cucumber, pepper and tobacco.

Preferably, the application method includes the following steps:

Applying the rare earth-doped hydrotalcite nano-optical fertilizer aqueous dispersion on the surface of crop leaves;

The concentration of the rare earth-doped hydrotalcite nano-light fertilizer aqueous dispersion liquid is 0.1-2 g/L;

The applied amount of the rare earth-doped hydrotalcite nano-light fertilizer is 5-20 g/mu.

The present invention provides a rare earth doped hydrotalcite nanometer light fertilizer, comprising hydrotalcite nanosheets and trivalent europium ions doped in the hydrotalcite nanosheet structure, wherein the trivalent europium ions are in the rare earth doped hydrotalcite The mass content of the nano light fertilizer is 2-30%. In the present invention, the europium element has good light conversion performance, and can convert the ultraviolet light in the natural spectrum into red light that can be efficiently used by plants, so as to improve the photosynthesis rate of crops, increase the content of chlorophyll, increase the leaf area, and improve the crops. The purpose of production; hydrotalcite is a layered doublehydroxide (LDH), with a two-dimensional layered structure composed of lamellae and interlayer intercalated molecules, wherein the lamellae are composed of metal atoms and hydroxyl groups according to six. It is composed of the principle of coordination and has a positive charge; the interlayer intercalated molecules are composed of acid ions and have a negative charge. In the present invention, the hydrotalcite nanosheet is used as the trivalent europium ion loading matrix, and the trivalent europium ion is doped into the hydrotalcite nanosheet structure, the structure is stable, photobleaching is not easy to occur, and the long-term stability of the light conversion performance of light fertilizer can be improved. At the same time, the two-dimensional confinement effect of hydrotalcite nanosheets helps to improve the quantum efficiency of light-converting materials. The invention achieves precise matching of crop growth requirements through the control of the europium doping ratio.

Description of drawings

Fig. 1 is the scanning electron microscope image of the rare earth-doped hydrotalcite nano-light fertilizer of embodiment 1 gained;

Fig. 2 is the transmission electron microscope picture of the rare earth-doped hydrotalcite nano-optical fertilizer of embodiment 1 gained;

Fig. 3 is the XRD pattern of the rare earth-doped hydrotalcite nano-light fertilizer obtained in Example 1;

Fig. 4 is the X-ray photoelectron analysis result of the rare earth doped hydrotalcite nano light fertilizer obtained in Example 1;

Fig. 5 is the ICP analysis result of the rare earth-doped hydrotalcite nano light fertilizer obtained in Example 1;

Fig. 6 is the absorption spectrum of the rare earth-doped hydrotalcite nano-light fertilizer obtained in Example 1;

Fig. 7 is the excitation emission spectrum of the rare earth-doped hydrotalcite nano-photofertilizer obtained in Example 1;

8 is the ICP analysis result of the rare earth-doped hydrotalcite nano-photofertilizer obtained in Example 2.

Detailed ways

The present invention provides a rare earth doped hydrotalcite nanometer light fertilizer, comprising hydrotalcite nanosheets and trivalent europium ions doped in the hydrotalcite nanosheet structure, wherein the trivalent europium ions are in the rare earth doped hydrotalcite The mass content of the nano light fertilizer is 2-30%, preferably 4-20%, more preferably 6-15%.

In the present invention, the chemical composition of the hydrotalcite nanosheet is preferably (M ₁ ) _x (M ₂ ) _1-x (OH) ₂ K _y ·zH ₂ O, wherein M ₁ is Mg ²⁺ , Ca ²⁺ , one or more of Zn ²⁺ ;

M ₂ is one or more of Fe ³⁺ , Cr ³⁺ or Al ³⁺ ;

K is an acid ion, preferably one or more of NO ₃ ^- , SO ₄ ^2- , Cl ^- and acetate;

x=0.2～0.5, preferably 0.3～0.4;

The value of y keeps the charge of (M ₁ ) _x (M ₂ ) _1-x (OH) ₂ K _y ·zH ₂ O conserved;

z=1-20, Preferably it is 3-15, More preferably, it is 5-10.

As a specific embodiment of the present invention, the chemical composition of the hydrotalcite nanosheets is Mg _0.45 Al _0.55 (OH) ₂ (NO ₃ ) _0.55 ·5H ₂ O, Ca _0.4 Al _0.6 (OH) ₂ (NO ₃ ) _0.6 · 5H ₂ O.

In the present invention, the chemical composition of the rare earth-doped hydrotalcite nano-photofertilizer is (M ₁ ) _x (EuM ₂ ) _1-x (OH) ₂ K _y ·zH ₂ O, wherein M ₁ , M ₂ , K The optional types of is the same as the above, and will not be repeated here; the value ranges of the x, y, and z are the same as the above, and will not be repeated here.

As a specific embodiment of the present invention, the chemical composition of the rare earth-doped hydrotalcite nano-photofertilizer is Mg _0.45 EuAl _0.55 (OH) ₂ (NO ₃ ) _3.55 5H ₂ O, Ca _0.4 EuAl _0.6 (OH) ₂ (NO ₃ ) _3.6 · 5H ₂ O.

In the present invention, the particle size of the rare earth-doped hydrotalcite nano-light fertilizer is preferably 20-200 nm, more preferably 60-100 nm.

The present invention provides a method for preparing the above rare earth-doped hydrotalcite nanometer light fertilizer, comprising the following steps:

A precursor solution for preparing hydrotalcite nanosheets is provided, the precursor solution includes a soluble metal salt solution and a strong alkali solution;

The soluble trivalent europium salt, the soluble metal salt solution and the strong alkali solution are mixed to carry out a co-precipitation reaction to obtain the rare earth doped hydrotalcite nanometer light fertilizer.

The present invention provides a precursor solution for preparing hydrotalcite nanosheets, and the precursor solution includes a soluble metal salt solution and a strong alkali solution. In the present invention, the soluble metal salt solution preferably includes a soluble divalent metal salt and a soluble trivalent metal salt. In the present invention, the soluble divalent metal salt is preferably one or more of soluble magnesium salt, soluble calcium salt and soluble zinc salt, specifically preferably magnesium chloride, calcium chloride, zinc chloride, magnesium sulfate and acetic acid One or more of zinc.

In the present invention, the soluble trivalent metal salt is preferably one or more of soluble iron salt, soluble chromium salt and soluble aluminum salt, and is preferably one or more of ferric nitrate, chromium nitrate and aluminum nitrate. kind.

In the present invention, the concentration of the soluble metal salt solution is preferably 0.005-0.5 mol/L, more preferably 0.01-0.45 mol/L, and more preferably 0.1-0.4 mol/L. In the present invention, the molar ratio of the soluble divalent metal salt and the soluble trivalent metal salt in the soluble metal salt solution is preferably 1-4:1, more preferably 2-3:1.

In the present invention, the strong alkali solution is preferably a NaOH solution; in the present invention, the concentration of the strong alkali solution is preferably 0.01-1.0 mol/L, more preferably 0.05-0.8 mol/L, further preferably 0.1 ~0.5mol/L.

In the present invention, the soluble trivalent europium salt, the soluble metal salt solution and the strong alkali solution are mixed, and a co-precipitation reaction is carried out to obtain the rare earth-doped hydrotalcite nanometer light fertilizer. In the present invention, the soluble trivalent europium salt is preferably one or more of europium nitrate, europium hydrochloride and europium sulfate.

In the present invention, the molar ratio of the soluble trivalent europium salt to other soluble metal salts is preferably 1:1-4, more preferably 1:2-3.

In the present invention, the co-precipitation reaction is preferably carried out under shearing conditions, and the shearing rate is preferably 3000-8000 r/min, more preferably 4000-6000 r/min, more preferably 5000-6000 r/min. In the present invention, the shearing time is preferably 1-5 min, more preferably 2-4 min. In the present invention, during the shearing process, the metal salt and sodium hydroxide between the two solutions undergo a co-precipitation reaction, and the growth process is controlled by high-speed shearing to make it reach nanometer size.

After the co-precipitation reaction, the present invention preferably performs solid-liquid separation on the obtained co-precipitation reaction liquid, and the solid-liquid separation is preferably centrifugation. In the present invention, the speed of the centrifugation is preferably 3000-8000 rpm, more preferably 4000-6000 rpm, and more preferably 8000 rpm. After the centrifugation, the present invention preferably disperses the obtained solid in water, and repeats the centrifugation until the centrifuged liquid is neutral.

The present invention provides the application of the rare earth-doped hydrotalcite nanometer light fertilizer in promoting crop photosynthesis. In the present invention, the crop is preferably one or more of cucumber, pepper and tobacco.

In the present invention, the application method comprises the following steps:

The rare earth-doped hydrotalcite nano-optical fertilizer aqueous dispersion was applied to the surface of crop leaves.

In the present invention, the concentration of the rare earth-doped hydrotalcite nano-light fertilizer aqueous dispersion is preferably 0.1-2 g/L, more preferably 0.5-1.5 g/L; the applied amount of the rare-earth-doped hydrotalcite nano-light fertilizer It is preferably 5 to 20 g/mu, more preferably 10 to 15 g/mu. In the present invention, the application is preferably a spray application.

The rare earth-doped hydrotalcite nano-light fertilizer provided by the present invention and its preparation method and application are described in detail below with reference to the examples, but they should not be construed as limiting the protection scope of the present invention.

Example 1

A preparation method of rare earth doped hydrotalcite nanometer light fertilizer, comprising the following steps:

(1) Weigh 25.6g of magnesium nitrate, 13.125g of aluminum nitrate, and 6.69g of europium nitrate (molar ratio Mg:Al:Eu=2:0.7:0.3) and dissolve them in 500mL of deionized water to prepare the concentration of 0.2mol/L respectively , 0.07mol/L, 0.03mol/L solution a;

(2) Weigh 12g of sodium hydroxide and dissolve it in 500mL of deionized water to prepare solution b with a concentration of 0.6mol/L;

(3) rapidly mixing solution a and solution b in a colloid mill, maintaining a rotating speed of 3000 r/min, and reacting for 2 min to obtain a rare earth-doped hydrotalcite nanosheet solution;

(4) High-speed centrifugation was performed on the prepared rare earth hydrotalcite nanosheet solution, and the rotation speed of 8000 r/min was maintained, and the reaction was carried out for 10 min. Remove the supernatant, add water to redisperse, and continue centrifugation. The centrifugation operation was repeated 3 times until the last supernatant was neutral to obtain the rare earth-doped hydrotalcite nano-light fertilizer.

Scanning electron microscopy and transmission electron microscopy were performed on the obtained rare earth-doped hydrotalcite nano-optical fertilizers, and the obtained scanning electron microscopy images were shown in FIG. It can be seen from Figures 1 and 2 that the rare earth hydrotalcite nanosheets have a regular hexagonal sheet structure with a uniform particle size distribution of about 60 nm.

The X-ray diffraction analysis was performed on the obtained rare earth-doped hydrotalcite nano-optical fertilizer, and the obtained XRD pattern was shown in FIG. 3 . It can be seen from Figure 3 that the prepared rare earth doped hydrotalcite has a complete crystal structure, ideal crystallinity and high purity, and realizes the effective doping of rare earth elements.

X-ray photoelectron analysis was performed on the obtained rare earth-doped hydrotalcite nano-photonic fertilizer, and the obtained results are shown in FIG. 4 . It can be seen from Figure 4 that in the hydrotalcite structure, the europium element exists in trivalent.

ICP analysis was performed on the obtained rare earth-doped hydrotalcite nano-optical fertilizer, and the obtained results are shown in FIG. 5 . It can be seen that in the hydrotalcite nano-light fertilizer prepared in Example 1, the contents of magnesium, aluminum and europium are 39.2%, 15.34%, and 6.05%, respectively, and the ratio is about 6.48:2.54:1, and the content of europium is about 9.9%.

The luminescence properties of the obtained rare earth-doped hydrotalcite nano-photofertilizer were tested, wherein the absorption spectrum of the rare-earth-doped hydrotalcite nanophotonic fertilizer is shown in FIG. 6 , and the excitation emission spectrum is shown in FIG. 7 . It can be seen from Figure 6 and Figure 7 that the maximum absorption spectrum of rare earth doped hydrotalcite nano-photofertilizer is 394nm, and this wavelength of ultraviolet light will be converted into red light at about 620 and 700nm to promote crop photosynthesis.

Example 2

A preparation method of rare earth doped hydrotalcite nanometer light fertilizer, comprising the following steps:

(1) Weigh 14.16g of calcium nitrate, 3.75g of aluminum nitrate, and 4.46g of europium nitrate (molar ratio Ca:Al:Eu=3:0.5:0.5) and dissolve them in 200mL of deionized water to prepare a concentration of 0.3mol/L respectively , 0.05mol/L, 0.05mol/L solution a;

(2) Weigh 6.4g of sodium hydroxide and dissolve it in 200mL of deionized water to prepare solution b with a concentration of 0.8mol/L;

(3) rapidly mixing solution a and solution b in a colloid mill, maintaining a rotating speed of 5000 r/min, and reacting for 1 min to obtain a hydrotalcite nanosheet solution;

(4) Perform high-speed centrifugation on the prepared hydrotalcite nanosheet solution, maintain a rotating speed of 8000 r/min, and react for 10 min. Remove the supernatant, add water to redisperse, and continue centrifugation. The centrifugation operation is repeated 3 to 5 times until the last supernatant is neutral to obtain the rare earth-doped hydrotalcite nano-light fertilizer.

The XRD, scanning electron microscope, transmission electron microscope, and luminescence performance test results of the rare earth-doped hydrotalcite nano-optical fertilizer obtained in Example 2 are similar to those in Example 1. ICP analysis is carried out on it, as shown in Figure 8, the content of calcium element, aluminum element and europium element is 50.78%, 12.76%, 22.46% respectively, the ratio is about 3.98:1:1.76, and the content of europium element is about 26.1% .

Test Example 1

Taking cucumber as an experimental crop, the effects of the rare earth-doped hydrotalcite nano-light fertilizers prepared in Examples 1 and 2 were evaluated. The test method is as follows: the rare earth doped hydrotalcite nano-light fertilizer is prepared into an aqueous dispersion with a concentration of 1.0g/L, and the europium salt solution (europium nitrate) of the same concentration is used as a control; when the cucumber seedling grows to the third true leaf Spraying was carried out every 3 days, and on the 30th day after application, various physiological indicators of the control group sprayed with nano-light fertilizer and not sprayed with nano-light fertilizer were counted. The results are shown in Table 1.

Table 1 Rare earth doped hydrotalcite nano light fertilizer promotes crop growth results

Further, in order to verify the photostability of the rare earth-doped hydrotalcite nano-light fertilizers, after UV aging for 120 hours, cucumber was used as the experimental crop, and the rare earth-doped hydrotalcite nano-light fertilizers prepared in Examples 1 and 2 were tested. Evaluation. The test method is as follows: the rare earth doped hydrotalcite nano-light fertilizer is prepared into an aqueous dispersion with a concentration of 1.0g/L, and the europium salt solution (europium nitrate) of the same concentration is used as a control; when the cucumber seedling grows to the third true leaf Spraying was carried out every 3 days, and on the 40th day after the application, the physiological indicators of the control group sprayed with nano-light fertilizer and not sprayed with nano-light fertilizer were counted. The results are shown in Table 2.

Table 2 The results of rare earth doped hydrotalcite nano-photofertilizer to promote crop growth after UV irradiation

Fresh weight/g dry weight/g Leaf area/cm² Plant height/cm control group 12.86±1.04 3.28±0.26 456.15±22.55 13.85±2.04 Example 1 14.75±0.61 3.83±0.28 604.97±30.53 16.01±2.49 Example 2 14.13±1.74 3.72±0.98 584.46±47.18 15.67±1.96 Europium salt solution 12.98±0.65 3.40±0.27 472.60±13.37 14.00±1.88

It can be seen from Table 1 and Table 2 that the rare earth-doped hydrotalcite nano-light fertilizer provided by the present invention has long-term and stable light conversion performance.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. The rare earth doped hydrotalcite nanometer optical fertilizer comprises a hydrotalcite nanosheet and trivalent europium ions doped in the hydrotalcite nanosheet structure, wherein the mass content of the trivalent europium ions in the rare earth doped hydrotalcite nanometer optical fertilizer is 2-30%.

2. The rare earth-doped hydrotalcite nanophotonic of claim 1Fertilizer characterized in that the hydrotalcite nanosheets have a chemical composition of (M) ₁ ) _x (M ₂ ) _1-x (OH) ₂ K _y ·zH ₂ O, wherein M ₁ Is Mg ²⁺ 、Ca ²⁺ 、Zn ²⁺ One or more of the above;

M ₂ is Fe ³⁺ 、Cr ³⁺ Or Al ³⁺ One or more of the above;

k is acid radical ion;

x is 0.2-0.5; y is equal to (M) ₁ ) _x (M ₂ ) _1-x (OH) ₂ K _y ·zH ₂ Charge conservation for O; and z is 1-20.

3. The rare earth-doped hydrotalcite nano-optical fertilizer according to claim 2, wherein the chemical composition of the rare earth-doped hydrotalcite nano-optical fertilizer is (M) ₁ ) _x (EuM ₂ ) _1-x (OH) ₂ K _y ·zH ₂ O。

4. The rare earth-doped hydrotalcite nano optical fertilizer according to claim 1, wherein the particle size of the rare earth-doped hydrotalcite nano optical fertilizer is 20-200 nm.

5. The preparation method of the rare earth doped hydrotalcite nano optical fertilizer according to any one of claims 1 to 4, comprising the following steps:

providing a precursor solution for preparing the hydrotalcite nano-sheets, wherein the precursor solution comprises a soluble metal salt solution and a strong base solution;

mixing soluble trivalent europium salt, soluble metal salt solution and strong base solution, and carrying out coprecipitation reaction to obtain the rare earth doped hydrotalcite nano optical fertilizer.

6. The preparation method according to claim 5, wherein the coprecipitation reaction is carried out under a shearing condition, and the shearing rate is 3000-8000 r/min and the time is 1-5 min.

7. The method according to claim 5, wherein the concentration of the soluble metal salt solution is 0.005 to 0.5mol/L, and the concentration of the alkali solution is 0.01 to 1.0 mol/L.

8. Application of the rare earth doped hydrotalcite nano optical fertilizer according to any one of claims 1 to 4 or the rare earth doped hydrotalcite nano optical fertilizer prepared by the preparation method according to any one of claims 5 to 7 in promoting crop photosynthesis.

9. The use according to claim 8, wherein the crop is one or more of cucumber, pepper and tobacco.

10. The application according to claim 8, characterized in that the application method comprises the following steps:

applying the rare earth doped hydrotalcite nano optical fertilizer water dispersion liquid to the surface of a crop leaf;

the concentration of the rare earth doped hydrotalcite nanometer optical fertilizer water dispersion liquid is 0.1-2 g/L;

the application amount of the rare earth doped hydrotalcite nanometer optical fertilizer is 5-20 g/mu.

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