A water and fertilizer retaining composition suitable for sandy soil and a method for preparing the same

Abstract

The present application relates to the field of fertilizer, in particular to a water and fertilizer retaining composition suitable for sandy soil and a preparation method thereof, the water and fertilizer retaining composition comprises, in weight parts, urea 24-40, monoammonium phosphate 10-18, potassium chloride 12-20, modified nitrification inhibitor 0.02-0.04, water and fertilizer retaining material 10-12, and chelated trace elements 3-5.The present application provides a water and fertilizer retaining composition suitable for sandy soil, the composition not only has higher fertilizer utilization rate and stronger water retention effect, but also the nitrification inhibitor in the urea-based fertilizer is not easy to fail and has better stability.

Description

Technical Field

[0001] This invention relates to the field of fertilizers, and more specifically to a water-retaining and fertilizer-retaining composition suitable for sandy soils and its preparation method. Background Technology

[0002] Sandy soil refers to soil with a high sand content and low clay content. It has poor aggregation, poor water and fertilizer retention capacity, and low nutrient utilization, which is detrimental to crop growth. Although productivity can be rapidly increased in the short term by applying chemical fertilizers, long-term improvement is needed to improve site conditions, increase organic matter content, and expand nutrient storage capacity. Currently, there are many types of soil conditioners on the market, but most are general-purpose products. There are few soil conditioners specifically designed for sandy soil. Furthermore, most soil conditioners are in powder or small granule form, making them difficult to apply to mechanized planting. Therefore, developing a soil-improving fertilizer specifically for sandy soil is of great significance for improving the current state of sandy soil in my country and increasing grain yield.

[0003] On the other hand, due to the poor water retention of sandy soil, nitrogen nutrients in the soil are more easily lost to water bodies through rainwater, irrigation water and other means, resulting in nutrient loss and non-point source pollution. Nitrification inhibitors can inhibit the conversion of ammonium nitrogen to nitrate nitrogen in the soil, thereby reducing the loss of nitrogen nutrients to water bodies or the atmosphere through leaching, runoff and denitrification. It is an effective means to improve fertilizer utilization and increase crop yield. However, the commonly used nitrification inhibitor DMPP (3,4-dimethylpyrazole phosphate) is prone to volatilization and inactivation when mixed with alkaline fertilizers and is not suitable for mixing with urea fertilizers. At the same time, its application effect is affected by soil, temperature and other factors. Therefore, there is an urgent need to develop a more stable nitrification inhibitor product. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a water-retaining and fertilizer-retaining composition suitable for sandy soil and its preparation method.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] In a first aspect, the present invention provides a water-retaining and fertilizer-retaining composition suitable for sandy soils, comprising, by weight parts:

[0007] Urea 24-40 parts, monoammonium phosphate 10-18 parts, potassium chloride 12-20 parts, modified nitrification inhibitor 0.02-0.04 parts, water-retaining and fertilizer-retaining material 10-12 parts, chelated trace elements 3-5 parts.

[0008] Preferably, the method for preparing the modified nitration inhibitor includes:

[0009] S1. Add difluoropyrazole carboxylic acid (1-(difluoro)-1H-pyrazole-3-carboxylic acid) and thionyl chloride to a reaction vessel, stir evenly, and reflux at 70-80℃ for 3-7 hours. After the reaction is completed, dry under reduced pressure to obtain difluoropyrazole acyl chloride.

[0010] S2. Difluoropyrazole chloride and diethyl aminophosphate are mixed in an organic solvent, with triethylamine as an acid-binding agent. The mixture is stirred at room temperature for 2-6 hours. After the reaction is completed, the solvent is removed under reduced pressure to obtain the crude product.

[0011] S3: The crude product is dried at 60°C until its mass remains unchanged. The precipitate obtained from S3 is then ground into powder with a particle size of 80-100 mesh using a ball mill to obtain the modified nitration inhibitor.

[0012] Preferably, in step S1, the difluoropyrazole carboxylic acid is 1-(difluoro)-1H-pyrazole-3-carboxylic acid, and the mass-volume ratio of difluoropyrazole carboxylic acid to sulfoxide is (0.8-1.6) g:(10-20) mL.

[0013] Preferably, in step S2, the organic solvent is one of dichloromethane, tetrahydrofuran, and toluene.

[0014] Preferably, in step S2, the mass-to-volume ratio of difluoropyrazolyl chloride, diethyl aminophosphate, and organic solvent is 1 g:(1.1-1.3) g:(20-30) mL.

[0015] Preferably, in step S2, the amount of triethylamine added is 2%-6% of the mass of difluoropyrazole acyl chloride.

[0016] Preferably, the preparation method of the water-retaining and fertilizer-retaining material includes the following steps:

[0017] (1) After crushing and sieving the attapulgite clay, it is activated with a silane coupling agent to obtain modified attapulgite clay.

[0018] (2) Weigh acrylic acid and add it to the alkaline solution. Stir evenly under ice-water bath conditions, then add sodium alginate aqueous solution dropwise, and add modified attapulgite clay, initiator and crosslinking agent. Stir and react at 75-80℃ for 3-4 hours.

[0019] (3) Collect the solid product obtained in step (2), wash it three times with anhydrous ethanol, and then dry it in a 60°C oven until the product quality remains unchanged. Then grind the product to 80-100 mesh to obtain the water-retaining and fertilizer-retaining material.

[0020] Preferably, the silane coupling agent in step (1) is one of sodium dodecylbenzenesulfonate, dodecyltrimethylammonium chloride, and hexadecyltrimethylammonium bromide.

[0021] Preferably, in step (2), the alkali solution is a sodium hydroxide solution with a mass fraction of 25%, and the sodium alginate aqueous solution has a mass fraction of 5%; the mass-volume ratio of acrylic acid, modified attapulgite, sodium alginate aqueous solution and alkali solution is 1g:(1-1.5)g:(10-20)mL:(10-20)mL.

[0022] Preferably, the initiator in step (2) is one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0023] Preferably, the crosslinking agent in step (2) is one or more of N,N-methylenebisacrylamide, epichlorohydrin, phosphorus oxychloride, sodium tripolyphosphate (or tripolyphosphate), sodium hexametaphosphate, borax, formaldehyde, acrolein, glyoxal, or glutaraldehyde.

[0024] Preferably, in step (2), the mass ratio of acrylic acid, initiator and crosslinking agent is 1:0.3:0.15.

[0025] Preferably, the chelated trace elements include one or more of EDTA-chelated calcium, EDTA-chelated magnesium, EDTA-chelated iron, EDTA-chelated zinc, and borax.

[0026] Secondly, the present invention provides a method for preparing a water-retaining and fertilizer-retaining composition suitable for sandy soil, comprising the following steps:

[0027] Step 1: Accurately weighed urea is added to a melting tank and heated to 135-140℃ to obtain molten urea;

[0028] Step 2: Accurately weighed monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitration inhibitor are heated to 100-105°C and added together with the molten urea obtained in S1 into a primary mixing tank, and heated to 110-120°C to obtain eutectic A.

[0029] Step 3: Add eutectic A and accurately weighed water-retaining and fertilizer-retaining materials to a secondary mixing tank and heat to 100-105℃ to obtain eutectic B. Then, granulate it using a spray granulation process, and after cooling and sieving, the particle size is 3-4mm to obtain the water-retaining and fertilizer-retaining composition suitable for sandy soil.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. This invention provides a water-retaining and fertilizer-retaining composition suitable for sandy soil. In addition to N / P / K fertilizers and trace elements, the composition also includes modified nitrification inhibitors and water-retaining and fertilizer-retaining materials. This makes the composition not only more efficient in fertilizer utilization and stronger in water retention, but also more stable in this urea-based fertilizer, as the nitrification inhibitors are less prone to failure.

[0032] 2. This invention prepares a novel nitrification inhibitor by combining difluoropyrazole carboxylic acid (1-(difluoro)-1H-pyrazole-3-carboxylic acid) and diethyl aminophosphate. Compared with the conventional nitrification inhibitor DMPP, the nitrification inhibitor prepared by this invention can be freely mixed with alkaline fertilizers without the problems of failure or poor stability.

[0033] 3. The water-retaining and fertilizer-retaining composition suitable for sandy soil provided by the present invention adds an environmentally friendly water-retaining and fertilizer-retaining material. This material is made from modified attapulgite, sodium alginate and acrylic acid. Its porous structure can not only adsorb ions such as NH4+ and H2PO4- in the soil to reduce nutrient loss, but also retain moisture, increase soil moisture content and increase crop yield.

[0034] 4. The water-retaining and fertilizer-retaining composition suitable for sandy soil provided by the present invention contains a modified nitrification inhibitor. The nitrification inhibitor is made from difluoropyrazole carboxylic acid and aminophosphate. Through the amide reaction of acyl chloride-amino, the introduction of fluorine, amide, phosphate and other groups can significantly improve the stability, lipophilicity and biological activity of the compound, thereby generating a more stable nitrification inhibitor, increasing the effective action time in sandy soil and significantly improving the utilization efficiency of nitrogen nutrients. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0036] The present invention will be further described below with reference to the following embodiments.

[0037] Example 1

[0038] A water- and fertilizer-retaining composition suitable for sandy soil, comprising, by weight, 30 parts urea, 18 parts monoammonium phosphate, 20 parts potassium chloride, 0.04 parts modified nitrification inhibitor, 10 parts water- and fertilizer-retaining material, and 4 parts chelated trace elements.

[0039] The preparation methods for modified nitration inhibitors include:

[0040] S1. Add 0.8 g of 1-(difluoro)-1H-pyrazole-3-carboxylic acid and 10 mL of thionyl chloride to a reaction vessel, stir until homogeneous, and then reflux at 70 °C for 7 h. After the reaction is completed, dry under reduced pressure to obtain difluoropyrazole acyl chloride.

[0041] S2. Mix 1g of difluoropyrazolyl chloride and 1.1g of diethyl aminophosphate in 20mL of dichloromethane, and use triethylamine as an acid-binding agent. The amount added is 2% of the mass of difluoropyrazolyl chloride. Stir at room temperature for 2h. After the reaction is completed, remove the solvent under reduced pressure to obtain the crude product.

[0042] S3: The crude product is dried at 60°C until its mass remains unchanged. The precipitate obtained from S3 is then ground into powder with a particle size of 80 mesh using a ball mill to obtain the modified nitration inhibitor.

[0043] The preparation method of the water-retaining and fertilizer-retaining material includes the following steps:

[0044] (1) Pulverize and grind the attapulgite clay to a particle size of 80 mesh, disperse the attapulgite clay powder in toluene, and after uniform dispersion, add hexadecyltrimethylammonium bromide according to the mass ratio of attapulgite clay to hexadecyltrimethylammonium bromide of 100:1. Ultrasonically treat at 35°C for 10 min to obtain modified attapulgite clay.

[0045] (2) Place the reaction vessel in an ice-water bath and slowly add 1g of acrylic acid to 10mL of 25% sodium hydroxide solution. After the reaction system cools to room temperature, add 1g of modified attapulgite, 10mL of 5% sodium alginate aqueous solution, 0.3g of ammonium persulfate and 0.15g of epichlorohydrin. Stir well and react at 80℃ for 3h.

[0046] (3) Wash the product with anhydrous ethanol three times, then dry the product in a 60°C oven until the product quality remains unchanged, and then grind the product to 100 mesh to obtain the water-retaining and fertilizer-retaining material.

[0047] The chelated trace elements include EDTA chelated calcium (10% calcium by mass), EDTA chelated magnesium (10% magnesium by mass), EDTA chelated iron (13% iron by mass), EDTA chelated zinc (15% zinc by mass), and borax (95% purity), with a mass ratio of 1:1:0.5:0.5:0.1.

[0048] The preparation method of the water-retaining and fertilizer-retaining composition suitable for sandy soil mentioned above includes the following steps:

[0049] Step 1: Accurately weighed urea is added to a melting tank and heated to 140°C to obtain molten urea;

[0050] Step 2: Accurately weighed monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitration inhibitor are heated to 105°C and added together with the molten urea obtained in S1 into a primary mixing tank, and heated to 120°C to obtain eutectic A.

[0051] Step 3: Add eutectic A and accurately weighed water-retaining and fertilizer-retaining materials to a secondary mixing tank, heat to 105°C to obtain eutectic B, then granulate using a spray granulation process, and then cool and sieve to obtain a particle size of 4 mm, thus obtaining the water-retaining and fertilizer-retaining composition suitable for sandy soil.

[0052] Example 2

[0053] A water- and fertilizer-retaining composition suitable for sandy soil, comprising, by weight, 36 parts urea, 10 parts monoammonium phosphate, 16 parts potassium chloride, 0.03 parts modified nitrification inhibitor, 11 parts water- and fertilizer-retaining material, and 5 parts chelated trace elements.

[0054] The preparation methods for modified nitration inhibitors include:

[0055] S1. Add 1.2 g of 1-(difluoro)-1H-pyrazole-3-carboxylic acid and 15 mL of thionyl chloride to a reaction vessel, stir until homogeneous, and then reflux at 75 °C for 5 h. After the reaction is completed, dry under reduced pressure to obtain difluoropyrazole acyl chloride.

[0056] S2. Mix 1g of difluoropyrazolyl chloride and 1.2g of diethyl aminophosphate in 25mL of dichloromethane, and use triethylamine as an acid-binding agent. The amount added is 4% of the mass of difluoropyrazolyl chloride. Stir at room temperature for 4h. After the reaction is completed, remove the solvent under reduced pressure to obtain the crude product.

[0057] S3: The crude product is dried at 60°C until its mass remains unchanged. The precipitate obtained in S3 is then ground into powder with a particle size of 100 mesh using a ball mill to obtain the modified nitration inhibitor.

[0058] The preparation method of the water-retaining and fertilizer-retaining material includes the following steps:

[0059] (1) Pulverize and grind the attapulgite clay to a particle size of 100 mesh, disperse the attapulgite powder in toluene, and after uniform dispersion, add sodium dodecylbenzene sulfonate according to the mass ratio of attapulgite clay to sodium dodecylbenzene sulfonate of 100:1. Ultrasonically treat at 35°C for 15 min to obtain modified attapulgite clay.

[0060] (2) Place the reaction vessel in an ice-water bath and slowly add 1g of acrylic acid to 15mL of 25% sodium hydroxide solution. After the reaction system cools to room temperature, add 1.2g of modified attapulgite, 15mL of 5% sodium alginate aqueous solution, 0.3g of sodium persulfate and 0.15g of N,N-methylenebisacrylamide. Stir well and react at 75℃ for 3h.

[0061] (3) Wash the product with anhydrous ethanol three times, then dry the product in a 60°C oven until the product quality remains unchanged, and then grind the product to 100 mesh to obtain the water-retaining and fertilizer-retaining material.

[0062] The chelated trace elements include EDTA chelated calcium (10% calcium by mass), EDTA chelated magnesium (10% magnesium by mass), EDTA chelated iron (13% iron by mass), EDTA chelated zinc (15% zinc by mass), and borax (95% purity), with a mass ratio of 1:1:0.5:0.5:0.1.

[0063] The preparation method of the water-retaining and fertilizer-retaining composition suitable for sandy soil mentioned above includes the following steps:

[0064] Step 1: Accurately weighed urea is added to a melting tank and heated to 135°C to obtain molten urea;

[0065] Step 2: Accurately weighed monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitration inhibitor are heated to 100°C and added together with the molten urea obtained in S1 into a primary mixing tank, and heated to 110°C to obtain eutectic A.

[0066] Step 3: Add eutectic A and accurately weighed water-retaining and fertilizer-retaining materials to a secondary mixing tank, heat to 100°C to obtain eutectic B, then granulate using a spray granulation process, and then cool and sieve to obtain a particle size of 3 mm, thus obtaining the water-retaining and fertilizer-retaining composition suitable for sandy soil.

[0067] Example 3

[0068] A water- and fertilizer-retaining composition suitable for sandy soil, comprising, by weight, 40 parts urea, 16 parts monoammonium phosphate, 12 parts potassium chloride, 0.02 parts modified nitrification inhibitor, 12 parts water- and fertilizer-retaining material, and 3 parts chelated trace elements.

[0069] The preparation methods for modified nitration inhibitors include:

[0070] S1. Add 1.6 g of 1-(difluoro)-1H-pyrazole-3-carboxylic acid and 20 mL of thionyl chloride to a reaction vessel, stir until homogeneous, and then reflux at 80 °C for 3 h. After the reaction is completed, dry under reduced pressure to obtain difluoropyrazole acyl chloride.

[0071] S2. Mix 1g of difluoropyrazolyl chloride and 1.3g of diethyl aminophosphate in 30mL of dichloromethane, and use triethylamine as an acid-binding agent. The amount added is 6% of the mass of difluoropyrazolyl chloride. Stir at room temperature for 6h. After the reaction is completed, remove the solvent under reduced pressure to obtain the crude product.

[0072] S3: The crude product is dried at 60°C until its mass remains unchanged. The precipitate obtained in S3 is then ground into powder with a particle size of 100 mesh using a ball mill to obtain the modified nitration inhibitor.

[0073] The preparation method of the water-retaining and fertilizer-retaining material includes the following steps:

[0074] (1) Pulverize and grind the attapulgite clay to a particle size of 100 mesh, disperse the attapulgite powder in toluene, and after uniform dispersion, add sodium dodecylbenzene sulfonate according to the mass ratio of attapulgite clay to sodium dodecylbenzene sulfonate of 100:1. Ultrasonically treat at 35°C for 15 min to obtain modified attapulgite clay.

[0075] (2) Place the reaction vessel in an ice-water bath and slowly add 1g of acrylic acid to 20mL of 25% sodium hydroxide solution. After the reaction system cools to room temperature, add 1.5g of modified attapulgite, 20mL of 5% sodium alginate aqueous solution, 0.3g of sodium persulfate and 0.15g of N,N-methylenebisacrylamide. Stir well and react at 75℃ for 3h.

[0076] (3) Wash the product with anhydrous ethanol three times, then dry the product in a 60°C oven until the product quality remains unchanged, and then grind the product to 100 mesh to obtain the water-retaining and fertilizer-retaining material.

[0077] The chelated trace elements include EDTA chelated calcium (10% calcium by mass), EDTA chelated magnesium (10% magnesium by mass), EDTA chelated iron (13% iron by mass), EDTA chelated zinc (15% zinc by mass), and borax (95% purity), with a mass ratio of 1:1:0.5:0.5:0.1.

[0078] The preparation method of the water-retaining and fertilizer-retaining composition suitable for sandy soil mentioned above includes the following steps:

[0079] Step 1: Accurately weighed urea is added to a melting tank and heated to 140°C to obtain molten urea;

[0080] Step 2: Accurately weighed monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitration inhibitor are heated to 105°C and added together with the molten urea obtained in S1 into a primary mixing tank, and heated to 120°C to obtain eutectic A.

[0081] Step 3: Add eutectic A and accurately weighed water-retaining and fertilizer-retaining materials to a secondary mixing tank, heat to 105°C to obtain eutectic B, then granulate using a spray granulation process, and then cool and sieve to obtain a particle size of 4 mm, thus obtaining the water-retaining and fertilizer-retaining composition suitable for sandy soil.

[0082] Comparative Example 1

[0083] A water-retaining and fertilizer-retaining composition differs from Example 2 only in that the water-retaining and fertilizer-retaining material used is a starch-acrylic acid copolymer water-retaining agent. The components, by weight, include 36 parts urea, 10 parts monoammonium phosphate, 16 parts potassium chloride, 0.03 parts modified nitration inhibitor, 11 parts starch-acrylic acid copolymer water-retaining agent, and 5 parts chelated trace elements.

[0084] The preparation method of the starch-acrylic acid copolymer water-retaining agent includes:

[0085] (1) Place the reaction vessel in an ice-water bath and slowly add 1g of acrylic acid to (10-20)mL of 25% sodium hydroxide solution. After the reaction system cools to room temperature, add (1-1.5)g of pregelatinized starch, 0.3g of sodium persulfate and 0.15g of N,N-methylenebisacrylamide. Stir well and react at 75℃ for 3h.

[0086] (2) The product was washed three times with anhydrous ethanol, and then dried in a 60°C oven until the product quality remained unchanged. The product was then ground to 100 mesh to obtain starch-acrylic acid copolymer water-retaining agent.

[0087] Comparative Example 2

[0088] A water- and fertilizer-retaining composition differs from Example 2 only in that the nitrification inhibitor used is 3,4-dimethylpyrazole phosphate (DMPP). The composition, by weight, includes 36 parts urea, 10 parts monoammonium phosphate, 16 parts potassium chloride, 0.03 parts DMPP, 11 parts water- and fertilizer-retaining material, and 5 parts chelated trace elements.

[0089] Experimental Example

[0090] The following pot experiment was conducted to determine the effects of different water-retaining and fertilizer-retaining compositions suitable for sandy soil on soil water retention, nitrogen fertilizer utilization, and maize quality and yield. The maize variety used was 'Zhengdan 958'. The test soil was selected from the 0-20cm topsoil layer of sandy farmland in Heze, Shandong Province. The basic physicochemical properties of the soil were: sand 75.6%, clay 11.6%, silt 12.8%, organic matter content 15.7 g / kg, total nitrogen 0.98 g / kg, available phosphorus 21.3 mg / kg, available potassium 106.6 mg / kg, and pH 7.36. After collection, the soil was sieved through a 2mm sieve after removing stones and debris. Maize was sown on April 20, 2023, and harvested on September 16, 2023. All treatments used basal application of fertilizer at a rate of 50 kg / mu. Other field management practices, including sowing, irrigation, weeding, pest and disease control, and chemical control, were consistent.

[0091] Table 1. Changes in soil moisture content over 28 days in the examples and comparative examples.

[0092] 0 days 7 days 14 days 21 days 28 days Example 1 100％ 80.35％ 65.72％ 53.88％ 44.25％ Example 2 100％ 82.38％ 66.95％ 55.23％ 46.07％ Example 3 100％ 79.64％ 63.98％ 52.63％ 43.91％ Comparative Example 1 100％ 71.12％ 51.36％ 36.77％ 25.68％ Comparative Example 2 100％ 74.25％ 62.33％ 49.60％ 40.56％

[0093] As shown in Table 1, compared with Comparative Example 1 (conventional nitrification inhibitor and water-retaining agent), the soil moisture content was significantly increased on day 28 after applying the water-retaining and fertilizer-retaining composition of the present invention suitable for sandy soil. Compared with Comparative Example 2 (conventional nitrification inhibitor), the soil moisture content was also increased to a certain extent on day 28.

[0094] Table 2. Changes in soil bulk density, porosity, and saturated water content (0-10 cm) over 28 days in the examples and comparative examples.

[0095]

[0096]

[0097] As shown in Table 2, compared with Comparative Example 1 (conventional nitrification inhibitor and water-retaining agent) and Comparative Example 2 (conventional nitrification inhibitor), after applying the water-retaining and fertilizer-retaining composition of the present invention suitable for sandy soil, the soil bulk density decreased, the soil porosity increased, and the soil saturated water content increased on day 28.

[0098] Table 3 Nitrogen fertilizer utilization rate, maize quality, and yield of the examples and comparative examples

[0099]

[0100] As shown in Table 3, compared with Comparative Example 2 (conventional nitrification inhibitor), the application of the water-retaining and fertilizer-retaining composition of the present invention suitable for sandy soil significantly improved nitrogen fertilizer utilization, number of corn ears, thousand-grain weight, and yield. Moreover, compared with the application of conventional DMPP, the application of the water-retaining and fertilizer-retaining composition of the present invention suitable for sandy soil also improved nitrogen fertilizer utilization, number of corn ears, thousand-grain weight, and yield to a certain extent.

[0101] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0102] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A water-retaining and fertilizer-retaining composition suitable for sandy soil, characterized in that, Calculated by weight, including: Urea 24-40 parts, monoammonium phosphate 10-18 parts, potassium chloride 12-20 parts, modified nitrification inhibitor 0.02-0.04 parts, water-retaining and fertilizer-retaining material 10-12 parts, chelated trace elements 3-5 parts; The preparation method of the modified nitration inhibitor includes: S1. Add difluoropyrazole carboxylic acid and thionyl chloride to a reaction vessel, stir evenly, and reflux at 70-80℃ for 3-7 hours. After the reaction is completed, dry under reduced pressure to obtain difluoropyrazole acyl chloride. S2. Difluoropyrazole chloride and diethyl aminophosphate are mixed in an organic solvent, with triethylamine as an acid-binding agent. The mixture is stirred at room temperature for 2-6 hours. After the reaction is completed, the solvent is removed under reduced pressure to obtain the crude product. S3: The crude product is dried at 60°C until its mass remains unchanged. The precipitate obtained in S3 is then ground into powder with a particle size of 80-100 mesh using a ball mill to obtain the modified nitration inhibitor. In step S1, the difluoropyrazole carboxylic acid is 1-(difluoro)-1H-pyrazole-3-carboxylic acid, and the mass-volume ratio of difluoropyrazole carboxylic acid to sulfoxide is (0.8-1.6) g:(10-20) mL; In step S2, the mass-volume ratio of difluoropyrazole acyl chloride, diethyl aminophosphate, and organic solvent is 1 g:(1.1-1.3) g:(20-30) mL.

2. The water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 1, characterized in that, The preparation method of the water-retaining and fertilizer-retaining material includes the following steps: (1) After crushing and sieving the attapulgite clay, it is activated with a silane coupling agent to obtain modified attapulgite clay. (2) Weigh acrylic acid and add it to the alkaline solution. Stir it evenly under ice-water bath conditions, then add sodium alginate aqueous solution dropwise, and add modified attapulgite, initiator and crosslinking agent at the same time. Stir and react at 75-80℃ for 3-4 hours. (3) Collect the solid product obtained in step (2), wash it three times with anhydrous ethanol, and then dry it in a 60°C oven until the product quality remains unchanged. Then grind the product to 80-100 mesh to obtain the water-retaining and fertilizer-retaining material.

3. The water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 2, characterized in that, In step (1), the silane coupling agent is one of sodium dodecylbenzenesulfonate, dodecyltrimethylammonium chloride, or hexadecyltrimethylammonium bromide.

4. The water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 2, characterized in that, In step (2), the alkali solution is a 25% sodium hydroxide solution and the sodium alginate aqueous solution has a 5% mass fraction. The mass-volume ratio of acrylic acid, modified attapulgite, sodium alginate aqueous solution and alkali solution is 1g:(1-1.5)g:(10-20)mL:(10-20)mL.

5. A water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 2, characterized in that, In step (2), the mass ratio of acrylic acid, initiator and crosslinking agent is 1:0.3:0.

15.

6. The water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 1, characterized in that, The chelated trace elements include one or more of the following: EDTA chelated calcium, EDTA chelated magnesium, EDTA chelated iron, EDTA chelated zinc, and borax.

7. A method for preparing the water-retaining and fertilizer-retaining composition suitable for sandy soil as described in claim 1, characterized in that the step... include: Step 1: Accurately weighed urea is added to a melting tank and heated to 135-140℃ to obtain molten urea; Step 2: Accurately weighed monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitration inhibitor are heated to 100-105°C and added together with the molten urea obtained in S1 into a primary mixing tank, and heated to 110-120°C to obtain eutectic A. Step 3: Add eutectic A and accurately weighed water-retaining and fertilizer-retaining materials to a secondary mixing tank and heat to 100-105℃ to obtain eutectic B. Then, granulate it using a spray granulation process, and after cooling and sieving, the particle size is 3-4mm to obtain the water-retaining and fertilizer-retaining composition suitable for sandy soil.

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