Water and fertilizer retention composition suitable for sandy soil and preparation method of water and fertilizer retention composition

Abstract

The invention relates to the field of fertilizers, in particular to a water and fertilizer retention composition suitable for sandy soil and a preparation method thereof.The water and fertilizer retention composition is prepared from, by weight, 24-40 parts of urea, 10-18 parts of monoammonium phosphate, 12-20 parts of potassium chloride, 0.02-0.04 part of a modified nitrification inhibitor, 10-12 parts of a water and fertilizer retention material and 3-5 parts of chelated microelements. The invention provides the water and fertilizer retention composition suitable for sandy soil, the N / P / K fertilizer and trace elements are added into the composition, and the modified nitrification inhibitor and the water and fertilizer retention material are also added, so that the composition is higher in fertilizer utilization rate and stronger in water retention effect; the nitrification inhibitor is not easy to lose efficacy and has better stability.

Description

Technical Field

[0001] The invention relates to the field of fertilizers, and in particular to a water- and fertilizer-retaining composition suitable for sandy soil and a preparation method thereof. Background Art

[0002] Sandy soil refers to soil with a high content of sand particles and a low content of clay particles in its structure. It has poor agglomeration, poor water and fertilizer retention capacity, and low nutrient utilization rate, which is not conducive to crop growth. Although productivity can be quickly improved by applying chemical fertilizers in the short term, in the long term, it is necessary to improve site conditions, increase organic matter content and nutrient storage capacity through soil improvement. There are many types of soil conditioner products on the market, but most of them are general-purpose products. There are few soil conditioner products specifically for sandy soil. At the same time, soil conditioner products are mostly in the form of powder or small particles, which are difficult to apply to mechanized planting. Therefore, the development of a soil-improving fertilizer for sandy soil is of great significance to improving the current situation of sandy soil in my country and increasing grain production.

[0003] On the other hand, due to the poor water retention of sandy soil, nitrogen nutrients in the soil are more likely to flow into water bodies through rainwater, irrigation water and other channels, causing nutrient loss and non-point source pollution. Nitrification inhibitors can inhibit the conversion of ammonium nitrogen in the soil to nitrate nitrogen, 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 yields. However, the commonly used nitrification inhibitor DMPP (3,4-dimethylpyrazole phosphate) on the market is easy to volatilize and become ineffective when mixed with alkaline fertilizers, and should not be mixed with urea fertilizers. At the same time, its application effect is affected by factors such as soil and temperature. Therefore, there is an urgent need to develop a more stable nitrification inhibitor product. Summary of the invention

[0004] In view of the problems existing in the prior art, the object of the present invention is to provide a water-retaining and fertilizer-retaining composition suitable for sandy soil and a preparation method thereof.

[0005] The purpose of the present invention is achieved by the following technical solutions:

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

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

[0008] Preferably, the preparation method of the modified nitrification inhibitor comprises:

[0009] S1. Add difluoropyrazolecarboxylic acid (1-(difluoro)-1H-pyrazole-3-carboxylic acid) and thionyl chloride into a reaction vessel, stir evenly, condense and reflux at 70-80° C. for 3-7 hours, and dry under reduced pressure after the reaction to obtain difluoropyrazole chloride;

[0010] S2. difluoropyrazole chloride and diethyl phosphoramidate are mixed in an organic solvent, triethylamine is used as an acid binding agent, and 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 a crude product;

[0011] S3: The crude product was dried at 60°C until the mass remained unchanged, and the precipitate obtained in S3 was ground into a powder with a particle size of 80-100 mesh using a ball mill to obtain a modified nitrification inhibitor.

[0012] Preferably, in step S1, the difluoropyrazolecarboxylic acid is 1-(difluoro)-1H-pyrazole-3-carboxylic acid, and the mass volume ratio of difluoropyrazolecarboxylic acid to thionyl chloride 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 volume ratio of difluoropyrazole chloride, diethyl phosphoramidite 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 chloride.

[0016] Preferably, the method for preparing the water-retaining and fertilizer-retaining material comprises the following steps:

[0017] (1) grinding and sieving attapulgite clay, and then activating it with a silane coupling agent to obtain modified attapulgite;

[0018] (2) Weighing acrylic acid and adding it to the alkali solution, stirring it evenly in an ice water bath, then dropping the sodium alginate aqueous solution, adding the modified attapulgite, adding the initiator and the cross-linking agent, and stirring the reaction at 75-80° C. for 3-4 hours;

[0019] (3) The solid product obtained in step (2) is collected, washed with anhydrous ethanol three times, and then dried in an oven at 60° C. until the product quality remains unchanged, and then the product is ground into 80-100 meshes to obtain the water-retaining and fertilizer-retaining material.

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

[0021] Preferably, the alkali solution in step (2) is a sodium hydroxide solution with a mass fraction of 25%, and the mass fraction of the sodium alginate aqueous solution is 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, in step (2), the cross-linking agent is one or more of N,N-methylenebisacrylamide, epichlorohydrin, phosphorus oxychloride, sodium trimetaphosphate (or tripoly)phosphate, sodium hexametaphosphate, borax, formaldehyde, acrolein, glyoxal or glutaraldehyde.

[0024] Preferably, in step (2), the mass ratio of acrylic acid, initiator and cross-linking 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] In a second aspect, the present invention provides a method for preparing a water-retaining and fertilizer-retaining composition suitable for sandy soil, the steps comprising:

[0027] Step 1: Add accurately weighed urea into a melting tank and heat it to 135-140° C. to obtain molten urea;

[0028] Step 2: accurately weighing monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitrification inhibitor are heated to 100-105° C., 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 into a secondary mixing tank, heat to 100-105° C. to obtain eutectic B, and then granulate it using a spray granulation process. After cooling and screening, the particles have a particle size of 3-4 mm to obtain the water-retaining and fertilizer-retaining composition suitable for sandy soil.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present 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 adds a modified nitrification inhibitor and water-retaining and fertilizer-retaining materials, so that the composition not only has a higher fertilizer utilization rate and a stronger water-retaining effect, but also in the urea fertilizer, the nitrification inhibitor is not easy to fail and has better stability.

[0032] 2. The present invention prepares a new type of nitrification inhibitor by combining difluoropyrazolecarboxylic acid (1-(difluoro)-1H-pyrazole-3-carboxylic acid) and diethyl aminophosphorate. Compared with the conventional nitrification inhibitor DMPP, the nitrification inhibitor prepared by the present invention can be mixed with alkaline fertilizers at will without the problem of failure and poor stability.

[0033] 3. The water-retaining and fertilizer-retaining composition suitable for sandy soil provided by the present invention is added with an environmentally friendly water-retaining and fertilizer-retaining material. The material uses modified attapulgite, sodium alginate and acrylic acid as raw materials. Its porous structure can not only absorb NH4+, H2PO4- and other ions in the soil to reduce nutrient loss, but also can retain water, increase soil moisture content, and increase crop yields.

[0034] 4. The water-retaining and fertilizer-retaining composition suitable for sandy soil provided by the present invention is added with a modified nitrification inhibitor. The nitrification inhibitor uses difluoropyrazole carboxylic acid and amino phosphoric acid ester as raw materials. The amide reaction of acyl chloride-amino group occurs. The introduction of fluorine, amide group, phosphate ester and other groups can significantly improve the stability, fat solubility 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 DESCRIPTION

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

[0036] The present invention will be further described below in conjunction with the following examples.

[0037] Example 1

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

[0039] Wherein, the preparation method of the modified nitrification inhibitor comprises:

[0040] S1. 0.8 g of 1-(difluoro)-1H-pyrazole-3-carboxylic acid and 10 mL of dichlorothionyl were added to a reaction vessel, stirred evenly, and refluxed at 70° C. for 7 h. After the reaction was completed, the mixture was dried under reduced pressure to obtain difluoropyrazole chloride;

[0041] S2. 1 g of difluoropyrazole chloride and 1.1 g of diethyl phosphoramidate were mixed in 20 mL of dichloromethane, triethylamine was used as an acid binding agent, and the amount added was 2% of the mass of difluoropyrazole chloride, and the mixture was stirred at room temperature for 2 h. After the reaction was completed, the solvent was removed under reduced pressure to obtain a crude product;

[0042] S3: The crude product was dried at 60°C until the mass remained unchanged, and the precipitate obtained from S3 was ground into a powder with a particle size of 80 mesh using a ball mill to obtain a modified nitrification inhibitor.

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

[0044] (1) crushing and grinding attapulgite clay to a particle size of 80 mesh, dispersing the attapulgite powder in toluene, and after uniform dispersion, adding hexadecyltrimethylammonium bromide according to a mass ratio of attapulgite to hexadecyltrimethylammonium bromide of 100:1, and ultrasonically treating at 35° C. for 10 min to obtain modified attapulgite;

[0045] (2) Place the reaction vessel in an ice water bath, slowly add 1 g of acrylic acid into 10 mL of 25% sodium hydroxide solution, and after the reaction system is cooled to room temperature, add 1 g of modified attapulgite, 10 mL of 5% sodium alginate aqueous solution, 0.3 g of ammonium persulfate and 0.15 g of epichlorohydrin, stir evenly and react at 80° C. for 3 h;

[0046] (3) The product was washed with anhydrous ethanol for three times, and then placed in an oven at 60° C. to dry until the product quality remained unchanged, and then the product was ground into 100 meshes to obtain the water-retaining and fertilizer-retaining material.

[0047] Among them, the chelated trace elements include EDTA chelated calcium (calcium content 10% by mass), EDTA chelated magnesium (magnesium content 10% by mass), EDTA chelated iron (iron content 13% by mass), EDTA chelated zinc (zinc content 15% by mass), and borax (purity 95%), 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 comprises the following steps:

[0049] Step 1: Add accurately weighed urea into a melting tank and heat it to 140° C. to obtain molten urea;

[0050] Step 2: accurately weighing monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitrification inhibitor are heated to 105° C., 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 into a secondary mixing tank, heat to 105° C. to obtain eutectic B, and then granulate it using a spray granulation process. After cooling and screening, the particles have a particle size of 4 mm to obtain the water-retaining and fertilizer-retaining composition suitable for sandy soil.

[0052] Example 2

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

[0054] Wherein, the preparation method of the modified nitrification inhibitor comprises:

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

[0056] S2. 1 g of difluoropyrazole chloride and 1.2 g of diethyl phosphoramidate were mixed in 25 mL of dichloromethane, triethylamine was used as an acid binding agent, and the amount added was 4% of the mass of difluoropyrazole chloride, and the mixture was stirred at room temperature for 4 h. After the reaction was completed, the solvent was removed under reduced pressure to obtain a crude product;

[0057] S3: The crude product was dried at 60°C until the mass remained unchanged, and the precipitate obtained from S3 was ground into a powder with a particle size of 100 mesh using a ball mill to obtain a modified nitrification inhibitor.

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

[0059] (1) crushing and grinding attapulgite clay to a particle size of 100 mesh, dispersing the attapulgite powder in toluene, adding sodium dodecylbenzene sulfonate according to a mass ratio of attapulgite to sodium dodecylbenzene sulfonate of 100:1 after uniform dispersion, and ultrasonically treating at 35° C. for 15 min to obtain modified attapulgite;

[0060] (2) Place the reaction vessel in an ice water bath, slowly add 1 g of acrylic acid into 15 mL of 25% sodium hydroxide solution, and after the reaction system is cooled to room temperature, add 1.2 g of modified attapulgite, 15 mL of 5% sodium alginate aqueous solution, 0.3 g of sodium persulfate and 0.15 g of N,N-methylenebisacrylamide, stir evenly and react at 75 °C for 3 h;

[0061] (3) The product was washed with anhydrous ethanol for three times, and then placed in an oven at 60° C. to dry until the product quality remained unchanged, and then the product was ground into 100 meshes to obtain the water-retaining and fertilizer-retaining material.

[0062] Among them, the chelated trace elements include EDTA chelated calcium (calcium content 10% by mass), EDTA chelated magnesium (magnesium content 10% by mass), EDTA chelated iron (iron content 13% by mass), EDTA chelated zinc (zinc content 15% by mass), and borax (purity 95%), 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 comprises the following steps:

[0064] Step 1: Add accurately weighed urea into a melting tank and heat it to 135° C. to obtain molten urea;

[0065] Step 2: accurately weighing monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitrification inhibitor are heated to 100° C., 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 into a secondary mixing tank, heat to 100° C. to obtain eutectic B, and then granulate it using a spray granulation process. After cooling and screening, the particles have a particle size of 3 mm to obtain the water-retaining and fertilizer-retaining composition suitable for sandy soil.

[0067] Example 3

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

[0069] Wherein, the preparation method of the modified nitrification inhibitor comprises:

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

[0071] S2. 1 g of difluoropyrazole chloride and 1.3 g of diethyl phosphoramidate were mixed in 30 mL of dichloromethane, triethylamine was used as an acid binding agent, and the amount added was 6% of the mass of difluoropyrazole chloride, and the mixture was stirred at room temperature for 6 h. After the reaction was completed, the solvent was removed under reduced pressure to obtain a crude product;

[0072] S3: The crude product was dried at 60°C until the mass remained unchanged, and the precipitate obtained from S3 was ground into a powder with a particle size of 100 mesh using a ball mill to obtain a modified nitrification inhibitor.

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

[0074] (1) crushing and grinding attapulgite clay to a particle size of 100 mesh, dispersing the attapulgite powder in toluene, adding sodium dodecylbenzene sulfonate according to a mass ratio of attapulgite to sodium dodecylbenzene sulfonate of 100:1 after uniform dispersion, and ultrasonically treating at 35° C. for 15 min to obtain modified attapulgite;

[0075] (2) Place the reaction vessel in an ice water bath, slowly add 1 g of acrylic acid into 20 mL of 25% sodium hydroxide solution, and after the reaction system is cooled to room temperature, add 1.5 g of modified attapulgite, 20 mL of 5% sodium alginate aqueous solution, 0.3 g of sodium persulfate and 0.15 g of N,N-methylenebisacrylamide, stir evenly and react at 75 °C for 3 h;

[0076] (3) The product was washed with anhydrous ethanol for three times, and then placed in an oven at 60° C. to dry until the product quality remained unchanged, and then the product was ground into 100 meshes to obtain the water-retaining and fertilizer-retaining material.

[0077] Among them, the chelated trace elements include EDTA chelated calcium (calcium content 10% by mass), EDTA chelated magnesium (magnesium content 10% by mass), EDTA chelated iron (iron content 13% by mass), EDTA chelated zinc (zinc content 15% by mass), and borax (purity 95%), 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 comprises the following steps:

[0079] Step 1: Add accurately weighed urea into a melting tank and heat it to 140° C. to obtain molten urea;

[0080] Step 2: accurately weighing monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitrification inhibitor are heated to 105° C., 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 into a secondary mixing tank, heat to 105° C. to obtain eutectic B, and then granulate it using a spray granulation process. After cooling and screening, the particles have a particle size of 4 mm to obtain the water-retaining and fertilizer-retaining composition suitable for sandy soil.

[0082] Comparative Example 1

[0083] A water-retaining and fertilizer-retaining composition, which 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 ingredients, by weight, include 36 parts of urea, 10 parts of monoammonium phosphate, 16 parts of potassium chloride, 0.03 parts of a modified nitrification inhibitor, 11 parts of a starch-acrylic acid copolymer water-retaining agent, and 5 parts of chelated trace elements.

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

[0085] (1) placing a reaction vessel in an ice water bath, slowly adding 1 g of acrylic acid into (10-20) mL of a 25% sodium hydroxide solution, and after the reaction system is cooled to room temperature, adding (1-1.5) g of pregelatinized starch, 0.3 g of sodium persulfate and 0.15 g of N,N-methylenebisacrylamide, stirring evenly, and reacting at 75° C. for 3 h;

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

[0087] Comparative Example 2

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

[0089] Experimental example

[0090] In the following, pot experiments were conducted to determine the effects of different test groups of water-retaining and fertilizer-retaining compositions suitable for sandy soil on soil water retention, nitrogen fertilizer utilization, and corn quality and yield. The corn variety was 'Zhengdan 958', and the test soil was selected from a 0-20cm plough layer of a sandy cultivated land in Heze, Shandong. The basic physical and chemical properties of the soil were 75.6% sand, 11.6% clay, 12.8% silt, 15.7g / kg organic matter, 0.98g / kg total nitrogen, 21.3mg / kg available phosphorus, 106.6mg / kg available potassium, and pH 7.36. The collected soil was sieved through a 2mm sieve after using stones and debris for later use. Corn was sown on April 20, 2023 and harvested on September 16, 2023. Base fertilizer was used for each treatment, and the fertilizer application rate was 50kg / mu. Other field management measures such as sowing, irrigation, weeding, pest control, and chemical control were the same.

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

[0092] Day 0 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 can be seen from Table 1, compared with Comparative Example 1 (conventional nitrification inhibitor and water retaining agent), after applying the water-retaining and fertilizer-retaining composition suitable for sandy soil of the present invention, the soil moisture content on the 28th day was significantly increased, and compared with Comparative Example 2 (conventional nitrification inhibitor), the soil content on the 28th day was also increased to a certain extent.

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

[0095]

[0096]

[0097] It can be seen from Table 2 that 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 suitable for sandy soil of the present invention, the soil bulk density decreased, the soil porosity increased, and the soil saturated water content increased on the 28th day.

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

[0099]

[0100] As can be seen from Table 3, compared with Comparative Example 2 (conventional nitrification inhibitor), after applying the water-retaining and fertilizer-retaining composition suitable for sandy soil of the present invention, the nitrogen fertilizer utilization rate, the number of corn cobs, the thousand-grain weight and the yield are significantly improved, and compared with the application of conventional DMPP, after applying the water-retaining and fertilizer-retaining composition suitable for sandy soil of the present invention, the nitrogen fertilizer utilization rate, the number of corn cobs, the thousand-grain weight and the yield are also improved to a certain extent.

[0101] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0102] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary 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: 24-40 parts of urea, 10-18 parts of monoammonium phosphate, 12-20 parts of potassium chloride, 0.02-0.04 parts of modified nitrification inhibitor, 10-12 parts of water and fertilizer retention materials, and 3-5 parts of chelated trace elements.

2. A water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 1, characterized in that: The preparation method of the modified nitrification inhibitor comprises: S1. Add difluoropyrazole carboxylic acid and thionyl chloride into a reaction vessel, stir evenly, condense and reflux at 70-80°C for 3-7h, and dry under reduced pressure after the reaction to obtain difluoropyrazole chloride; S2. difluoropyrazole chloride and diethyl phosphoramidate are mixed in an organic solvent, triethylamine is used as an acid binding agent, and 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 a crude product; S3: The crude product was dried at 60°C until the mass remained unchanged, and the precipitate obtained in S3 was ground into a powder with a particle size of 80-100 mesh using a ball mill to obtain a modified nitrification inhibitor.

3. A water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 2, characterized in that: 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 thionyl chloride is (0.8-1.6) g:(10-20) mL.

4. A water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 2, characterized in that: In step S2, the mass volume ratio of difluoropyrazole chloride, diethyl phosphoramidite and organic solvent is 1 g: (1.1-1.3) g: (20-30) mL.

5. 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 comprises the following steps: (1) grinding and sieving attapulgite clay, and then activating it with a silane coupling agent to obtain modified attapulgite; (2) Weighing acrylic acid and adding it to the alkali solution, stirring it evenly in an ice water bath, then dropping the sodium alginate aqueous solution, adding the modified attapulgite, adding the initiator and the cross-linking agent, and stirring the reaction at 75-80° C. for 3-4 hours; (3) The solid product obtained in step (2) is collected, washed with anhydrous ethanol three times, and then dried in an oven at 60° C. until the product quality remains unchanged, and then the product is ground into 80-100 meshes to obtain the water-retaining and fertilizer-retaining material.

6. A water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 5, characterized in that: In step (1), the silane coupling agent is one of sodium dodecylbenzene sulfonate, dodecyltrimethylammonium chloride and hexadecyltrimethylammonium bromide.

7. The water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 5, characterized in that: In step (2), the alkali solution is a sodium hydroxide solution with a mass fraction of 25%, and the mass fraction of the sodium alginate aqueous solution is 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.

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

15.

9. 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 EDTA chelated calcium, EDTA chelated magnesium, EDTA chelated iron, EDTA chelated zinc and borax.

10. A method for preparing the water-retaining and fertilizer-retaining composition suitable for sandy soil according to claim 1, characterized in that the steps include: Step 1: Add accurately weighed urea into a melting tank and heat it to 135-140° C. to obtain molten urea; Step 2: accurately weighing monoammonium phosphate, potassium chloride, chelated trace elements, and modified nitrification inhibitor are heated to 100-105° C., 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 into a secondary mixing tank, heat to 100-105° C. to obtain eutectic B, and then granulate it using a spray granulation process. After cooling and screening, the particles have a particle size of 3-4 mm to obtain the water-retaining and fertilizer-retaining composition suitable for sandy soil.

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