Rice controlled-release fertilizer and preparation method and application method thereof

Abstract

This invention relates to the field of rice fertilizer technology, specifically disclosing a controlled-release fertilizer for rice and its preparation and application methods. The controlled-release fertilizer is a blended type, composed of a first and a second blended component. The first component contains urea, monoammonium phosphate, potassium chloride, and polymer resin-coated urea, with optional addition of phosphogypsum. The second component consists of ammonium chloride, zinc sulfate, and multi-effect silicon fertilizer. The total fertilizer nutrients are: N 31%-33%, P2O5 10%-11%, K2O 8%-9%, Zn 3%, and Si 2%, with controlled-release nitrogen accounting for more than 8% of the total nitrogen. This invention adopts a combined fast and slow fertilization mode, with nutrient release adapted to the nutrient requirements of rice, improving nitrogen fertilizer utilization. Combined with silicon, zinc, and phosphogypsum, it can improve soil, enhance rice's stress resistance, and increase yield and quality. This fertilizer can be applied as a single basal application, adaptable to different rice planting patterns, simplifying the fertilization process, reducing non-point source pollution, and is green, practical, and suitable for large-scale promotion.

Description

Technical Field

[0001] This invention relates to the field of rice fertilizer technology, specifically to a controlled-release rice fertilizer and its preparation and application methods. Background Technology

[0002] Rice is one of my country's major food crops, and the rational application of fertilizers during its production has a significant impact on yield and quality. Currently, traditional compound fertilizers are widely used as the main fertilizer source in rice cultivation. However, in practice, traditional compound fertilizers have problems such as rapid nutrient release and a mismatch with the nutrient requirements of rice, resulting in a nitrogen fertilizer utilization rate that is generally below 40% in the current season. Nitrogen that is not absorbed by rice is lost through volatilization, leaching, runoff, and soil fixation, which not only reduces the economic benefits of fertilizers but also leads to significant agricultural non-point source pollution.

[0003] To improve fertilizer utilization and prolong its duration of effect, various improvement measures have been attempted in existing technologies. For example, applying soil urease inhibitors to delay urea hydrolysis, or using polymer resin coating technology to prepare controlled-release fertilizers, attempts are made to synchronize nutrient release with the nutrient requirements of rice. These technologies have reduced the number of fertilization applications and improved nitrogen use efficiency to some extent, but they still have the following shortcomings: Limited precision in nutrient release control: The release curves of some coated fertilizers are unstable under field conditions and are greatly affected by environmental factors such as temperature and moisture, making it difficult to achieve long-term and stable fertilization effects.

[0004] The formula structure is simple and lacks specificity: existing controlled-release fertilizers mostly focus on the controlled release of nitrogen, and do not adequately consider the synergistic supply of phosphorus, potassium and micronutrients (such as silicon and zinc), thus failing to fully meet the nutritional needs of rice throughout its entire growth period.

[0005] Lack of soil improvement function: Most controlled-release fertilizer products only focus on nutrient supply and ignore the fertilizer's role in improving the physical and chemical properties of the soil. Long-term use may still lead to problems such as soil compaction and acidification.

[0006] The application methods are complicated and farmers have low acceptance: Some products need to be applied in multiple times or used in combination with ordinary fertilizers, which increases the difficulty of operation and labor costs, thus limiting their promotion and application in large-scale rice cultivation.

[0007] Therefore, developing a long-acting controlled-release fertilizer that can improve nitrogen fertilizer utilization, extend fertilizer effect, and can be applied in one application while taking into account both soil improvement and rice quality enhancement has become an urgent technical problem to be solved in the current rice production field. Summary of the Invention

[0008] The purpose of this invention is to address the deficiencies of the prior art by providing a controlled-release fertilizer for rice, its preparation method, and its application method, thereby solving the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a controlled-release fertilizer for rice, wherein the controlled-release fertilizer is a blended fertilizer, composed of a first blending component and a second blending component; The first blending component comprises the following raw materials in weight percentages: urea 45.7%-50%, monoammonium phosphate 16.7%-18.4%, potassium chloride 13.4%-15.0%, and polymer resin-coated urea 20.0%; The second blending component comprises the following raw materials by weight percentage: 90% ammonium chloride, 5% zinc sulfate, and 5% multi-effect silicon fertilizer; The total nutrient weight percentage in the controlled-release fertilizer is: N 31%-33%, P2O5 10%-11%, K2O 8%-9%, Zn 3%, Si 2%, and the controlled-release nitrogen accounts for more than 8% of the total nitrogen. The first blending component also selectively includes phosphogypsum, wherein the amount of phosphogypsum added is 0.15%-1.0% of the total weight of the first blending component.

[0010] As a preferred embodiment of the present invention, when the first blending component does not contain phosphogypsum, its raw material weight percentage is: urea 50%, monoammonium phosphate 16.7%, potassium chloride 13.4%, and polymer resin coated urea 20.0%.

[0011] As a preferred embodiment of the present invention, when the first blending component contains phosphogypsum, the weight percentage of its raw materials is: urea 45.7%, monoammonium phosphate 18.4%, potassium chloride 15.0%, polymer resin coated urea 20.0%, and phosphogypsum 1.0%.

[0012] As a preferred embodiment of the present invention, when the first blending component contains phosphogypsum, the weight percentage of its raw materials is: urea 48.2%, monoammonium phosphate 16.7%, potassium chloride 15.0%, polymer resin coated urea 20.0%, and phosphogypsum 0.15%.

[0013] As a preferred embodiment of the present invention, the coating material of the polymer resin-coated urea is a thermosetting resin or a thermoplastic resin.

[0014] As a preferred embodiment of the present invention, the effective silicon SiO2 content in the multi-effect silicon fertilizer is ≥20%, and the zinc Zn content in the zinc sulfate is ≥20%.

[0015] A method for preparing controlled-release fertilizer for rice as described above, comprising the following specific steps: Step 1: The raw materials of the first blending component are fed into the mixer in proportion and mixed evenly, and then packaged in 40 kg / bags; Step 2: Preparation of the second blending component: Ammonium chloride, zinc sulfate, and multi-effect silicon fertilizer are fed into a mixer in a certain proportion and mixed evenly. The mixture is then compressed into granules by an extruder and packaged in 20 kg / bags.

[0016] A method for applying controlled-release fertilizer for rice as described above includes the following steps: Step 1: Mix the first blending component and the second blending component at a ratio of 40 kg: 20 kg; Step 2: For manually transplanted rice or hybrid japonica rice, apply the first and second blending components as base fertilizers to the soil during land preparation. The application rate is 40 kg / mu for the first blending component and 20 kg / mu for the second blending component. Step 3: For machine-transplanted rice or directly sown rice, apply the first blending component into the soil during land preparation at a rate of 40 kg / mu. After the herbicide is applied, apply the second blending component into the paddy field at a rate of 20 kg / mu.

[0017] As a preferred embodiment of the present invention, the first and second admixtures are mixed into the soil layer by spreading and then tilling.

[0018] As a preferred embodiment of the present invention, the controlled-release fertilizer is used as a base fertilizer for rice, and after a single application, no additional nitrogen fertilizer is required during the entire growth period.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. Significantly improves fertilizer utilization and achieves long-term nutrient supply. This invention achieves a "rapid-release and slow-release" nutrient combination by compounding ordinary urea with polymer resin-coated urea and optimizing the overall ratio of nitrogen, phosphorus, potassium, and micronutrients (N(31-33)-P2O5(10-11)-K2O(8-9)-Zn3-Si2, with controlled-release nitrogen accounting for more than 8%). Ordinary fertilizer meets the nutrient requirements of rice in the early stages of growth, while polymer resin-coated urea controls the release rate of nitrogen in the soil, making the nutrient supply curve highly synchronized with the nutrient requirements of rice throughout its entire growth period. Compared with the less than 40% nitrogen utilization rate of traditional compound fertilizers, this invention can significantly reduce nitrogen volatilization, leaching, and soil fixation, thereby increasing nitrogen utilization to a higher level.

[0020] 2. Simplify the fertilization process, enabling one-time application and saving labor costs. This invention provides a blended controlled-release fertilizer, along with a matching "base fertilizer + auxiliary granules" packaging and application scheme (40 kg / mu + 20 kg / mu). It allows for one or at most two fertilizations for different planting methods, including manual transplanting, hybrid japonica rice, machine transplanting, and direct seeding of rice, significantly reducing the number of topdressing applications during rice growth. This not only simplifies field operations but also significantly reduces farmers' labor input and time costs, thereby improving agricultural production efficiency.

[0021] 3. Improve soil structure and enhance arable land quality. This invention innovatively incorporates phosphogypsum into its formulation (as in Examples 2 and 3). Phosphogypsum, an industrial byproduct, is rich in medium-level elements such as calcium, sulfur, and silicon. When applied to the soil, it effectively improves soil aggregate structure, reduces soil bulk density, increases soil permeability, and has an ameliorative effect on acidic soils. Simultaneously, the combined use of multi-effect silicon fertilizer and zinc sulfate helps alleviate soil compaction and secondary salinization caused by long-term application of chemical fertilizers, promoting healthy root development in rice.

[0022] 4. Improve rice yield and quality, and increase economic benefits. By balancing the supply of key nutrients such as nitrogen, phosphorus, potassium, silicon, and zinc, this invention effectively promotes the robust growth of rice plants. Silicon enhances rice's resistance to lodging, pests, diseases, and drought; zinc participates in auxin metabolism, playing a crucial role in improving grain fullness and seed setting rate. Field applications show that rice treated with this invention exhibits full grain filling, high milling rate, and improved rice quality. Under conditions of equal or reduced nutrient input, this invention can increase rice yield and quality, improve the input-output ratio, and increase farmers' income.

[0023] 5. Reduces environmental pollution risks and meets the requirements of green agriculture. By significantly improving fertilizer utilization and reducing nitrogen leaching and volatilization losses, this invention lowers the risk of agricultural non-point source pollution at its source and alleviates environmental pressures such as eutrophication caused by excessive fertilization. Simultaneously, utilizing industrial byproducts such as phosphogypsum for soil improvement embodies the environmentally friendly concept of resource recycling and aligns with current policy guidelines promoting green and sustainable rice production. Attached Figure Description

[0024] Figure 1 This is a flowchart of the application method of the present invention. Detailed Implementation

[0025] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0026] This invention provides a controlled-release fertilizer for rice, its preparation method, and its application method. This controlled-release fertilizer is a blended fertilizer that scientifically combines a fast-acting nitrogen source (ordinary urea) with a controlled-release nitrogen source (polymer resin-coated urea), and adds nutrients such as phosphorus, potassium, silicon, and zinc, as well as selectively adding phosphogypsum. This achieves a synergistic effect of long-term nutrient supply and soil improvement throughout the entire rice growth period.

[0027] In the description of this invention, unless otherwise stated, "%" refers to weight percentage. The polymer resin-coated urea can use conventional thermosetting resins (such as polyurethane resin) or thermoplastic resins (such as polyethylene resin) as coating materials, with a controlled-release period generally of 60-120 days, which can be selected according to the length of the rice growth period. The effective silicon (calculated as SiO2) content in the multi-effect silicon fertilizer is preferably ≥20%, and the zinc (Zn) content in the zinc sulfate is preferably ≥20%. The phosphogypsum is an industrial by-product phosphogypsum with a CaSO4·2H2O content ≥75% and a pH value generally of 2-4. Before use, it can be dried and pulverized to ensure its fineness passes through a 100-mesh sieve.

[0028] The present invention will be further illustrated by specific embodiments below. Example 1

[0029] This embodiment provides a controlled-release fertilizer for rice that does not contain phosphogypsum, suitable for paddy fields with good soil physicochemical properties that do not require special modification.

[0030] 1. Fertilizer formulation The raw material composition of the first blending component (basic blended fertilizer) is as follows:

[0031] The raw material composition of the second blending component (enhancing blending particles) is as follows:

[0032] Calculations show that the total nutrient content of the controlled-release fertilizer in this embodiment is: N 33%, P2O5 10%, K2O 8%, Zn 3%, and Si 2%. Among them, the controlled-release nitrogen (from polymer resin-coated urea) accounts for 8.5% of the total nitrogen.

[0033] 2. Production Method Preparation of the first blending component: Accurately weigh urea, monoammonium phosphate, potassium chloride, and polymer resin-coated urea according to the above weight percentages, and sequentially feed them into a horizontal mixer. Stir at 30-50 rpm for 10-15 minutes at room temperature until all components are uniformly mixed. Package the uniformly mixed material into 40 kg bags using an automatic metering system, seal the bags, and stack them for storage.

[0034] Preparation of the second blending component: Accurately weigh ammonium chloride, zinc sulfate, and multi-effect silicon fertilizer according to the above weight percentages, and feed them into a vertical mixer for thorough mixing. The thoroughly mixed material is then fed into a roller extrusion granulator, where it is compressed into irregular particles with a diameter of 2-4 mm under a pressure of 15-25 MPa. The extruded particles are then graded and screened by a vibrating screen. After removing the powder, the particles are packaged in 20 kg bags. The screened powder can be returned to the extrusion granulator for re-granulation.

[0035] 3. Application method For manual transplanting of rice or hybrid japonica rice: When preparing the land, the first and second blending components are evenly spread on the field surface at one time, with the application rates being 40 kg / mu for the first blending component and 20 kg / mu for the second blending component. Then, rotary tillage or plowing is carried out to fully mix the fertilizer with the topsoil. After that, the soil is irrigated and leveled, and transplanting is carried out according to conventional methods.

[0036] For machine-transplanted or direct-seeded rice cultivation: During land preparation, first evenly spread 40 kg / mu of the first blending component on the field surface, then rotary till and mix it thoroughly, followed by irrigation and harrowing to level the surface, and then complete the transplanting or sowing operations. 3-5 days after applying herbicides (usually pre-emergence or early post-emergence), evenly spread 20 kg / mu of the second blending component in the paddy field, maintaining a shallow water layer of 3-5 cm to allow the fertilizer granules to slowly dissolve and release nutrients. Example 2

[0037] This embodiment provides a controlled-release fertilizer for rice containing phosphogypsum, which is suitable for paddy fields with acidic soil, heavy compaction, or those requiring soil improvement. The addition of phosphogypsum helps improve soil structure and provides calcium and sulfur nutrients.

[0038] 1. Fertilizer formulation The raw material composition of the first blending component (basic blended fertilizer) is as follows:

[0039] The raw material composition of the second blending component (enhancing blending particles) is the same as that of Example 1: 90% ammonium chloride, 5% zinc sulfate, and 5% multi-effect silicon fertilizer.

[0040] Calculations show that the total nutrient content of the controlled-release fertilizer in this embodiment is: N 31%, P2O5 11%, K2O 9%, Zn 3%, and Si 2%. Among them, controlled-release nitrogen accounts for 9.0% of the total nitrogen.

[0041] 2. Production Method Preparation of the first blending component: Phosphogypsum needs to be pretreated before use, namely, dried at 105℃ until the moisture content is ≤3%, then pulverized and passed through a 100-mesh sieve. The pretreated phosphogypsum, urea, monoammonium phosphate, potassium chloride, and polymer resin-coated urea are accurately weighed according to the above weight percentages and sequentially fed into a horizontal mixer. The mixture is stirred at 30-50 rpm for 12-18 minutes at room temperature to ensure the phosphogypsum is uniformly dispersed in the fertilizer system. Subsequent packaging procedures are the same as in Example 1.

[0042] The preparation method of the second blending component is exactly the same as that in Example 1, and will not be repeated here.

[0043] 3. Application method The application method is exactly the same as in Example 1. It should be noted that, due to the high hygroscopicity of phosphogypsum, it is recommended to open the packaging to check its flowability before application. If clumps are present, gently tap the packaging bag to loosen them, or sieve it before application. Example 3

[0044] This embodiment provides another controlled-release fertilizer for rice containing phosphogypsum, with a low phosphogypsum addition amount (0.15%), suitable for paddy fields with slight soil acidification and mainly for supplementing calcium and sulfur nutrients.

[0045] 1. Fertilizer formulation The raw material composition of the first blending component (basic blended fertilizer) is as follows:

[0046] The raw material composition of the second blending component (enhancing blending particles) is the same as that in Examples 1 and 2: 90% ammonium chloride, 5% zinc sulfate, and 5% multi-effect silicon fertilizer.

[0047] Calculations show that the total nutrient content of the controlled-release fertilizer in this embodiment is: N 32%, P2O5 10%, K2O 9%, Zn 3%, and Si 2%. Among them, controlled-release nitrogen accounts for 8.7% of the total nitrogen.

[0048] 2. Production Method The preparation method is exactly the same as in Example 2. The pretreatment process of phosphogypsum (drying, crushing, sieving) and the mixing process with other raw materials are the same as in Example 2.

[0049] 3. Application method The application method is exactly the same as in Examples 1 and 2.

[0050] Comparative examples (for reference) To better illustrate the effects of the present invention, the following comparative experiments were conducted: Comparative Example 1 (Ordinary Compound Fertilizer): Commercially available ordinary compound fertilizer was used, with a nutrient content of N-P2O5-K2O of 15-15-15, free of controlled-release nitrogen, silicon, zinc, and phosphogypsum. It was applied according to the conventional fertilization method, namely 40 kg / mu of base fertilizer + 10 kg / mu of tillering fertilizer + 5 kg / mu of heading fertilizer.

[0051] Comparative Example 2 (containing only controlled-release fertilizer, excluding silicon and zinc): The formula is: 52% urea, 16% monoammonium phosphate, 12% potassium chloride, and 20% polymer resin-coated urea, excluding zinc sulfate, multi-effect silicon fertilizer, and phosphogypsum. The application method is the same as in Example 1.

[0052] Comparative Example 3 (containing only silicon and zinc, without controlled-release nitrogen): The formula is: 65% urea, 13% monoammonium phosphate, 12% potassium chloride, 5% zinc sulfate, and 5% multi-effect silicon fertilizer, without polymer resin-coated urea. The application method is the same as in Example 1.

[0053] Field trial results Examples 1-3 and Comparative Examples 1-3 were compared in the same paddy field in Guanyun County, Jiangsu Province. The rice variety used was the locally cultivated hybrid japonica rice. The experiment adopted a randomized block design, with three replicates per treatment and a plot area of ​​30m². 2 The experimental results are shown in the table below:

[0054] The experimental results show that, compared with Comparative Example 1 (ordinary compound fertilizer), the nitrogen fertilizer utilization rate of Examples 1-3 of this invention increased by 13.7-15.5 percentage points, the yield per mu increased by 60.2-66.9 kg, and the soil bulk density decreased by 0.07-0.14 g / cm³ (indicating improved soil looseness). Simultaneously, the number of fertilization applications decreased from 3 to 1. Compared with Comparative Example 2 (containing only controlled-release nitrogen, without silicon and zinc), the examples of this invention show significant improvements in both yield and soil improvement. Compared with Comparative Example 3 (containing only silicon and zinc, without controlled-release nitrogen), the examples of this invention have significant advantages in nitrogen fertilizer utilization rate and yield. Overall, Example 2 (1.0% phosphogypsum addition) shows the best performance in terms of nitrogen fertilizer utilization rate, yield, and soil improvement.

[0055] Regarding the controlled-release period of polymer resin-coated urea: Depending on the growth period of different rice varieties, those skilled in the art can appropriately adjust the controlled-release period of polymer resin-coated urea. For late-season rice varieties with a longer growth period (≥150 days), a controlled-release period of 90-120 days can be used; for early-season rice varieties with a shorter growth period (≤130 days), a controlled-release period of 60-90 days can be used. As long as the proportion of controlled-release nitrogen to total nitrogen is maintained at 8% or more, the technical effects of this invention can be achieved.

[0056] Regarding the amount of phosphogypsum added: In this invention, the amount of phosphogypsum added can be adjusted within the range of 0.15%-1.0% of the total weight of the first blending components. For strongly acidic soils (pH≤5.5) or severely compacted soils, a higher addition amount (e.g., 0.8%-1.0%) can be selected; for neutral or slightly acidic soils, a lower addition amount (e.g., 0.15%-0.5%) can be selected. The amount of phosphogypsum added should not exceed 1.5%, otherwise it may lead to excessive sulfur content in the soil, affecting the growth of rice roots.

[0057] For large-scale farms, the first and second blending components can be mixed evenly in a 40:20 ratio before application and then broadcast in one go. However, it should be noted that the mixed fertilizer should not be stored for a long time, because the ammonium chloride in the second blending component is highly hygroscopic and may cause the whole mixture to absorb moisture and clump after mixing. It is recommended to apply it within 24 hours after mixing.

[0058] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A controlled-release fertilizer for rice, characterized in that, The controlled-release fertilizer is a blended fertilizer, composed of a first blending component and a second blending component; The first blending component comprises the following raw materials in weight percentages: urea 45.7%-50%, monoammonium phosphate 16.7%-18.4%, potassium chloride 13.4%-15.0%, and polymer resin-coated urea 20.0%; The second blending component comprises the following raw materials by weight percentage: 90% ammonium chloride, 5% zinc sulfate, and 5% multi-effect silicon fertilizer; The total nutrient weight percentage in the controlled-release fertilizer is: N 31%-33%, P2O5 10%-11%, K2O 8%-9%, Zn 3%, Si 2%, and the controlled-release nitrogen accounts for more than 8% of the total nitrogen. The first blending component also selectively includes phosphogypsum, wherein the amount of phosphogypsum added is 0.15%-1.0% of the total weight of the first blending component.

2. The controlled-release fertilizer for rice according to claim 1, characterized in that, When the first blending component does not contain phosphogypsum, its raw material weight percentage is: urea 50%, monoammonium phosphate 16.7%, potassium chloride 13.4%, and polymer resin coated urea 20.0%.

3. The controlled-release fertilizer for rice according to claim 1, characterized in that, When the first blending component contains phosphogypsum, its raw material weight percentage is: urea 45.7%, monoammonium phosphate 18.4%, potassium chloride 15.0%, polymer resin coated urea 20.0%, and phosphogypsum 1.0%.

4. The controlled-release fertilizer for rice according to claim 1, characterized in that, When the first blending component contains phosphogypsum, its raw material weight percentage is: urea 48.2%, monoammonium phosphate 16.7%, potassium chloride 15.0%, polymer resin coated urea 20.0%, and phosphogypsum 0.15%.

5. The controlled-release fertilizer for rice according to claim 1, characterized in that, The coating material of the polymer resin-coated urea is a thermosetting resin or a thermoplastic resin.

6. The controlled-release fertilizer for rice according to claim 1, characterized in that, The effective silicon SiO2 content in the multi-effect silicon fertilizer is ≥20%, and the zinc content in the zinc sulfate is ≥20%.

7. A method for preparing rice controlled-release fertilizer as described in any one of claims 1-6, characterized in that, The specific steps are as follows: Step 1: Preparation of the first blending component: The raw materials of the first blending component are fed into a mixer in proportion and stirred evenly, and then packaged in 40 kg / bags. Step 2: Preparation of the second blending component: Ammonium chloride, zinc sulfate, and multi-effect silicon fertilizer are fed into a mixer in a certain proportion and mixed evenly. The mixture is then compressed into granules by an extruder and packaged in 20 kg / bags.

8. A method for applying controlled-release fertilizer for rice according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Mix the first blending component and the second blending component at a ratio of 40 kg: 20 kg; Step 2: For manually transplanted rice or hybrid japonica rice, apply the first and second blending components as base fertilizers to the soil during land preparation. The application rate is 40 kg / mu for the first blending component and 20 kg / mu for the second blending component. Step 3: For machine-transplanted rice or directly sown rice, apply the first blending component into the soil during land preparation at a rate of 40 kg / mu. After the herbicide is applied, apply the second blending component into the paddy field at a rate of 20 kg / mu.

9. The application method according to claim 8, characterized in that, The first and second admixtures are mixed into the soil layer by spreading and then tilling.

10. The application method according to claim 8, characterized in that, The controlled-release fertilizer is used as a base fertilizer for rice, and after a single application, no additional nitrogen fertilizer is required during the entire growth period.

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