Preparation method and application of saline-alkali soil improvement fertilizer

Abstract

The invention relates to the technical field of soil improvement, and discloses a preparation method and application of a saline-alkali soil improvement fertilizer. The saline-alkali soil improvement fertilizer sequentially comprises acorus calamus-gypsum particles, a humic acid loaded activated carbon coating layer and a chitosan coating layer from inside to outside. The saline-alkali soil improvement fertilizer provided by the invention can effectively reduce the salt content and pH value of saline-alkali soil, and can effectively improve the organic matter content and total nitrogen content of the saline-alkali soil. The saline-alkali soil improvement fertilizer provided by the invention can effectively inhibit salt and alkali return of saline-alkali soil.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of soil improvement, in particular to a preparation method and application of a saline-alkali soil improvement fertilizer. BACKGROUND

[0002] The high salt content and high pH value environment of the saline-alkali soil can cause the soil structure to deteriorate and the aggregate structure to be destroyed, and further affect the soil air permeability and water and fertilizer retention capacity; meanwhile, the excessive salt content can also cause ion toxicity and osmotic stress to plants, hinder the normal water absorption and nutrient absorption of the plant roots, and cause the crops to grow poorly, reduce yield or even be absolutely barren, and seriously restrict the sustainable development of agriculture.

[0003] Therefore, the saline-alkali soil improvement fertilizer becomes a technical problem to be solved by those skilled in the art. SUMMARY

[0004] The application aims to provide a preparation method and application of a saline-alkali soil improvement fertilizer.

[0005] To achieve the above object, the application provides the following technical scheme. One of the technical schemes of the application is as follows: A saline-alkali soil improvement fertilizer comprises, from inside to outside, a Acorus calamus-gypsum particle, a humic acid loaded activated carbon coating layer and a chitosan coating layer.

[0006] Another of the technical schemes of the application is as follows: The preparation method of the saline-alkali soil improvement fertilizer comprises the following steps. 1. Preparing an Acorus calamus-gypsum particle; 2. Forming a humic acid loaded activated carbon coating layer on the surface of the Acorus calamus-gypsum particle obtained in step 1; 3. Forming a chitosan coating layer on the surface of the humic acid loaded activated carbon coating layer formed in step 2 to obtain the saline-alkali soil improvement fertilizer.

[0007] Further, the preparation of the Acorus calamus-gypsum particle specifically comprises the following steps. 1. Mixing Acorus calamus and a straw composting agent, composting to obtain composted Acorus calamus; 2. Mixing the composted Acorus calamus obtained in step 1 with desulfurized gypsum, grinding, sieving, compacting to obtain the Acorus calamus-gypsum particle.

[0008] Further, in step 1, the mass ratio of the Acorus calamus to the straw composting agent is (10-20):1.

[0009] Further, in step 1, the composting is specifically carried out at 60-80 DEG C for 1-2 h.

[0010] Further, in step 2), the mass ratio of the Acorus calamus and the desulfurized gypsum is 1: (0.4-0.6).

[0011] Further, the forming of the humic acid loaded activated carbon coating layer specifically comprises the following steps: 1) placing the Acorus calamus-gypsum particles obtained in step 1) in a glucose solution to perform a hydrothermal reaction, thereby obtaining carbon-coated Acorus calamus-gypsum particles; 2) mixing a Ca(OH)2 solution and a ZnCl2 solution to obtain an etching solution; 3) placing the carbon-coated Acorus calamus-gypsum particles obtained in step 1) in the etching solution obtained in step 2) to perform etching, thereby obtaining activated carbon-coated Acorus calamus-gypsum particles; 4) placing the activated carbon-coated Acorus calamus-gypsum particles obtained in step 3) in a sodium humate solution to perform adsorption, thereby obtaining humic acid loaded activated carbon-coated Acorus calamus-gypsum particles, i.e. forming a humic acid loaded activated carbon coating layer on the surface of the Acorus calamus-gypsum particles.

[0012] Further, in step 1), the concentration of the glucose solution is 1-3 mol / L.

[0013] Further, in step 1), the mass-to-volume ratio of the Acorus calamus-gypsum particles and the glucose solution is 1 g: (5-15) mL.

[0014] Further, in step 1), the hydrothermal reaction is specifically performed at 140-160°C for 24-48 h.

[0015] Further, in step 2), the volume ratio of the Ca(OH)2 solution and the ZnCl2 solution is 1:1.

[0016] Further, in step 2), the concentration of the Ca(OH)2 solution is 0.05 mol / L.

[0017] Further, in step 2), the concentration of the ZnCl2 solution is 0.1 mol / L.

[0018] Further, in step 3), the mass-to-volume ratio of the carbon-coated Acorus calamus-gypsum particles and the etching solution is 1 g: (5-15) mL.

[0019] Further, in step 3), the etching is specifically performed at 300-400°C for 20-40 min.

[0020] Further, in step 4), the mass-to-volume ratio of the activated carbon-coated Acorus calamus-gypsum particles and the sodium humate solution is 1 g: (5-15) mL.

[0021] Further, in the step 4), the adsorbing is specifically: adsorbing for 6-12 hours at room temperature.

[0022] Further, the forming of the chitosan coating layer specifically comprises the following steps: The humic acid loaded activated carbon coated Acorus calamus-paste particles obtained in the step 2 are placed in a chitosan solution to form a chitosan coating layer on the surface of the humic acid loaded activated carbon coating layer formed in the step 2, thereby obtaining the saline-alkali soil improvement fertilizer.

[0023] Further, the concentration of the chitosan solution is 20-40 mg / mL.

[0024] Further, the mass-volume ratio of the humic acid loaded activated carbon coated Acorus calamus-paste particles and the chitosan solution is 1 g:(5-15) mL.

[0025] Further, the adsorbing is specifically: adsorbing for 1-3 hours at room temperature.

[0026] The third technical solution of the present application is: The above-mentioned saline-alkali soil improvement fertilizer is applied in the improvement of saline-alkali soil.

[0027] Further, the application is specifically: the saline-alkali soil improvement fertilizer is applied on the surface of the saline-alkali soil in an application amount of 10-30 g / m 2 , and the ploughing depth is controlled to be 10 cm to plough the saline-alkali soil.

[0028] Compared with the prior art, the present application has the following beneficial effects: The saline-alkali soil improvement fertilizer provided by the present application can effectively reduce the salt content and pH value of the saline-alkali soil, and can effectively increase the organic matter content and total nitrogen content of the saline-alkali soil.

[0029] The saline-alkali soil improvement fertilizer provided by the present application can effectively inhibit the salt and alkali return of the saline-alkali soil. BRIEF DESCRIPTION OF DRAWINGS

[0030] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of preferred embodiments, and are not meant to limit the present application. Furthermore, the same reference numerals are used throughout the several views to denote the same or similar parts. In the drawings: Figure 1 The cross-sectional structure of the saline-alkali soil improvement fertilizer provided by the present application is shown in the figure. DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0032] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] In the following examples and comparative examples, all raw materials used were commercially available. The straw composting agent was an organic fertilizer composting agent purchased from Shandong Yixiou Biotechnology Co., Ltd., and the desulfurized gypsum was a hemihydrate desulfurized gypsum powder purchased from Hebei Yousheng Refractory Materials Co., Ltd.

[0037] The following embodiments illustrate a method for preparing a fertilizer for improving saline-alkali land, comprising the following steps: 1. Preparation of Acorus calamus-gypsum granules 1) Mix calamus and straw composting agent at a mass ratio of (10-20):1 and compost at 60-80℃ for 1-2 hours to obtain composted calamus; 2) mixing the rotten alocasia and desulfurized gypsum obtained in step 1) according to a mass ratio of the rotten alocasia to the desulfurized gypsum of 1: (0.4-0.6), grinding, passing through an 80-mesh sieve, and compacting under 200 Kpa to obtain the alocasia-gypsum granules; 2, forming a humic acid loaded activated carbon coating layer 1) placing the alocasia-gypsum granules obtained in step 1 into a glucose solution with a concentration of 1-3 mol / L according to a mass-volume ratio of the alocasia-gypsum granules to the glucose solution of 1 g: (5-15) mL, and hydrothermally reacting at 140-160 DEG C for 24-48 h to obtain carbon layer coated alocasia-gypsum granules; 2) mixing a Ca(OH)2 solution with a concentration of 0.05 mol / L and a ZnCl2 solution with a concentration of 0.1 mol / L according to a volume ratio of the Ca(OH)2 solution to the ZnCl2 solution of 1:1 to obtain an etching solvent; 3) placing the carbon layer coated alocasia-gypsum granules obtained in step 1 into the etching solvent obtained in step 2 according to a mass-volume ratio of the carbon layer coated alocasia-gypsum granules to the etching solvent of 1 g: (5-15) mL, and etching at 300-400 DEG C for 20-40 min to obtain activated carbon coated alocasia-gypsum granules; 4) placing the activated carbon coated alocasia-gypsum granules obtained in step 3 into a sodium humate solution with a concentration of 2 g / L according to a mass-volume ratio of the activated carbon coated alocasia-gypsum granules to the sodium humate solution of 1 g: (5-15) mL, and adsorbing at room temperature for 6-12 h to obtain humic acid loaded activated carbon coated alocasia-gypsum granules, i.e., a humic acid loaded activated carbon coating layer is formed on the surface of the alocasia-gypsum granules; 3, forming a chitosan coating layer placing the humic acid loaded activated carbon coated alocasia-gypsum granules obtained in step 2 into a chitosan solution with a concentration of 20-40 mg / mL according to a mass-volume ratio of the humic acid loaded activated carbon coated alocasia-gypsum granules to the chitosan solution of 1 g: (5-15) mL, and complexing at room temperature for 1-3 h to form a chitosan coating layer on the surface of the humic acid loaded activated carbon coating layer formed in step 2, thereby obtaining the saline-alkali soil improvement fertilizer.

[0038] The saline-alkali soil improvement fertilizer provided by the application has a cross-sectional structure as shown in Figure 1 .

[0039] Example 1 A saline-alkali soil improvement fertilizer 1, preparation of alocasia-gypsum granules 1) mixing alocasia and straw composting agent according to a mass ratio of 10:1, and composting at 60 DEG C for 1 h to obtain rotten alocasia; 2) The rotten Acorus calamus and desulfurized gypsum obtained in step 1) are mixed according to a mass ratio of 1:0.4, ground, passed through an 80-mesh sieve, and compacted under a pressure of 200 Kpa to obtain the Acorus calamus-gypsum particles with a particle size of about 1 mm; 2. Forming a humic acid-loaded activated carbon coating layer 1) The Acorus calamus-gypsum particles obtained in step 1 are placed in a glucose solution with a concentration of 1 mol / L according to a mass-to-volume ratio of 1 g:5 mL, and subjected to hydrothermal reaction at 140°C for 24 h to obtain carbon-coated Acorus calamus-gypsum particles; 2) A Ca(OH)2solution with a concentration of 0.05 mol / L and a ZnCl2solution with a concentration of 0.1 mol / L are mixed according to a volume ratio of 1:1 to obtain an etching solution; 3) The carbon-coated Acorus calamus-gypsum particles obtained in step 1 are placed in the etching solution obtained in step 2 according to a mass-to-volume ratio of 1 g:5 mL, and etched at 300°C for 20 min to obtain activated carbon-coated Acorus calamus-gypsum particles; 4) The activated carbon-coated Acorus calamus-gypsum particles obtained in step 3 are placed in a sodium humate solution with a concentration of 2 g / L according to a mass-to-volume ratio of 1 g:5 mL, and adsorbed at room temperature for 6 h to obtain humic acid-loaded activated carbon-coated Acorus calamus-gypsum particles, i.e., a humic acid-loaded activated carbon coating layer is formed on the surface of the Acorus calamus-gypsum particles, with a layer thickness of about 0.5 mm; 3. Forming a chitosan coating layer The humic acid-loaded activated carbon-coated Acorus calamus-gypsum particles obtained in step 2 are placed in a chitosan solution with a concentration of 20 mg / mL according to a mass-to-volume ratio of 1 g:5 mL, and inclusions are formed at room temperature for 1 h to form a chitosan coating layer on the surface of the humic acid-loaded activated carbon coating layer formed in step 2, with a layer thickness of about 0.5 mm, thereby obtaining the saline-alkali soil improvement fertilizer.

[0040] Example 2 A saline-alkali soil improvement fertilizer 1. Preparation of Acorus calamus-gypsum particles 1) Acorus calamus and straw composting agent are mixed according to a mass ratio of 15:1, and subjected to composting at 70°C for 1.5 h to obtain rotten Acorus calamus; 2) The rotten Acorus calamus obtained in step 1 and desulfurized gypsum are mixed according to a mass ratio of 1:0.5, ground, passed through an 80-mesh sieve, and compacted under a pressure of 200 Kpa to obtain the Acorus calamus-gypsum particles with a particle size of about 1 mm; 2. Forming a humic acid loaded activated carbon coating layer 1) According to the mass-volume ratio of alocasia-paste particle and glucose solution being 1 g: 10 mL, the alocasia-paste particle obtained in step 1 is placed in a glucose solution with a concentration of 2 mol / L, and hydrothermal reaction is carried out at 150°C for 36 h to obtain carbon-coated alocasia-paste particles; 2) According to the volume ratio of Ca(OH)2 solution and ZnCl2 solution being 1:1, a Ca(OH)2 solution with a concentration of 0.05 mol / L and a ZnCl2 solution with a concentration of 0.1 mol / L are mixed to obtain an etching solution; 3) According to the mass-volume ratio of carbon-coated alocasia-paste particles and etching solution being 1 g: 10 mL, the carbon-coated alocasia-paste particles obtained in step 1) are placed in the etching solution obtained in step 2), and etching is carried out at 350°C for 30 min to obtain activated carbon-coated alocasia-paste particles; 4) According to the mass-volume ratio of activated carbon-coated alocasia-paste particles and humic acid sodium solution being 1 g: 10 mL, the activated carbon-coated alocasia-paste particles obtained in step 3) are placed in a humic acid sodium solution with a concentration of 2 g / L, and adsorption is carried out at room temperature for 8 h to obtain humic acid loaded activated carbon-coated alocasia-paste particles, i.e. a humic acid loaded activated carbon coating layer is formed on the surface of the alocasia-paste particles, and the layer thickness is about 0.5 mm; 3. Forming a chitosan coating layer According to the mass-volume ratio of humic acid loaded activated carbon coated alocasia-paste particles and chitosan solution being 1 g: 10 mL, the humic acid loaded activated carbon coated alocasia-paste particles obtained in step 2 are placed in a chitosan solution with a concentration of 30 mg / mL, and inclusion is carried out at room temperature for 2 h to form a chitosan coating layer on the surface of the humic acid loaded activated carbon coating layer formed in step 2, and the layer thickness is about 0.5 mm, thereby obtaining the saline-alkali soil improvement fertilizer.

[0041] Example 3 A saline-alkali soil improvement fertilizer 1. Preparation of alocasia-paste particles 1) According to the mass ratio of alocasia and straw composting agent being 20:1, the alocasia and straw composting agent are mixed, composting is carried out at 80°C for 2 h, and composted alocasia is obtained; 2) According to the mass ratio of composted alocasia and desulfurized gypsum being 1:0.6, the composted alocasia obtained in step 1) and the desulfurized gypsum are mixed, ground, and passed through a 80-mesh sieve, and compaction is carried out at 200 Kpa to obtain the alocasia-paste particles, and the particle size is about 1 mm; 2. Forming a humic acid loaded activated carbon coating layer 1) According to the mass-volume ratio of the Acorus calamus-gypsum particles and the glucose solution being 1 g: 15 mL, the Acorus calamus-gypsum particles obtained in step 1 were placed in a glucose solution with a concentration of 3 mol / L, and hydrothermal reaction was carried out at 160°C for 48 h to obtain carbon layer coated Acorus calamus-gypsum particles; 2) According to the volume ratio of the Ca(OH)2 solution and the ZnCl2 solution being 1:1, a Ca(OH)2 solution with a concentration of 0.05 mol / L and a ZnCl2 solution with a concentration of 0.1 mol / L were mixed to obtain an etching solution; 3) According to the mass-volume ratio of the carbon layer coated Acorus calamus-gypsum particles and the etching solution being 1 g: 15 mL, the carbon layer coated Acorus calamus-gypsum particles obtained in step 1 were placed in the etching solution obtained in step 2, and etching was carried out at 400°C for 40 min to obtain active carbon coated Acorus calamus-gypsum particles; 4) According to the mass-volume ratio of the active carbon coated Acorus calamus-gypsum particles and the sodium humate solution being 1 g: 15 mL, the active carbon coated Acorus calamus-gypsum particles obtained in step 3 were placed in a sodium humate solution with a concentration of 2 g / L, and adsorption was carried out at room temperature for 12 h to obtain humic acid loaded active carbon coated Acorus calamus-gypsum particles, i.e. a humic acid loaded active carbon coating layer was formed on the surface of the Acorus calamus-gypsum particles, and the layer thickness was about 0.5 mm; 3, forming a chitosan coating layer According to the mass-volume ratio of the humic acid loaded active carbon coated Acorus calamus-gypsum particles and the chitosan solution being 1 g: 15 mL, the humic acid loaded active carbon coated Acorus calamus-gypsum particles obtained in step 2 were placed in a chitosan solution with a concentration of 40 mg / mL, and inclusion was carried out at room temperature for 3 h to form a chitosan coating layer on the surface of the humic acid loaded active carbon coating layer formed in step 2, and the layer thickness was about 0.5 mm, thereby obtaining the saline-alkali soil improvement fertilizer.

[0042] Comparative Example 1 A saline-alkali soil improvement fertilizer 1, preparation of corn straw-gypsum particles 1) According to the mass ratio of corn straw and straw composting agent being 15:1, corn straw and straw composting agent were mixed, and composting was carried out at 70°C for 1.5 h to obtain composted corn straw; 2) According to the mass ratio of the composted corn straw and the desulfurized gypsum being 1:0.5, the composted corn straw obtained in step 1 and the desulfurized gypsum were mixed, ground, and sieved through an 80 mesh sieve, and then compacted at 200 Kpa to obtain the corn straw-gypsum particles with a particle size of about 1 mm; 2, forming a humic acid loaded active carbon coating layer 1) According to the mass-volume ratio of corn straw-gypsum particles and glucose solution being 1 g: 10 mL, the corn straw-gypsum particles obtained in step 1 were placed in a glucose solution with a concentration of 2 mol / L, and hydrothermal reaction was carried out at 150°C for 36 h to obtain carbon layer coated corn straw-gypsum particles; 2) According to the volume ratio of Ca(OH)2solution and ZnCl2solution being 1:1, a Ca(OH)2solution with a concentration of 0.05 mol / L and a ZnCl2solution with a concentration of 0.1 mol / L were mixed to obtain an etching solvent; 3) According to the mass-volume ratio of carbon layer coated corn straw-gypsum particles and etching solvent being 1 g: 10 mL, the carbon layer coated corn straw-gypsum particles obtained in step 1 were placed in the etching solvent obtained in step 2, and etching was carried out at 350°C for 30 min to obtain active carbon coated corn straw-gypsum particles; 4) According to the mass-volume ratio of active carbon coated corn straw-gypsum particles and sodium humate solution being 1 g: 10 mL, the active carbon coated corn straw-gypsum particles obtained in step 3 were placed in a sodium humate solution with a concentration of 2 g / L, and adsorption was carried out at room temperature for 8 h to obtain humic acid loaded active carbon coated corn straw-gypsum particles, i.e. a humic acid loaded active carbon coating layer was formed on the surface of the corn straw-gypsum particles, and the layer thickness was about 0.5 mm; 3, forming a chitosan coating layer According to the mass-volume ratio of humic acid loaded active carbon coated corn straw-gypsum particles and chitosan solution being 1 g: 10 mL, the humic acid loaded active carbon coated corn straw-gypsum particles obtained in step 2 were placed in a chitosan solution with a concentration of 30 mg / mL, and complexation was carried out at room temperature for 2 h to form a chitosan coating layer on the surface of the humic acid loaded active carbon coating layer formed in step 2, and the layer thickness was about 0.5 mm, thereby obtaining the saline-alkali soil improvement fertilizer.

[0043] Comparative Example 2 A saline-alkali soil improvement fertilizer 1, preparation of a alocasia-gypsum particle According to the mass ratio of alocasia and desulfurized gypsum being 1:0.5, the alocasia and desulfurized gypsum were mixed, ground, and sieved through an 80 mesh sieve, and then compacted at 200 Kpa to obtain the alocasia-gypsum particles, and the particle size was about 1 mm; 2, forming a humic acid loaded active carbon coating layer 1) According to the mass-volume ratio of alocasia-gypsum particles and glucose solution being 1 g: 10 mL, the alocasia-gypsum particles obtained in step 1 were placed in a glucose solution with a concentration of 2 mol / L, and hydrothermal reaction was carried out at 150°C for 36 h to obtain carbon layer coated alocasia-gypsum particles; 2) Ca(OH)2solution and ZnCl2solution were mixed in a volume ratio of 1:1, with the concentration of Ca(OH)2solution being 0.05 mol / L and the concentration of ZnCl2solution being 0.1 mol / L, to obtain the etching solvent; 3) The carbon layer coated Acorus calamus-particle was placed in the etching solvent obtained in step 2, and etched at 350°C for 30 min, with the mass-volume ratio of the carbon layer coated Acorus calamus-particle and the etching solvent being 1 g:10 mL, to obtain the activated carbon coated Acorus calamus-particle; 4) The activated carbon coated Acorus calamus-particle obtained in step 3 was placed in a 2 g / L sodium humate solution, and adsorbed at room temperature for 8 h, with the mass-volume ratio of the activated carbon coated Acorus calamus-particle and the sodium humate solution being 1 g:10 mL, to obtain the activated carbon coated Acorus calamus-particle loaded with humic acid, i.e. a humic acid loaded activated carbon coating layer was formed on the surface of the Acorus calamus-particle, with the layer thickness being about 0.5 mm; 3, forming a chitosan coating layer The activated carbon coated Acorus calamus-particle loaded with humic acid obtained in step 2 was placed in a 30 mg / mL chitosan solution, and complexed at room temperature for 2 h, with the mass-volume ratio of the activated carbon coated Acorus calamus-particle loaded with humic acid and the chitosan solution being 1 g:10 mL, to form a chitosan coating layer on the surface of the humic acid loaded activated carbon coating layer formed in step 2, with the layer thickness being about 0.5 mm, thereby obtaining the saline-alkali soil improvement fertilizer.

[0044] Comparative Example 3 A saline-alkali soil improvement fertilizer 1, preparation of Acorus calamus particles Acorus calamus and straw composting agent were mixed in a mass ratio of 15:1, and composted at 70°C for 1.5 h to obtain composted Acorus calamus, which was ground, sieved through an 80 mesh sieve, and compacted at 200 Kpa to obtain the Acorus calamus particles, with the particle size being about 1 mm; 2, forming a humic acid loaded activated carbon coating layer 1) The Acorus calamus particles obtained in step 1 were placed in a 2 mol / L glucose solution, and hydrothermally reacted at 150°C for 36 h, with the mass-volume ratio of the Acorus calamus particles and the glucose solution being 1 g:10 mL, to obtain the carbon layer coated Acorus calamus particles; 2) Ca(OH)2solution and ZnCl2solution were mixed in a volume ratio of 1:1, with the concentration of Ca(OH)2solution being 0.05 mol / L and the concentration of ZnCl2solution being 0.1 mol / L, to obtain the etching solvent; 3) According to the mass-volume ratio of carbon layer coated alocasia particles and etching solvent is 1g:10mL, the carbon layer coated alocasia particles obtained in step 1) is placed in the etching solvent obtained in step 2), and etching is carried out at 350°C for 30min to obtain activated carbon coated alocasia particles; 4) According to the mass-volume ratio of activated carbon coated alocasia particles and humic acid sodium solution is 1g:10mL, the activated carbon coated alocasia particles obtained in step 3) is placed in 2g / L humic acid sodium solution, and adsorption is carried out at room temperature for 8h to obtain humic acid loaded activated carbon coated alocasia particles, that is, a humic acid loaded activated carbon coating layer is formed on the surface of alocasia particles, and the layer thickness is about 0.5mm; 3, forming a chitosan coating layer According to the mass-volume ratio of humic acid loaded activated carbon coated alocasia particles and chitosan solution is 1g:10mL, the humic acid loaded activated carbon coated alocasia particles obtained in step 2 is placed in a chitosan solution with a concentration of 30mg / mL, and the mixture is incubated at room temperature for 2h. A chitosan coating layer is formed on the surface of the humic acid loaded activated carbon coating layer formed in step 2, and the layer thickness is about 0.5mm. Thus, the saline-alkali soil improvement fertilizer is obtained.

[0045] Comparative Example 4 A saline-alkali soil improvement fertilizer 1, Preparation of alocasia-gypsum particles 1) According to the mass ratio of alocasia and straw composting agent is 15:1, the alocasia and straw composting agent are mixed, and composting is carried out at 70°C for 1.5h to obtain composted alocasia; 2) According to the mass ratio of composted alocasia and desulfurized gypsum is 1:0.5, the composted alocasia obtained in step 1) and the desulfurized gypsum are mixed, ground, and sieved through an 80 mesh sieve, and then compacted at 200Kpa to obtain the alocasia-gypsum particles, and the particle size is about 1mm; 2, forming a humic acid loaded carbon coating layer 1) According to the mass-volume ratio of alocasia-gypsum particles and glucose solution is 1g:10mL, the alocasia-gypsum particles obtained in step 1 are placed in a glucose solution with a concentration of 2mol / L, and hydrothermal reaction is carried out at 150°C for 36h to obtain carbon layer coated alocasia-gypsum particles; 2) According to the mass-volume ratio of carbon layer coated alocasia-gypsum particles and humic acid sodium solution is 1g:10mL, the carbon layer coated alocasia-gypsum particles obtained in step 1) is placed in 2g / L humic acid sodium solution, and adsorption is carried out at room temperature for 8h to obtain humic acid loaded carbon layer coated alocasia-gypsum particles, that is, a humic acid loaded carbon coating layer is formed on the surface of alocasia-gypsum particles, and the layer thickness is about 0.5mm; 3, forming a chitosan coating layer According to the mass-volume ratio of humic acid loaded carbon coated alocasia-gypsum particles and chitosan solution is 1 g: 10 mL, the humic acid loaded carbon coated alocasia-gypsum particles obtained in step 2 are placed in a chitosan solution with a concentration of 30 mg / mL, and are wrapped at room temperature for 2 h. A chitosan coating layer is formed on the surface of the humic acid loaded carbon coating layer formed in step 2, with a layer thickness of about 0.5 mm, to obtain the saline-alkali soil improvement fertilizer.

[0046] Comparative Example 5 A saline-alkali soil improvement fertilizer 1. Preparation of alocasia-gypsum particles 1) According to the mass ratio of alocasia and straw composting agent is 15:1, the alocasia and straw composting agent are mixed, and composted at 70°C for 1.5 h to obtain composted alocasia; 2) According to the mass ratio of composted alocasia and desulfurized gypsum is 1:0.5, the composted alocasia obtained in step 1) and desulfurized gypsum are mixed, ground, and passed through an 80 mesh sieve, and then compacted at 200 Kpa to obtain the alocasia-gypsum particles with a particle size of about 1 mm; 2. Forming an activated carbon coating layer 1) According to the mass-volume ratio of alocasia-gypsum particles and glucose solution is 1 g: 10 mL, the alocasia-gypsum particles obtained in step 1 are placed in a glucose solution with a concentration of 2 mol / L, and are hydrothermally reacted at 150°C for 36 h to obtain carbon layer coated alocasia-gypsum particles; 2) According to the volume ratio of Ca(OH)2 solution and ZnCl2 solution is 1:1, a Ca(OH)2 solution with a concentration of 0.05 mol / L and a ZnCl2 solution with a concentration of 0.1 mol / L are mixed to obtain an etching solvent; 3) According to the mass-volume ratio of carbon layer coated alocasia-gypsum particles and etching solvent is 1 g: 10 mL, the carbon layer coated alocasia-gypsum particles obtained in step 1) are placed in the etching solvent obtained in step 2), and are etched at 350°C for 30 min to obtain activated carbon coated alocasia-gypsum particles, i.e. an activated carbon coating layer is formed on the surface of the alocasia-gypsum particles, with a layer thickness of about 0.5 mm; 3. Forming a chitosan coating layer According to the mass-volume ratio of activated carbon coated alocasia-gypsum particles and chitosan solution is 1 g: 10 mL, the activated carbon coated alocasia-gypsum particles obtained in step 2 are placed in a chitosan solution with a concentration of 30 mg / mL, and are wrapped at room temperature for 2 h. A chitosan coating layer is formed on the surface of the activated carbon coating layer formed in step 2, with a layer thickness of about 0.5 mm, to obtain the saline-alkali soil improvement fertilizer.

[0047] Comparative Example 6 A saline-alkali soil improvement fertilizer 1. Preparation of alocasia-gypsum particles 1) Acorus calamus and straw humic agent were mixed according to the mass ratio of 15:1, and humification was carried out at 70°C for 1.5h to obtain humified Acorus calamus; 2) Humified Acorus calamus obtained in step 1) and desulfurized gypsum were mixed according to the mass ratio of 1:0.5, ground, sieved through an 80-mesh sieve, and compacted at 200Kpa to obtain the Acorus calamus-gypsum particles with a particle size of about 1mm; 2, forming a humic acid-loaded activated carbon coating layer 1) Acorus calamus-gypsum particles obtained in step 1 were placed in a glucose solution with a concentration of 2mol / L according to the mass-volume ratio of 1g:10mL, and hydrothermal reaction was carried out at 150°C for 36h to obtain carbon-coated Acorus calamus-gypsum particles; 2) A Ca(OH)2solution with a concentration of 0.05mol / L and a ZnCl2solution with a concentration of 0.1mol / L were mixed according to the volume ratio of 1:1 to obtain an etching solvent; 3) Carbon-coated Acorus calamus-gypsum particles obtained in step 1 were placed in the etching solvent obtained in step 2 according to the mass-volume ratio of 1g:10mL, and etching was carried out at 350°C for 30min to obtain activated carbon-coated Acorus calamus-gypsum particles; 4) Activated carbon-coated Acorus calamus-gypsum particles obtained in step 3 were placed in a humic acid sodium solution with a concentration of 2g / L according to the mass-volume ratio of 1g:10mL, and adsorption was carried out at room temperature for 8h to obtain humic acid-loaded activated carbon-coated Acorus calamus-gypsum particles, i.e., a humic acid-loaded activated carbon coating layer was formed on the surface of the Acorus calamus-gypsum particles with a thickness of about 0.5mm, thereby obtaining the saline-alkali soil improvement fertilizer.

[0048] Comparative Example 7 A saline-alkali soil improvement fertilizer 1) Acorus calamus and straw humic agent were mixed according to the mass ratio of 15:1, and humification was carried out at 70°C for 1.5h to obtain humified Acorus calamus; 2) Activated carbon was placed in a humic acid sodium solution with a concentration of 2g / L according to the mass-volume ratio of 1g:10mL, and adsorption was carried out at room temperature for 8h to obtain humic acid-loaded activated carbon; 3) according to the mass ratio of the Acorus calamus, desulfurized gypsum and humic acid loaded activated carbon being 1:0.5:0.5 (the mass ratio is similar to the mass ratio of the Acorus calamus, desulfurized gypsum and humic acid loaded activated carbon in the saline-alkali soil improvement fertilizer finally obtained in Example 2), the Acorus calamus, desulfurized gypsum and humic acid loaded activated carbon are mixed, and compaction is carried out under 200 Kpa to obtain mixed particles with a particle size of about 1.5 mm; 4) according to the mass-volume ratio of the mixed particles and the chitosan solution being 1 g:10 mL, the mixed particles obtained in step 3) are placed in a chitosan solution with a concentration of 30 mg / mL, and are coated for 2 h at room temperature to form a chitosan coating layer on the surface of the mixed particles with a layer thickness of about 0.5 mm, thereby obtaining the saline-alkali soil improvement fertilizer.

[0049] Effect verification According to the application amount of 20 g / m 2 The saline-alkali soil improvement fertilizers prepared in Examples 1-3 and Comparative Examples 1-7 are applied to the surface of saline-alkali soil with a salt content of 0.6%, and the ploughing depth is controlled to be 10 cm. Soil quality detection is carried out on the saline-alkali soil on the 3rd day after the fertilizer is applied, and the detection results are shown in Table 1. Table 1 Soil quality detection

[0050] As can be seen from the data in Table 1, the saline-alkali soil improvement fertilizer provided by the present application can effectively reduce the salt content and pH value of the saline-alkali soil, and can effectively increase the organic matter content and total nitrogen content of the saline-alkali soil.

[0051] To detect the inhibition of the saline-alkali soil improvement fertilizer provided by the present application on the salinization and alkalization of the saline-alkali soil, soil quality detection is carried out on the saline-alkali soil on the 90th day after the fertilizer is applied, and the detection results are shown in Table 2. Table 2 Soil quality detection

[0052] As can be seen from the data in Table 2, the saline-alkali soil improvement fertilizer provided by the present application can effectively inhibit the salinization and alkalization of the saline-alkali soil.

[0053] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application. Any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A fertilizer for improving saline-alkali land, characterized in that, The saline-alkali land improvement fertilizer consists of, from the inside out, calamus-gypsum granules, a humic acid-loaded activated carbon coating layer, and a chitosan coating layer.

2. A method for preparing the saline-alkali land improvement fertilizer as described in claim 1, characterized in that, Includes the following steps:

1. Preparation of calamus-gypsum granules; 2. A humic acid-loaded activated carbon coating layer is formed on the surface of the calamus-gypsum particles obtained in step 1; 3. A chitosan coating layer is formed on the surface of the humic acid-loaded activated carbon coating layer formed in step 2 to obtain the saline-alkali land improvement fertilizer.

3. The preparation method according to claim 2, characterized in that, The preparation of calamus-gypsum granules specifically includes the following steps: 1) Mix calamus and straw composting agent, compost to obtain composted calamus; 2) Mix the decomposed calamus and desulfurized gypsum obtained in step 1), grind, sieve, and compact to obtain the calamus-gypsum granules.

4. The preparation method according to claim 3, characterized in that, In step 1), the mass ratio of the calamus to the straw composting agent is (10-20):1; In step 1), the fermentation specifically refers to fermenting at 60-80℃ for 1-2 hours; In step 2), the mass ratio of the decomposed calamus to the desulfurized gypsum is 1: (0.4 to 0.6).

5. The preparation method according to claim 2, characterized in that, The formation of the humic acid-supported activated carbon coating layer specifically includes the following steps: 1) Place the calamus-gypsum granules obtained in step 1 in a glucose solution and perform a hydrothermal reaction to obtain carbon-coated calamus-gypsum granules; 2) Mix Ca(OH)2 solution and ZnCl2 solution to obtain the etching solvent; 3) Place the carbon-coated calamus-gypsum particles obtained in step 1) into the etching solvent obtained in step 2) and etch to obtain activated carbon-coated calamus-gypsum particles; 4) Place the activated carbon-coated calamus-gypsum particles obtained in step 3) into a sodium humate solution for adsorption, and obtain humic acid-loaded activated carbon-coated calamus-gypsum particles, that is, a humic acid-loaded activated carbon coating layer is formed on the surface of the calamus-gypsum particles.

6. The preparation method according to claim 5, characterized in that, In step 1), the concentration of the glucose solution is 1–3 mol / L; In step 1), the mass-to-volume ratio of the calamus-gypsum granules and the glucose solution is 1 g : (5-15) mL; In step 1), the hydrothermal reaction specifically refers to a hydrothermal reaction at 140–160°C for 24–48 hours. In step 2), the volume ratio of the Ca(OH)2 solution to the ZnCl2 solution is 1:1; In step 2), the concentration of the Ca(OH)₂ solution is 0.05 mol / L; In step 2), the concentration of the ZnCl2 solution is 0.1 mol / L; In step 3), the mass-to-volume ratio of the carbon layer-coated calamus-gypsum particles to the etching solvent is 1 g : (5-15) mL; In step 3), the etching specifically involves etching at 300–400°C for 20–40 minutes. In step 4), the mass-to-volume ratio of the activated carbon-coated calamus-gypsum particles and the sodium humate solution is 1 g : (5-15) mL; Furthermore, in step 4), the adsorption specifically involves adsorption at room temperature for 6–12 hours.

7. The preparation method according to claim 2, characterized in that, The formation of the humic acid-supported activated carbon coating layer specifically includes the following steps: The humic acid-loaded activated carbon-coated calamus-gypsum particles obtained in step 2 are placed in a chitosan solution for encapsulation. A chitosan coating layer is formed on the surface of the humic acid-loaded activated carbon coating layer formed in step 2, thus obtaining the saline-alkali land improvement fertilizer.

8. The preparation method according to claim 7, characterized in that, The concentration of the chitosan solution is 20–40 mg / mL; The mass-to-volume ratio of the humic acid-loaded activated carbon-coated calamus-gypsum particles and chitosan solution is 1 g: (5-15) mL. The inclusion process specifically involves inclusion at room temperature for 1–3 hours.

9. The application of the saline-alkali land improvement fertilizer as described in claim 1 in the improvement of saline-alkali land.

10. The application according to claim 9, characterized in that, The specific application is as follows: according to 10-30g / m 2 The amount of fertilizer applied is specified, and the saline-alkali land improvement fertilizer is applied to the surface of the saline-alkali land. The tillage depth is controlled at 10cm, and the saline-alkali land is tilled.

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