A controlled-release phosphate fertilizer containing a phosphorus signaling substance for special use in corn and a preparation method thereof

Abstract

The present invention discloses a controlled-release phosphate fertilizer for corn containing a phosphorus signal substance and a preparation method thereof, belonging to the technical field of controlled-release fertilizer production. The present invention first provides a coating material containing a phosphorus signal substance, comprising the following raw materials in parts by weight: 3-15 parts of the signal substance and 10 parts of fucoidan; the signal substance is selected from one or more of succinic acid, chitosan oligosaccharide or cetyl dimethyl tertiary amine. The present invention also provides a controlled-release phosphate fertilizer for corn containing a phosphorus signal substance. The present invention combines the synergistic characteristics of controlled-release phosphate fertilizer and nutrient signal substances. Compared with traditional controlled-release phosphate fertilizers, the controlled-release phosphate fertilizer for corn containing a phosphorus signal substance can continuously release signal substances into the soil while releasing phosphorus. On the one hand, it can stimulate the efficient absorption and utilization of phosphate fertilizer by corn roots and improve the disease resistance of corn; on the other hand, it can also recruit soil phosphate-solubilizing microorganisms to promote the activation and turnover of phosphorus and improve the phosphorus utilization efficiency of corn.

Description

Technical Field

[0001] The present invention relates to the technical field of controlled-release fertilizer production, and particularly relates to a special controlled-release phosphate fertilizer for corn containing phosphorus signaling substances and a preparation method thereof. Background Art

[0002] Phosphorus is one of the essential macronutrients for plants. The phosphorus obtained by plants mainly comes from the natural soil phosphorus pool and the application and transformation of phosphate fertilizers. During the development and maturation of crops, phosphorus can not only form important functional substances in the crop such as enzymes, nucleic acids, deoxyribonucleic acids, etc., but also participate in the metabolic reactions in the plant body. When the soil phosphorus is sufficient, it can promote the rapid development of crops, improve the root activity at each stage, ensure the normal carbon and nitrogen metabolism in the crop body, be beneficial to accumulating more dry matter, and significantly improve the yield and quality of crops. Therefore, applying phosphate fertilizers is beneficial to enhancing the supply capacity of soil phosphorus and improving the growth of crops, helping them to obtain high yields.

[0003] However, the amount of phosphorus applied is not the more the better. Due to the poor mobility of phosphate fertilizers, most of the phosphate fertilizers are retained in the soil. Excessive application of phosphate fertilizers will cause crops to absorb too much phosphorus from the soil, thus promoting the strengthening of the respiration of crops and consuming the organic matter and energy stored in the crop body. Excessive application of phosphate fertilizers will also cause symptoms such as silicon deficiency and zinc deficiency in crops. In addition, due to the wide variety of soils, crops, and fertilizers, the phosphorus fertilizer requirements of different crops are not the same, and the effects of different fertilizers applied to different soil types are also different.

[0004] Coated phosphate fertilizer is a new type of controlled-release fertilizer. The phosphorus in the fertilizer will be slowly released into the soil, reducing the fixation and loss of phosphate fertilizers in the soil. However, the shapes of phosphate fertilizer particles are mostly irregular, with many pits and protrusions on the surface, and it is difficult to prepare coated phosphate fertilizers.

[0005] Corn is one of the most important food crops in China, and its growth, development and yield formation depend on the supply of soil phosphorus. The key to improving the utilization rate of phosphate fertilizer lies in synchronizing the nutrient supply of soil and fertilizer with the nutrient demand of crops. The critical nutrient period of corn is the three-leaf stage, which is the period when it turns from absorbing nutrients from seeds to absorbing soil nutrients. Phosphorus deficiency at this stage will lead to retarded development and poor effect of supplementing nutrients in the later stage; the maximum efficiency period of corn is the large trumpet-mouth stage, during which the nutrient absorption amount is the largest and the absorption rate is fast. Although the existing coated controlled-release phosphate fertilizers can avoid direct contact between phosphate fertilizers and the soil and reduce the risk of phosphate fertilizers being fixed in the soil. After the coated controlled-release phosphate fertilizers are applied to the soil, phosphate ions diffuse around the fertilization point in the soil solution, forming a phosphate gradient. Corn roots have the characteristic of growing towards fertilizers and will grow towards the fertilization point. However, on the one hand, due to the poor mobility of phosphorus in the soil, the release of phosphorus will be relatively slow after being coated with a film shell, which is likely to cause phosphorus deficiency in the early growth stage of crops; on the other hand, current controlled-release phosphate fertilizers are mostly general-purpose and are not designed and optimized according to the needs of corn, which limits their popularization and application in corn production.

[0006] The ocean is the largest ecosystem on Earth and provides a rich variety of resources. As a marine resource, the application of seaweed extracts in agricultural production has received increasing attention. Seaweed extracts are usually derived from specific brown algae, red algae or green algae and have functions such as growth promotion, stress resistance improvement, nutrient absorption enhancement, soil structure improvement, disease protection enhancement, crop yield and quality improvement in agriculture. Reasonably utilizing marine resources such as seaweed extracts, developing new type of crop-specific controlled-release phosphate fertilizers through seaweed extracts, and enhancing the ability of crops to absorb and utilize nutrients have important application values for the sustainable development of agriculture. Summary of the Invention

[0007] Aiming at the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a corn-specific controlled-release phosphate fertilizer containing phosphorus signal substances and its preparation method.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect of the present invention, a coating material containing phosphorus signal substances is provided, which comprises the following raw materials in parts by weight:

[0010] Signal substances 3 - 15 parts, fucoidan 10 parts;

[0011] The signal substances are selected from one or more of succinic acid, chitosan oligosaccharide or cetyl dimethyl tertiary amine.

[0012] Preferably, the coating material comprises the following raw materials in parts by weight:

[0013] Signal substances 5 parts, fucoidan 10 parts.

[0014] Preferably, the signaling substance is composed of succinic acid, chitosan oligosaccharide, and cetyl dimethyl tertiary amine in a weight ratio of 1:1:1.

[0015] In the second aspect of the present invention, there is provided the use of the above coating material in the preparation of a controlled-release phosphate fertilizer containing a phosphorus signaling substance for corn.

[0016] In the third aspect of the present invention, there is provided a controlled-release phosphate fertilizer containing a phosphorus signaling substance for corn, comprising the following raw materials in parts by weight:

[0017] 1000 parts of phosphate fertilizer, 10 - 20 parts of the first coating material, and 20 - 30 parts of the second coating material;

[0018] The first coating material is the coating material containing a phosphorus signaling substance as described above.

[0019] Preferably, the second coating material is bio-based polyurethane.

[0020] Preferably, the phosphate fertilizer is diammonium phosphate.

[0021] The controlled-release phosphate fertilizer containing a phosphorus signaling substance for corn of the present invention has a release period of more than 50 days, releases no less than 40% of the nutrients in the first 20 days of corn growth, no less than 60% of the nutrients in the first 50 days, and no less than 80% of the nutrients in the first 80 days; effectively solving the problem of phosphorus deficiency in the early stage of corn growth of the existing coated controlled-release phosphate fertilizers.

[0022] In the fourth aspect of the present invention, there is provided a method for preparing the above controlled-release phosphate fertilizer, comprising the following steps:

[0023] (1) Mix the signaling substance and fucoidan evenly in a weight ratio of (3 - 15):10 as the first coating material, and spray the first coating material onto the surface of the phosphate fertilizer to form a first film layer;

[0024] (2) Then spray the second coating material on the surface of the first film layer and cure it into a film to prepare the controlled-release phosphate fertilizer containing a phosphorus signaling substance for corn.

[0025] Preferably, in step (1), the signaling substance and fucoidan are mixed evenly in a weight ratio of 1:2 as the first coating material; the spraying amount of the first coating material is 1.5% of the weight of the phosphate fertilizer.

[0026] Preferably, in step (2), the spraying amount of the second coating material is 2.5% of the weight of the phosphate fertilizer.

[0027] Advantages of the present invention:

[0028] (1) In view of the characteristics of phosphate fertilizers and the nutritional requirements of corn, the present invention designs a coating material containing phosphorus signaling substances. The coating material of the present invention includes signaling substances and fucoidan; among them, succinic acid, chitosan oligosaccharide and cetyl dimethyl tertiary amine are used as signaling substances. Succinic acid and cetyl dimethyl tertiary amine in the signaling substances can efficiently regulate the growth of corn roots and the absorption of phosphorus, while chitosan oligosaccharide can promote the contribution of the microbial pathway to corn phosphorus nutrition by promoting the colonization of beneficial microorganisms such as arbuscular mycorrhizal fungi. Fucoidan is a bioactive seaweed extract, which has multiple functions. On the one hand, it can be used as an adhesive; on the other hand, it can release fucose, a polysaccharide molecule with signaling function, to improve the disease resistance and phosphorus absorption efficiency of corn; moreover, fucoidan comes from marine resources and has a wide source. The signaling substances and fucoidan act synergistically, thereby improving the utilization efficiency of phosphate fertilizers by corn.

[0029] (2) Compared with coated nitrogen fertilizers, it is more difficult to prepare coated phosphate fertilizers because the shapes of phosphate fertilizer particles are irregular and the surfaces are full of pits and protrusions. The present invention first sprays diammonium phosphate with a coating material containing phosphorus signaling substances, which has a surface modification effect on phosphate fertilizer particles and is beneficial to improving the controlled release performance of fertilizers.

[0030] (3) The controlled release phosphate fertilizer for corn containing phosphorus signaling substances prepared by the present invention combines the synergistic characteristics of controlled release phosphate fertilizers and nutrient signaling substances. Compared with traditional controlled release phosphate fertilizers, the controlled release phosphate fertilizer for corn containing phosphorus signaling substances can continuously release signaling substances into the soil while releasing phosphorus. On the one hand, it can stimulate the efficient absorption and utilization of phosphate fertilizers by corn roots and improve the disease resistance of corn; on the other hand, it can recruit soil phosphorus-solubilizing microorganisms to promote the activation and turnover of phosphorus and improve the phosphorus utilization efficiency of corn. Description of the Drawings

[0031] Figure 1 : Corn yields under different treatments.

[0032] Figure 2 : Phosphate fertilizer utilization rates of corn under different treatments.

[0033] Figure 3 : Mycorrhizal infection rates of corn under different treatments.

[0034] Figure 4 : Determination results of phosphorus release rates of different coated controlled release phosphate fertilizers.

[0035] Figure 5 : Comparison chart of fertilizer effects of different coating methods. Detailed Embodiments

[0036] It should be noted that the following detailed description is illustrative and aims to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0037] As mentioned above, due to the poor mobility of phosphate fertilizers, most phosphate fertilizers are retained in the soil. Therefore, the utilization rate of phosphate fertilizers by crops has always been low. Compared with coated nitrogen fertilizers, since the shapes of phosphate fertilizer particles are mostly irregular and the surfaces are full of pits and protrusions, it is more difficult to prepare coated phosphate fertilizers, and there are fewer reports on coated controlled-release phosphate fertilizers; moreover, the existing coated controlled-release phosphate fertilizers are mostly general-purpose and not designed and optimized according to the needs of corn, resulting in a mismatch between the release of phosphorus and the demand of corn for phosphorus.

[0038] In view of this, the present invention first designs a coating material containing a phosphorus signal substance. In a preferred embodiment of the present invention, the coating material is composed of a signal substance and fucoidan mixed in a weight ratio of 1:2, wherein the signal substance is composed of succinic acid, chitosan oligosaccharide and cetyl dimethyl tertiary amine in a weight ratio of 1:1:1.

[0039] Furthermore, based on the designed coating material, the present invention also designs a corn-specific controlled-release phosphate fertilizer containing a phosphorus signal substance. The present invention first sprays the phosphate fertilizer particles with the coating material containing the phosphorus signal substance to modify the surface of the phosphate fertilizer particles, which is beneficial to reducing the preparation difficulty of the coated phosphate fertilizer and improving the controlled-release performance of the fertilizer; then a layer of bio-based polyurethane is sprayed.

[0040] During the release period of fertilizer nutrients, the signal substance in the corn-specific controlled-release phosphate fertilizer containing a phosphorus signal substance can stimulate the absorption of fertilizer nutrients by plants; the fucose released by fucoidan can stimulate the absorption of phosphorus by roots and also inhibit soil indigenous pathogens; as chitosan oligosaccharide is released, corn can establish a good symbiotic relationship with phosphorus-solubilizing microorganisms such as arbuscular mycorrhizal fungi, thereby synergistically improving the nutrient utilization efficiency of corn.

[0041] The special slow-release phosphate fertilizer for corn containing diammonium phosphate, fucoidan, and signal substances used in the present invention can continuously release signal substances into the soil during the growth period of corn compared with traditional slow-release fertilizers, stimulate the growth and metabolism of roots, promote the colonization of phosphate-solubilizing microorganisms, and improve the utilization rate of phosphate fertilizer for corn. At the same time, the fucoidan used in the present invention has biological activity and can increase the disease resistance of corn seedlings. Compared with traditional soil activators / synergists, it saves time and labor and reduces the risk of signal substances being degraded by soil miscellaneous bacteria and shielded by organic matter. Therefore, the phosphate fertilizer containing phosphorus signal substances has a certain yield increase effect compared with the conventional fertilization treatment, but the yield increase effect is better after coating. Generally speaking, compared with traditional fertilizers and ordinary slow-release phosphate fertilizers, the special slow-release phosphate fertilizer for corn containing phosphorus signal substances prepared in the present invention significantly increases the yield of corn.

[0042] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0043] The test materials used in the examples and comparative examples of the present invention are all conventional test materials in the art and can be obtained through commercial channels. Among them, fucoidan was purchased from Xi'an Ruilin Biotechnology Co., Ltd.; chitosan oligosaccharide was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0044] Bio-based polyurethane is synthesized by reacting soybean oil polyol and isocyanate in a weight ratio of 2:1. For the specific preparation method, refer to: Yu Zhen, Research on the Creation and Nutrient Slow-Release Mechanism of Self-Healing Bio-Based Polyurethane Coated Urea, Doctoral Dissertation, Shandong Agricultural University, 2023.

[0045] Example 1: Preparation of Special Slow-Release Phosphate Fertilizer for Corn Containing Phosphorus Signal Substances

[0046] (1) Using succinic acid as the signal substance, the signal substance and fucoidan are mixed in a weight ratio of 1:2 as the first coating material; the first coating material is evenly sprayed on the surface of diammonium phosphate to form the first film layer; the spraying amount of the first coating material is 1.5% of the weight of diammonium phosphate.

[0047] (2) The diammonium phosphate sprayed with the first coating material in step (1) is added to a coating machine, preheated at 65°C for 35 min, and then the second coating material (bio-based polyurethane) is sprayed on the surface of the first film layer. The rotation speed of the coating machine is 40 rpm, the temperature is set at 65°C, and the hot air flow rate is 330 m 3 min -1 , and the spraying speed is 4.5 g min -1, the reaction curing time of the coating material is 10 min, the addition amount of the second coating material each time is 0.5% of the mass of diammonium phosphate, continue spraying after curing, and the total spraying amount of the second coating material is 2.5% of the weight of diammonium phosphate, to prepare a controlled-release phosphate fertilizer for corn containing phosphorus-containing signal substances.

[0048] Example 2: Preparation of a controlled-release phosphate fertilizer for corn containing phosphorus-containing signal substances

[0049] (1) Using chitosan oligosaccharide as the signal substance, mixing the signal substance and fucoidan in a weight ratio of 1:2 as the first coating material; uniformly spraying the first coating material on the surface of diammonium phosphate to form the first film layer; the spraying amount of the first coating material is 1.5% of the weight of diammonium phosphate.

[0050] (2) Add the diammonium phosphate sprayed with the first coating material in step (1) into a coating machine, preheat at 65 °C for 35 min, and then spray the second coating material (bio-based polyurethane) on the surface of the first film layer. The rotation speed of the coating machine is 40 rpm, the temperature is set at 65 °C, and the hot air flow rate is 330 m 3 min -1 , the spraying speed is 4.5 g min -1 , the reaction curing time of the coating material is 10 min, the addition amount of the second coating material each time is 0.5% of the mass of diammonium phosphate, continue spraying after curing, and the total spraying amount of the second coating material is 2.5% of the weight of diammonium phosphate, to prepare a controlled-release phosphate fertilizer for corn containing phosphorus-containing signal substances.

[0051] Example 3: Preparation of a controlled-release phosphate fertilizer for corn containing phosphorus-containing signal substances

[0052] (1) Using cetyl dimethyl tertiary amine as the signal substance, mixing the signal substance and fucoidan in a weight ratio of 1:2 as the first coating material; uniformly spraying the first coating material on the surface of diammonium phosphate to form the first film layer; the spraying amount of the first coating material is 1.5% of the weight of diammonium phosphate.

[0053] (2) Add the diammonium phosphate sprayed with the first coating material in step (1) into a coating machine, preheat at 65 °C for 35 min, and then spray the second coating material (bio-based polyurethane) on the surface of the first film layer. The rotation speed of the coating machine is 40 rpm, the temperature is set at 65 °C, and the hot air flow rate is 330 m 3 min -1 , the spraying speed is 4.5 g min -1 , the reaction curing time of the coating material is 10 min, the addition amount of the second coating material each time is 0.5% of the mass of diammonium phosphate, continue spraying after curing, and the total spraying amount of the second coating material is 2.5% of the weight of diammonium phosphate, to prepare a controlled-release phosphate fertilizer for corn containing phosphorus-containing signal substances.

[0054] Example 4: Preparation of Controlled-Release Phosphate Fertilizer for Corn Containing Phosphorus Signal Substances

[0055] (1) Mix succinic acid and chitosan oligosaccharide in a weight ratio of 1:1 as the signal substance, and mix the signal substance and fucoidan in a weight ratio of 1:2 as the first coating material; spray the first coating material evenly on the surface of diammonium phosphate to form the first film layer; the spraying amount of the first coating material is 1.5% of the weight of diammonium phosphate.

[0056] (2) Add the diammonium phosphate sprayed with the first coating material in step (1) into a coating machine, preheat it at 65°C for 35 min, and then spray the second coating material (bio-based polyurethane) on the surface of the first film layer. The rotation speed of the coating machine is 40 rpm, the temperature is set at 65°C, and the hot air flow rate is 330 m 3 min -1 , the spraying speed is 4.5 g min -1 , the reaction curing time of the coating material is 10 min, the addition amount of the second coating material each time is 0.5% of the mass of diammonium phosphate, and continue spraying after curing. The total spraying amount of the second coating material is 2.5% of the weight of diammonium phosphate, and the controlled-release phosphate fertilizer for corn containing phosphorus signal substances is prepared.

[0057] Example 5: Preparation of Controlled-Release Phosphate Fertilizer for Corn Containing Phosphorus Signal Substances

[0058] (1) Mix succinic acid and cetyl dimethyl tertiary amine in a weight ratio of 1:1 as the signal substance, and mix the signal substance and fucoidan in a weight ratio of 1:2 as the first coating material; spray the first coating material evenly on the surface of diammonium phosphate to form the first film layer; the spraying amount of the first coating material is 1.5% of the weight of diammonium phosphate.

[0059] (2) Add the diammonium phosphate sprayed with the first coating material in step (1) into a coating machine, preheat it at 65°C for 35 min, and then spray the second coating material (bio-based polyurethane) on the surface of the first film layer. The rotation speed of the coating machine is 40 rpm, the temperature is set at 65°C, and the hot air flow rate is 330 m 3 min -1 , the spraying speed is 4.5 g min -1 , the reaction curing time of the coating material is 10 min, the addition amount of the second coating material each time is 0.5% of the mass of diammonium phosphate, and continue spraying after curing. The total spraying amount of the second coating material is 2.5% of the weight of diammonium phosphate, and the controlled-release phosphate fertilizer for corn containing phosphorus signal substances is prepared.

[0060] Example 6: Preparation of Controlled-Release Phosphate Fertilizer for Corn Containing Phosphorus Signal Substances

[0061] (1) Mix chitosan oligosaccharide and cetyl dimethyl tertiary amine in a weight ratio of 1:1 as the signal substance, and mix the signal substance and fucoidan in a weight ratio of 1:2 as the first coating material; spray the first coating material evenly on the surface of diammonium phosphate to form the first film layer; the spraying amount of the first coating material is 1.5% of the weight of diammonium phosphate.

[0062] (2) Add the diammonium phosphate sprayed with the first coating material in step (1) into a coating machine, preheat it at 65 °C for 35 min, and then spray the second coating material (bio-based polyurethane) on the surface of the first film layer. The rotation speed of the coating machine is 40 rpm, the temperature is set at 65 °C, and the hot air flow rate is 330 m 3 min -1 , the spraying speed is 4.5 g min -1 , the reaction curing time of the coating material is 10 min, the addition amount of the second coating material each time is 0.5% of the mass of diammonium phosphate, and continue spraying after curing. The total spraying amount of the second coating material is 2.5% of the weight of diammonium phosphate, and a controlled-release phosphate fertilizer for corn containing phosphorus signal substances is prepared.

[0063] Example 7: Preparation of a controlled-release phosphate fertilizer for corn containing phosphorus signal substances

[0064] (1) Mix succinic acid, chitosan oligosaccharide and cetyl dimethyl tertiary amine in a weight ratio of 1:1:1 as the signal substance, and mix the signal substance and fucoidan in a weight ratio of 1:2 as the first coating material; spray the first coating material evenly on the surface of diammonium phosphate to form the first film layer; the spraying amount of the first coating material is 1.5% of the weight of diammonium phosphate.

[0065] (2) Add the diammonium phosphate sprayed with the first coating material in step (1) into a coating machine, preheat it at 65 °C for 35 min, and then spray the second coating material (bio-based polyurethane) on the surface of the first film layer. The rotation speed of the coating machine is 40 rpm, the temperature is set at 65 °C, and the hot air flow rate is 330 m 3 min -1 , the spraying speed is 4.5 g min -1 , the reaction curing time of the coating material is 10 min, the addition amount of the second coating material each time is 0.5% of the mass of diammonium phosphate, and continue spraying after curing. The total spraying amount of the second coating material is 2.5% of the weight of diammonium phosphate, and a controlled-release phosphate fertilizer for corn containing phosphorus signal substances is prepared.

[0066] Comparative Example 1:

[0067] Mix succinic acid, chitosan oligosaccharide, and cetyl dimethyl tertiary amine in a weight ratio of 1:1:1 as the signal substance, and mix the signal substance and fucoidan in a weight ratio of 1:2 as the coating material; spray the coating material evenly on the surface of diammonium phosphate, and the spraying amount of the coating material is 1.5% of the weight of diammonium phosphate to prepare the coated phosphate fertilizer.

[0068] Comparative Example 2:

[0069] Spray fucoidan as the first coating material on the surface of diammonium phosphate, and the spraying amount of the first coating material is 1.0% of the weight of diammonium phosphate; then spray the second coating material (bio-based polyurethane) on the surface of the first coating material, and the spraying amount of the second coating material is 2.5% of the weight of diammonium phosphate. Prepare the controlled-release phosphate fertilizer containing fucoidan.

[0070] Comparative Example 3:

[0071] Directly spray bio-based polyurethane on the surface of diammonium phosphate, and the spraying amount is 2.5% of the weight of diammonium phosphate to prepare the controlled-release phosphate fertilizer without fucoidan.

[0072] Test Example 1:

[0073] 1. Test method:

[0074] To investigate the effect of the controlled-release phosphate fertilizer containing phosphorus signal substance for corn prepared by the present invention on corn yield, a pot experiment was carried out at Shandong Agricultural University. The corn variety used was "Zhengdan 958", and 1 corn plant was left in each pot. The specific test treatments are as follows:

[0075] Treatment NK (no phosphorus application): Apply 7.5 g of urea and 4.5 g of potassium sulfate;

[0076] Treatment NPK (conventional nitrogen, phosphorus, and potassium fertilization): Apply 5.3 g of urea, 7.5 g of diammonium phosphate, and 4.5 g of potassium sulfate;

[0077] Treatment CM1: Apply 5.3 g of urea, 7.5 g of diammonium phosphate, 4.5 g of potassium sulfate; 7.8 g of the controlled-release phosphate fertilizer prepared in Example 1, and 4.5 g of potassium sulfate;

[0078] Treatment CM2: Apply 5.3 g of urea, 7.8 g of the controlled-release phosphate fertilizer prepared in Example 2, and 4.5 g of potassium sulfate;

[0079] Treatment CM3: Apply 5.3 g of urea, 7.8 g of the controlled-release phosphate fertilizer prepared in Example 3, and 4.5 g of potassium sulfate;

[0080] Treatment CM4: Apply 5.3 g of urea, 7.8 g of the controlled-release phosphate fertilizer prepared in Example 4, and 4.5 g of potassium sulfate;

[0081] Treatment CM5: Apply 5.3 g of urea, 7.8 g of controlled-release phosphate fertilizer prepared in Example 5, and 4.5 g of potassium sulfate;

[0082] Treatment CM6: Apply 5.3 g of urea, 7.8 g of controlled-release phosphate fertilizer prepared in Example 6, and 4.5 g of potassium sulfate;

[0083] Treatment CM7: Apply 5.3 g of urea, 7.8 g of controlled-release phosphate fertilizer prepared in Example 7, and 4.5 g of potassium sulfate;

[0084] Treatment M7: Apply 5.3 g of urea, 7.6 g of controlled-release phosphate fertilizer prepared in Comparative Example 1, and 4.5 g of potassium sulfate.

[0085] For each of the above treatments, when applying fertilizers, fill 40 kg of soil in each pot. For each treatment, the nitrogen fertilizer and potassium fertilizer are evenly mixed into 40 kg of soil, and the phosphate fertilizer and corn seeds are applied to the soil in the way of simultaneous sowing of seed fertilizer; the soil components of each treatment are kept consistent, each treatment is repeated four times, and the corn is harvested after growing for 96 days. After harvesting, calculate the grain yield as the corn yield according to the water content of 14%.

[0086] Determine the phosphorus fertilizer utilization rate of each of the above treatments. The specific determination method is as follows: Determine the total phosphorus content in the plants by the combined digestion of concentrated sulfuric acid - hydrogen peroxide and molybdenum antimony anti-colorimetry. The phosphorus uptake of corn = corn biomass * total phosphorus content in plants.

[0087] Phosphorus fertilizer utilization rate (%) = (phosphorus uptake of corn in the phosphorus application treatment - phosphorus uptake of corn in the NK treatment) / phosphorus application amount × 100

[0088] Determine the infection rate of arbuscular mycorrhizal fungi in each of the above treatments. The specific determination method is as follows: Cut the corn root samples stored at -20 °C into root segments about 1 cm long. Through steps such as KOH digestion, HCl acidification, trypan blue staining, and decolorization with 1:1 lactic acid glycerol, observe the infection situation of the root segments by microscopy, and calculate the mycorrhizal infection rate through MYCOCALC software.

[0089] 2. Test results:

[0090] (1) Corn yield:

[0091] The statistical results of the corn yield of each treatment are as Figure 1 shown. The results show that applying the controlled-release diammonium phosphate containing succinic acid prepared in Example 1 can increase the corn yield. Compared with the non-phosphorus application treatment, the corn yield has increased by 33.9%; compared with the NPK treatment, the corn yield has increased by 8.4%.

[0092] Applying the controlled-release diammonium phosphate containing chitosan oligosaccharide prepared in Example 2 can increase the yield of corn. Compared with the treatment without phosphorus application, the yield of corn increased by 32.4%; compared with the NPK treatment, the yield of corn increased by 7.2%.

[0093] Applying the controlled-release diammonium phosphate containing cetyl dimethyl tertiary amine prepared in Example 3 can increase the yield of corn. Compared with the treatment without phosphorus application, the yield of corn increased by 32.8%; compared with the NPK treatment, the yield of corn increased by 7.5%.

[0094] Applying the controlled-release diammonium phosphate prepared in Example 4 can increase the yield of corn. Compared with the treatment without phosphorus application, the yield of corn increased by 39.3%; compared with the NPK treatment, the yield of corn increased by 12.76%.

[0095] Applying the controlled-release diammonium phosphate prepared in Example 5 can increase the yield of corn. Compared with the treatment without phosphorus application, the yield of corn increased by 35.0%; compared with the NPK treatment, the yield of corn increased by 9.3%.

[0096] Applying the controlled-release diammonium phosphate prepared in Example 6 can increase the yield of corn. Compared with the treatment without phosphorus application, the yield of corn increased by 37.4%; compared with the NPK treatment, the yield of corn increased by 11.2%.

[0097] Applying the controlled-release diammonium phosphate prepared in Example 7 can increase the yield of corn. Compared with the treatment without phosphorus application, the yield of corn increased by 41.6%; compared with the NPK treatment, the yield of corn increased by 14.6%.

[0098] (2) Phosphorus fertilizer utilization rate:

[0099] The results of the phosphorus fertilizer utilization rate of each treatment are as Figure 2 shown. Compared with the NPK treatment, the phosphorus fertilizer utilization rate of the CM1 treatment increased by 4.9 percentage points, the CM2 treatment increased by 4.6 percentage points, the CM3 treatment increased by 8.4 percentage points, the CM4 treatment increased by 6.3 percentage points, the CM5 treatment increased by 7.8 percentage points, the CM6 treatment increased by 7.0 percentage points, the M7 treatment increased by 5.6 percentage points, and the CM7 treatment increased by 11.8 percentage points.

[0100] (3) Infection rate of arbuscular mycorrhizal fungi:

[0101] The measured results of the infection rate of arbuscular mycorrhizal fungi in each treatment are as Figure 3As shown, the application of controlled-release diammonium phosphate containing succinic acid, chitosan oligosaccharide, and cetyl dimethyl tertiary amine can significantly increase the infection rate of arbuscular mycorrhizal fungi. Compared with the NPK treatment, the mycorrhizal infection rate of the CM1 treatment increased by 6.5 percentage points, that of the CM2 treatment increased by 7.0 percentage points, that of the CM3 treatment increased by 8.5 percentage points, that of the CM4 treatment increased by 5.75 percentage points, that of the CM5 treatment increased by 8.5 percentage points, that of the CM6 treatment increased by 7.8 percentage points, that of the M7 treatment increased by 8.5 percentage points, and that of the CM7 treatment increased by 14.0 percentage points. This indicates that the controlled-release phosphate fertilizer containing signal substances of the present invention is beneficial to strengthening the establishment of a mutualistic symbiotic relationship between maize and beneficial microorganisms and promoting the acquisition of soil phosphorus by maize.

[0102] In summary, in the controlled-release phosphate fertilizer of the present invention, by adding succinic acid, chitosan oligosaccharide, and cetyl dimethyl tertiary amine as signal substances, the utilization rate of phosphate fertilizer and the infection rate of arbuscular mycorrhizal fungi can be increased, thereby increasing the yield of maize. Compared with the use of a single signal substance, the combination of succinic acid, chitosan oligosaccharide, and cetyl dimethyl tertiary amine used as signal substances can further improve the effect of phosphate fertilizer on the same basis of the same addition amount, and has a significant synergistic effect.

[0103] Test Example 2:

[0104] The phosphorus release rate of the controlled-release diammonium phosphate prepared in Example 7 and Comparative Example 3 was measured. The measurement method used the static water immersion method at 25°C, referring to: Yan Xiao, Zhang Min, Wei Zongqiang, etc. Rapid determination of nutrients in controlled-release urea and study on nitrogen release rate in field soil. Journal of Soil and Water Conservation, 2010, 24(1): 167-171.

[0105] The results are as Figure 4 shown. When maize grows for 14-20 days, the phosphorus release of the controlled-release phosphate fertilizer in Example 7 is relatively fast. At this time, it is the period when maize is more sensitive to phosphorus (around the three-leaf stage), and the release of fertilizer phosphorus helps to meet the demand during the phosphorus-sensitive period of maize. When maize grows to 40-50 days, the release rate of the fertilizer significantly accelerates. The nutrient release of Comparative Example 3 is almost completed, while the controlled-release phosphate fertilizer in Example 7 still has a long release period, which is beneficial to the growth of maize at the jointing stage and the formation of the later yield.

[0106] Test Example 3:

[0107] The fertilizers prepared in Comparative Example 2 and Comparative Example 3 were photographed and compared. The results are as Figure 5 shown. After a layer of fucoidan is coated on the surface of diammonium phosphate, compared with the non-addition of fucoidan, the coating effect of diammonium phosphate is significantly improved.

[0108] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A coating material containing a phosphorus signal substance, characterized in that, Comprising the following raw materials in parts by weight: Signal substance 3 - 15 parts, fucoidan 10 parts; The signal substance is composed of succinic acid, chitosan oligosaccharide and cetyl dimethyl tertiary amine in a weight ratio of 1:1:

1.

2. The coating material according to claim 1, characterized in that, Comprising the following raw materials in parts by weight: Signal substance 5 parts, fucoidan 10 parts.

3. Use of the coating material according to claim 1 or 2 in the preparation of a controlled-release phosphate fertilizer for corn containing a phosphorus element signal substance.

4. A controlled-release phosphate fertilizer for corn containing a phosphorus signal substance, characterized in that, Prepared by the following method: (1) Mix the signal substance and fucoidan in claim 1 evenly according to a weight ratio of (3 - 15):10 as the first coating material, and spray the first coating material onto the surface of the phosphate fertilizer to form a first film layer; (2) Then spray a second coating material on the surface of the first film layer and cure it into a film to prepare a controlled-release phosphate fertilizer for corn containing a phosphorus element signal substance; The second coating material is bio-based polyurethane; the spraying amount of the first coating material is 1.5% of the weight of the phosphate fertilizer;, the spraying amount of the second coating material is 2.5% of the weight of the phosphate fertilizer.

5. The controlled-release phosphate fertilizer according to claim 4, wherein The phosphate fertilizer is diammonium phosphate.

6. The controlled-release phosphate fertilizer according to claim 4, wherein In step (1), the signal substance and fucoidan are mixed evenly according to a weight ratio of 1:2 as the first coating material.

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