Manganese fertilizer compound passivator for increasing rice yield and preparation method and application thereof

Abstract

The invention discloses a manganese fertilizer compound passivator for increasing the yield of rice as well as a preparation method and application of the manganese fertilizer compound passivator. The manganese fertilizer compound passivator disclosed by the invention is prepared from the following components in parts by weight: 1 to 10 parts of mineral manganese and 1 to 20 parts of alkaline passivator. The mineral manganese is any one of pyrolusite, hausmannite and manganite, and the alkaline passivator is any one of diatomite, hydroxyapatite and charcoal. The manganese fertilizer compound passivator can reduce the content of Cd and As in rice grains and improve the yield of rice.

Description

Technical Field

[0001] The invention relates to the technical field of soil heavy metal pollution control and soil improvement, and in particular to a manganese fertilizer compound passivator for improving rice yield, and a preparation method and application thereof. Background Art

[0002] As industrialization, urbanization and agricultural production release a large amount of heavy metals, resulting in high soil background values, farmland soil is seriously polluted by heavy metals, and most of them exist in the form of complex pollution. According to the 2014 National Soil Pollution Survey Bulletin, the point-to-point excess rates of cadmium (Cd) and arsenic (As) reached 7.0% and 2.7%, respectively, and they are highly transferable from agricultural soil to crops, which can directly or indirectly threaten life and health.

[0003] Cd and As are two typical heavy metal pollutants with the characteristics of strong toxicity, long environmental half-life and easy accumulation. Cadmium can enter crops through plant roots and accumulate in the food chain, causing serious pollution to crops. Arsenic is highly toxic to plants and can cause widespread health hazards. At present, there are many studies on the pollution control methods of Cd and As, mainly including in situ fixation and stabilization, ex situ soil remediation, soil leaching, plant remediation, etc. Most of the immobilization materials for in situ immobilization are simple, easy to obtain and inexpensive, and are widely used in soil remediation. However, since the bioavailability of Cd and As is often affected by soil pH and Eh in the opposite way, the actual remediation effect usually loses one while taking care of the other. This has led to the complexity of the remediation agents on the market, and there is a lack of remediation agents specifically for cadmium and arsenic compound contaminated soils.

[0004] Therefore, there is an urgent need for a remediation agent for cadmium and arsenic contaminated soil. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a manganese fertilizer compound passivator for increasing rice yield and its preparation method and application. The raw materials of the manganese fertilizer compound passivator of the present invention include mineral manganese and alkaline passivator, and the manganese fertilizer compound passivator can reduce the Cd and As content in rice grains and increase rice yield.

[0006] To achieve the above purpose, the technical solution designed by the present invention is as follows:

[0007] The present invention provides a manganese fertilizer compound passivator for improving rice yield. The manganese fertilizer compound passivator is composed of 1 to 10 parts of mineral manganese and 1 to 20 parts of an alkaline passivator in parts by weight.

[0008] The mineral manganese is any one of pyrolusite, hausmannite and manganite, and the alkaline passivating agent is any one of diatomite, hydroxyapatite and biochar.

[0009] Furthermore, the manganese fertilizer compound passivator is composed of 4 parts of mineral manganese and 2 to 16 parts of alkaline passivator in parts by weight.

[0010] Furthermore, the mineral manganese is a dry powder with a particle size of 100 to 200 meshes, and the effective content of mineral manganese is ≥99%.

[0011] Furthermore, the alkaline passivating agents are all dry powders with a particle size of 150 to 200 meshes, wherein the effective content of SiO2 in diatomaceous earth is ≥85%, the effective content of P2O5 in hydroxyapatite is ≥97%, and the effective content of organic carbon in biochar is ≥78%.

[0012] Furthermore, the manganese fertilizer compound passivator consists of 4 parts of pyrolusite and 16 parts of diatomaceous earth.

[0013] Furthermore, the manganese fertilizer compound passivator consists of 4 parts of pyrolusite and 2 parts of hydroxyapatite.

[0014] The present invention also provides a method for preparing the manganese fertilizer composite passivator, comprising the following steps:

[0015] (1) Weigh mineral manganese and alkaline passivating agent according to the above weight parts;

[0016] (2) The mineral manganese and the alkaline passivator are mixed evenly to obtain a manganese fertilizer compound passivator for increasing rice yield.

[0017] The present invention also provides an application of the manganese fertilizer compound passivating agent in repairing heavy metal cadmium and arsenic compound contaminated soil. The manganese fertilizer compound passivating agent is applied to the heavy metal cadmium and arsenic compound contaminated soil at a mass ratio of 0.3 to 1:2500, and the heavy metal cadmium and arsenic compound contaminated soil can be repaired after 7 to 8 days of equilibration.

[0018] Furthermore, the heavy metal cadmium and arsenic composite contaminated soil is a medium to light composite contaminated soil with a Cd content of 0.6 to 1.5 mg / kg and an As content of 30 to 100 mg / kg.

[0019] The present invention also provides an application of the manganese fertilizer compound passivator in synchronously reducing the Cd and As contents in rice grains and increasing rice yield.

[0020] Beneficial effects of the present invention:

[0021] The manganese fertilizer compound passivator of the present invention selects high-quality raw materials and optimizes the content of each component, and adopts manganese fertilizer and alkaline passivator with appropriate proportions. The manganese fertilizer compound passivator not only gives full play to the advantages of each component, but also achieves mutual complementation and promotion. The manganese fertilizer compound passivator finally prepared has the remarkable effect of simultaneously reducing the Cd and As contents in rice grains and increasing rice yield.

[0022] (1) Manganese is the third most abundant transition metal element in the earth's crust and an essential trace element for crop growth. It can promote the thickening of the iron film on the root surface, which is beneficial for blocking the harm of other heavy metals to plants. The addition of manganese fertilizer can increase manganese oxides in the soil, thereby reducing the absorption of arsenic and cadmium by rice grains through the competitive effect. At the same time, manganese fertilizer can be applied to both acidic and alkaline soils.

[0023] (2) pH is closely related to the Cd content in rice grains. As pH increases, the effective Cd content in the soil decreases, which reduces the Cd content that is transported upward and reduces the Cd content in the grains. Alkaline passivators can quickly increase pH to achieve the effect of acid adjustment and cadmium control. Diatomaceous earth can improve the physical structure of the soil, enhance the air permeability and water retention capacity of the soil, thereby promoting plant growth and helping the migration and fixation of heavy metals; hydroxyapatite has a strong adsorption capacity and can form insoluble complexes with metal ions through phosphates, thereby effectively reducing the effectiveness of heavy metals; biochar can adjust soil pH, improve the alkaline environment of the soil, and effectively reduce the solubility and mobility of heavy metals, reducing their toxic effects on plants.

[0024] In summary, the combined application of manganese fertilizer and alkaline passivator can produce significant synergistic effects. The manganese ions in manganese fertilizer and alkaline passivator work together to form a more stable heavy metal precipitation or adsorption complex, further reducing the bioavailability of heavy metals. At the same time, manganese fertilizer and alkaline passivator have strong complementarity in their mechanism of action. Manganese fertilizer improves the tolerance and repair ability of plants to heavy metals by enhancing the physiological functions and antioxidant capacity of plants; while alkaline passivator reduces the bioavailability of heavy metals and reduces their migration into the plant body by changing the chemical properties of the soil. In addition, the two materials are inexpensive and widely available, so the combination of manganese fertilizer and alkaline passivator shows many advantages in terms of repair effect, environmental adaptability and cost-effectiveness. This method can significantly reduce the content of heavy metals in soil and rice grains, and has the characteristics of simple preparation process and environmental friendliness. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand.

[0026] Experimental material requirements:

[0027] 1. Manganese fertilizer is mineral manganese, dry powder with a particle size of 100-200 mesh, and the effective content of mineral manganese is ≥99%;

[0028] 2. The alkaline passivating agents are all dry powders with a particle size of 150 to 200 meshes, wherein the effective content of SiO2 in diatomaceous earth is ≥85%, the effective content of P2O5 in hydroxyapatite is ≥97%, and the effective content of organic carbon in biochar is ≥78%.

[0029] Example 1

[0030] A manganese fertilizer compound passivator for increasing rice yield

[0031] The manganese fertilizer composite passivator of the present embodiment is composed of 4 parts of pyrolusite and 16 parts of diatomaceous earth by weight, and its preparation method specifically comprises the following steps:

[0032] 1. Weigh pyrolusite and diatomaceous earth according to the above parts by weight;

[0033] 2. At room temperature, pyrolusite and diatomaceous earth are mixed evenly to obtain a powdered mixture with a coefficient of variation of ≤10%, which is a manganese fertilizer compound passivator for increasing rice yield. When the coefficient of variation of the manganese fertilizer compound passivator is small, the mixing ratio of each component is relatively stable, which helps to ensure that the performance of the passivator remains consistent during production and application, and is not easily affected by external factors.

[0034] Prepare 2g of manganese fertilizer compound passivator according to the above steps

[0035] Example 2

[0036] A manganese fertilizer compound passivator for increasing rice yield

[0037] The manganese fertilizer compound passivator of this embodiment is composed of 4 parts of pyrolusite and 2 parts of hydroxyapatite by weight. The preparation method is the same as that of Example 1, and the manganese fertilizer compound passivator for improving rice yield is obtained, and its coefficient of variation is ≤10%.

[0038] According to the above steps, 0.6 g of manganese fertilizer compound passivator was prepared.

[0039] Example 3

[0040] A manganese fertilizer compound passivator for increasing rice yield

[0041] In terms of weight, the manganese fertilizer compound passivator of this embodiment is composed of 4 parts of pyrolusite and 12 parts of biochar. Its preparation method is the same as that of Example 1, and a manganese fertilizer compound passivator for improving rice yield is obtained, and its coefficient of variation is ≤10%.

[0042] According to the above steps, 1.6 g of manganese fertilizer compound passivator was prepared.

[0043] Example 4

[0044] A manganese fertilizer compound passivator for increasing rice yield

[0045] In terms of weight, the manganese fertilizer compound passivation agent of this embodiment is composed of 1 part of ferromanganese ore and 20 parts of biochar. Its preparation method is the same as that of Example 1, and the manganese fertilizer compound passivation agent for improving rice yield is obtained, and its coefficient of variation is ≤10%.

[0046] Example 5

[0047] A manganese fertilizer compound passivator for increasing rice yield

[0048] In terms of weight, the manganese fertilizer compound passivator of this embodiment is composed of 20 parts of manganite and 1 part of hydroxyapatite. Its preparation method is the same as that of Example 1, and the manganese fertilizer compound passivator for improving rice yield is obtained, and its coefficient of variation is ≤10%.

[0049] Comparative Example 1

[0050] A compound passivating agent

[0051] The composite passivating agent of this comparative example is composed of 4 parts of pyrolusite, and the preparation method is the same as that of Example 1.

[0052] Prepare 0.4 g of a composite passivating agent.

[0053] Comparative Example 2

[0054] A compound passivating agent

[0055] The composite passivating agent of this comparative example is composed of 16 parts of diatomaceous earth, and the preparation method is the same as that of Example 1.

[0056] Prepare 1.6 g of a composite passivating agent.

[0057] Comparative Example 3

[0058] A compound passivating agent

[0059] The composite passivating agent of this comparative example is composed of 2 parts of hydroxyapatite, and the preparation method is the same as that of Example 1.

[0060] Prepare 0.2 g of a compound passivating agent.

[0061] Comparative Example 4

[0062] A compound passivating agent

[0063] The composite passivating agent of this comparative example is composed of 12 parts of biochar, and the preparation method is the same as that of Example 1.

[0064] Prepare 1.2 g of a compound passivating agent.

[0065] Comparative Example 5

[0066] A compound passivating agent

[0067] The composite passivating agent of this comparative example is composed of 6 parts of pyrolusite, 6 parts of biochar and 3 parts of quicklime, and the preparation method is the same as that of Example 1.

[0068] Prepare 0.9 g of a composite passivating agent.

[0069] Example 6

[0070] Application of compound passivating agent in manganese fertilizer

[0071] The manganese fertilizer compound passivating agent prepared in Examples 1 to 3 was used to repair the heavy metal cadmium and arsenic compound contaminated soil, as experimental groups 1, 2 and 3 (the cost of the manganese fertilizer compound passivating agent used in experimental groups 1, 2 and 3 was the same), and the compound passivating agent prepared in Comparative Examples 1 to 5 was used to repair the heavy metal cadmium and arsenic compound contaminated soil, as control groups 1, 2, 3, 4 and 5, and no manganese fertilizer compound passivating agent or compound passivating agent was applied as blank groups.

[0072] The test soil is a heavy metal cadmium and arsenic compound contaminated soil in Hubei. The basic physical and chemical properties of the soil are: pH = 6.01, total iron 23.01g / kg, total manganese 170mg / kg, total cadmium 1.19mg / kg, total arsenic 41.16mg / kg. According to the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB15618-2018), the Cd and As contents in the soil are between the soil screening value and the risk control value, and crops can be planted. The rice variety tested is Huanghuazhan.

[0073] 1. Sterilize rice seeds with 30% H2O2 for 10 minutes, rinse with deionized water three times, place on soaked gauze, and culture in a light incubator until germination. The culture conditions are: 28°C, a constant temperature incubator without light.

[0074] 2. After germination, the seeds are moved to a special rice seedling medium for seedling cultivation. Before transplanting, the composite contaminated soil is placed in a culture pot, 5 kg of soil is added to each pot, and 1.6 g of urea, 0.9 g of potassium chloride and 0.55 g of calcium hydrogen phosphate are applied as base fertilizer. Manganese fertilizer compound passivator or compound passivator is added to each pot, mixed with the soil, and water is added for balance for 7 days before transplanting the rice.

[0075] 3. After transplanting, the rice is cultivated in a greenhouse using conventional rice planting methods until the rice matures. After the rice matures, the rice is harvested, threshed and husked to obtain brown rice. At the same time, mature soil samples are collected, naturally air-dried, ground and sieved through a 20-mesh sieve for analysis of the effective states of cadmium and arsenic in the soil. The effective state of soil Cd is analyzed using the DTPA extraction method, and the effective state of soil As is analyzed using the NaHCO3 extraction method.

[0076] 4. The brown rice obtained by threshing and husking the mature rice was tested. The test results are shown in Table 1 below.

[0077] Table 1 Concentrations and yields of Cd and As in brown rice after harvest in different experimental groups

[0078]

[0079]

[0080] Note: Different lowercase letters indicate significant differences among different treatments, p<0.05.

[0081] As can be seen from Table 1, the concentrations of cadmium and arsenic in the brown rice treated by the blank group reached 0.89 mg / kg and 0.59 mg / kg, respectively. Eating such rice will bring certain health risks to the human body. The manganese fertilizer compound passivator of the present invention can significantly reduce the content of Cd and As in rice grains. Compared with the blank group, the experimental groups can significantly reduce the content of Cd in rice grains by 52.76% to 56.64%; at the same time, the experimental groups can also simultaneously reduce the As content in rice grains by 45.66% to 49.13%, and the experimental groups can be reduced to the national food safety standard for grain As. Compared with the experimental group and the control group 1, it can be seen that the alkaline passivator can increase the cadmium reduction rate and the arsenic reduction rate, respectively, by 13.97% to 21.03% and 3.10% to 3.31%. Among them, the cadmium reduction rate of experimental group 2 was the highest, and the arsenic reduction rate of experimental group 1 was high. Compared with experimental groups 1, 2, and 3 and control groups 2, 3, and 4, it was found that manganese fertilizer could simultaneously reduce the concentrations of Cd and As in rice grains. At the same time, it was found that manganese fertilizer combined with passivator could increase rice yield by 2.65% to 2.73%, achieving the effect of promoting plant growth.

[0082] 5. The collected soil was air-dried and ground before testing. The test results are shown in Table 2 below.

[0083] Table 2 Soil pH and soil available Cd and As concentrations in different experimental groups

[0084]

[0085]

[0086] Note: Different lowercase letters indicate significant differences among different treatments, p<0.05.

[0087] As shown in Table 2, compared with the blank group, the experimental groups can increase the pH of the soil. Under the environment of increased pH, the content of available Cd in the soil also decreases synchronously, with a decrease of 7.39% to 12.39%, which is the main reason for the reduction of Cd content in rice grains. Compared with the control group 1, the experimental group found that the alkaline passivator can increase the pH of the soil and significantly reduce the content of available Cd in the soil; indicating that the alkaline passivator has a significant effect on the reduction of available Cd in the soil. Compared with the implementation groups 1, 2, and 3 and the control groups 2, 3, and 4, it was found that manganese fertilizer had no significant effect on soil pH.

[0088] In summary, the manganese fertilizer compound passivator of the present invention can effectively and simultaneously reduce the Cd and As contents in rice grains, and at the same time, it also has a certain reducing effect on the contents of effective Cd and As in the soil. In addition, the manganese fertilizer compound passivator can also significantly increase the yield of rice. The manganese fertilizer compound passivator of the present invention adopts a mechanical mixing method, is simple to operate, is cost-effective, can be widely promoted and replicated, and can provide a new way out for the prevention and control of heavy metals in agricultural products in soils with moderate to mild Cd and As compound pollution.

[0089] Although the above embodiments have been described in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A manganese fertilizer compound passivator for increasing rice yield, characterized in that: The manganese fertilizer compound passivator is composed of 1 to 10 parts of mineral manganese and 1 to 20 parts of alkaline passivator in parts by weight; The mineral manganese is any one of pyrolusite, hausmannite and manganite, and the alkaline passivating agent is any one of diatomaceous earth, hydroxyapatite and biochar.

2. The composite passivating agent for manganese fertilizer according to claim 1, characterized in that: Calculated by weight, the manganese fertilizer compound passivator consists of 4 parts of mineral manganese and 2 to 16 parts of alkaline passivator.

3. The composite passivating agent for manganese fertilizer according to claim 2, characterized in that: The mineral manganese is a dry powder with a particle size of 100-200 meshes, and the effective content of the mineral manganese is ≥99%.

4. The composite passivating agent for manganese fertilizer according to claim 2, characterized in that: The alkaline passivating agents are all dry powders with a particle size of 150-200 meshes, wherein the effective content of SiO2 in diatomaceous earth is ≥85%, the effective content of P2O5 in hydroxyapatite is ≥97%, and the effective content of organic carbon in biochar is ≥78%.

5. The composite passivating agent for manganese fertilizer according to claim 2, characterized in that: The manganese fertilizer compound passivator consists of 4 parts of pyrolusite and 16 parts of diatomaceous earth.

6. The composite passivating agent for manganese fertilizer according to claim 2, characterized in that: The manganese fertilizer compound passivator consists of 4 parts of pyrolusite and 2 parts of hydroxyapatite.

7. A method for preparing the composite passivating agent for manganese fertilizer according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Weigh mineral manganese and alkaline passivating agent according to the above weight parts; (2) The mineral manganese and the alkaline passivator are mixed evenly to obtain a manganese fertilizer compound passivator for increasing rice yield.

8. Use of the manganese fertilizer compound passivator according to any one of claims 1 to 6 in remediating soil contaminated by heavy metal cadmium and arsenic, characterized in that: The manganese fertilizer compound passivator is applied to the heavy metal cadmium arsenic composite contaminated soil at a mass ratio of 0.3 to 1:2500, and the heavy metal cadmium arsenic composite contaminated soil can be repaired after 7 to 8 days of equilibrium.

9. The use according to claim 9, characterized in that: The heavy metal cadmium and arsenic composite contaminated soil is a medium to light composite contaminated soil with a Cd content of 0.6 to 1.5 mg / kg and an As content of 30 to 100 mg / kg.

10. Use of the manganese fertilizer compound passivator according to any one of claims 1 to 6 in simultaneously reducing the Cd and As content in rice grains and increasing rice yield.

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