CN116751090A - PH responsive controlled-release iron fertilizer and preparation method thereof - Google Patents

PH responsive controlled-release iron fertilizer and preparation method thereof Download PDF

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CN116751090A
CN116751090A CN202310803042.8A CN202310803042A CN116751090A CN 116751090 A CN116751090 A CN 116751090A CN 202310803042 A CN202310803042 A CN 202310803042A CN 116751090 A CN116751090 A CN 116751090A
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iron
chitosan
fertilizer
iron fertilizer
parts
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崔振岭
刘皓夫
高子登
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China Agricultural University
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China Agricultural University
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Abstract

The invention discloses a pH response type controlled release iron fertilizer and a preparation method thereof. The pH response type controlled release iron fertilizer provided by the invention comprises an adsorption carrier and an iron-containing compound; the adsorption carrier is prepared from the following raw materials: 100-200 parts of organic polymer material, 50-250 parts of organic acid, 5-200 parts of cross-linking agent and 100-200 parts of colloid stabilizer. The pH response type controlled release iron fertilizer can control nutrient release according to the pH environmental change of soil, and crops can quickly absorb nutrients in acid-base stress soil to increase the stress resistance level of the crops in the seedling stage.

Description

PH responsive controlled-release iron fertilizer and preparation method thereof
Technical Field
The invention relates to the field of fertilizers, in particular to a pH response type controlled release iron fertilizer and a preparation method thereof.
Background
Iron is the major redox system in plants and has been found to play important roles in plant growth and metabolism, such as chlorophyll synthesis, respiration, nitrogen fixation, proliferation and shelf life extension. Iron deficiency is a common micronutrient imbalance in many crops, especially those growing in calcareous and high pH soil areas. In general, soil application of inorganic iron sources (such as ferrous sulfate) is ineffective in treating such micronutrient deficiencies because under these soil conditions, iron rapidly converts to an unusable, insoluble form, such as ferric oxide; but hydroxide ions are formed especially in alkaline and calcareous soils by carbonate and bicarbonate ions, which can only be dissolved in strong acids (pH 2.25). The iron availability of plants is reduced by a factor of 1000 for every one unit increase in soil pH. Thus, there is a need for a coating or carrier that can regulate the release of elemental iron based on the different pH environments of the soil.
For micronutrients, the addition of a nutrient source to the coating of fertilizer granules is a well known method. However, the coating materials of conventional fertilizers are mostly petroleum-based polymers, which delay the release of nutrients and prevent the loss of nutrients. However, a major disadvantage with this coating method is that the resistance of the synthetic polymer to the action of biological systems leads to the accumulation of plastic residues in the soil after the fertilization process. Based on the above limitations, biodegradable polymers are often tested as plastic substitutes for such applications. The Chinese patent application (CN 103626598A) applied by the Shidanli fertilizer stock, inc. Zhou Li, etc. discloses a functional chitosan biological slow-release fertilizer which is prepared by coating a chitosan coating agent on core fertilizer particles, thereby remarkably reducing the cost of the coated slow-release fertilizer; the membrane material is produced without using organic solvent, has no pollution, is easy to degrade in soil, has no residue, and can obviously improve the soil. The Chinese patent (CN 115093855A) of Beijing Jinrong agricultural technology Co.Ltd Liu Hanfa discloses a multi-element soil conditioner, which is prepared by mixing chitosan, polylactic acid, eutrophic polysaccharide and genipin, and can realize the immobilization of nutrition and play a role in releasing nutrient elements for a long time. The Chinese patent (CN 105532280A) applied by Guangxi scientific and technical institute Qian Shanqin discloses a method for promoting the growth of green vegetables, which takes genipin as a yield increasing agent, improves the accumulation of soluble sugar and protein by promoting the chlorophyll content and the light energy conversion efficiency of the chlorophyll of the green vegetables, and promotes the growth and the yield improvement of the green vegetables. However, these conventional methods have limited micronutrients that can be carried, and plants still lack micronutrients due to the inability to address the soil release environment.
For this reason, the prior art began to demonstrate the use of biobased carriers to adsorb micronutrients for direct application as a trace element fertilizer to the soil. However, most of research results related to bio-based carriers are concentrated on drug delivery or pesticide preparations at present, and lack of related research on trace element fertilizers, so that development of a pH-responsive slow/controlled release iron fertilizer is necessary.
Disclosure of Invention
The pH responsive controlled-release iron fertilizer can control nutrient release according to the pH environmental change of soil, and crops can quickly absorb nutrients in acid-base stress soil to increase the stress resistance level of the crops in the seedling stage.
The invention firstly provides a pH response type controlled release iron fertilizer, which comprises an adsorption carrier and an iron-containing compound;
the adsorption carrier is prepared from the following raw materials: 100-200 parts of organic polymer material, 50-250 parts of organic acid, 5-200 parts of cross-linking agent and 100-200 parts of colloid stabilizer.
In the pH response type controlled release iron fertilizer, the loading amount of the iron-containing compound is 150-350 mg/g; specifically, the loading amount is 250-330 mg/g, and the loading amount is calculated by the mass of iron in the iron-containing compound.
The iron-containing compound is flocculently adsorbed around the hole wall of the adsorption carrier.
In the pH response type controlled release iron fertilizer, the organic high polymer material is chitosan and/or chitosan salt;
specifically, the chitosan and chitosan salt are at least one selected from chitosan, N-carboxymethyl chitosan, chitosan and maleic acid chitosan.
In the pH responsive controlled release iron fertilizer, the organic acid is at least one selected from acetic acid, malic acid, citric acid, salicylic acid, methanesulfonic acid and ascorbic acid;
the cross-linking agent is at least one selected from glutaraldehyde, formaldehyde, succinaldehyde, genipin, sodium tripolyphosphate, polyalcohol, N-dimethyl acetyl, dialdehyde end group PEO, toluene diisocyanate, diphenylmethane diisocyanate and epichlorohydrin;
the iron-containing compound is at least one selected from ferrous sulfate, ferric sulfate, ferrous chloride, ferric chloride, ferrous acetate, ferrous carbonate, ferrous nitrate and ferrous sulfate heptahydrate;
the colloid stabilizer is at least one of glycerol, ethylene glycol, propylene glycol, isoprene glycol, hexylene glycol, polyethylene glycol, polyvinyl alcohol and pentaerythritol.
In the pH response type controlled release iron fertilizer, the cross-linking agent is any one of the following components:
1) When the cross-linking agent is genipin, the cross-linking agent is 8-40 parts by mass, 8 parts by mass, 12 parts by mass, 16 parts by mass, 20 parts by mass or 40 parts by mass;
2) When the cross-linking agent is sodium tripolyphosphate, the cross-linking agent is 20-160 parts by mass, 20 parts by mass, 40 parts by mass, 80 parts by mass, 120 parts by mass or 160 parts by mass;
3) When the cross-linking agent is glutaraldehyde, the cross-linking agent is 20-160 parts by mass, 20 parts by mass, 40 parts by mass, 80 parts by mass, 120 parts by mass or 160 parts by mass;
4) When the cross-linking agent is succinaldehyde, the cross-linking agent is 20-160 parts by mass, 20 parts by mass, 40 parts by mass, 80 parts by mass, 120 parts by mass or 160 parts by mass.
In the pH response type controlled release iron fertilizer, the raw materials of the adsorption carrier also comprise water;
the adsorption carrier is aerogel.
The specific surface area of the adsorption carrier is 0.5-50 m 2 Per g, it may be specifically 8 to 23m 2 The effective pore volume per gram is 0.003-0.5 cm 3 Per g, it may be specifically 0.03 to 0.08cm 3 /g。
In the pH response type controlled release iron fertilizer, the adsorption carrier is prepared by a method comprising the following steps:
1) Mixing the organic polymer material, organic acid and water to form a water phase a;
2) Mixing the colloidal stabilizer with the aqueous phase a to form an aqueous phase b;
3) Mixing the aqueous phase b with a cross-linking agent solution to prepare wet gel;
4) And aging, freezing and drying the wet gel to obtain the adsorption carrier.
In the step 1), the mass ratio of the organic polymer material to the water is 1:25-1:50;
in the step 3), the mass ratio of the cross-linking agent to the water in the cross-linking agent solution is 1:10-1:100; specifically, the ratio may be 1:50 to 1:100.
In the step 4), the aging is carried out for 24 to 48 hours at room temperature; specifically, the time can be 24 hours;
the freezing is carried out for 12-24 hours at the temperature of minus 20-minus 50 ℃, and can be specifically carried out for 12 hours at the temperature of minus 20 ℃.
In the preparation method of the adsorption carrier, the wet gel is aged after being washed; specifically, the washing is performed by using ethanol and water.
The invention also provides a preparation method of the pH response type controlled release iron fertilizer, which comprises the following steps: preparing the iron-containing compound into an iron-containing compound aqueous solution, immersing the adsorption carrier in the iron-containing compound aqueous solution, and taking out the adsorption carrier to obtain the pH-responsive controlled-release iron fertilizer.
In the preparation method, the mass ratio of the iron-containing compound to the water is 1:5-1:15; specifically, the ratio of the raw materials can be 1:8-1:15, and more specifically, the ratio of the raw materials can be 1:10-1:13;
the mass ratio of the adsorption carrier to the iron-containing compound is 1:25-100;
the adsorption carrier is immersed in the iron-containing compound aqueous solution to be stirred, the stirring speed is 200-400 rpm, and the stirring time is 12-24 h.
In the preparation method, the preparation method further comprises the steps of washing the adsorption carrier with water and drying after impregnation.
The room temperature in the present invention is well known to those skilled in the art and is generally 15 to 35 ℃.
According to the invention, the nutrient elements and the organic acid are complexed by the network structure formed by chemical crosslinking of chitosan and the crosslinking agent, the ferrous ions are chelated by the network structure of chitosan aerogel, and the stress resistance of crops in acid-base stress environment is enhanced by releasing the pH responsive controlled release iron element of the release carrier. The organic acid in the adsorption carrier material can promote activation of rhizosphere microenvironment, protect released ferrous ions, prevent the ferrous ions from being quickly fixed and oxidized by soil, and enable plants to fully absorb iron elements; meanwhile, the organic acid can activate nutrient elements such as phosphorus in soil, and the absorption of crop root systems to the nutrient elements is improved. The chitosan aerogel can generate different glycoside substances after being degraded in soil, which is beneficial to stress resistance, rooting, budding, chlorophyll synthesis, biomass accumulation and the like of plants.
Compared with the traditional iron fertilizer, the invention carries out crosslinking modification on the chitosan polymer material, and uses the chitosan polymer material as an adsorption carrier to bear trace elements to prepare the pH response type controlled release iron fertilizer, and has the following advantages:
1) The release carrier is a green and environment-friendly natural organic matter, and the material can be completely biodegraded, so that the pollution to soil and the environment is avoided;
2) The pH sensitive material is added, the chitosan-based carrier is dissolved under an acidic condition, and a coordination bond with iron is broken under an alkaline condition, so that the carrier is released to control and release nutrients according to different soil pH environments, and crops can quickly absorb the nutrients in acid-base stress soil to increase the stress resistance level of the crops in the seedling stage;
3) The adsorption carrier material of the invention generates various glycosides after degradation, and has promotion effects on plant rooting, sprouting, biomass accumulation, chlorophyll synthesis and crop stress resistance;
4) The adsorption carrier material of the invention has the advantages that the activation of rhizosphere microenvironment can be promoted by the organic acid with proper proportion, ferrous ions are protected to the maximum extent, and the rapid fixation and oxidation of the rhizosphere microenvironment by soil are prevented, so that plants can fully absorb iron elements; meanwhile, the organic acid can activate nutrient elements such as phosphorus in the soil, and the absorption of crop root systems to the nutrient elements is improved;
5) The multi-effect controlled release linkage design of the fertilizer is particularly suitable for promoting root and strengthening seedlings of crops in a adversity environment in the seedling stage, so that yield and production are ensured.
Drawings
FIG. 1 shows the structure of a pH responsive controlled release iron fertilizer in example 1.
Fig. 2 shows the hydrolysis of genii Ping Ke polysaccharide aerogel of example 1.
FIG. 3 is a photograph and SEM image of genitals Ping Ke polysaccharide aerogel and pH-responsive controlled release iron fertilizer of example 1; wherein a-1 and a-2 in FIG. 3 are photographs of the surface and the cross section of the genipin Ping Ke glycan aerogel, respectively; b-1, b-2 is a genipin Ping Ke glycan aerogel SEM image; c-1 and c-2 are SEM images of the pH responsive controlled release iron fertilizer.
FIG. 4 is a FT-IR chart of genii Ping Ke glycan aerogel and pH responsive controlled release iron fertilizer of example 1; in the figure, (a) is chitosan; (b) is genii Ping Ke glycan aerogel; and (c) the pH response type controlled release iron fertilizer.
FIG. 5 is an XRD pattern of genii Ping Ke glycan aerogel and pH responsive controlled release iron fertilizer of example 1; in the figure, (a) is chitosan; (b) is genii Ping Ke glycan aerogel; and (c) the pH response type controlled release iron fertilizer.
FIG. 6 is a TGA graph of genii Ping Ke glycan aerogel and pH responsive controlled release iron fertilizer of example 1; in the figure, a is chitosan; b is genii Ping Ke glycan aerogel; c is pH response type controlled release iron fertilizer.
Fig. 7 shows iron release and swelling ratio of the pH-responsive controlled-release iron fertilizer of example 1 at different pH.
FIG. 8 shows the effect of the pH-responsive controlled-release iron fertilizer and ferrous sulfate prepared in example 1 on the emergence rate of wheat seeds.
Fig. 9 shows the effect of pH-responsive controlled release iron fertilizer and ferrous sulfate prepared in example 1 on tomato seedling growth traits at different application levels.
Fig. 10 is the effect of pH-responsive controlled release iron fertilizer prepared in example 1 and ferrous sulfate on nutrient content of tomato seedling plants at different application levels.
Fig. 11 is the effect of pH-responsive controlled release iron fertilizer and ferrous sulfate prepared in example 1 on the elemental content of tomato seedling substrate extract at different application levels.
Detailed Description
The following detailed description of the invention is provided in connection with the accompanying drawings that are presented to illustrate the invention and not to limit the scope thereof.
The experimental methods in the following examples are conventional methods unless otherwise specified.
Materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.
The "parts" described in the following examples are all "parts by mass".
In the examples described below, low viscosity chitosan (100-200 mpa.s), N-carboxymethyl chitosan, high viscosity chitosan (viscosity >400 mpa.s), and maleic acid chitosan were all purchased from ala Ding Shenghua technologies limited (Aladdin Biochemical Technology co., ltd. (Shanghai, china)).
The release performance and biosafety of the pH-responsive controlled-release iron fertilizer were evaluated in the following manner in the following examples:
the GB/T23148-2009 recommendation method is adopted, and the specific operation is as follows: weighing about 10g (0.01 g) of the prepared controlled release fertilizer, placing the prepared controlled release fertilizer into a small bag made of 100-mesh nylon gauze, sealing, placing the small bag into a 250mL glass bottle or a plastic bottle, adding 200mL of water, sealing by a cover, respectively placing the small bag into a biochemical constant temperature incubator at 25 ℃, and taking out the small bag until the cumulative nutrient dissolution rate reaches more than 80%, wherein the sampling time is 1h,2h,4h,24h,48h,72h,96h and 120 h. When sampling, the bottle is turned upside down for three times to make the concentration of the liquid in the bottle consistent, the bottle is moved into a 250mL volumetric flask, and the bottle is cooled to room temperature and then fixed to the scale for nutrient determination. Then, 200mL of water was added to the flask containing the sample pouch, and the flask was capped and sealed, and then placed in a biochemical incubator to continue culturing. Wherein Fe is 2+ The element is measured by adopting a phenanthroline spectrophotometry of GB/T223.70-2008.
Example 1
1. preparation of pH response type controlled release iron fertilizer
100 parts of low viscosity chitosan (100-200 mpa.s) was dissolved in deionized water (5000 parts) containing 250 parts of acetic acid to prepare a chitosan solution. 100 parts of glycerol is slowly added into the chitosan solution to prepare a chitosan/glycerol mixed solution. Genipin solution was prepared by dissolving 20 parts genipin in deionized water (2000 parts). Mixing the chitosan/glycerol mixed solution with the genipin solution, uniformly stirring to obtain genipin chitosan wet gel, washing the genipin chitosan wet gel with ethanol and deionized water for 3 times, standing at room temperature for aging for 24 hours, then placing into a-20 ℃ for freezing for 12 hours, and finally placing into a vacuum dryer for drying to obtain the genipin Ping Ke glycan aerogel. 500 parts of ferrous sulfate is dissolved in deionized water (5000 parts), then genii Ping Ke glycan aerogel is added into ferrous sulfate solution (the mass ratio of genii Ping Ke glycan aerogel to ferrous sulfate is 1:25), stirring is carried out for 24 hours at 400rpm, the fertilizer is washed by deionized water for 3 times, and then drying is carried out, so that the pH response type controlled release iron fertilizer (the material dissolution pH is 2.6+/-0.5) is obtained.
SEM, FT-IR scan, XRD test, TGA test were performed on the pH-responsive controlled-release iron fertilizer prepared in example 1. FIG. 1 shows the structure of a pH responsive controlled release iron fertilizer in example 1. The chitosan and genipin firstly undergo chemical crosslinking reaction to generate amide bonds, form gel and present a network structure. After adsorbing iron, the net structure of the genii Ping Ke glycan aerogel is coordinated with ferrous ions; at the same time, amino, hydroxyl and ferrous ions in the chitosan are combined with organic acid (acetic acid). The chitosan aerogel reticular structure chelates ferrous ions, and the pH responsiveness of the release carrier is used for controlling the release of the iron element, so that the stress resistance of crops in acid-base stress environments is enhanced. The organic acid in the adsorption carrier material can promote activation of rhizosphere microenvironment, protect released ferrous ions, prevent the ferrous ions from being quickly fixed and oxidized by soil, and enable plants to fully absorb iron elements; meanwhile, the organic acid can activate nutrient elements such as phosphorus in soil, and the absorption of crop root systems to the nutrient elements is improved. Fig. 2 shows the hydrolysis of genii Ping Ke polysaccharide aerogel of example 1. The genipin Ping Ke polysaccharide aerogel is hydrolyzed under acid-base conditions to generate various glycoside substances, which is beneficial to stress resistance, rooting, budding, chlorophyll synthesis, biomass accumulation and the like of plants. Fig. 3 is a photograph and SEM image of genii Ping Ke glycan aerogel and pH-responsive controlled release iron fertilizer of example 1. As shown in a-1, a-2, b-1 and b-2 in the figure 3, the chitosan shows a sequential pore structure after being subjected to crosslinking modification, and the chitosan is proved to be successfully crosslinked. As shown in c-1 and c-2 in fig. 3, the genie Ping Ke polysaccharide aerogel was adsorbed in flocculent form around the pore walls after carrying iron.
FIG. 4 is a FT-IR chart of genii Ping Ke polysaccharide aerogel and pH responsive controlled release iron fertilizer in example 1. As can be seen from FIG. 4, 3000-3500 cm in (a) -1 The broad absorption peaks of (a) represent-OH and-NH respectively 2 This means that chitosan contains a large number of active amino groups and hydroxyl groups, which readily form intramolecular and intermolecular hydrogen bonds. (b) Absorption peaks-OH and-NH can be seen in 2 Weakening at the same time of 1410cm -1 Represents the flexural vibration absorption peak of-CO-NH, which means that a chemical crosslinking reaction of a large amount of amino groups with genipin occurs to form amide bonds. (c) Mid-spectrum shows SO 4 2- Characteristic peaks at 606 and 1125cm -1 The method comprises the steps of carrying out a first treatment on the surface of the Wherein the characteristic peak of the corresponding-C-O-C is 1100cm -1 The peak value moves to 989cm due to coordination with Fe -1 Meaning that genipin aerogel was successful in carrying iron.
Fig. 5 is an XRD pattern of genii Ping Ke glycan aerogel and pH-responsive controlled release iron fertilizer of example 1. As can be seen from fig. 5, the broad diffraction peaks in (a) occur near 2θ=11.86° and 21.31 °, indicating that CS has a relatively regular lattice, mainly due to the large amount of-NH on CS 2 And the presence of intramolecular or intermolecular hydrogen bonds between-OH. (b) The middle diffraction peak shifted to the 2θ=19.56° -20.29 °, indicating that the molecular chains were rearranged during the crosslinking process. (c) The middle diffraction peak shifted to 26.16 ° (corresponding to FeSO) 4 )。
N using a Brunauer-Emmett-Teller (BET) surface area Analyzer (AutosorbiQ 2, quantachrome instrument) 2 Adsorption-desorption analysis, the specific surface area and the effective pore volume of the pH response type controlled release iron fertilizer are measured to be 20.6060m respectively 2 /g and 0.068722cm 3 /g。
The Fe content of the pH responsive controlled release iron fertilizer was measured using inductively coupled plasma atomic emission spectrometry (ICP-AES) and was 326.15mg/g.
The thermal sensitivity of genie Ping Ke glycan aerogel and pH response type controlled release iron fertilizer was evaluated by thermogravimetric analysis. The measurement was performed by heating the sample from 25℃to 900 ℃. TGA was heated under nitrogen using a Labsys Evo (Setaram, lyon, france) apparatus. As shown in fig. 6, the genipin cross-linking agent has little improvement of the heat stability of chitosan, and after iron loading, the temperature of 50% of the mass of the pH-responsive controlled-release iron fertilizer is lost due to the higher melting point of ferrous sulfate.
The pH value of the fertilizer solution is adjusted to 3, 5, 7 or 9 by using 1mol/L hydrochloric acid or 1mol/L sodium hydroxide solution, and the release rate of the pH response type controlled release iron fertilizer under different pH environments is measured by using a GB/T23148-2009 recommended method. To examine the swelling behaviour of genii Ping Ke glycan aerogel, 100mg of sample was weighed and placed in a small petri dish filled with 50mL of swelling medium. PBS solution was used as swelling medium, which was adjusted to different pH using 1mol/L hydrochloric acid or 1mol/L sodium hydroxide solution. After a predetermined regular interval, the sample is removed from the plate and the excess water is tapped with the aid of tissue.
The final weight of the sample was taken and the% swelling calculated according to the following formula:
%Swelling=(W 2 -W 1 )/W 1 x 100
wherein W is 2 Is the final weight of the sample, W 1 Is the initial weight of the sample.
The results are shown in fig. 7, and fig. 7 shows the iron release amount and swelling ratio of the pH-responsive controlled-release iron fertilizer of example 1 at different pH. As in (a) of fig. 7, the release rate of the pH-responsive controlled-release iron fertilizer in a strong acid environment is greater than that in a strong base environment. As in (b) of fig. 7, the swelling behavior of the pH-responsive controlled-release iron fertilizer at different pH is matched to the release behavior.
2. Application of
1. Biological safety evaluation
Experiment settings three treatments: CK: no fertilizer is put in; GE: adding a pH responsive controlled release iron fertilizer; fe is added with ferrous sulfate; wherein, the pH response type controlled release iron fertilizer and ferrous sulfate are respectively put into 1mg.
Each petri dish was placed into 20 full wheat seeds which were sterilized and selected, after different treatments (3 replicates were set for each treatment), sufficient water was added to keep the filter paper moist, and then placed into a thermostatic incubator at 25 ℃ for cultivation, during which time water was added to keep the filter paper moist.
Germination percentage (%) = (number of germination/total number of seeds) ×100%
FIG. 8 shows the effect of the pH-responsive controlled-release iron fertilizer and ferrous sulfate prepared in example 1 on the emergence rate of wheat seeds. As shown in fig. 8, the emergence rate of wheat seeds treated with the pH-responsive controlled-release iron fertilizer was 10% higher than that of non-fertilized (CK) and 7% higher than that of ferrous sulfate at the fifth day.
2. Effect on tomatoes
Experiment settings three treatments: CK: no fertilizer is applied; GE: applying a pH responsive controlled release iron fertilizer; fe: application of FeSO 4 . Wherein GE and Fe each set four different application level: 2.5 mg/strain, 5.0 mg/strain, 7.5 mg/strain and 10.0 mg/strain.
All potted plants were cultivated with Hoagland complete nutrient solution (without iron) and vermiculite. The pot irrigation uses Hoagland complete nutrient solution (without iron) to irrigate according to the nutrition demand of the normal growth of tomato (red dwarf) seedlings, quantitative irrigation (100 mL/plant) is carried out every 3 days (8:00-9:00), and the vermiculite water content is kept at about 60%. The pH value of the nutrient solution is maintained to be 5.8 plus or minus 0.2.
Samples were taken every 7 days for each treatment (6 replicates per treatment) for a total of 3 samples, for a total of 21 days.
(1) Tomato plant height, root length, stem thickness, leaf length and width: measuring by adopting a vernier caliper;
the SPAD value is obtained by measuring different leaves 5 times from top to bottom by using a hand-held chlorophyll instrument (SPAD-502 PIU), and taking the average value as the SPAD value of the tomato plant;
fresh and dry weight of tomato: the method is implemented by adopting a ten-thousandth balance. Wherein the dry weight: baking the root, stem and leaf of the aerial parts of the tomatoes at 105 ℃ for 30min for fixation, drying at 65 ℃ to constant weight, and weighing.
Leaf area: la=0.347× (lxw) -10.7
Wherein LA is the actual leaf area; l and W represent the leaf length and leaf width, respectively.
The results are shown in FIG. 9, which is the effect of the medium pH responsive controlled release iron fertilizer (GE) prepared in example 1 and ferrous sulfate on tomato seedling growth traits at different application levels. As shown in FIG. 9 (a), on day 21, when GE was used as the iron source, GE-5.0 strain was highest, higher than CK37%; in FeSO 4 When the strain is an iron source, the Fe-5.0 strain is highest and is higher than CK16%. As shown in FIG. 9 (b), on day 21, GE-5.0 roots were longest, 39% higher than CK, with GE as the iron source; in FeSO 4 When the Fe-B-C alloy is an iron source, the length of Fe-5.0 is longest and is higher than 10% of CK. As in FIG. 9 (c), on day 21, GE-5.0 stems were the greatest in thickness, above CK38%; in FeSO 4 When the Fe-5.0 is an iron source, the stem thickness is maximum and is higher than CK22%. As in FIG. 9 (d), on day 21, GE-5.0 chlorophyll content was maximum, above CK25%; in FeSO 4 When the iron source is used, the content of Fe-5.0 chlorophyll is the largest and is higher than CK by 12 percent. As shown in FIG. 9 (e), on day 21, GE-5.0 leaves were the most, higher than CK13% with GE as the iron source; in FeSO 4 When the iron source is used, the maximum number of Fe-5.0 blades is higher than CK2%. As shown in FIG. 9 (f), on day 21, GE-5.0 leaf area was maximum, higher than CK52% with GE as iron source; in FeSO 4 When the Fe-5.0 is an iron source, the leaf area is maximum and is higher than CK16%. In conclusion, compared with ferrous sulfate, the pH response type controlled release iron fertilizer has more remarkable promotion effects on plant height, root length, stem thickness, chlorophyll content, leaf number, leaf area and fresh dry weight.
(2) And (3) measuring the nutrient content of plants: samples were taken on day 21 of the test to determine the total nitrogen (N) and P, K, ca, mg, fe, mn, zn content of the plants. The total nitrogen (N) content of the plants is measured by a Kjeldahl nitrogen determination method; the content of P, K, ca, mg, fe, mn, zn was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). Fig. 10 is the effect of pH-responsive controlled release iron fertilizer prepared in example 1 and ferrous sulfate on nutrient content of tomato seedling plants at different application levels. As shown in fig. 10, the pH-responsive controlled release iron fertilizer has a more pronounced effect on plant nutrient elevation than ferrous sulfate. Wherein N, P, K, mg, fe and other elements are obviously promoted.
(3) The total nitrogen (N) content of the matrix leaching solution is measured by a Kjeldahl method.
And (3) taking vermiculite and air drying after the experiment 21 is finished. 5.00mL of air-dried vermiculite (sieved through a 2mm nylon sieve) was taken with a syringe, the mass was weighed and recorded, 50.0mL of M3 leaching agent was added with a syringe, and stirred with a stirrer for 5min. Then filtered through dry filter paper and the filtrate was collected in a 50mL plastic bottle. The whole leaching process should be carried out under the constant temperature condition, and the temperature is controlled to be 25+/-1 ℃.
M3 leaching agent: measuring 2000mL of deionized water with 1000mL or 2000mL measuring cylinder, adding into 5000mL plastic barrel, weighing 100.0g of ammonium nitrate, dissolving, adding 20.0mL of M3 stock solution, and adding 57.5mL of glacial acetic acid (17.4 mol/L) and concentrated HNO 3 (HNO 3 68% -70% of analytically pure) 4.1mL, diluting the solution to 5000mL by adding water into a dosage cylinder, and fully and uniformly mixing, wherein the pH value of the solution is 2.5+/-0.1.
And respectively measuring P and K in the matrix leaching solution by adopting a molybdenum-antimony colorimetric method and a flame spectrophotometry method.
The content of Ca, mg, fe, mn, zn in the matrix leaching solution was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).
Fig. 11 is the effect of pH-responsive controlled release iron fertilizer and ferrous sulfate prepared in example 1 on the elemental content of tomato seedling substrate extract at different application levels. As shown in fig. 11, the genii Ping Ke polysaccharide aerogel iron fertilizer has more obvious nutrient lifting effect on the effective form in the matrix compared with ferrous sulfate. Wherein the dissolution state N, P, ca, mg, mn, zn and other elements are obviously improved.
Example 2
200 parts of N-carboxymethyl chitosan was dissolved in deionized water (5000 parts) containing 50 parts of citric acid to prepare a chitosan solution. 150 parts of glycerol was slowly added to the chitosan solution to prepare a chitosan/glycerol mixed solution. 40 parts of sodium tripolyphosphate was dissolved in deionized water (2000 parts) to prepare a sodium tripolyphosphate solution. Mixing the chitosan/glycerol mixed solution with the sodium tripolyphosphate solution, stirring uniformly to obtain sodium tripolyphosphate chitosan wet gel, and adjusting the pH of the gel to 6.0+/-0.5 by using sodium hydroxide solution. Washing the sodium tripolyphosphate chitosan wet gel with ethanol and deionized water for 3 times, standing at room temperature for aging for 24 hours, then placing the gel into a-20 ℃ for freezing for 12 hours, and finally placing the gel into a vacuum dryer for drying to obtain the chitosan tripolyphosphate aerogel. 500 parts of ferrous sulfate is dissolved in deionized water (5000 parts), then the chitosan tripolyphosphate aerogel is put into a ferrous sulfate solution (the mass ratio of the chitosan tripolyphosphate aerogel to the ferrous sulfate is 1:50), the mixture is stirred for 24 hours at 400rpm, the fertilizer is washed with deionized water for 3 times, and then the pH response type controlled release iron fertilizer is obtained after drying.
The pH-responsive controlled-release iron fertilizer prepared in example 2 was subjected to the same physical characterization and fertilizer release experiments as in example 1. The specific surface area and the effective pore volume of the pH response type controlled release iron fertilizer are measured to be 8.0390m respectively 2 /g and 0.034499cm 3 And/g. The Fe content of the pH responsive controlled release iron fertilizer was 311.00mg/g.
Example 3
A chitosan solution was prepared by dissolving 150 parts of high viscosity chitosan (viscosity >400 mpa.s) in deionized water (5000 parts) containing 100 parts malic acid. 200 parts of glycerol is slowly added into the chitosan solution to prepare a chitosan/glycerol mixed solution. 40 parts of glutaraldehyde was dissolved in deionized water (2000 parts) to prepare a glutaraldehyde solution. Mixing the chitosan/glycerol mixed solution with the glutaraldehyde solution, uniformly stirring to obtain glutaraldehyde chitosan wet gel, washing the glutaraldehyde chitosan wet gel with ethanol and deionized water for 3 times, standing at room temperature for aging for 24 hours, then placing into a-20 ℃ for freezing for 12 hours, and finally placing into a vacuum dryer for drying to obtain glutaraldehyde chitosan aerogel. 400 parts of ferrous sulfate is dissolved in deionized water (5000 parts), then glutaraldehyde chitosan aerogel is added into ferrous sulfate solution (the mass ratio of glutaraldehyde chitosan aerogel to ferrous sulfate is 1:75), stirring is carried out for 24 hours at 400rpm, the fertilizer is washed with deionized water for 3 times, and then drying is carried out, so that the pH response type controlled release iron fertilizer is obtained.
The pH-responsive controlled-release iron fertilizer prepared in example 3 was subjected to the same physical characterization and fertilizer release experiments as in examples 1 and 2. The specific surface area and the effective pore volume of the pH response type controlled release iron fertilizer are measured to be 11.6148m respectively 2 /g and 0.036459cm 3 And/g. The Fe content of the pH responsive controlled release iron fertilizer was 283.54mg/g.
Example 4
A chitosan solution was prepared by dissolving 150 parts of maleic chitosan in deionized water (5000 parts) containing 50 parts of salicylic acid. 200 parts of glycerol is slowly added into the chitosan solution to prepare a chitosan/glycerol mixed solution. 40 parts of succinaldehyde was dissolved in deionized water (2000 parts) to prepare a succinaldehyde solution. Mixing the chitosan/glycerol mixed solution with the succinyl aldehyde solution, uniformly stirring to obtain succinyl aldehyde chitosan wet gel, washing the succinyl aldehyde chitosan wet gel with ethanol and deionized water for 3 times, standing at room temperature for aging for 24 hours, then putting into a-20 ℃ for freezing for 12 hours, and finally putting into a vacuum dryer for drying to obtain the succinyl aldehyde chitosan aerogel. 450 parts of ferrous sulfate is dissolved in deionized water (5000 parts), then succinaldehyde chitosan aerogel is added into ferrous sulfate solution (the mass ratio of the succinaldehyde chitosan aerogel to the ferrous sulfate is 1:100), stirring is carried out for 24 hours at 400rpm, the fertilizer is washed by the deionized water for 3 times, and then drying is carried out, so that the pH response type controlled release iron fertilizer is obtained.
The pH-responsive controlled-release iron fertilizer prepared in example 4 was subjected to the same physical characterization and fertilizer release experiments as in examples 1 and 2. The specific surface area and the effective pore volume of the pH response type controlled release iron fertilizer are measured to be 8.7542m respectively 2 /g and 0.030175cm 3 And/g. The Fe content of the pH responsive controlled release iron fertilizer was 297.79mg/g.
Example 5 Cross-linker concentration screening experiments
1.1 preparation method of pH-responsive controlled-release iron fertilizer the same as in example 1, except that the amount of genipin cross-linker was replaced, five concentration gradients (0.4 wt.%, 0.6wt.%, 0.8wt.%, 1.0wt.%, and 2.0 wt.%) were set together, where the percentages refer to the weight percent concentration of cross-linker in deionized water, as in example 1, 20 parts genipin was dissolved in 2000 parts deionized water, and genipin concentration was 1.0 wt.%) and the amount of pH-responsive controlled-release iron fertilizer iron prepared at the different cross-linker concentrations was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).
As can be seen from the concentration screening experiments, when genipin was selected as the cross-linking agent, the pH-responsive controlled release iron-on-fertilizer iron amounts prepared from 0.4wt.%, 0.6wt.%, 0.8wt.%, 1.0wt.% and 2.0wt.% genipin were 281.22mg/g, 268.25mg/g, 310.97mg/g, 326.15mg/g and 289.62mg/g, respectively. Wherein, the pH response type controlled release iron fertilizer prepared from 1.0wt.% genipin has the highest iron carrying amount.
1.2 effects of pH-responsive controlled-release iron fertilizer prepared with different concentration gradients of genipin on wheat seed germination using the experimental method of fig. 8 in example 1. Experiments found that at day 5, the germination rates under treatment of pH-responsive controlled release iron fertilizer prepared with 0.4wt.%, 0.6wt.%, 0.8wt.%, 1.0wt.%, and 2.0wt.% genipin were 78.35%, 81.65%, 83.35%, 80.00%, and 71.65%, respectively. Wherein the germination rate of the wheat seeds treated by the pH response type controlled release iron fertilizer prepared from 0.8wt.% genipin is highest.
2.1 preparation method of pH responsive controlled release iron fertilizer the same as in example 2, except that the amount of sodium tripolyphosphate cross-linking agent was replaced, five concentration gradients (1.0 wt.%, 2.0wt.%, 4.0wt.%, 6.0wt.%, and 8.0 wt.%) were set together, and the iron carrying amount of pH responsive controlled release iron fertilizer prepared at different cross-linking agent concentrations was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).
As can be seen from the concentration screening experiments, when sodium tripolyphosphate was selected as the cross-linking agent, the pH-responsive controlled release iron fertilizer iron loads prepared from 1.0wt.%, 2.0wt.%, 4.0wt.%, 6.0wt.%, and 8.0wt.% sodium tripolyphosphate were 264.17mg/g, 311.00mg/g, 253.18mg/g, 273.84mg/g, and 214.10mg/g, respectively. Wherein, the pH response type controlled release iron fertilizer prepared from 2.0wt.% of sodium tripolyphosphate has the highest iron carrying amount.
2.2 effects of pH responsive controlled Release iron fertilizer prepared with sodium tripolyphosphate at different concentration gradients on wheat seed germination Using the experimental procedure of FIG. 8 in example 1. Experiments found that at day 5, the germination rates under treatment of pH-responsive controlled release iron fertilizer prepared from 1.0wt.%, 2.0wt.%, 4.0wt.%, 6.0wt.%, and 8.0wt.% sodium tripolyphosphate were 73.35%, 81.65%, 78.35%, 90.00%, and 70.00%, respectively. Wherein the germination rate of the wheat seeds treated by the pH response type controlled release iron fertilizer prepared from 6.0wt.% sodium tripolyphosphate is highest.
3.1 preparation method of pH responsive controlled release iron fertilizer the same as in example 3, except that the amount of glutaraldehyde crosslinking agent was replaced, five concentration gradients (1.0 wt.%, 2.0wt.%, 4.0wt.%, 6.0wt.%, and 8.0 wt.%) were set in total, and the iron carrying amount of pH responsive controlled release iron fertilizer prepared at different crosslinking agent concentrations was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).
As can be seen from the concentration screening experiments, when glutaraldehyde was selected as the cross-linking agent, the pH-responsive controlled release iron-carrying amounts prepared from 1.0wt.%, 2.0wt.%, 4.0wt.%, 6.0wt.% and 8.0wt.% glutaraldehyde were 192.75mg/g, 283.54mg/g, 244.96mg/g, 260.19mg/g and 227.26mg/g, respectively. Wherein, the pH response type controlled release iron fertilizer prepared from 2.0wt.% glutaraldehyde has the highest iron carrying amount.
3.2 influence of pH responsive controlled Release iron fertilizer prepared with glutaraldehyde at different concentration gradients on wheat seed germination Using the experimental procedure of FIG. 8 in example 1. Experiments found that at day 5, the germination rates under treatment of pH-responsive controlled release iron fertilizers prepared from 1.0wt.%, 2.0wt.%, 4.0wt.%, 6.0wt.%, and 8.0wt.% glutaraldehyde were 71.65%, 78.35%, 81.65%, 80.00%, and 83.35%, respectively. Wherein, the germination rate of the wheat seeds treated by the pH response type controlled release iron fertilizer prepared from 4.0wt.% glutaraldehyde is highest.
4.1 preparation method of pH responsive controlled release iron fertilizer the same as in example 4, except that the amount of succinyl aldehyde cross-linking agent was replaced, five concentration gradients (1.0 wt.%, 2.0wt.%, 4.0wt.%, 6.0wt.%, and 8.0 wt.%) were set in total, and the iron carrying amount of pH responsive controlled release iron fertilizer prepared at different cross-linking agent concentrations was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).
As can be seen from the concentration screening experiments, when succinaldehyde was selected as the cross-linking agent, the pH-responsive controlled release iron-carrying amounts prepared from 1.0wt.%, 2.0wt.%, 4.0wt.%, 6.0wt.% and 8.0wt.% succinaldehyde were 205.47mg/g, 297.79mg/g, 261.65mg/g, 242.47mg/g and 229.38mg/g, respectively. Wherein, 2.0wt.% of succinyl aldehyde is used for preparing the pH response type controlled release iron fertilizer with highest iron carrying amount.
4.2 influence of pH responsive controlled-release iron fertilizer prepared with different concentration gradient succinaldehyde on wheat seed germination using the experimental method in FIG. 8 in example 1. Experiments found that at day 5, the germination rates under treatment of pH-responsive controlled release iron fertilizer prepared from 1.0wt.%, 2.0wt.%, 4.0wt.%, 6.0wt.%, and 8.0wt.% succinaldehyde were 73.15%, 83.35%, 80.00%, 78.15%, and 75.35%, respectively. Wherein the germination rate of the wheat seeds treated by the pH response type controlled release iron fertilizer prepared from 2.0wt.% succinaldehyde is highest.

Claims (10)

1. A pH responsive controlled release iron fertilizer comprises an adsorption carrier and an iron-containing compound;
the adsorption carrier is prepared from the following raw materials: 100-200 parts of organic polymer material, 50-250 parts of organic acid, 5-200 parts of cross-linking agent and 100-200 parts of colloid stabilizer.
2. The pH-responsive controlled-release iron fertilizer of claim 1, wherein: in the pH response type controlled release iron fertilizer, the loading amount of the iron-containing compound is 150-350 mg/g, and the loading amount is calculated by the mass of iron in the iron-containing compound.
3. The pH-responsive controlled-release iron fertilizer according to claim 1 or 2, characterized in that: the organic polymer material is chitosan and/or chitosan salt;
specifically, the chitosan and chitosan salt are at least one selected from chitosan, N-carboxymethyl chitosan, chitosan and maleic acid chitosan.
4. A pH-responsive controlled-release iron fertilizer according to any one of claims 1-3, characterized in that: the organic acid is at least one selected from acetic acid, malic acid, citric acid, salicylic acid methane sulfonic acid and ascorbic acid;
the cross-linking agent is at least one selected from glutaraldehyde, formaldehyde, succinaldehyde, genipin, sodium tripolyphosphate, N-dimethyl acetyl, dialdehyde end group PEO, toluene diisocyanate, diphenylmethane diisocyanate and epichlorohydrin;
the iron-containing compound is at least one selected from ferrous sulfate, ferric sulfate, ferrous chloride, ferric chloride, ferrous acetate, ferrous carbonate, ferrous nitrate and ferrous sulfate heptahydrate;
the colloid stabilizer is at least one of glycerol, ethylene glycol, propylene glycol, isoprene glycol, polyethylene glycol, polyvinyl alcohol, hexylene glycol and pentaerythritol.
5. The pH-responsive controlled-release iron fertilizer of any one of claims 1-4, wherein: the raw material of the adsorption carrier also comprises water.
6. The pH-responsive controlled-release iron fertilizer of any one of claims 1-5, wherein: the adsorption carrier is aerogel; the specific surface area of the adsorption carrier is 0.5-50 m 2 Per g, effective pore volume of 0.003-0.5 cm 3 /g。
7. The pH-responsive controlled-release iron fertilizer of any one of claims 1-6, wherein: the preparation method of the adsorption carrier comprises the following steps:
1) Mixing the organic polymer material, organic acid and water to form a water phase a;
2) Mixing the colloidal stabilizer with the aqueous phase a to form an aqueous phase b;
3) Mixing the aqueous phase b with a cross-linking agent solution to prepare wet gel;
4) And aging, freezing and drying the wet gel to obtain the adsorption carrier.
8. The pH-responsive controlled-release iron fertilizer of claim 7, wherein: in the step 1), the mass ratio of the organic polymer material to the water is 1:25-1:50;
in the step 3), the mass ratio of the cross-linking agent to the water in the cross-linking agent solution is 1:10-1:100;
in the step 4), the aging is carried out for 24 to 48 hours at room temperature; the freezing is carried out for 12-24 hours at the temperature of minus 20-minus 50 ℃.
9. The method for preparing a pH-responsive controlled-release iron fertilizer as claimed in any one of claims 1 to 8, comprising the steps of: preparing an iron-containing compound into an iron-containing compound aqueous solution, immersing the adsorption carrier in the iron-containing compound aqueous solution, and taking out the adsorption carrier to obtain the pH-responsive controlled-release iron fertilizer.
10. The method of manufacturing according to claim 9, wherein: the mass ratio of the iron-containing compound to the water is 1:5-1:15;
the adsorption carrier is immersed in the iron-containing compound aqueous solution to be stirred, the stirring speed is 200-400 rpm, and the stirring time is 12-24 h.
CN202310803042.8A 2023-07-03 2023-07-03 PH responsive controlled-release iron fertilizer and preparation method thereof Pending CN116751090A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118005451A (en) * 2024-04-10 2024-05-10 中国农业大学 Double-nutrient chitosan coated urea for saline-alkali soil and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118005451A (en) * 2024-04-10 2024-05-10 中国农业大学 Double-nutrient chitosan coated urea for saline-alkali soil and preparation method thereof
CN118005451B (en) * 2024-04-10 2024-07-05 中国农业大学 Double-nutrient chitosan coated urea for saline-alkali soil and preparation method thereof

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