CN118005451A - Double-nutrient chitosan coated urea for saline-alkali soil and preparation method thereof - Google Patents
Double-nutrient chitosan coated urea for saline-alkali soil and preparation method thereof Download PDFInfo
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- CN118005451A CN118005451A CN202410423875.6A CN202410423875A CN118005451A CN 118005451 A CN118005451 A CN 118005451A CN 202410423875 A CN202410423875 A CN 202410423875A CN 118005451 A CN118005451 A CN 118005451A
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- 229920001661 Chitosan Polymers 0.000 title claims abstract description 200
- 239000002689 soil Substances 0.000 title claims abstract description 156
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 154
- 239000004202 carbamide Substances 0.000 title claims abstract description 154
- 239000003513 alkali Substances 0.000 title claims abstract description 104
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- YGSDEFSMJLZEOE-UHFFFAOYSA-N salicylic acid Chemical compound OC(=O)C1=CC=CC=C1O YGSDEFSMJLZEOE-UHFFFAOYSA-N 0.000 claims abstract description 126
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 120
- FJKROLUGYXJWQN-UHFFFAOYSA-N papa-hydroxy-benzoic acid Natural products OC(=O)C1=CC=C(O)C=C1 FJKROLUGYXJWQN-UHFFFAOYSA-N 0.000 claims abstract description 63
- 229960004889 salicylic acid Drugs 0.000 claims abstract description 63
- 229910052742 iron Inorganic materials 0.000 claims abstract description 54
- 239000010410 layer Substances 0.000 claims abstract description 37
- 239000002346 layers by function Substances 0.000 claims abstract description 30
- 150000001875 compounds Chemical class 0.000 claims abstract description 25
- 239000003431 cross linking reagent Substances 0.000 claims abstract description 25
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000004327 boric acid Substances 0.000 claims abstract description 24
- 239000002861 polymer material Substances 0.000 claims abstract description 18
- 239000002994 raw material Substances 0.000 claims abstract description 16
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000000576 coating method Methods 0.000 claims description 73
- 239000011248 coating agent Substances 0.000 claims description 67
- UPMLOUAZCHDJJD-UHFFFAOYSA-N 4,4'-Diphenylmethane Diisocyanate Chemical compound C1=CC(N=C=O)=CC=C1CC1=CC=C(N=C=O)C=C1 UPMLOUAZCHDJJD-UHFFFAOYSA-N 0.000 claims description 30
- 239000002245 particle Substances 0.000 claims description 28
- 235000015097 nutrients Nutrition 0.000 claims description 23
- 230000009977 dual effect Effects 0.000 claims description 17
- 239000012074 organic phase Substances 0.000 claims description 14
- 229920000620 organic polymer Polymers 0.000 claims description 12
- 238000005507 spraying Methods 0.000 claims description 10
- 239000003960 organic solvent Substances 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 7
- FKTHNVSLHLHISI-UHFFFAOYSA-N 1,2-bis(isocyanatomethyl)benzene Chemical compound O=C=NCC1=CC=CC=C1CN=C=O FKTHNVSLHLHISI-UHFFFAOYSA-N 0.000 claims description 6
- 239000005057 Hexamethylene diisocyanate Substances 0.000 claims description 6
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 claims description 6
- DVKJHBMWWAPEIU-UHFFFAOYSA-N toluene 2,4-diisocyanate Chemical compound CC1=CC=C(N=C=O)C=C1N=C=O DVKJHBMWWAPEIU-UHFFFAOYSA-N 0.000 claims description 6
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 claims description 5
- MCDLETWIOVSGJT-UHFFFAOYSA-N acetic acid;iron Chemical compound [Fe].CC(O)=O.CC(O)=O MCDLETWIOVSGJT-UHFFFAOYSA-N 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 4
- 229960002089 ferrous chloride Drugs 0.000 claims description 4
- 239000008187 granular material Substances 0.000 claims description 4
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 4
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 3
- 239000011790 ferrous sulphate Substances 0.000 claims description 3
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 3
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 3
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 3
- 230000001737 promoting effect Effects 0.000 claims description 3
- 239000004277 Ferrous carbonate Substances 0.000 claims description 2
- 229910002651 NO3 Inorganic materials 0.000 claims description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 2
- KORSJDCBLAPZEQ-UHFFFAOYSA-N dicyclohexylmethane-4,4'-diisocyanate Chemical compound C1CC(N=C=O)CCC1CC1CCC(N=C=O)CC1 KORSJDCBLAPZEQ-UHFFFAOYSA-N 0.000 claims description 2
- RAQDACVRFCEPDA-UHFFFAOYSA-L ferrous carbonate Chemical compound [Fe+2].[O-]C([O-])=O RAQDACVRFCEPDA-UHFFFAOYSA-L 0.000 claims description 2
- 235000019268 ferrous carbonate Nutrition 0.000 claims description 2
- 229960004652 ferrous carbonate Drugs 0.000 claims description 2
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims description 2
- 229910000015 iron(II) carbonate Inorganic materials 0.000 claims description 2
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 2
- 239000012528 membrane Substances 0.000 abstract description 43
- 239000000463 material Substances 0.000 abstract description 17
- 238000010521 absorption reaction Methods 0.000 abstract description 13
- 229910001448 ferrous ion Inorganic materials 0.000 abstract description 13
- 229910001415 sodium ion Inorganic materials 0.000 abstract description 12
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 abstract description 10
- 239000002681 soil colloid Substances 0.000 abstract description 10
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 abstract description 7
- 229910001424 calcium ion Inorganic materials 0.000 abstract description 7
- 230000015572 biosynthetic process Effects 0.000 abstract description 5
- 229910000019 calcium carbonate Inorganic materials 0.000 abstract description 5
- 230000015556 catabolic process Effects 0.000 abstract description 5
- RQFQJYYMBWVMQG-IXDPLRRUSA-N chitotriose Chemical compound O[C@@H]1[C@@H](N)[C@H](O)O[C@H](CO)[C@H]1O[C@H]1[C@H](N)[C@@H](O)[C@H](O[C@H]2[C@@H]([C@@H](O)[C@H](O)[C@@H](CO)O2)N)[C@@H](CO)O1 RQFQJYYMBWVMQG-IXDPLRRUSA-N 0.000 abstract description 5
- 238000006731 degradation reaction Methods 0.000 abstract description 5
- 238000004090 dissolution Methods 0.000 abstract description 5
- 239000002688 soil aggregate Substances 0.000 abstract 1
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- 239000007788 liquid Substances 0.000 description 35
- 239000003337 fertilizer Substances 0.000 description 29
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- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical group CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 13
- 238000000034 method Methods 0.000 description 11
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 241000220259 Raphanus Species 0.000 description 6
- 235000006140 Raphanus sativus var sativus Nutrition 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- 238000004132 cross linking Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- WSMYVTOQOOLQHP-UHFFFAOYSA-N Malondialdehyde Chemical compound O=CCC=O WSMYVTOQOOLQHP-UHFFFAOYSA-N 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000015784 hyperosmotic salinity response Effects 0.000 description 4
- 238000002386 leaching Methods 0.000 description 4
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- 238000005259 measurement Methods 0.000 description 4
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- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 3
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 3
- 239000012615 aggregate Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 3
- 239000011976 maleic acid Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
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- 238000005070 sampling Methods 0.000 description 3
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- 239000002881 soil fertilizer Substances 0.000 description 3
- 239000006228 supernatant Substances 0.000 description 3
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
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- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 2
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- -1 salt ions Chemical class 0.000 description 2
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- 239000011780 sodium chloride Substances 0.000 description 2
- 238000002798 spectrophotometry method Methods 0.000 description 2
- 230000037303 wrinkles Effects 0.000 description 2
- QPXZSVUBSZNWBF-UHFFFAOYSA-N 1,4-diaminocyclohexa-2,4-diene-1-carbaldehyde Chemical compound NC1=CCC(N)(C=O)C=C1 QPXZSVUBSZNWBF-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 239000005714 Chitosan hydrochloride Substances 0.000 description 1
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- GYCKQBWUSACYIF-UHFFFAOYSA-N Ethyl salicylate Chemical compound CCOC(=O)C1=CC=CC=C1O GYCKQBWUSACYIF-UHFFFAOYSA-N 0.000 description 1
- 229910017135 Fe—O Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 238000013494 PH determination Methods 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910052770 Uranium Inorganic materials 0.000 description 1
- DGEZNRSVGBDHLK-UHFFFAOYSA-N [1,10]phenanthroline Chemical compound C1=CN=C2C3=NC=CC=C3C=CC2=C1 DGEZNRSVGBDHLK-UHFFFAOYSA-N 0.000 description 1
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- HYBBIBNJHNGZAN-UHFFFAOYSA-N furfural Chemical group O=CC1=CC=CO1 HYBBIBNJHNGZAN-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Fertilizers (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
Abstract
The invention discloses double-nutrient chitosan coated urea for saline-alkali soil and a preparation method thereof. The inner slow release layer is prepared from raw materials including an organic high polymer material, salicylic acid, boric acid and an organic cross-linking agent; the external functional layer is made of a material including an internal slow-release layer material and an iron-containing compound material. The external functional layer preferentially releases salicylic acid and iron elements, replaces sodium ions on the surface of the soil colloid, dissolves calcium carbonate in the soil, promotes calcium ions to replace sodium ions on the surface of the soil colloid, and reduces the alkalization degree. Ferrous ions promote the formation of large soil aggregates and improve the soil structure. Along with the dissolution and degradation of the inner and outer membrane shells, salicylic acid, chitosan oligosaccharide and iron element are slowly released, so that the stress resistance of crops in the seedling stage is increased, and N absorption and growth and development of plants are promoted.
Description
Technical Field
The invention relates to the field of soil improvement, in particular to double-nutrient chitosan coated urea for saline-alkali soil and a preparation method thereof.
Background
Saline-alkali soil refers to the presence of a higher concentration of soluble salt ions in the soil. The high salinity and high alkalinity of saline-alkali soil lead to loss of a large amount of humus and organic matters, the soil structure is destroyed, the hardening is easy, and the ventilation and the air permeability are poor. In severe cases, such soil can lead to plant wilting and death, resulting in crop yield loss. The saline-alkali soil is taken as a part of an ecological system, and the unique physical and chemical and biological properties of the soil often generate unusual ecological system substances and energy circulation processes, so that the waste of agricultural resources and the fragile ecological environment are caused, and economic loss and secondary hazard are caused. At present, the saline-alkali soil in China is mainly distributed in the north of northwest China, north China, huang-Huai-Hai plain and the north of Song-Qing plain, and the improvement of the soil cultivation quality and productivity level is significant for improving the quality level of cultivated soil in China.
The saline-alkali soil improvement method mainly comprises the steps of adding chemical modifier, improving cultivation mode, bioremediation and the like. Wherein the chemical modifier is added mainly by utilizing Ca 2+ in the additive to exchange sites with Na + in the soil, thereby removing the Ca 2+ from the soil. Traditional chemical improvers include natural gypsum, sulfuric acid, and organics. However, conventional chemical modifiers are too costly and often do not perform well. The improved cultivation method removes salt through deep ploughing, fresh water leaching and drainage systems. However, conventional methods are inefficient, labor intensive, slow to repair, and thus, they are not widely used. Likewise, the cost of bioremediation is too high to be widely used in practice. Among them, application of desalinated saline-alkali soil fertilizer was found to be a method for saline-alkali soil improvement that can be used to combine soil improvement with plant nutrients. Most of coating materials of the traditional controlled release fertilizer are petroleum-based polymers, although the release of nutrients is delayed, and the loss of the nutrients is prevented; 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 invention patent (CN 106365833A) of Chuzhou Yi agricultural science and technology company Xin Song discloses a chitosan coated controlled release fertilizer for saline-alkali soil, which is prepared by fermenting wastes such as straw, animal manure, furfural residue and the like and then embedding the wastes with chitosan, so that the fertilizer can be slowly released, thereby prolonging the fertilizer efficiency, improving the fertilizer utilization rate, better improving the saline-alkali soil condition and relieving salt damage. The invention patent (CN 110452054A) of the China applied by the Shandongsheng Wen saline-alkali soil science and technology Co-Ltd Wang Sheng discloses a special multilayer compound fertilizer granule for improving the saline-alkali soil and a preparation method thereof, wherein the multilayer compound fertilizer granule sequentially comprises a core layer, a first slow release layer, a soil restoration layer, a second slow release layer and a degradable coating layer from inside to outside, has good effect when being used for improving the saline-alkali soil, improves the fertility of the saline-alkali soil to a certain extent, and has simple preparation method and low cost. However, the manufacturing process and raw materials of the desalted saline-alkali soil fertilizer are complex, and the manufacturing cost in the early stage and the popularization difficulty in the later stage of the fertilizer are certainly increased.
Therefore, by combining the biodegradable polymer and the saline-alkali soil improvement function, it is necessary to develop an efficient green desalinated saline-alkali soil fertilizer.
Disclosure of Invention
The invention provides a double-nutrient chitosan coated urea for saline-alkali soil and a preparation method thereof, wherein iron-containing compounds and salicylic acid on the outer layer of the double-nutrient chitosan coated urea for saline-alkali soil are released preferentially, ferrous ions replace sodium ions on the surface of soil colloid, the alkalinity of the soil is neutralized, calcium carbonate in the soil is dissolved, calcium ions replace the sodium ions on the surface of the soil colloid, and the alkalization degree is reduced; in addition, ferrous ions can also increase the porosity of soil and improve the soil structure. The salicylic acid can reduce the content of malondialdehyde in plants, enhance the activity of antioxidase, enhance the salt tolerance and stress resistance of plants, reduce the pH of soil and maintain the activity of ferrous ions. Along with the dissolution of the external functional layer and the degradation of the membrane shell, salicylic acid, chitosan oligosaccharide and iron elements can be slowly released, the stress resistance of crops in the seedling stage is increased, N absorption by plants is promoted, the root system environment of the crops is protected, and the saline-alkali soil is improved.
The invention provides double-nutrient chitosan coated urea for saline-alkali soil, which consists of urea particles, an inner slow-release layer and an outer functional layer;
The inner slow release layer and the outer functional layer are sequentially coated on the surface of the urea particles;
the inner slow release layer is prepared from raw materials comprising an organic high polymer material, salicylic acid, boric acid and an organic cross-linking agent;
The outer functional layer is made of a raw material including the inner slow-release layer and an iron-containing compound.
In the double-nutrient chitosan coated urea for the saline-alkali soil, the mass of the inner slow-release layer accounts for 1% -7% of the total mass of the urea particles and the inner slow-release layer;
the mass of the external functional layer accounts for 0.7% -1% of the total mass of the dual-nutrient chitosan coated urea for the saline-alkali soil;
In the double-nutrient chitosan coated urea for the saline-alkali soil, the load of the iron-containing compound is 0.7% -0.8%, and the load is calculated by the mass of iron in the iron-containing compound.
In the double-nutrient chitosan coated urea for the saline-alkali soil, the organic polymer material is chitosan and/or chitosan derivatives;
Specifically, the chitosan derivative can be at least one of N-carboxymethyl chitosan, hydroxypropyl chitosan, maleic acid chitosan, chitosan hydrochloride and chitosan sulfonate;
the chitosan can be at least one of low-viscosity chitosan (viscosity <200 mpa.s), medium-viscosity chitosan (viscosity 200-400 mpa.s) and high-viscosity chitosan (viscosity >400 mpa.s);
The organic cross-linking agent is selected from at least one of diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4, 4' -diisocyanate and xylylene diisocyanate;
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.
In the double-nutrient chitosan coated urea for the saline-alkali soil, the inner slow-release layer is prepared from the following raw materials in parts by mass: 4-28 parts of organic polymer material, 3.5-28 parts of salicylic acid, 3-21 parts of boric acid and 8-70 parts of organic cross-linking agent;
the mass ratio of the organic polymer material to the salicylic acid is 1:0.9-1; specifically, the ratio of the raw materials can be 1:1;
the external functional layer is prepared from the following raw materials in parts by mass: 4 parts of organic polymer material, 3.5-4 parts of salicylic acid, 3 parts of boric acid, 8-10 parts of organic cross-linking agent and 20-30 parts of iron-containing compound.
In the double-nutrient chitosan coated urea for the saline-alkali soil, the raw materials of the inner slow-release layer and the outer functional layer also comprise organic solvents;
Specifically, the organic solvent is N, N-dimethylacetamide.
The invention also provides a preparation method of the double-nutrient chitosan coated urea for the saline-alkali soil, which comprises the following steps:
(1) Mixing the organic polymer material, salicylic acid, boric acid and an organic solvent to form an organic phase a;
(2) Mixing the iron-containing compound with the organic phase a to form an organic phase b;
(3) Pouring the urea granules into a drum coating machine, and preheating;
(4) Spraying the organic cross-linking agent on the surfaces of the urea particles at a constant speed, and spraying the organic phase a on the surfaces of the urea particles at a constant speed when the organic cross-linking agent is uniformly covered on the surfaces of the urea particles to obtain chitosan coated urea;
(5) And uniformly spraying the organic cross-linking agent on the surface of the chitosan coated urea, and uniformly spraying the organic phase b on the surface of the chitosan coated urea when the organic cross-linking agent is uniformly covered on the surface of the chitosan coated urea, so as to obtain the double-nutrient chitosan coated urea for the saline-alkali soil.
In the preparation method, in the step (4), 500 parts by mass of urea particles are prepared from the following raw materials in parts by mass: 4 parts of organic polymer material, 3.5-4 parts of salicylic acid, 3 parts of boric acid, 8-10 parts of organic cross-linking agent and 150-200 parts of organic solvent;
In the step (5), 500 parts by mass of urea particles are prepared from the following raw materials in parts by mass: 4 parts of organic polymer material, 3.5-4 parts of salicylic acid, 3 parts of boric acid, 8-10 parts of organic cross-linking agent, 20-30 parts of iron-containing compound and 150-180 parts of organic solvent.
The operation of the step (4) is repeated for 1 to 7 times.
In the preparation method, in the step (3), the preheating temperature is 70-80 ℃ and the preheating time is 15-20 min.
In the preparation method, in the steps (4) and (5), the coating rotating speed is 40-70 rpm, and the temperature is 50-80 ℃.
In the preparation method, in the step (5), the organic phase b is sprayed on the surface of the chitosan coated urea at a constant speed and then dried; specifically, the drying time is 20-30 min.
In the preparation method, the organic solvent is N, N-dimethylacetamide.
In the double-nutrient chitosan coated urea for the saline-alkali soil, the nitrogen content of the coated urea is 39.39-44.28% (mass percent).
Finally, the invention also provides application of the double-nutrient chitosan coated urea for the saline-alkali soil in any one of the following:
1) Improving the saline-alkali soil;
2) Increasing the stress resistance of crops in seedling stage;
3) Promoting the crop to absorb N;
4) Protecting the root system environment of crops;
5) In the saline-alkali soil environment, root and seedling are promoted in the seedling stage of crops.
The invention converts the traditional chitosan water phase system into an organic phase system mixed with salicylic acid, boric acid and N, N-dimethylacetamide, not only blends the salicylic acid into a coating system, but also ensures that the coating effect and the fertilizer form are not influenced by the intake of water in the fertilizer coating process. The invention provides double-nutrient chitosan coated urea for saline-alkali soil, which sequentially comprises a core layer, an inner slow-release layer and an outer functional layer. The inner slow release layer is a reticular structure formed by chemical crosslinking of chitosan and a crosslinking agent; the external functional layer is a network structure formed by chemically crosslinking chitosan and a crosslinking agent and complexing an iron-containing compound and salicylic acid. When the double-nutrient chitosan coated urea for the saline-alkali soil is used for the saline-alkali soil, the external functional layer is preferentially dissolved under the action of moisture in the saline-alkali soil, so that iron-containing compounds and salicylic acid are released in the soil, ferrous ions replace sodium ions on the surface of a soil colloid, the alkalinity of the soil is neutralized, calcium carbonate in the soil is dissolved, calcium ions replace the sodium ions on the surface of the soil colloid, and the alkalinity is reduced. In addition, ferrous ions can promote the formation of soil macro-aggregates and improve the soil structure. The salicylic acid can reduce the content of malondialdehyde in plants, enhance the activity of antioxidase, enhance the salt tolerance and stress resistance of plants, reduce the pH of soil and maintain the activity of ferrous ions. Along with the dissolution of the external functional layer and the degradation of the membrane shell, salicylic acid, chitosan oligosaccharide and iron element can be slowly released, so that the seedling stress resistance of crops is increased, and N absorption of plants is promoted. After improving the soil microenvironment, the inner slow-release layer gradually begins to dissolve, and the inner fertilizer core is gradually absorbed by the root system of crops, so that the utilization rate of the N fertilizer can be jointly improved by Fe 2+, chitosan and salicylic acid.
Compared with the traditional coated urea, the invention utilizes the reticular structure formed by the chitosan polymer material and the cross-linking agent to complex salicylic acid and iron elements, and prepares the double-nutrient chitosan coated urea for the saline-alkali soil, and has the following advantages:
1) The membrane shell 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 traditional chitosan water phase coating system is converted into an organic phase system, salicylic acid is introduced into the system to coordinate with chitosan, and the salicylic acid is soluble in water to produce ethyl salicylate and chitosan oligosaccharide in the release process, so that the malondialdehyde content in plants can be reduced, the activity of antioxidant enzymes can be enhanced, the salt tolerance and stress resistance of the plants can be enhanced, and N absorption of the plants can be promoted;
3) The invention is divided into an inner functional layer and an outer functional layer, the outer functional layer preferentially releases salicylic acid and iron elements, ferrous ions replace sodium ions on the surface of the soil colloid, the soil alkalinity is neutralized, calcium carbonate in the soil is dissolved, calcium ions are promoted to replace the sodium ions on the surface of the soil colloid, and the alkalization degree is reduced; meanwhile, ferrous ions can promote the formation of soil macro-aggregates and improve the soil structure; in addition, salicylic acid can also reduce the pH of soil and keep the activity of ferrous ions;
4) The multi-effect controlled release linkage design of the fertilizer is particularly suitable for promoting root and strengthening seedlings of crops in a saline-alkali soil environment in a seedling stage, so that yield and production are ensured.
Drawings
Fig. 1 is a schematic diagram of a process flow of preparing dual-nutrient chitosan coated urea for saline-alkali soil in example 1. Wherein CS represents chitosan, MDI represents diphenylmethane diisocyanate, SA represents salicylic acid, CSCU is a chitosan coated urea.
FIG. 2 shows the inner and outer layer structure of the double nutrient chitosan coated urea for saline-alkali soil in example 1.
FIG. 3 is an SEM image of a dual nutrient chitosan coated urea membrane shell for saline-alkali soil in example 1; wherein (a), (b) and (c) in fig. 3 are respectively a chitosan membrane shell (CS), a chitosan MDI crosslinked membrane shell (cs@mdi) and an iron-containing chitosan MDI crosslinked membrane shell (cs@mdi@fe).
FIG. 4 is a FT-IR diagram of a dual nutrient chitosan coated urea membrane shell for saline-alkali soil in example 1; in the figure, (a) is a chitosan membrane shell (CS); (b) is chitosan MDI cross-linked membrane shell (CS@MDI); (c) is an iron-containing chitosan MDI cross-linked membrane shell (CS@MDI@Fe).
FIG. 5 is an XRD pattern of a dual-nutrient chitosan coated urea membrane shell for saline-alkali soil in example 1; in the figure, (a) is a chitosan membrane shell (CS); (b) is chitosan MDI cross-linked membrane shell (CS@MDI); (c) is an iron-containing chitosan MDI cross-linked membrane shell (CS@MDI@Fe).
FIG. 6 is a TGA graph of a dual nutrient chitosan coated urea membrane shell for saline-alkali soil in example 1.
FIG. 7 is a graph of water contact angle and water absorption of a dual-nutrient chitosan coated urea film shell for saline-alkali soil in example 1; fig. 7 (a) shows a chitosan membrane shell (CS); (b) is chitosan MDI cross-linked membrane shell (CS@MDI); (c) is an iron-containing chitosan MDI cross-linked membrane shell (CS@MDI@Fe); (d) is the water absorption of three membrane shells.
FIG. 8 is a graph showing the N and Fe release curves of the dual nutrient chitosan coated urea for saline-alkali soil in example 1.
FIG. 9 shows the germination rate of double-nutrient chitosan coated urea salinized seeds for saline-alkali soil in example 1; fig. 9 (a) shows seed germination rates of different fertilizers under different concentrations of salt stress; (b) The germination rate of seeds of different fertilizers under different concentrations of alkali stress; s1 is non-fertilizing (CK), S2 is chitosan coated urea (CS@MDI) and S3 is double-nutrient chitosan coated urea (CS@MDI@Fe) for saline-alkali soil.
FIG. 10 is the effect of dual nutrient chitosan coated urea for saline-alkali soil on soil pH and EC in example 1; fig. 10 (a) and (b) are the effects of different treatments on soil pH and EC, CK: no fertilizer is applied; u: urea is applied; n: chitosan coated urea; fe: the double-nutrient chitosan coated urea for the saline-alkali soil is applied.
FIG. 11 is the effect of dual nutrient chitosan coated urea for saline-alkali soil on soil salinity in example 1; fig. 11 (a), (b), (c) and (d) show the effect of different treatments on soil K +、Ca2+、Na+、Mg2+, CK: no fertilizer is applied; u: urea is applied; n: chitosan coated urea; fe: the double-nutrient chitosan coated urea for the saline-alkali soil is applied.
FIG. 12 is a graph showing the effect of different salicylic acid concentrations on chitosan MDI membrane shell and chitosan coated urea in example 5; wherein figure (a) is a chitosan MDI membrane shell prepared by high-concentration salicylic acid, and figure (b) is chitosan coated urea coated by chitosan organic coating liquid prepared by high-concentration salicylic acid; FIG. (c) shows a chitosan MDI membrane shell prepared from medium-concentration salicylic acid; figure (d) is a chitosan coated urea coated with a chitosan organic coating solution prepared from medium-concentration salicylic acid.
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.
The quantitative tests in the following examples were all set up in triplicate and the results averaged.
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 "parts by mass"; the percentages are mass percentages unless otherwise indicated.
In the examples described below, chitosan (cat No. C105801, viscosity <200 mpa.s), N-carboxymethyl chitosan, chitosan (cat No. C105803, viscosity >400 mpa.s), maleic acid chitosan were all purchased from ala Ding Shenghua technologies limited (Aladdin Biochemical Technology co., ltd. (Shanghai, china)).
The urea used in the following examples was purchased from Hua Luheng chemical company, shandong, inc., and had a nitrogen content of 46wt%.
The following examples all evaluate the release performance and biosafety of the double-nutrient chitosan coated urea for saline-alkali soil according to the following methods:
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 accumulated nutrient dissolution rate reaches more than 80%, wherein the sampling time is 1h,4h,8h,12h,24h,48h,72h,96h,120h and 144 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 N element is determined by adopting a p-diaminobenzaldehyde spectrophotometry, and Fe element is determined by adopting an o-phenanthroline spectrophotometry of GB/T223.70-2008.
Example 1
1. Preparation of double-nutrient chitosan coated urea for saline-alkali soil
Chitosan (viscosity <200 mpa.s), salicylic acid and boric acid are dissolved in N, N-dimethylacetamide, and the mixture is stirred at 400rpm and 60 ℃ until the materials are completely dissolved, so as to prepare the chitosan organic coating liquid a. Mixing ferrous chloride with the chitosan organic coating liquid a, and stirring at 400rpm and 30 ℃ until the materials are completely dissolved, so as to prepare the chitosan organic coating liquid b. 500 parts of granular urea are poured into a drum coater and preheated for 15 minutes at a temperature of 70 ℃. The temperature and the rotating speed of a drum coating machine are set to be 60 ℃ and 50rpm respectively, 8 parts of diphenylmethane diisocyanate are poured into the drum coating machine, 200 parts of chitosan organic coating liquid a (wherein the mass parts of each substance in the organic coating liquid a are as follows: 4 parts of chitosan, 4 parts of salicylic acid, 3 parts of boric acid and 189 parts of N, N-dimethylacetamide) are poured into the drum coating machine when the diphenylmethane diisocyanate is uniformly coated on the surface of the granular urea, the chitosan organic coating liquid a is rotated for 5 minutes, so that the coating amount of the fertilizer is about 1wt%, and the coating process is repeated for 5 times, thereby obtaining the chitosan coated urea. Pouring 8 parts of diphenylmethane diisocyanate into a drum coating machine, and when the diphenylmethane diisocyanate is uniformly covered on the surfaces of chitosan coated urea particles, pouring 200 parts of chitosan organic coating liquid b (wherein the organic coating liquid b comprises the following substances in parts by mass; detecting to obtain the double-nutrient chitosan coated urea for the saline-alkali soil, wherein the mass of the inner slow-release layer accounts for 4.9% of the total mass of urea particles and the inner slow-release layer; the mass of the external functional layer accounts for 1.0% of the total mass of the double-nutrient chitosan coated urea for the saline-alkali soil; the iron loading was 0.7% based on the mass of iron in the iron-containing compound.
Fig. 1 is a schematic diagram of a process flow of preparing the dual-nutrient chitosan coated urea for the saline-alkali soil. After the particle urea is preheated, firstly, diphenylmethane diisocyanate is sprayed on the surface of the particle urea at a constant speed, then, chitosan and salicylic acid mixed organic matters are sprayed on the surface of the particle urea at a constant speed, and the particle urea is rotated and dried for 5 minutes to prepare the chitosan coated urea. And spraying diphenylmethane diisocyanate onto the surface of the chitosan coated urea at a constant speed, spraying the mixed organic matters of chitosan, salicylic acid and iron onto the surface of the chitosan coated urea at a constant speed, and finally rotating and drying for 30 minutes to obtain the double-nutrient chitosan coated urea.
SEM, FT-IR scan, XRD test and TGA test were performed on the saline-alkali soil prepared in example 1 by using the dual-nutrient chitosan coated urea. Fig. 2 is a double-layer membrane shell structure of the double-nutrient chitosan coated urea for the saline-alkali soil in example 1. The chitosan, the salicylic acid and the diphenylmethane diisocyanate undergo chemical crosslinking reaction to form a reticular structure, so as to form an internal controlled release layer; the inner controlled release layer is complexed with ferrous chloride to form an iron-containing functional layer. The double-nutrient chitosan coated urea for the saline-alkali soil is divided into an inner functional layer and an outer functional layer, the outer functional layer preferentially releases iron-containing compounds and salicylic acid, ferrous ions replace sodium ions on the surface of a soil colloid, the soil alkalinity is neutralized, calcium carbonate in the soil is dissolved, calcium ions replace the sodium ions on the surface of the soil colloid, and the alkalization degree is reduced. In addition, ferrous ions can promote the formation of soil macro-aggregates and improve the soil structure. The salicylic acid can reduce the content of malondialdehyde in plants, enhance the activity of antioxidase, enhance the salt tolerance and stress resistance of plants, reduce the pH of soil and maintain the activity of ferrous ions. Along with the dissolution of the external functional layer and the degradation of the membrane shell, salicylic acid, chitosan oligosaccharide and iron elements can be slowly released, the stress resistance of crops in the seedling stage is increased, N absorption by plants is promoted, the root system environment of the crops is protected, and the saline-alkali soil is improved.
Fig. 3 is an SEM image of a dual-nutrient chitosan coated urea membrane shell for saline-alkali soil in example 1. As shown in fig. 3 (a), the CS membrane shell surface is dense and smooth, with no fine voids and bubbles. As shown in fig. 3 (b), some wrinkles appear on the cs@mdi membrane shell surface due to MDI crosslinking changing the hydrophilic-hydrophobic properties, surface properties, morphology changes. As shown in fig. 3 (c), cs@mdi@fe membrane shell, after adding Fe to the cs@mdi system, the membrane shell surface wrinkles decreased, and sequential protrusions were formed on the surface, demonstrating that the membrane shell hydrophobic properties decreased after chelating the iron.
FIG. 4 is a FT-IR diagram of a dual nutrient chitosan coated urea membrane shell for saline-alkali soil in example 1. As can be seen from FIG. 4, there is a broad front at 3300-3500cm -1 in (a) due to the stretching vibrations of-NH 2 and-OH. (b) The bandwidth of the band decreases and blue shift occurs because-OH in CS forms-NCOO-with-NCO in MDI. The bending vibration front of-CO-NH at 1310cm -1 occurs in CS because of the amide bond produced by-NH 2 in CS with-OH of Salicylic Acid (SA), while the band is greatly weakened in (c) because of the complexation of the amide bond with iron. Both (a) and (b) present a characteristic peak of the primary amine front (R-NH 2) at 1660cm -1, and this front is diminished in (c) because of coordination with iron. (c) The Fe-O stretching vibration front appears at 590cm -1 and the Cl - characteristic peak appears at 600-700cm -1, which indicates that the film shell has been complexed with iron.
FIG. 5 is an XRD pattern of a dual nutrient chitosan coated urea membrane shell for saline-alkali soil in example 1. As can be seen from fig. 5, (a) a broad diffraction peak occurs near 2θ=20.10°, indicating that CS has a relatively regular lattice, mainly due to the presence of intramolecular or intermolecular hydrogen bonds between the bulk-NH 2 and-OH on CS. This diffraction peak in (b) becomes weaker after introduction of MDI, because the-OH in CS forms-NCOO-with-NCO in MDI and the crosslinking reaction breaks the chitosan ordered structure. After the introduction of iron, the diffraction peak in (c) is further weakened, which is the coordination of iron with-NH 2, -OH and-NCOO-, further breaking the ordered structure of chitosan.
And the thermosensitive property of the double-nutrient chitosan coated urea membrane shell for the saline-alkali soil is evaluated by adopting a thermogravimetric analysis method. The measurement was performed by heating the sample from 25℃to 650 ℃. TGA was heated under nitrogen using Labsys Evo (Setaram, lyon, france) apparatus. The results are shown in fig. 6, where three mass loss stages were observed for each of the three membrane shells. The first stage is due to loss of free water; the second stage is due to thermal cracking and cleavage of C-O and C-C and decomposition of sugar units, resulting in the formation of volatiles; the third stage represents complete degradation and disruption of the network structure. (a) the first stage of decomposition is carried out before the other two membrane shells, the introduction of MDI and CS are crosslinked to form a network structure, and (b) and (c) the overall thermal stability is increased. (c) The highest thermal stability, 50% mass loss temperature 553 ℃, is due to the small amount of iron introduced into the system.
FIG. 7 is a graph of water contact angle and water absorption of a dual nutrient chitosan coated urea film for saline-alkali soil in example 1. Static water contact angle measurements of the three membrane shells were performed using a contact angle meter (WCA, JC2000C2, shanghai). The contact angles of CS@MDI and CS@MDI@Fe film shells are obviously larger than those of CS film materials, namely 93.7 degrees and 82.6 degrees, which shows that the introduction of MDI obviously improves the hydrophobicity of the film shells. Measurement of Water absorption: three membrane shells with certain sizes are prepared, placed in 300mL of deionized water, cultured for 24 hours at the ambient temperature of 25 ℃, taken out of the membrane material and used for removing redundant water on the surface of the membrane shell by using water absorbing paper. The weight of each water-swellable film was recorded and each treatment was repeated three times.
The% water absorption was calculated according to the following formula:
Water absorption (%)= (W2-W1)/W1 × 100%
Where W 1 is the dry shell weight and W 2 is the water-swellable shell weight.
CS, CS@MDI, CS@MDI@Fe membrane shells have water absorption rates of 149%, 10% and 23% respectively after 48h of culture; the results show that the CS film shell of the hydrophobic material absorbs more water, and the CS@MDI and CS@MDI@Fe film shells have enhanced hydrophobicity and reduced water absorption due to the introduction of MDI.
FIG. 8 is a graph showing the N and Fe release curves of the dual nutrient chitosan coated urea for saline-alkali soil in example 1. The release rate of the double-nutrient chitosan coated urea N for the saline-alkali soil in still water is 26% in 24 hours, and the total release period is 144 hours; the release rate of Fe in still water for 8h is 29%, and the total release period is 72h.
2. Application of
1. Salted seed germination
Salt stress seed germination: experiment settings three treatments: CK: no fertilizer is put in; CS@MDI: adding 0.01g of chitosan coated urea; CS@MDI@Fe: and (3) placing 0.01g of double-nutrient chitosan coated urea for saline-alkali soil. NaCl and Na 2SO4 were mixed in a 9:1 molar ratio, and salt stress was set to a total of three treatment concentrations of 80, 120, 160 mmol/L, respectively. Each dish was filled with sterilized and selected 20 full radish seeds (purchased from Tianjin cultivation Co., ltd., sha-nest radish (fruit)), after various treatments (3 replicates per treatment), sufficient water was added to keep the filter paper moist, and then the dish was placed in 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. 9 is an effect of the chitosan coated urea prepared in example 1 and the dual nutrient chitosan coated urea for alkaline land on the emergence rate of radish seeds. As shown in (a) of FIG. 9, after 48 hours, the germination rate difference of the radish seeds is maximum in 160mmol/L environment, wherein the germination rate of the saline-alkali soil treated by the double-nutrient chitosan coated urea is 100+/-0.1% at the maximum and 3.44% higher than CK (96.67+/-1.67%).
Germination of alkali stress seeds: experiment settings three treatments: CK: no fertilizer is put in; CS@MDI: adding 0.01g of chitosan coated urea; CS@MDI@Fe: and (3) placing 0.01g of double-nutrient chitosan coated urea for saline-alkali soil. NaHCO 3 and Na 2CO3 were mixed in a 9:1 molar ratio and salt stress was set to a total of three treatment concentrations of 30, 40, 50mmol/L, respectively. Placing sterilized and selected 20 plump radish seeds into each culture dish, performing different treatments (3 repeats are arranged for each treatment), adding sufficient water to keep the filter paper moist, and then placing the filter paper into a constant-temperature incubator at 25 ℃ for culturing, and timely supplementing water to keep the filter paper moist.
As shown in (b) of FIG. 9, after 48 hours, the germination rate difference of radish seeds in the environment of 50mmol/L is maximum, wherein the germination rate of saline-alkali soil treated by the double-nutrient chitosan coated urea is 100+/-0.1% at the highest, and 15.38% higher than CK (86.67+/-1.67%).
2. Saline-alkali soil improvement evaluation
Four treatments were set up: CK: no fertilizer is applied; u: urea is applied; n: chitosan coated urea; fe: the double-nutrient chitosan coated urea for the saline-alkali soil is applied. Wherein U, N and Fe are applied in an amount of 0.2 g/pot. Samples were taken at 1, 3, 7, 15 and 30 days (3 replicates per treatment) for a total of 30 days. Soil samples from each sampling were air dried naturally and ground with a grinder and leached with deionized water (water to soil volume ratio 5:1).
Determination of pH and EC: taking supernatant of the soil leaching solution, and measuring the pH value by a pH meter (PHSJ-4A, shanghai Lei Ci); the supernatant of the soil leaching solution was taken and the EC value was determined by a conductivity meter (DDS-11A, shanghai Lei Ci).
Determination of water-soluble ions (K +、Ca2+、Na+、Mg2+): the supernatant of the soil leaching solution was measured by inductively coupled plasma atomic emission spectrometry (ICP-OES). Test saline soil was collected in the fine variety farm farmland plough layer soil (37 ° 35 ʹ N,118 ° 35 ʹ E) in Kenli region of eastern camping city of shandong province, soil physicochemical properties before the start of the test: the pH value is 8.60, the EC value is 6.34 mS/cm, the water-soluble potassium content is 64.15 mg/kg, the water-soluble calcium content is 1115.00 mg/kg, the water-soluble sodium content is 1419.25 mg/kg, and the water-soluble magnesium content is 487.65 mg/kg.
The results are shown in FIG. 10, which shows the effect of the dual nutrient chitosan coated urea for saline-alkali soil prepared in example 1 on soil pH and EC, as shown in (a) of FIG. 10, the Fe treated soil pH was the lowest (8.30.+ -. 0.03), less than 3.49% for CK (8.60.+ -. 0.02), and less than 4.71% for U treatment (8.71.+ -. 0.07). As in (b) of FIG. 9, the Fe treated soil has the lowest EC (5.25.+ -. 0.13 mS/cm) which is 19.72% lower than the CK (6.54.+ -. 0.24 mS/cm).
The results are shown in FIG. 11, which shows the effect of the dual nutrient chitosan coated urea for saline-alkali soil prepared in example 1 on soil salt ion, as shown in (a) in FIG. 11, the Fe treated soil K + is lowest (50.80 + -1.00 mg/kg), and is lower than CK (82.65 + -7.10 mg/kg) 38.54%. As shown in FIG. 11 (b), the Fe treated soil Ca 2+ was lowest (988.05.+ -. 34.75 mg/kg) and was 31.48% lower than CK (1442.00.+ -. 7.50 mg/kg). As in (c) of FIG. 11, the Fe treated soil Na + was lowest (1472.50.+ -. 62.75 mg/kg) and was 20.49% lower than CK (1852.00.+ -. 96.50 mg/kg). As shown in FIG. 11 (d), the Fe treated soil Mg 2+ was lowest (350.65.+ -. 35.25 Mg/kg) and was 35.09% lower than CK (540.25.+ -. 40.75 Mg/kg).
Example 2
Dissolving N-carboxymethyl chitosan, salicylic acid and boric acid in N, N-dimethylacetamide, and stirring at 400rpm and 60 ℃ until the materials are completely dissolved, thus preparing the chitosan organic coating liquid a. Mixing ferric chloride with the chitosan organic coating liquid a, and stirring at 400rpm and 30 ℃ until the materials are completely dissolved, so as to prepare the chitosan organic coating liquid b. 500 parts of granular urea are poured into a drum coater and preheated for 15 minutes at 80 ℃. And (3) respectively setting the temperature and the rotating speed of a drum coating machine to 70 ℃ and 40rpm, pouring 10 parts of toluene diisocyanate into the drum coating machine, and when the toluene diisocyanate is uniformly covered on the surface of the granular urea, pouring 200 parts of chitosan organic coating liquid a (wherein the mass parts of each substance in the organic coating liquid a are as follows, 4 parts of chitosan, 4 parts of salicylic acid, 3 parts of boric acid and 189 parts of N, N-dimethylacetamide) into the drum coating machine, and rotating for 3 minutes to ensure that the chitosan organic coating liquid a is uniformly covered on the surface of the granular urea, wherein the coating rate of the fertilizer is about 1%, and repeating the coating process for 7 times to obtain the chitosan coated urea. And pouring 10 parts of toluene diisocyanate into a drum coating machine, and when the toluene diisocyanate is uniformly covered on the surfaces of chitosan coated urea particles, pouring 200 parts of chitosan organic coating liquid b (wherein the organic coating liquid b comprises the following substances in parts by mass. Detecting to obtain the double-nutrient chitosan coated urea for the saline-alkali soil, wherein the mass of the inner slow-release layer accounts for 5.9% of the total mass of urea particles and the inner slow-release layer; the mass of the external functional layer accounts for 1.0% of the total mass of the double-nutrient chitosan coated urea for the saline-alkali soil; the iron loading was 0.8% based on the mass of iron in the iron-containing compound.
The same fertilizer release experiment as in example 1 was performed on the saline-alkali soil prepared in example 2 with the dual-nutrient chitosan coated urea. The release rate of N in still water is 19% in 24 hours, and the total release period is 168 hours; the release rate of Fe in still water for 8h is 29%, and the total release period is 72h.
Example 3
Dissolving maleic acid chitosan, salicylic acid and boric acid in N, N-dimethylacetamide, and stirring at 400rpm and 60 ℃ until the materials are completely dissolved, thus preparing the chitosan organic coating liquid a. Mixing ferrous sulfate with the chitosan organic coating liquid a, and stirring at 400rpm and 30 ℃ until the materials are completely dissolved, so as to prepare the chitosan organic coating liquid b. 500 parts of granular urea are poured into a drum coater and preheated at a temperature of 75℃for 15 minutes. The temperature and the rotating speed of a drum coating machine are respectively set to 50 ℃ and 60rpm, 10 parts of hexamethylene diisocyanate are poured into the drum coating machine, when the hexamethylene diisocyanate is uniformly covered on the surface of the granular urea, 200 parts of chitosan organic coating liquid a (wherein the mass parts of each substance in the organic coating liquid a are as follows: 4 parts of chitosan, 4 parts of salicylic acid, 3 parts of boric acid and 189 parts of N, N-dimethylacetamide) are poured into the drum coating machine, and the drum coating machine rotates for 3 minutes, so that the chitosan organic coating liquid a is uniformly covered on the surface of the granular urea, and the coating rate of the fertilizer is about 1%, and the coating process is repeated for 3 times, thereby obtaining the chitosan coated urea. And pouring 10 parts of hexamethylene diisocyanate into a drum coating machine, and when the hexamethylene diisocyanate is uniformly covered on the surfaces of the obtained chitosan coated urea particles, pouring 200 parts of chitosan organic coating liquid b (wherein the organic coating liquid b comprises the following substances in parts by mass. Detecting to obtain the double-nutrient chitosan coated urea for the saline-alkali soil, wherein the mass of the inner slow-release layer accounts for 2.5% of the total mass of urea particles and the inner slow-release layer; the mass of the external functional layer accounts for 1.0% of the total mass of the double-nutrient chitosan coated urea for the saline-alkali soil; the iron loading was 0.8% based on the mass of iron in the iron-containing compound.
The same fertilizer release experiment as in example 1 was performed on the saline-alkali soil prepared in example 3 with the dual-nutrient chitosan coated urea. The release rate of N in still water is 29% by measurement, and the total release period is 96h; the release rate of Fe in still water for 8 hours is 71%, and the total release period is 48 hours.
Example 4
Chitosan (viscosity >400 mpa.s), salicylic acid and boric acid are dissolved in N, N-dimethylacetamide, and the mixture is stirred at 400rpm and 60 ℃ until the materials are completely dissolved, so as to prepare the chitosan organic coating liquid a. Mixing ferrous acetate with the chitosan organic coating liquid a, and stirring at 400rpm and 30 ℃ until the materials are completely dissolved, so as to prepare the chitosan organic coating liquid b. 500 parts of granular urea are poured into a drum coater and preheated for 15 minutes at 80 ℃. And (3) setting the temperature and the rotating speed of a drum coating machine to 60 ℃ and 60rpm respectively, pouring 10 parts of xylylene diisocyanate into the drum coating machine, and pouring 200 parts of chitosan organic coating liquid a into the drum coating machine when the xylylene diisocyanate is uniformly coated on the surface of the granular urea, and rotating for 4 minutes to uniformly coat the chitosan organic coating liquid a (wherein the mass parts of each substance in the organic coating liquid a are as follows: 4 parts of chitosan, 4 parts of salicylic acid, 3 parts of boric acid and 189 parts of N, N-dimethylacetamide) on the surface of the granular urea, and the coating rate of the fertilizer is about 1% at the moment, so as to obtain the chitosan coated urea. And pouring 10 parts of xylylene diisocyanate into a drum coating machine, and when the xylylene diisocyanate is uniformly covered on the surfaces of chitosan coated urea particles, pouring 200 parts of chitosan organic coating liquid b (wherein the mass parts of each substance in the organic coating liquid b are as follows: 4 parts of chitosan, 4 parts of salicylic acid, 3 parts of boric acid, 20 parts of ferrous acetate and 169 parts of N, N-dimethylacetamide) into the drum coating machine, and drying for 20 minutes to obtain the double-nutrient chitosan coated urea for the saline-alkali soil. Detecting to obtain the double-nutrient chitosan coated urea for the saline-alkali soil, wherein the mass of the inner slow-release layer accounts for 1.0% of the total mass of urea particles and the inner slow-release layer; the mass of the external functional layer accounts for 1.0% of the total mass of the double-nutrient chitosan coated urea for the saline-alkali soil; the iron loading was 0.7% based on the mass of iron in the iron-containing compound.
The same fertilizer release experiment as in example 1 was performed on the saline-alkali soil prepared in example 4 with the dual-nutrient chitosan coated urea. The release rate of N in still water is 43% in 24 hours, and the total release period is 96 hours; the release rate of Fe in still water for 8 hours is 89%, and the total release period is 24 hours.
Example 5 salicylic acid dosage screening experiments
The same procedure as in example 1 for the preparation of the chitosan organic coating solution was followed, except that the amount of salicylic acid was changed: 4 parts of chitosan (viscosity <200 mpa.s), 3 parts of boric acid in N, N-dimethylacetamide (189 parts); salicylic acid is added according to three concentrations of low (2 parts), medium (4 parts) and high (8 parts), wherein the low-concentration salicylic acid can not dissolve chitosan, so that the preparation of the chitosan organic coating liquid fails; high concentration salicylic acid, although capable of dissolving chitosan faster, generates a lot of bubbles after reacting with the crosslinking agent, and the crosslinking speed during the coating process is too fast, resulting in non-uniform coating, as shown in fig. 12 (a, b).
According to the salicylic acid dosage screening experiment, when the mass ratio of chitosan to salicylic acid is close to 1:1, the mechanical strength, the extensibility and the crosslinking speed of the chitosan MDI membrane shell are optimal, and the chitosan double-nutrient chitosan coated urea can be prepared well, as shown in fig. 12 (c and d).
Claims (10)
1. The double-nutrient chitosan coated urea for the saline-alkali soil is characterized in that: the double-nutrient chitosan coated urea for the saline-alkali soil consists of urea particles, an inner slow-release layer and an outer functional layer;
The inner slow release layer and the outer functional layer are sequentially coated on the surface of the urea particles;
the inner slow release layer is prepared from raw materials comprising an organic high polymer material, salicylic acid, boric acid and an organic cross-linking agent;
The outer functional layer is made of a raw material including the inner slow-release layer and an iron-containing compound.
2. The dual nutrient chitosan coated urea for saline-alkali soil according to claim 1, wherein: the mass of the inner slow release layer accounts for 1% -7% of the total mass of the urea particles and the inner slow release layer;
the mass of the external functional layer accounts for 0.7% -1% of the total mass of the dual-nutrient chitosan coated urea for the saline-alkali soil;
In the double-nutrient chitosan coated urea for the saline-alkali soil, the load of the iron-containing compound is 0.7% -0.8%, and the load is calculated by the mass of iron in the iron-containing compound.
3. The dual nutrient chitosan coated urea for saline-alkali soil according to claim 1, wherein: the organic polymer material is chitosan and/or chitosan derivatives;
The organic cross-linking agent is selected from at least one of diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4, 4' -diisocyanate and xylylene diisocyanate;
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.
4. The dual nutrient chitosan coated urea for saline-alkali soil according to claim 1, wherein: the inner slow release layer is prepared from the following raw materials in parts by mass: 4-28 parts of organic polymer material, 3.5-28 parts of salicylic acid, 3-21 parts of boric acid and 8-70 parts of organic cross-linking agent;
The external functional layer is prepared from the following raw materials in parts by mass: 4 parts of organic high polymer material, 3.5-4 parts of salicylic acid, 3 parts of boric acid, 8-10 parts of organic cross-linking agent and 20-30 parts of iron-containing compound;
the mass ratio of the organic polymer material to the salicylic acid is 1:0.9-1.
5. The preparation method of the double-nutrient chitosan coated urea for the saline-alkali soil, which is disclosed by any one of claims 1 to 4, comprises the following steps:
(1) Mixing the organic polymer material, salicylic acid, boric acid and an organic solvent to form an organic phase a;
(2) Mixing the iron-containing compound with the organic phase a to form an organic phase b;
(3) Pouring the urea granules into a drum coating machine, and preheating;
(4) Spraying the organic cross-linking agent on the surfaces of the urea particles at a constant speed, and spraying the organic phase a on the surfaces of the urea particles at a constant speed when the organic cross-linking agent is uniformly covered on the surfaces of the urea particles to obtain chitosan coated urea;
(5) And uniformly spraying the organic cross-linking agent on the surface of the chitosan coated urea, and uniformly spraying the organic phase b on the surface of the chitosan coated urea when the organic cross-linking agent is uniformly covered on the surface of the chitosan coated urea, so as to obtain the double-nutrient chitosan coated urea for the saline-alkali soil.
6. The method of manufacturing according to claim 5, wherein: in the step (4), 500 parts by mass of urea particles are prepared from the following raw materials in parts by mass: 4 parts of organic polymer material, 3.5-4 parts of salicylic acid, 3 parts of boric acid, 8-10 parts of organic cross-linking agent and 150-200 parts of organic solvent;
In the step (5), 500 parts by mass of urea particles are prepared from the following raw materials in parts by mass: 4 parts of organic high polymer material, 3.5-4 parts of salicylic acid, 3 parts of boric acid, 8-10 parts of organic cross-linking agent, 20-30 parts of iron-containing compound and 150-180 parts of organic solvent;
the operation of the step (4) is repeated for 1 to 7 times.
7. The method of manufacturing according to claim 5, wherein: in the step (3), the preheating temperature is 70-80 ℃ and the preheating time is 15-20 min.
8. The method of manufacturing according to claim 5, wherein: in the steps (4) and (5), the coating rotating speed is 40-70 rpm, and the temperature is 50-80 ℃.
9. The method of manufacturing according to claim 5, wherein: in the step (5), the organic phase b is sprayed on the surface of the chitosan coated urea at a constant speed, and then the step of drying is carried out.
10. Use of the dual nutrient chitosan coated urea for saline-alkali soil as defined in any one of claims 1-4 in any one of the following applications:
1) Improving the saline-alkali soil;
2) Increasing the stress resistance of crops in seedling stage;
3) Promoting the crop to absorb N;
4) Protecting the root system environment of crops;
5) In the saline-alkali soil environment, root and seedling are promoted in the seedling stage of crops.
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| WO2023126895A1 (en) * | 2021-12-31 | 2023-07-06 | Sabic Global Technologies B.V. | Nano bio-carrier with plant additives coated on chemical fertilizers |
| CN116751090A (en) * | 2023-07-03 | 2023-09-15 | 中国农业大学 | PH responsive controlled-release iron fertilizer and preparation method thereof |
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