Inorganic mineral material for relieving nitrogen release of bio-organic fertilizer and application of inorganic mineral material

Abstract

The invention belongs to the technical field of fertilizer slow-release materials, and particularly relates to an inorganic mineral material for relieving nitrogen release of a biological organic fertilizer and application of the inorganic mineral material. The invention relates to an inorganic mineral material, wherein the inorganic mineral material is limestone. According to the invention, the natural mineral material limestone is selected as a fertilizer coating material, so that the release peak of inorganic nitrogen in soil is delayed and the emission of nitrous oxide is reduced. Compared with treatment by adding a biological organic fertilizer, the biological organic slow-release fertilizer prepared by coating the limestone powder delays an inorganic nitrogen release peak by about 10 days, and the discharge flux of nitrous oxide is remarkably reduced. Therefore, the inorganic mineral material limestone can delay the nitrogen release peak of the fertilizer granules so as to cater to the nitrogen absorption law of crops, the nitrous oxide discharge amount can be reduced, and finally the nitrogen utilization efficiency of the fertilizer can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizer slow-release materials, and in particular relates to an inorganic mineral material for alleviating nitrogen release of biological organic fertilizer and application thereof. Background Art

[0002] By 2021, global agricultural demand for fertilizers will reach 185.9 million tons. However, crop uptake of key nutrients remains relatively low, with only 30-60% of fertilizer nitrogen uptake. This inefficiency raises multiple issues, such as nitrogen loss into aquatic and atmospheric ecosystems through processes such as volatilization, leaching, denitrification, runoff, and erosion, reducing fertilizer utilization efficiency and increasing environmental pollution risks. To address these challenges, there is growing interest in the development of slow-release fertilizers, which release nutrients at a controlled rate and improve crop uptake of nutrients compared to traditional fertilizers. Various types of slow-release fertilizers have been widely explored, such as chemical synthesis, loading methods, coating technology, application of biodegradable polymers, and hydrogel systems. Slow-release fertilizers are produced by coating the fertilizer surface with hydrophobic materials or incorporating elemental fertilizers into macromolecules to form composite materials, both of which can slow down the nutrient release process. The materials used to prepare slow-release fertilizers are mainly organic polymers and inorganic materials. Over the years, many types of coating materials have been explored, ranging from inorganic materials to synthetic and natural polymers. However, the high cost of slow-release fertilizers compared to traditional fertilizers has hampered their widespread adoption in agriculture. In addition, some types of coating-based slow-release fertilizers are often non-biodegradable and may emit toxic gases, posing risks to the soil and atmospheric environment. Therefore, there is a growing trend to use natural materials to address these challenges.

[0003] At present, biochar as a modified natural material has become a research hotspot for coated slow-release fertilizers. Studies have found that biochar-coated urea prepared from poplar branches can significantly reduce the leaching of ammonium nitrogen and nitrate nitrogen, and increase the content of ammonium nitrogen and nitrate nitrogen in the soil. However, the slow-release property of coated fertilizers prepared from biochar is too dependent on the adsorption capacity of biochar itself for nutrients. The differences in biochar types and preparation methods lead to uneven slow-release properties of fertilizers. In addition, the biochar preparation process is complicated, which will also increase the economic cost of biochar-coated slow-release fertilizers. Therefore, it is urgent to select low-cost and environmentally friendly natural materials as slow-release fertilizer coating materials, which can be applied to the soil to achieve the purpose of slow-release of nutrients.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide an inorganic mineral material for alleviating the release of nitrogen in biological organic fertilizer and application thereof.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The first object of the present invention is to provide an inorganic mineral material, wherein the inorganic mineral material is limestone.

[0008] Preferably, the particle size of the inorganic mineral material is 100 mesh.

[0009] The second object of the present invention is to provide the use of the inorganic mineral material in alleviating the release of nitrogen from biological organic fertilizer.

[0010] The third object of the present invention is to provide a biological organic slow-release fertilizer with the function of alleviating nitrogen release, wherein the biological organic slow-release fertilizer is prepared by the following method: grinding the biological organic fertilizer at room temperature, passing through a 100-mesh sieve, adding a binder solution to form spherical particles; and uniformly wrapping the inorganic mineral material described in claim 1 on the outer layer of the spherical particles to obtain the biological organic slow-release fertilizer.

[0011] Preferably, the biological organic fertilizer is an organic fertilizer containing Trichoderma harzianum produced by Nanjing Sino-Agricultural Research Institute Co., Ltd.

[0012] Preferably, the binder is a modified starch solution with a mass fraction of 1.5%; the binder is added in an amount such that the water content is 35-40%.

[0013] Preferably, the particle size of the spherical particles is 4-5 mm.

[0014] Preferably, the mass of the inorganic mineral material is 5% of the mass of the bio-organic fertilizer.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention selects natural mineral material limestone as fertilizer coating material, which delays the peak of inorganic nitrogen release in soil and reduces the effect of N2O emission. Compared with the treatment of adding biological organic fertilizer, the biological organic slow-release fertilizer prepared by limestone powder coating delays the peak of inorganic nitrogen release in soil by about 10 days, significantly reducing the emission flux of nitrous oxide. It can be seen that the inorganic mineral material limestone of the present invention can delay the peak of nitrogen release of fertilizer particles to meet the nitrogen absorption law of plants, can reduce nitrous oxide emissions, and ultimately can improve the nitrogen utilization efficiency of fertilizers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the change diagram of soil inorganic nitrogen after fertilization;

[0018] Figure 2 This is the change diagram of soil microbial biomass nitrogen and dissolved organic nitrogen after fertilization;

[0019] Figure 3 This is a dynamic diagram of soil nitrous oxide emissions after fertilization. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solution of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example

[0022] 1. Preparation of Materials

[0023] Take the bio-organic fertilizer containing Trichoderma (effective live bacteria ≥ 1 billion / g) produced by Nanjing Sino Bio-Organic Fertilizer Research Institute Co., Ltd. and limestone, grind them through a 100-mesh sieve at room temperature respectively; take modified starch to prepare a solution with a mass fraction of 1.5%.

[0024] Modified starch solution was added to the bio-organic fertilizer powder until the water content was 35%, resulting in spherical particles with a particle size of 4 mm, which were recorded as bio-organic fertilizer particles.

[0025] Modified starch solution was added to the bio-organic fertilizer powder until the water content was 35%, resulting in spherical particles with a particle size of 4 mm; limestone powder accounting for 5% of the mass of the bio-organic fertilizer powder was evenly wrapped on the outer layer of the spherical particles, and finally spherical particles with a particle size of 5 mm were obtained, which were recorded as bio-organic slow-release fertilizer particles.

[0026] 2. Cultivation Experiment Setup

[0027] 2.1 Test soil

[0028] Acidic soil (pH 4.14, exchangeable calcium ion concentration 2.14 cmol kg) developed on clastic rocks –1 ) and calcareous soils developed on limestone (pH 6.48, exchangeable calcium ion concentration 28.43 cmol kg –1 ).

[0029] 2.2 Fertilization treatment

[0030] Treatment a: no fertilizer, pure soil culture, CK;

[0031] Treatment b: Adding bio-organic fertilizer granules, fertilizer amount: 225 kg N ha -1 (100 mg N kg -1), M;

[0032] Treatment c: Adding bio-organic slow-release fertilizer granules, fertilizer rate: 225 kg N ha -1 (100 mg N kg -1 ), MCa.

[0033] The same fertilization treatments were arranged in the two test soils, with 3 replicates for each treatment. The incubation experiment lasted for 80 days, and destructive sampling was carried out on the 5th, 10th, 20th, 50th and 80th days to collect soil samples, with 3 replicates for each treatment, for a total of 90 treatments.

[0034] In addition, a group of fertilization treatments were arranged in the two test soils for collecting gas samples, with 3 replicates for each treatment. Repeated sampling was performed on the 1st, 3rd, 5th, 10th, 20th, 35th, 50th and 80th days to collect gas samples. Three replicates were collected for each treatment each time gas was collected, for a total of 18 treatments. All treatments needed to be cultured in an incubator at the same temperature (25°C), and water was added regularly to maintain a weight moisture content of 30%.

[0035] 3. Sample Collection

[0036] 3.1 Soil sample collection

[0037] Soil samples were collected on the 5th, 10th, 20th, 50th and 80th day of the experiment. Each time a treatment device was sampled, all soil within 2 cm around the fertilizer particle was collected as a soil sample to be tested. Three treatment devices were collected for each fertilization treatment as duplicate samples. A total of 90 soil samples were collected on the two soils for the determination of soil nitrogen content and other indicators.

[0038] 3.2 Gas sample collection

[0039] Gas samples were collected on the 1st, 3rd, 5th, 10th, 20th, 35th, 50th and 80th day of the experiment. Each time, about 60 mL of gas was extracted from the gas culture device with a syringe and immediately transferred to a 120 mL gas bag by injection. Three treatment devices were collected as replicate samples for each fertilization treatment. A total of 144 gas samples were collected on the two soils for the determination of nitrous oxide (N2O) emissions.

[0040] 3.3 Soil sample pretreatment

[0041] Soil samples were stored at 4 °C for determination of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), ammonium nitrogen (NH4 + ) and nitrate nitrogen (NO3 − )concentration.

[0042] 4. Sample index determination

[0043] 4.1 Determination of nitrogen content in soil samples

[0044] DOC and DON concentrations were determined by wet oxidation and persulfate oxidation methods, respectively;

[0045] NH4 + and NO3 − Using AA3 flow analyzer;

[0046] MBC and MBN concentrations were determined using the fumigation method and a total carbon analyzer (TOC).

[0047] 4.2 Gas concentration measurement

[0048] A gas chromatograph (Agilent GC 7890A, Agilent, USA) was used to measure the N2O concentration, and the N2O emission and cumulative amount were calculated.

[0049] 5. Results and Analysis

[0050] 5.1 Changes in soil inorganic nitrogen after fertilization

[0051] The results are shown in Figure 1 .

[0052] Inorganic nitrogen is an effective nitrogen source that can be directly absorbed and utilized by crops. It mainly includes ammonium nitrogen and nitrate nitrogen. The change in its content in the soil can reflect the nitrogen supply capacity of the soil. After fertilization, the content of ammonium nitrogen and nitrate nitrogen in both soils increased significantly during the entire cultivation period ( Figure 1 ), on the 10th and 20th day, the biological organic fertilizer treatment (M) and the biological organic slow-release fertilizer (MCa) reached the peak of inorganic nitrogen release respectively. On the calcareous soil, NH4 + (139.54 mg kg -1 ) and NO3 − (407.66 mg kg -1 ) reached the peak release on the 10th day, but under MCa treatment, NH4 + (88.85mg kg -1 ) and NO3 − (270.47 mg kg -1 ) reached their release peaks on the 20th and 10th days, respectively. In acidic soil, NH4 + (314.44 mg kg -1 ) and NO3 − (90.87 mgkg -1 ) reached the peak release on the 10th day, while NH4 +(250.17 mg kg -1 ) and NO3 − 60.48 mg kg -1 ) reached the release peak on the 20th day. Compared with the M treatment, regardless of soil type, the MCa treatment delayed the peak of soil inorganic nitrogen content by 10 days and reduced the content of soil inorganic nitrogen in the early stage of cultivation, indicating that biological organic slow-release fertilizer can delay the peak of soil inorganic nitrogen release to meet the nitrogen absorption law of plants, and at the same time reduce the risk of nitrogen loss in the early stage after fertilization.

[0053] With the culture time, after 50 days of culture, NH4 + and NO3 − were significantly higher than those in the M treatment ( Figure 1 ). At 80 days, under MCa treatment on calcareous soil, NH4 + and NO3 − 1.33 and 1.22 times of those in the M treatment, respectively, while the NH4 + and NO3 − They were 1.74 and 1.52 times of those in the M treatment, respectively. Compared with the M treatment, regardless of soil type, the MCa treatment could significantly increase the inorganic nitrogen content in the late cultivation period, indicating that the bio-organic slow-release fertilizer also has the potential to provide sufficient inorganic nitrogen for crops in the late growth period of crops, which is conducive to promoting crop growth and increasing crop yield.

[0054] 5.2 Changes in soil microbial biomass nitrogen and dissolved organic nitrogen after fertilization

[0055] Results Figure 2 .

[0056] Microbial biomass nitrogen is an important reserve of soil nitrogen and is the most active component. It can release nitrogen that can be absorbed by crops through mineralization to meet the growth needs of crops. After fertilization, the content of microbial biomass nitrogen in the two soils gradually increased ( Figure 2 a, b). Compared with the M treatment, the microbial biomass nitrogen in the MCa treatment was lower in both soils in the first 20 days of incubation, while the microbial biomass nitrogen in the MCa treatment was higher after 50 days of incubation. At the end of the incubation period (80 days), the microbial biomass nitrogen in the MCa treatment on calcareous and acidic soils was 1.08 and 1.23 times that of the M treatment, respectively. These results indicate that the bio-organic slow-release fertilizer significantly increased the soil microbial biomass nitrogen content in the late incubation period, which means that the soil reserve nitrogen pool was increased.

[0057] Dissolved organic nitrogen can also be used as a nitrogen source directly absorbed and utilized by crops, which has an important impact on the growth and development of crops. After fertilization, the dissolved organic nitrogen in the soil first increases and then decreases ( Figure 2c, d). The dissolved organic nitrogen content in the two soils under the M treatment reached the maximum on the 10th day, which were 954.44 mg kg -1 and 506.74 mg kg -1 The dissolved organic nitrogen content in the two soils under the MCa treatment reached its maximum on the 20th day, which was 695.96 and 425.25 mg kg -1 . Starting from the 20th day, the dissolved organic nitrogen content in the MCa treatment on both soils began to gradually increase compared with the M treatment. At the end of the incubation period, the dissolved organic nitrogen content in the MCa treatment of calcium and acidic soils was 1.21 and 1.39 times that of the M treatment, respectively. These results show that biological organic slow-release fertilizer can also delay the peak of soil dissolved organic nitrogen content by about 10 days, reduce the peak release of soil dissolved organic nitrogen in the early stage of incubation, and increase the content of soil dissolved organic nitrogen in the later stage, which also caters to the nitrogen absorption law of crops and can reduce the risk of soil nitrogen loss.

[0058] 5.3 Dynamics of soil nitrous oxide emissions after fertilization

[0059] Results Figure 3 .

[0060] Agricultural ecosystems are the main source of N2O, and large amounts of N2O emissions will exacerbate climate warming in the troposphere and harm the ecological environment. After fertilization, soil N2O emission flux increased significantly ( Figure 3 a, b), M (2.38 ng N g -1 soilh -1 ) and MCa (1.74 ng N g -1 soil -1 ) treatments reached their peak emission on the 10th day, while M (2.49 ng N g -1 soil -1 ) and MCa (1.83 ng N g -1 soil -1 ) treatments reached their emission peak on the 20th day. Compared with the M treatment, the MCa treatment significantly reduced the N2O emissions of the two soils during the entire incubation period. From the cumulative emission results, it can be seen that at the end of the incubation period, the MCa treatment significantly reduced the cumulative N2O emissions, which were reduced by about 38% and 30% on calcareous and acidic soils, respectively. Figure 3 c, d). These results indicate that bio-organic slow-release fertilizer can significantly reduce soil N2O emissions and reduce the risk of nitrogen loss.

[0061] In summary, the present invention selects natural mineral material limestone as fertilizer coating material, which delays the peak of inorganic nitrogen release in the soil and reduces the effect of N2O emission. Compared with the treatment of adding biological organic fertilizer, the biological organic slow-release fertilizer prepared by limestone powder coating delays the peak of inorganic nitrogen release in the soil by about 10 days, significantly reducing the emission flux of N2O. It can be seen that the inorganic mineral material limestone of the present invention can delay the peak of nitrogen release of fertilizer particles to meet the nitrogen absorption law of the plant, can reduce N2O emissions, and ultimately can improve the nitrogen utilization efficiency of fertilizers.

[0062] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. An inorganic mineral material, characterized in that: The inorganic mineral material is limestone.

2. The inorganic mineral material according to claim 1, characterized in that: The particle size of the inorganic mineral material is 100 mesh.

3. Use of the inorganic mineral material according to claim 1 in alleviating the release of nitrogen from biological organic fertilizers.

4. A biological organic slow-release fertilizer with the function of slowing down nitrogen release, characterized in that: The bio-organic slow-release fertilizer is prepared by the following method: grinding the bio-organic fertilizer at room temperature, passing it through a 100-mesh sieve, adding a binder solution to form spherical particles; and uniformly wrapping the inorganic mineral material described in claim 1 on the outer layer of the spherical particles to obtain the bio-organic slow-release fertilizer.

5. The bio-organic slow-release fertilizer according to claim 4, characterized in that: The biological organic fertilizer is an organic fertilizer containing Trichoderma harzianum produced by Nanjing Sino-Agricultural Research Institute Co., Ltd.

6. The bio-organic slow-release fertilizer according to claim 4, characterized in that: The binder is a modified starch solution with a mass fraction of 1.5%; the amount of the binder added is such that the water content is 35-40%.

7. The bio-organic slow-release fertilizer according to claim 4, characterized in that: The particle size of the spherical particles is 4-5 mm.

8. The bio-organic slow-release fertilizer according to claim 4, characterized in that: The mass of the inorganic mineral material is 5% of the mass of the bio-organic fertilizer.

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