A special micronutrient fertilizer for fruit trees

Abstract

This invention discloses a micronutrient fertilizer specifically for fruit trees, comprising a fast-acting component and a controlled-release component. The fast-acting component is a water-soluble micronutrient fertilizer containing at least two of calcium, magnesium, boron, and zinc. The controlled-release component consists of micronutrient fertilizer granules encapsulated in a biodegradable polymer material. This biodegradable polymer material automatically degrades after reaching its degradation cycle under natural conditions. The biodegradable polymer material is selected from one or more of polylactic acid, polycaprolactone, and starch-based blends. The mass ratio of the fast-acting component to the controlled-release component is 30–70:70–30. This invention, by mixing the fast-acting and controlled-release components in the fertilizer, allows the fast-acting component to meet the micronutrient requirements of fruit trees in the early stages of growth, while the controlled-release component degrades and releases nutrients during the fruiting period. A single application can cover the entire growth period of the fruit tree, reducing the frequency of topdressing and lowering labor costs.

Description

Technical Field

[0001] This invention relates to the technical field of agricultural fertilizers, particularly micronutrient fertilizers specifically for fruit trees. Background Technology

[0002] In addition to macronutrients such as nitrogen, phosphorus, and potassium, fruit trees also have a high demand for micronutrients such as calcium, magnesium, boron, and zinc during their growth. Calcium enhances fruit firmness and prevents fruit cracking and bitter pit; magnesium is an important component of chlorophyll and participates in photosynthesis; boron promotes pollen germination and pollen tube elongation, increasing fruit set; and zinc participates in auxin synthesis and prevents little leaf disease and cluster leaf disease. However, traditional micronutrient fertilization methods have the following shortcomings:

[0003] Conventional micronutrient fertilizers are mostly fast-acting and are easily fixed or leached after being applied to the soil. Fruit trees cannot continuously absorb them, leading to nutrient deficiency symptoms in the later stages of growth, such as frequent occurrences of apple bitter pit, citrus fruit cracking, and little leaf disease.

[0004] Fruit farmers need to apply fertilizer multiple times according to the growth period of fruit trees, which is labor-intensive, has high labor costs, and the timing of fertilization is difficult to grasp accurately, often missing the best fertilization period. Summary of the Invention

[0005] The purpose of this invention is to solve the problems in the prior art and to propose a special micronutrient fertilizer for fruit trees that can meet the needs of fruit trees for micronutrients such as calcium, magnesium, boron, and zinc during the entire growth period from budding to fruit ripening with a single application.

[0006] To achieve the above objectives, the present invention proposes a micronutrient fertilizer for fruit trees, comprising a fast-acting component and a controlled-release component, wherein the fast-acting component is a water-soluble micronutrient fertilizer containing at least two of calcium, magnesium, boron, and zinc.

[0007] The controlled-release portion is a micronutrient fertilizer granule encapsulated in a biodegradable polymer material. The biodegradable polymer material automatically degrades after reaching its degradation cycle under natural conditions. The biodegradable polymer material is selected from one or more of polylactic acid, polycaprolactone, and starch-based blends.

[0008] The mass ratio of the fast-acting portion to the controlled-release portion is 30-70:70-30;

[0009] Water-soluble calcium, magnesium, boron, and zinc fertilizers are mixed in proportion, crushed and sieved to obtain fast-acting powder or granulated to obtain fast-acting granules.

[0010] The core material of micronutrient fertilizer is placed in a fluidized bed coating machine, and an organic solution or aqueous dispersion of biodegradable polymer material is sprayed in. The coating is dried and coated at 40-60℃, and the coating thickness is controlled to obtain controlled-release granules.

[0011] The fast-acting and controlled-release components are physically mixed evenly in a certain proportion.

[0012] Preferably, the fast-acting component comprises, by weight, 20-40 parts of water-soluble calcium salt, 15-30 parts of water-soluble magnesium salt, 5-15 parts of water-soluble boron compound, and 5-15 parts of water-soluble zinc compound.

[0013] Preferably, the water-soluble calcium salt is calcium nitrate, calcium chloride, or calcium sulfate; the water-soluble magnesium salt is magnesium sulfate, magnesium chloride, or magnesium nitrate; the water-soluble boron compound is boric acid or borax; and the water-soluble zinc compound is zinc sulfate, zinc chloride, or zinc nitrate.

[0014] Preferably, the coating thickness of the controlled-release portion is 50–200 μm, and the degradation period is 1–6 months.

[0015] Preferably, the controlled-release portion contains at least two types of particles with different degradation cycles, and the degradation cycle of the particles is controlled by encapsulating biodegradable polymer materials with different degradation cycles.

[0016] Preferably, the biodegradable polymer material further contains a pore-forming agent, which is polyethylene glycol or starch, and the amount of pore-forming agent is 1 to 10% of the weight of the coating material.

[0017] Preferably, the controlled-release portion contains at least two types of particles with different degradation initiation times. By coating the outside of the degradable polymer material with a hydrophobic layer that delays water penetration, the particles remain essentially non-degradable for a predetermined period after being applied to the soil.

[0018] Preferably, the hydrophobic layer is selected from one or more of paraffin wax, stearic acid, polylactic acid wax or hydrogenated vegetable oil, and the thickness of the hydrophobic layer is 5 to 30 μm.

[0019] Preferably, the controlled-release portion has a double-layer structure, with an inner layer being a dense biodegradable polymer layer and an outer layer being a porous biodegradable polymer layer, wherein the porous layer contains a water-soluble pore-forming agent; in the soil, the outer layer first absorbs water and forms pores to create channels, and the water penetrates into the inner layer and gradually degrades the inner layer.

[0020] Preferably, the thickness ratio of the inner layer to the outer layer is 2:1 to 1:2, the inner layer material is selected from polylactic acid or polycaprolactone, and the outer layer material is selected from starch-based blends or blends of polylactic acid and polyethylene glycol.

[0021] The beneficial effects of this invention, a special micronutrient fertilizer for fruit trees, are as follows: By mixing a fast-acting component and a controlled-release component in the fertilizer, the fast-acting component meets the micronutrient requirements of fruit trees in the early stages of growth, while the controlled-release component degrades and releases nutrients during the fruiting period. A single application can cover the entire growth period of the fruit tree, reducing the number of topdressings and lowering labor costs. The controlled-release component prevents nutrients from being fixed or leached by the soil, increasing the effective utilization rate of micronutrients by more than 30% compared to conventional fast-acting fertilizers. The coating material is a biodegradable polymer that degrades into carbon dioxide and water in the soil, eliminating the problem of microplastic residues. By adjusting the coating thickness, adding pore-forming agents, and setting a hydrophobic layer or a double-layer structure, the degradation cycle and degradation start time can be flexibly controlled to match the nutrient requirements of different fruit tree varieties.

[0022] The features and advantages of the present invention will be described in detail through embodiments. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0024] In the description of this invention, it should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to or indirectly connected to the other element.

[0025] In the description of this invention, it should be noted that the terms "center," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the shown orientation or positional relationship, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0026] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] Example 1:

[0028] This embodiment describes a special micronutrient fertilizer for fruit trees, comprising a fast-acting component: 30 parts calcium nitrate, 20 parts magnesium sulfate, 10 parts boric acid, and 10 parts zinc sulfate, which are mixed, pulverized, and passed through a 100-mesh sieve.

[0029] Controlled-release component: The core material consists of granulated particles with the same components as the fast-acting component, with a diameter of 3 mm. The coating material is polylactic acid (PLA) with a molecular weight of 100,000 and a coating thickness of 100 μm. The mass ratio of core material to coating is 90:10.

[0030] The ratio of the fast-acting portion to the controlled-release portion is 40:60.

[0031] Preparation method:

[0032] Quick-acting component: Weigh 3 kg of calcium nitrate, 2 kg of magnesium sulfate, 1 kg of boric acid, and 1 kg of zinc sulfate, mix them evenly, and pulverize them through a 100-mesh sieve to obtain a quick-acting powder.

[0033] Controlled-release portion: Fertilizers with the same formulation as above were mixed and granulated to obtain core material granules. 5 kg of core material granules were placed in a fluidized bed coating machine, sprayed at a pressure of 0.2 MPa and an inlet air temperature of 50°C, and coated with a 10% concentration of PLA dichloromethane solution. The coating weight gain was approximately 11%. After drying, controlled-release granules were obtained. Testing showed that the coating thickness was approximately 100 μm, and the degradation period in soil slurry was approximately 4 months.

[0034] Mixing: Mix 4 parts of fast-acting powder with 6 parts of controlled-release granules evenly to obtain the finished product.

[0035] Effect test:

[0036] Experimental location: An apple orchard in Anhui Province, with soil pH 6.5 and moderate organic matter content. Test variety: Fuji apple, 8 years old.

[0037] Experimental design: Three treatments were set up, each with three replicates, in a randomized block design. Treatment 1: Fertilizer of Example 1 of this invention, applied once as basal fertilizer, at a rate of 2 kg / plant; Treatment 2: Conventional micronutrient fertilizer (same composition, but without controlled-release component), applied twice as top dressing (1 kg / plant during budding and 1 kg / plant during fruit expansion); Treatment 3: No micronutrient fertilizer was applied.

[0038] Results: Micronutrient contents in leaves (measured in August): Treatment 1: calcium, magnesium, boron, and zinc contents were 1.85%, 0.48%, 45 mg / kg, and 28 mg / kg, respectively; Treatment 2: 1.52%, 0.39%, 38 mg / kg, and 22 mg / kg, respectively; Treatment 3: 1.20%, 0.30%, 28 mg / kg, and 15 mg / kg, respectively. Treatment 1 was significantly higher than Treatment 2 and Treatment 3.

[0039] The firmness of the fruit treated with treatment 1 was 8.6 kg / cm². 2 Soluble solids content was 15.2%, and the incidence of bitter pit was 2.3%; the fruit firmness of treatment 2 was 7.9 kg / cm². 2 Soluble solids content was 14.1%, and the incidence of pox was 5.8%; the values ​​for treatment 3 were 7.2 kg / cm³. 2 Treatment 1 yielded the best fruit quality, with a significant reduction in fruit cracking and bitter pit. Treatment 1 showed the highest fruit quality, with a significant reduction in fruit cracking and bitter pit.

[0040] Treatment 1 requires only one application of fertilizer, saving the labor cost of one additional application compared to Treatment 2, thus saving on both labor and fertilizer costs.

[0041] Example 2:

[0042] This embodiment further processes the biodegradable polymer material based on the basic formulation of Example 1. The controlled-release portion is composed of a fast-degrading type (degradation period of 2 months, coating thickness of 50 μm), a medium-degrading type (degradation period of 4 months, coating thickness of 100 μm), and a slow-degrading type (degradation period of 6 months, coating thickness of 150 μm) mixed in a mass ratio of 1:1:1. The mass ratio of the fast-acting portion to the controlled-release portion is 30:70. Other aspects are the same as in Example 1.

[0043] This formula is suitable for fruit trees with a long growing season (such as citrus and grapes), and provides nutrients even in the later stages of fruit enlargement, significantly increasing the weight and sugar content of individual fruits.

[0044] Example 3:

[0045] This embodiment further processes the biodegradable polymer material based on the basic formulation of Example 1. A porogen, polyethylene glycol (PEG-4000), is added to the controlled-release coating material at 5% of the PLA weight. The coating thickness is 80 μm, and the degradation period is approximately 3 months. Other aspects are the same as in Example 1. Experiments show that the addition of the porogen shortens the coating degradation period by approximately 25%, and the release curve is more stable.

[0046] Example 4:

[0047] In the controlled-release portion, 50% of the particles were coated with a layer of paraffin wax (15 μm thick) on the outside of the PLA coating as a hydrophobic layer, while the remaining 50% of the particles were not coated. After mixing, the degradation initiation time of the particles with the hydrophobic layer was delayed by approximately 30 days, achieving batch release. Other procedures were the same as in Example 1.

[0048] Example 5:

[0049] The controlled-release component employs a double-layer coating: the inner layer is PLA (60 μm thick), and the outer layer is a starch-based blend (60 μm thick, containing 8% starch as a pore-forming agent). In soil, the outer layer first absorbs water to form micropores. Water then permeates to the inner layer and gradually degrades it. The degradation initiation time is delayed by approximately 20 days compared to a single-layer PLA (120 μm) structure, but the release window is more concentrated. Other aspects are the same as in Example 1.

[0050] Comparative Example 1:

[0051] Only the fast-acting portion prepared in Example 1 was used; there was no controlled-release portion.

[0052] After applying the fertilizer once in the early stage, the crop was observed and it was found that the nutrient concentration was too high in the early stage, and the crop was severely deficient in nutrients in the later stage, resulting in poor fruit quality.

[0053] Comparative Example 2:

[0054] Only the controlled-release fraction (degradation period of 4 months) prepared in Example 1 was used; there was no fast-acting fraction.

[0055] After the fertilizer was applied in one go, the crop was observed and it was found that the crop was deficient in nutrients in the early stage, the leaves were yellowing, and the fruit setting rate was low.

[0056] The above embodiments and comparative examples demonstrate that the present invention, through a reasonable combination of rapid-acting and controlled-release fertilizers, and by introducing regulatory means such as pore-forming agents, hydrophobic layers, and bilayer structures, can achieve balanced fertilization throughout the entire growth period, resulting in significant yield increases, quality improvements, and labor savings.

[0057] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection for this invention. Therefore, any changes and modifications made to the embodiments described herein based on the innovative concept of this invention, or any equivalent structural or procedural transformations made using the specifications of this invention, directly or indirectly applying the above technical solutions to other related technical fields, are all included within the scope of protection of this invention.

Claims

1. A micronutrient fertilizer specifically for fruit trees, comprising a fast-acting component and a controlled-release component, characterized in that: The fast-acting component is a water-soluble micronutrient fertilizer containing at least two of calcium, magnesium, boron, and zinc. The controlled-release portion is a micronutrient fertilizer granule encapsulated in a biodegradable polymer material. The biodegradable polymer material automatically degrades after reaching its degradation cycle under natural conditions. The biodegradable polymer material is selected from one or more of polylactic acid, polycaprolactone, and starch-based blends. The mass ratio of the fast-acting portion to the controlled-release portion is 30-70:70-30; Water-soluble calcium, magnesium, boron, and zinc fertilizers are mixed in proportion, crushed and sieved to obtain fast-acting powder or granulated to obtain fast-acting granules. The core material of micronutrient fertilizer is placed in a fluidized bed coating machine, and an organic solution or aqueous dispersion of biodegradable polymer material is sprayed in. The coating is dried at 40-60°C, and the coating thickness is controlled to obtain controlled-release granules. The fast-acting part and the controlled-release part are physically mixed evenly in proportion.

2. The micronutrient fertilizer for fruit trees as described in claim 1, characterized in that, By weight, the fast-acting component comprises: 20-40 parts of water-soluble calcium salt, 15-30 parts of water-soluble magnesium salt, 5-15 parts of water-soluble boron compound, and 5-15 parts of water-soluble zinc compound.

3. The micronutrient fertilizer for fruit trees as described in claim 2, characterized in that: The water-soluble calcium salt is calcium nitrate, calcium chloride, or calcium sulfate; the water-soluble magnesium salt is magnesium sulfate, magnesium chloride, or magnesium nitrate; the water-soluble boron compound is boric acid or borax; and the water-soluble zinc compound is zinc sulfate, zinc chloride, or zinc nitrate.

4. The micronutrient fertilizer for fruit trees as described in claim 1, characterized in that: The controlled-release portion has a coating thickness of 50–200 μm and a degradation period of 1–6 months.

5. A micronutrient fertilizer for fruit trees as described in claim 1, characterized in that: The controlled-release portion contains at least two types of particles with different degradation cycles, and the degradation cycle of the particles is controlled by encapsulating biodegradable polymer materials with different degradation cycles.

6. The micronutrient fertilizer for fruit trees as described in claim 1, characterized in that: The biodegradable polymer material also contains a porogen, which is polyethylene glycol or starch, and the amount of porogen used is 1 to 10% of the weight of the coating material.

7. A micronutrient fertilizer for fruit trees as described in claim 1, characterized in that: The controlled-release portion contains at least two types of particles with different degradation initiation times. By coating the outside of the degradable polymer material with a hydrophobic layer that delays water penetration, the particles remain essentially non-degradable for a predetermined period after being applied to the soil.

8. A micronutrient fertilizer for fruit trees as described in claim 7, characterized in that: The hydrophobic layer is selected from one or more of paraffin wax, stearic acid, polylactic acid wax or hydrogenated vegetable oil, and the thickness of the hydrophobic layer is 5 to 30 μm.

9. A micronutrient fertilizer for fruit trees as described in claim 1, characterized in that: The controlled-release portion has a double-layer structure, with an inner layer being a dense biodegradable polymer layer and an outer layer being a porous biodegradable polymer layer. The porous layer contains a water-soluble pore-forming agent. In the soil, the outer layer first absorbs water and forms channels, and the water penetrates into the inner layer and gradually degrades the inner layer.

10. A micronutrient fertilizer for fruit trees as described in claim 9, characterized in that: The thickness ratio of the inner layer to the outer layer is 2:1 to 1:

2. The inner layer material is selected from polylactic acid or polycaprolactone, and the outer layer material is selected from starch-based blends or blends of polylactic acid and polyethylene glycol.