A method of applying a phosphorus fertilizer

Abstract

The present application relates to the fertilizer technical field, the present application provides a kind of fertilization method of synergistic phosphorus fertilizer, comprising the following steps: S1, preparation of soil conditioner, nano magnesium oxide is mixed with zeolite uniformly, the zeolite is treated by microwave calcination, and application amount is adjusted according to soil pH value;S2, again, phosphorus ore powder is mixed with sulfonated humic acid uniformly, is treated using chitosan coating process, and application amount is adjusted according to soil available phosphorus content;S3, the soil conditioner described in step S1 is applied for 2-4d, and phosphorus-solubilizing bacteria agent starts to be applied;The present application constructs "physical conditioning-chemical slow-release-biological activation" chain mechanism: nano magnesium oxide neutralizes soil acidification quickly, zeolite adsorbs excess acidic substances, and effectively adjusts pH;Humic acid and chitosan coating synergistic effect, both reduce phosphorus fixation, and match crop fertilizer requirement law through complexation-slow-release mechanism, improve the soil environment to efficiently activate insoluble phosphorus, improve soil organic matter decomposition and microbial diversity.

Description

Technical Field

[0001] This invention relates to the field of fertilizer technology, and specifically to a method for applying phosphate fertilizer with enhanced efficiency. Background Technology

[0002] In agricultural production, phosphate fertilizer is one of the key nutrients for ensuring crop yield. However, traditional phosphate fertilizer application generally suffers from low utilization rate, serious loss, and strong soil fixation. Especially in acidic or alkaline soils, water-soluble phosphorus readily combines with ions such as iron, aluminum, and calcium to form insoluble compounds, causing most of the phosphorus to lose its effectiveness in the short term. This not only increases fertilization costs but also brings the risk of non-point source pollution and ecological degradation. To improve the utilization efficiency of phosphate fertilizer, slow-release fertilizers have gradually become a research hotspot.

[0003] Although various types of phosphate fertilizer products have emerged, such as compound fertilizers with added functional combinations of humic acid, zeolite, and nano-magnesium oxide, most technologies remain at the level of "component superposition," lacking a systematic design for dynamic responses to the soil environment. These solutions often mix and apply multiple functional materials at once, ignoring the temporal differences and spatial competition of the different components' mechanisms of action in the soil. This results in ineffective synergy between conditioners, slow-release materials, and microorganisms, and may even lead to antagonistic effects. For example, if a strongly alkaline conditioner is applied simultaneously with a microbial inoculant, it may directly inhibit the activity of the inoculant, thereby weakening its biological activation function.

[0004] More importantly, existing technologies generally lack a dynamic management concept of "phased and on-demand application." Parameters such as soil pH, available phosphorus content, and microbial community structure are dynamically changing, while traditional fertilization methods use a fixed, one-size-fits-all approach, making it difficult to adapt to the actual needs of different plots and different growth stages. Especially in acidic soils, phosphorus is easily fixed by iron ions, and simply relying on slow-release chemical forms or controlled-release adsorption materials cannot fundamentally solve the problem of effective phosphorus activation. Furthermore, although microbial agents have been gradually introduced, they are mostly simply mixed in as "additives" without forming an organic connection with soil conditioning and nutrient release processes, and their activation potential is far from being fully released.

[0005] Therefore, the application methods for enhancing the efficiency of phosphate fertilizers still need further optimization. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a method for applying phosphate fertilizer with enhanced efficiency, which solves the technical problems of application conflicts caused by insufficient component synergy, mismatch between phosphate fertilizer release and soil environment dynamics, and disconnection from biological activation functions in existing technologies.

[0007] First, this invention provides a method for applying phosphate fertilizer with enhanced efficiency, comprising the following steps: S1, Prepare a soil conditioner by mixing nano-magnesium oxide with zeolite, wherein the zeolite is microwave-calcined and the application amount is adjusted according to the soil pH value. S2, then sulfonated humic acid is mixed with phosphate rock powder and treated with chitosan coating process. The application rate is adjusted according to the available phosphorus content of the soil. S3, 2-4 days after applying the soil conditioner as described in step S1, begin applying the phosphate-solubilizing agent.

[0008] Based on the aforementioned technical solution, the preparation method of the nano-magnesium oxide is further optimized by comprising the following steps: reacting MgCl2 with NH4OH in a water bath at 45-50℃, adjusting the pH value to 8-10, modifying with polyethylene glycol, and calcining at 500-550℃ for 2-3 hours to obtain nano-magnesium oxide.

[0009] Based on the aforementioned technical solution, the molar ratio of MgCl2 to NH4OH is further optimized to be 1:1.8-2.2.

[0010] Based on the aforementioned technical solution, further optimization is achieved by having the degree of sulfonation of the sulfonated humic acid be 1.5-2 mmol / g and the P2O5 content in the phosphate rock powder be 23%-26%.

[0011] Based on the aforementioned technical solution, and further optimized, the mass ratio of nano-magnesium oxide to zeolite in step S1 is 2-2.5:1.

[0012] Based on the aforementioned technical solution, and further optimized, the mass ratio of sulfonated humic acid to phosphate rock powder in step S2 is 1:4-6.2.

[0013] Based on the aforementioned technical solution, in a further optimized manner, the chitosan coating process described in step S2 involves adding chitosan coating at a ratio of 5-8% of the total amount of sulfonated humic acid and phosphate rock powder.

[0014] Based on the aforementioned technical solution, further optimized, the particle size of the nano-magnesium oxide is 50-100 nm, and the particle size of the zeolite is 8-50 mesh.

[0015] Based on the aforementioned technical solution, further optimization is achieved by adjusting the application amount in step S1 according to the soil pH value. If the soil pH value is <6.0, the amount of nano-magnesium oxide is increased by 10-20%. The application amount in step S2 is adjusted according to the available phosphorus content in the soil. If the available phosphorus is <15mg / kg, the amount of sulfonated humic acid and phosphate rock powder is increased by 10-20%.

[0016] Based on the aforementioned technical solution, the concentration of the phosphate-solubilizing bacterial agent is further optimized to be ≥1.2×10⁻⁶. 9 CFU / g.

[0017] The fertilization method for enhancing the efficiency of phosphate fertilizer provided by this invention has the following advantages over the prior art: (1) In the prior art, the antagonistic effect of alkaline conditioners and microbial agents often occurs when they are mixed and applied, which inhibits the activity of phosphate-solubilizing bacteria. The present invention avoids the direct inhibition of microorganisms by the high alkaline environment by applying soil conditioner (nano magnesium oxide + microwave roasted zeolite) in stages to stabilize soil pH, and then applying humic acid slow-release phosphate fertilizer and simultaneously inoculating phosphate-solubilizing bacteria. This method increases the survival rate of phosphate bacteria by more than 30% and the phosphorus activation rate by 20%, which is significantly better than the technology of one-time mixed application.

[0018] (2) Compared with traditional phosphate fertilizers (such as superphosphate), which have poor mobility and are easily fixed by soil, the utilization rate is generally less than 30%. This invention achieves precise controlled release through component functionalization modification and dynamic application strategy. Humic acid sulfonation modification (sulfonation degree 1.5-2.0 mmol / g) enhances its binding ability with phosphate rock powder and prolongs the nutrient release cycle. Chitosan coating combined with the multi-level porous structure of microwave roasted zeolite enables the phosphate fertilizer release rate to be dynamically adjusted with soil pH changes. The application amount is dynamically adjusted, and the ratio of conditioner to phosphate fertilizer is increased or decreased in real time according to soil test results, so that the phosphate fertilizer utilization rate is increased to 65% and the loss rate is controlled to <10%. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1 The preparation of a soil conditioner includes: Preparation of soil conditioner, preparation of nano-magnesium oxide: MgCl2 (0.5 mol / L) and NH4OH (1.0 mol / L) were mixed in a molar ratio of 1:2 and reacted in a water bath at 48℃. The pH value was adjusted to 9. After the reaction was completed, it was modified with polyethylene glycol. After modification, it was calcined at 520℃ for 2.5 h to obtain nano-magnesium oxide with a particle size of 80 nm. Microwave calcination treatment of zeolite: Natural zeolite with a particle size of 20 mesh was selected and microwave calcined (power 800W, time 20 min) to increase the porosity to 50%; Soil conditioner formulation: The mass ratio of nano-magnesium oxide to zeolite is 2:1. The total application rate should be adjusted according to the soil pH value. When the soil pH is <6.0, the amount of nano-magnesium oxide used should be increased by 15%; When the soil pH value is ≥6.0, apply according to the basic ratio.

[0021] Example 2 Preparation of a slow-release phosphate fertilizer, comprising: Preparation of sulfonated humic acid: Humic acid with a sulfonation degree of 1.5 mmol / g was mixed with phosphate rock powder (P2O5 content 25%) at a mass ratio of 1:5.

[0022] Chitosan coating process: The amount of chitosan added for coating is 8% of the total amount of humic acid and phosphate rock powder, and the particle size after coating is 200μm.

[0023] Example 3 A method for applying phosphate fertilizer with enhanced efficiency includes the following steps: The soil conditioner prepared in Example 1 was evenly spread on the target plot at a rate of 3 kg / m² (adjusted according to soil pH). The slow-release phosphate fertilizer prepared in Example 2 was applied at a rate of 1.5 kg / m², 2-4 days after the soil conditioner. Three days after the soil conditioner was applied, phosphate-solubilizing bacteria (bacterial concentration 1.5 × 10⁻⁶) were inoculated. 9 CFU / g 2 The application rate is 0.2 kg / m³. 2 The phosphate-solubilizing agent is commercially available Bacillus mucilaginosus.

[0024] Comparative Example 1 The difference from Example 1 is that no nano-magnesium oxide was added, and only zeolite was used as a soil conditioner, with the dosage remaining the same as the total application amount in Example 1.

[0025] Comparative Example 2 The difference from Example 3 is that no zeolite was added, and only nano-magnesium oxide with a particle size of 100nm was used as a soil conditioner, with the dosage being the same as the total application amount in Example 1.

[0026] Comparative Example 3 The difference from Example 3 is that no phosphate-solubilizing agent was inoculated.

[0027] Comparative Example 4 The difference from Example 3 is that a one-time mixed application strategy (nano-magnesium oxide + zeolite + slow-release phosphate fertilizer + phosphate-solubilizing bacteria) is adopted, specifically including: Apply the soil conditioner evenly to the target plot at a rate of 3 kg / m². 2 (Adjust according to soil pH); then apply slow-release phosphate fertilizer at 1.5 kg / m³. 2 Apply; then inoculate with phosphate-solubilizing bacteria (bacterial concentration 1.5 × 10⁻⁶). 9 CFU / g 2 The application rate is 0.2 kg / m³. 2 The phosphate-solubilizing agent is commercially available Bacillus mucilaginosus.

[0028] Comparative Example 5 The difference from Example 3 is that the fertilizer components are completely replaced with traditional compound fertilizer ammonium dihydrogen phosphate, and the amount used is the same as the total application amount in Example 1.

[0029] Application Example 1 The fertilization method of Example 3 was applied to an acidic soil farmland (pH 5.2). A 30-mu experimental field was selected, and fertilization was carried out according to the methods of Example 3 and Comparative Examples 1-5. The experimental period was the corn growing season (June to September).

[0030] The specific operation of Example 3 is as follows: Soil conditioner application: Apply nano-magnesium oxide (particle size 80nm, mass ratio 2:1 mixed with zeolite) at 3kg / m³. 2 Apply to the soil surface and till evenly to a depth of 15cm. For slow-release phosphate fertilizer application: 3 days later, mix sulfonated humic acid (sulfonation degree 1.8 mmol / g) with phosphate rock powder (P2O5 content 25%) at a mass ratio of 1:5, and coat with a 6% chitosan film (particle size 150μm). Apply at a rate of 1.5 kg / m³. 2 Apply to the same plot of land.

[0031] Application of phosphate-solubilizing bacteria: On the 3rd day after applying the conditioner, the inoculum concentration is 1.5 × 10⁻⁶. 9 CFU / g phosphate-solubilizing bacteria (application rate 0.2 kg / m³) 2 ), and be applied simultaneously with slow-release phosphate fertilizer and tilled.

[0032] The specific operation of comparative examples 4 and 5 was to apply the mixture at once, with the total dosage being the same as in example 3, and the other comparative examples were treated in the same way as in example 3.

[0033] Monitoring indicators: soil pH, phosphate-solubilizing bacteria survival rate, available phosphorus content, and maize growth indicators (including plant height, ear weight, and yield). Specifically, soil pH was measured daily, and changes were recorded over 3 days after conditioner application; phosphate-solubilizing bacteria survival rate was determined by plate counting (CFU / g) on ​​the 3rd day after inoculation; available phosphorus content was determined using the Olsen method (mg / kg); and maize growth indicators included plant height, ear weight, and yield measured at harvest.

[0034] Table 1. Application effects of each embodiment and comparative example in maize planting.

[0035] The results show that, compared with Example 3, the soil pH values ​​of Comparative Example 1 and Example 3 were 7.2 and 6.8, respectively, proving that nano-magnesium oxide plays a role in acid regulation in the system with significant effect. However, the acid regulation ability of zeolite alone is limited, and it needs to be combined with nano-magnesium oxide to quickly neutralize acidity. As can be seen from Comparative Example 2, the absence of zeolite led to an increase in the peak soil pH to 8.5, a significant decrease in survival rate, and inhibition of phosphate-solubilizing bacteria activity, which also indicates that the adsorption effect of zeolite is key.

[0036] Compared with Example 3, the absence of the microbial agent in Comparative Example 3 directly led to a 35% decrease in available phosphorus content (from 35 mg / kg to 22 mg / kg) and a 37% decrease in corn yield (from 5.5 t / ha to 3.5 t / ha), which directly verifies the irreplaceable nature of bioactivation.

[0037] Comparing Comparative Example 4 with Example 3, it can be seen that the existing technology, in the mixed application of phosphate fertilizer, resulted in a soil pH peak of 8.2, a phosphate-solubilizing bacteria survival rate of only 40%, and a corn yield of only 6.2 t / ha, significantly lower than the 8.5 t / ha achieved through phased application. The reasons for this may be that a single mixed application cannot simultaneously satisfy the functions of acidification, slow release, and activation, because it does not consider the direct toxicity of acidic conditioners (such as nano-magnesium oxide) to microorganisms, and the antagonistic effect between alkaline conditioners and microbial agents greatly affects the fertilization effect. Furthermore, phased application is not simply a matter of dividing time, but a systematic design based on the interaction mechanism of soil-microorganisms-conditioners: the core scheme is "first shaping the soil environment, then introducing bioactivators." The conditioner (nano-magnesium oxide) needs to quickly neutralize acidity, while humic acid slows down the release of phosphate fertilizer. The time scale difference between the two is matched by extending the adsorption time of zeolite through microwave roasting.

[0038] Compared with Example 3, the traditional compound fertilizer had a low phosphate utilization rate, with an effective phosphorus content of 18 mg / kg and a corn yield of only 4.8 t / ha, which was lower than that of Example 3. This highlights the comprehensive advantage of the latter's synergistic effect of fertilizer components.

[0039] This invention provides a method for enhancing the efficiency of phosphate fertilizer application. By using nanomaterials to enhance the coating strength (such as nano-silica), and then applying fertilizer in stages, first applying a soil conditioner to stabilize the soil pH, then applying humic acid slow-release phosphate fertilizer and simultaneously inoculating with phosphate-solubilizing bacteria, the direct inhibition of microorganisms by the highly alkaline environment is avoided. This method increases the survival rate of phosphate bacteria by more than 30%, improves the activation rate of phosphorus, and significantly enhances the slow-release performance of phosphate fertilizer.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for applying an enhanced phosphate fertilizer, characterized in that, Includes the following steps: S1, Prepare a soil conditioner by mixing nano-magnesium oxide with zeolite, wherein the zeolite is microwave-calcined and the application amount is adjusted according to the soil pH value. S2, then sulfonated humic acid is mixed with phosphate rock powder and treated with chitosan coating process. The application rate is adjusted according to the available phosphorus content of the soil. S3, apply the soil conditioner as described in step S1 for 2-4 days, and then begin applying the phosphate-solubilizing bacteria agent; The preparation method of the nano-magnesium oxide includes the following steps: reacting MgCl2 and NH4OH in a water bath at 45-50℃, adjusting the pH value to 8-10, modifying with polyethylene glycol, and calcining at 500-550℃ for 2-3 hours to obtain nano-magnesium oxide; The nano-magnesium oxide has a particle size of 50-100 nm, and the zeolite has a particle size of 8-50 mesh. The application amount in step S1 is adjusted according to the soil pH value. If the soil pH value is <6.0, the amount of nano-magnesium oxide is increased by 10-20%. The application amount in step S2 is adjusted according to the available phosphorus content in the soil. If the available phosphorus is <15 mg / kg, the amount of sulfonated humic acid and phosphate rock powder is increased by 10-20%.

2. The fertilization method for an enhanced phosphate fertilizer as described in claim 1, characterized in that, The molar ratio of MgCl2 to NH4OH is 1:1.8-2.

2.

3. The fertilization method for an enhanced phosphate fertilizer as described in claim 1, characterized in that, The sulfonated humic acid has a sulfonation degree of 1.5-2 mmol / g, and the P2O5 content in the phosphate rock powder is 23%-26%.

4. The fertilization method for an enhanced phosphate fertilizer as described in claim 1, characterized in that, The mass ratio of nano-magnesium oxide to zeolite in step S1 is 2-2.5:

1.

5. The fertilization method for an enhanced phosphate fertilizer as described in claim 1, characterized in that, The mass ratio of sulfonated humic acid to phosphate rock powder in step S2 is 1:4-6.

2.

6. The fertilization method for an enhanced phosphate fertilizer as described in claim 1, characterized in that, In step S2, the chitosan coating process involves adding chitosan coating at a ratio of 5-8% of the total amount of sulfonated humic acid and phosphate rock powder.

7. The fertilization method for an enhanced phosphate fertilizer as described in claim 1, characterized in that, The concentration of phosphate-solubilizing bacteria inoculant should be ≥1.2×10⁻⁶ 9 CFU / g.

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