Selenium-rich cadmium-resistant bio-organic fertilizer and preparation method thereof

Abstract

The invention provides a selenium-rich cadmium-resistant bio-organic fertilizer and a preparation method thereof. The bio-organic fertilizer comprises the following components in parts by mass: 10-15 parts of functional components and 85-90 parts of decomposed materials, the functional component is prepared from iron powder, sodium selenite, zinc sulfate monohydrate, calcium peroxide, calcium sulfate and potassium fulvate according to the weight ratio of 1.0: 0.1: 1.0: 1.0: 1.0: 1.0: 1.0; the rotten material is composed of walnut residues, mushroom residues and a rotten microbial inoculum, the weight ratio of the walnut residues to the mushroom residues is (5-6): (4-5), and the rotten microbial inoculum accounts for 0.2% of the total weight of the walnut residues and the mushroom residues. The bio-organic fertilizer can improve the crop root soil environment, reduce the effectiveness of cadmium in the soil, reduce the absorption of cadmium by crops, provide rich nutrients, promote the growth and development of crops, and improve the absorption and utilization of selenium by crops, thereby producing selenium-rich and low-cadmium safe agricultural products.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural biofertilizers, and in particular to a selenium-rich cadmium-blocking bio-organic fertilizer and a preparation method thereof. Background Art

[0002] Soil cadmium pollution refers to the phenomenon that the content of cadmium (Cd) in the soil exceeds the natural background value and may have a negative impact on the ecological environment and human health. It mainly leads to reduced crop yields, damage to human health after long-term consumption of agricultural products containing excessive cadmium, and harm to arable land quality.

[0003] Selenium-enriched agricultural products are grown in selenium-rich soils and enriched with selenium through natural absorption or bio-nutrient fortification. Because selenium is an essential trace element for the human body and has multiple physiological and health benefits, selenium-enriched agricultural products have attracted considerable attention due to their high selenium content.

[0004] The selenium-cadmium interaction effect in agricultural products refers to the interaction between selenium and heavy metal cadmium during the production of selenium-rich agricultural products, which can easily lead to excessive cadmium content and pose a risk to the safety of agricultural products. This greatly restricts the development of selenium-rich agriculture.

[0005] Currently, the development of selenium-enriched functional agriculture primarily relies on spraying selenium-enriched foliar fertilizers. However, the vast majority of selenium-enriched foliar fertilizers on the market typically use selenite or selenite fermented or chelated with a complexing agent, followed by multiple foliar sprays. This method has numerous drawbacks: first, significant residual inorganic selenium, posing a potential toxic risk; second, low conversion rates of selenium in agricultural products, resulting in high costs; third, the foliar fertilizer application process carries the risk of burning the plants themselves; and fourth, the workload and labor costs associated with multiple sprayings are substantial.

[0006] The scientific use of fertilizers can effectively increase crop yields and farmers' incomes. However, the long-term use of chemical fertilizers has led to crop dependence, resulting in increasing fertilizer usage and, in turn, increasing soil compaction. Long-term excessive fertilizer use inevitably leads to a variety of drawbacks, including soil compaction, decreased organic matter content, and nutrient imbalances. Furthermore, due to long-term fertilization and land pollution, existing soils contain large amounts of heavy metal ions. These ions are adsorbed by plant roots and accumulate there. These toxic heavy metal ions can affect the quality and safety of agricultural products.

[0007] Organic fertilizer, as an ideal environmentally friendly and sustainable fertilizer alternative, has many advantages, including improving soil texture, enhancing soil water retention capacity, and providing nutrients required by plants. However, existing bio-organic fertilizers do not solve the problem of heavy metal ions such as cadmium, arsenic and copper in the soil, which pose a threat to plants and agricultural products.

[0008] When applied as a base fertilizer, selenium-rich, cadmium-blocking bio-organic fertilizers achieve efficient conversion and absorption of inorganic selenium through the long-term dual action of soil microorganisms and crops, increasing the organic selenium content in agricultural products. Simultaneously, the decomposed materials and functional components in the organic fertilizers physically adsorb and chemically passivate heavy metals such as cadmium in the soil, inhibiting their effectiveness and reducing their absorption by crop roots, effectively reducing the cadmium content in agricultural products. Furthermore, the organic matter and rich minerals in the bio-organic fertilizers also provide nutrients for crop growth and development. Therefore, the rational application of selenium-rich, cadmium-blocking bio-organic fertilizers is the primary and safest way to produce selenium-rich, low-cadmium agricultural products. Summary of the Invention

[0009] Technical problem to be solved: In view of the shortcomings and deficiencies of the existing technology, the present invention provides a selenium-rich cadmium-blocking bio-organic fertilizer and a preparation method thereof. The bio-organic fertilizer can improve the soil environment of crop roots, reduce the effectiveness of cadmium in the soil, reduce the absorption of cadmium by crops, provide rich nutrients, promote crop growth and development, and improve the absorption and utilization of selenium by crops, thereby producing safe agricultural products rich in selenium and low in cadmium.

[0010] Technical solution: A selenium-rich cadmium-blocking bio-organic fertilizer, which contains the following components by weight: 10-15 parts of functional components and 85-90 parts of decomposed materials;

[0011] The functional components are composed of iron powder, sodium selenite, zinc sulfate monohydrate, calcium peroxide, calcium sulfate, and potassium fulvate in a weight ratio of 1.0:0.1:1.0:1.0:1.0:1.0;

[0012] The decomposed material consists of walnut residue, mushroom residue and decomposing bacteria agent, wherein the weight ratio of walnut residue to mushroom residue is (5-6): (4-5), and the weight of the decomposing bacteria agent is 0.2% of the total weight of the walnut residue and mushroom residue.

[0013] The mesh size of the iron powder is 200 meshes.

[0014] The effective component of the sodium selenite described above accounts for 98%.

[0015] The effective component of the calcium peroxide described above accounts for 60%.

[0016] The effective component of the zinc sulfate monohydrate described above accounts for 98%.

[0017] The effective component of the calcium sulfate described above accounts for 98%.

[0018] The technical indicators of the potassium fulvate mentioned above are: fulvic acid ≥52%, potassium chloride ≥12%, humic acid ≥50%, and organic matter ≥80%.

[0019] The preparation method of the above-mentioned selenium-rich cadmium-blocking biological organic fertilizer comprises the following steps:

[0020] 1) mixing iron powder, sodium selenite, zinc sulfate monohydrate, calcium peroxide, calcium sulfate, and potassium fulvate in a weight ratio of 1.0:0.1:1.0:1.0:1.0:1.0 to obtain a functional component;

[0021] 2) After the walnut residue, mushroom residue and decomposing agent are evenly mixed, the composting is carried out in a windrowing manner. After the composting temperature rises to 50-55° C., the compost is turned over. The first fermentation lasts for 25 days, and the compost is turned over every 7-8 days. After the first fermentation is completed, the compost is transported to a secondary fermentation workshop and statically fermented for 20-25 days to obtain a decomposed material.

[0022] 3) Evenly mixing the functional components and the decomposed materials to obtain the selenium-rich and cadmium-blocking biological organic fertilizer.

[0023] Beneficial effects: The selenium-rich cadmium-blocking biological organic fertilizer and its preparation method provided by the present invention have the following beneficial effects:

[0024] 1. The present invention uses organic fertilizer as a carrier to develop an iron-based selenium-rich bio-organic fertilizer. The organic fertilizer uses the activity of iron to passivate cadmium in the soil and uses organic decomposed materials to adsorb cadmium, thereby reducing the content of effective cadmium in the soil and reducing the absorption and accumulation of cadmium by crop roots. At the same time, sodium selenite is added exogenously and converted into organic selenium by crops, thereby enhancing the crops' immunity to cadmium, having a good conditioning effect on both crops and soil, and thereby increasing the possibility of producing selenium-rich and low-cadmium agricultural products.

[0025] 2. The selenium-rich cadmium-blocking biological organic fertilizer of the present invention has organic matter ≥40%, total nutrients ≥5%, pH ≥6.5, effective viable bacteria count ≥50 million / g, selenium (Se) ≥0.04%, trace elements ≥5%, total arsenic (As) ≤15 mg / kg, total mercury (Hg) ≤2 mg / kg, total lead (Pb) ≤50 mg / kg, total chromium (Cr) ≤150 mg / kg, fecal coliform count ≤100 / g, and no ascaris eggs detected, which fully complies with the NY / T525-2021 standard. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below through specific embodiments. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0027] The experimental methods in the following examples are conventional methods unless otherwise specified; the experimental materials used in the following examples are purchased from commercial channels unless otherwise specified.

[0028] The iron powder, sodium selenite, zinc sulfate monohydrate, calcium peroxide, calcium sulfate, potassium fulvate, and composting agent used in the following examples can all be purchased from conventional commercial channels.

[0029] Mushroom residue is a large amount of waste generated after harvesting mushrooms in large-scale mushroom cultivation bases.

[0030] Walnut residue is the waste left after the food factory extracts the walnut flavor.

[0031] This embodiment provides a method for preparing a selenium-rich cadmium-blocking biological organic fertilizer, the steps of which are as follows:

[0032] 1) mixing iron powder, sodium selenite, zinc sulfate monohydrate, calcium peroxide, calcium sulfate, and potassium fulvate in a weight ratio of 1.0:0.1:1.0:1.0:1.0:1.0 to obtain a functional component;

[0033] 2) After the walnut residue, mushroom residue and decomposing agent are mixed uniformly in a weight ratio of 5:5:0.02, the compost is treated by windrowing, and the compost is turned after the compost temperature rises to 50-55° C. The first fermentation lasts for 25 days, and the compost is turned every 7-8 days. After the first fermentation is completed, the compost is transported to a secondary fermentation workshop and statically fermented for 20-25 days to obtain a decomposed material;

[0034] 3) The functional components and the decomposed materials are mixed uniformly according to a weight ratio of 1:9 to obtain a powdered selenium-rich cadmium-blocking biological organic fertilizer.

[0035] This selenium-rich, cadmium-resistant biological organic fertilizer has organic matter ≥40%, total nutrients ≥5%, pH ≥6.5, effective live bacteria count ≥50 million / g, selenium (Se) ≥0.04%, trace elements ≥5%, total arsenic (As) ≤15mg / kg, total mercury (Hg) ≤2mg / kg, total lead (Pb) ≤50mg / kg, total chromium (Cr) ≤150mg / kg, fecal coliform count ≤100 / g, and no ascaris eggs detected, which fully complies with the NY / T 525-2021 standard.

[0036] Example 1

[0037] The selenium-rich, cadmium-blocking biological organic fertilizer (denoted as A1) prepared above was applied to rice. The specific process and results are as follows.

[0038] 1. Test varieties

[0039] Xizi No. 3.

[0040] 2. Test fertilizer

[0041] Selenium-rich cadmium-blocking biological organic fertilizer (A1), bamboo charcoal organic fertilizer (A2, purchased from Jiangxi Diyuankang Biotechnology Co., Ltd.) and conventional compound fertilizer (N:P2O5:K2O=15:15:15) (A0, purchased from Jiangxi Huaxin Fertilizer Co., Ltd.).

[0042] 3. Experimental Design

[0043] A field fertilizer efficiency test was conducted from July to November 2024. The soil type of the test site is brown soil, which had previously been cultivated with rice. However, due to excessive cadmium content in the soil, management measures were implemented in accordance with the "Soil Environmental Quality Standard" (GB15618-1995), including the conversion to turf cultivation to improve soil conditions. Currently, the soil fertility is good, and irrigation and drainage conditions are excellent. Pre-test soil physical and chemical properties are shown in Table 1.

[0044] Table 1

[0045]

[0046] The experiment was conducted with three treatments and three replicates, and the plot area was 66.7 m 2 , randomly arranged, and a protection row of 1m is set up in the cell. The specific treatment is as follows:

[0047] (1) Treatment 1: Conventional compound fertilizer (A0) fertilization treatment, basal fertilizer was applied on July 1, every 667m 2 Use 40kg of 45% compound fertilizer per 667m on August 20 2 Topdress urea 10kg;

[0048] (2) Treatment 2: In addition to the conventional compound fertilizer (A0), 80 kg / 667 m3 of selenium-rich and cadmium-blocking biological organic fertilizer (A1) was applied. 2 , spread it in the plot before planting and then plow it;

[0049] (3) Treatment 3: In addition to the conventional compound fertilizer (A0), bamboo charcoal organic fertilizer (A2) was applied at 160 kg / 667 m 2 , spread it in the plot before planting and then plow it.

[0050] On July 18, rice fields were sown by hand; at harvest time, each plot was harvested and sampled separately, and other cultivation and management were consistent with local management practices.

[0051] 4. Results and Analysis

[0052] (1) Effects of different treatments on rice yield

[0053] Each treatment was harvested separately in each plot, and the rice was weighed and recorded after harvest. The results showed that the effects of adding selenium-rich, cadmium-blocking bio-organic fertilizer (A1) and conventional compound fertilizer (A0) on rice yield were significantly different, as shown in Table 2 below.

[0054] Table 2

[0055]

[0056] (2) Effects of different treatments on selenium and cadmium contents in rice grains

[0057] During rice harvest, samples were collected from each plot after harvest, and the samples were processed and measured for selenium and cadmium content. The measured data were recorded separately. The results showed that the effects of applying a selenium-rich, cadmium-blocking bio-organic fertilizer (A1) and conventional fertilization (A0) on the selenium and cadmium content of rice grains were significantly different, as shown in Table 3 below.

[0058] Table 3

[0059]

[0060] 5. Conclusion

[0061] (1) The selenium-rich cadmium-blocking bio-organic fertilizer of the present invention can increase rice yield. On the basis of conventional fertilization, the average yield per mu of the application of the selenium-rich cadmium-blocking bio-organic fertilizer is 35.75 kg higher than that of the application of no organic fertilizer, and 32.75 kg higher than that of the application of commercial organic fertilizer, which is a significant increase in yield.

[0062] (2) The selenium-rich cadmium-blocking bio-organic fertilizer of the present invention can significantly increase the selenium content and reduce the cadmium content of rice. The rice that is fertilized with the selenium-rich cadmium-blocking bio-organic fertilizer (A1) on the basis of conventional fertilization has a selenium content increased by 0.022 mg / kg, an increase of 32.35%, compared with the rice that is not fertilized with organic fertilizer; the cadmium content of the rice that is fertilized with conventional fertilizer is reduced by 0.612 mg / kg, a decrease of 96.99%. The selenium content of the rice that is fertilized with commercial organic fertilizer (A2) is increased by 0.017 mg / kg, an increase of 23.29%; the cadmium content of the rice that is fertilized with commercial organic fertilizer is reduced by 0.024 mg / kg, a decrease of 55.81%.

[0063] Example 2

[0064] The selenium-rich, cadmium-blocking biological organic fertilizer (denoted as B1) prepared above was applied to sweet potatoes. The specific process and results are as follows.

[0065] 1. Test varieties

[0066] Ordinary potato 32.

[0067] 2. Test fertilizer

[0068] Selenium-rich cadmium-blocking bio-organic fertilizer (B1), bio-organic fertilizer (B2, purchased from Jiangxi Kangrun Biotechnology Co., Ltd.) and conventional compound fertilizer (N:P2O5:K2O=15:15:15) (B0, purchased from Jiangxi Huaxin Fertilizer Co., Ltd.).

[0069] 3. Experimental Design

[0070] A sweet potato field fertilizer efficiency test was conducted from May to October 2024. The test site was red soil with continuous sweet potato cultivation, sufficient soil fertility, and good irrigation and drainage conditions. Pre-test soil selenium levels were 0.46 mg / kg and cadmium levels were 0.06 mg / kg.

[0071] The experiment was conducted with three treatments and three replicates, and the plot area was 66.7 m 2 , randomly arranged, and a protection row of 1m is set up in the cell. The specific treatment is as follows:

[0072] (1) Treatment 1: Conventional compound fertilizer (B0) fertilization treatment, base fertilizer application on May 20, every 667m 2 Use 40kg of 40% compound fertilizer;

[0073] (2) Treatment 2: In addition to the conventional compound fertilizer (B0), 80 kg / 667 m3 of selenium-rich and cadmium-blocking biological organic fertilizer (B1) was applied. 2 , spread it in the plot before planting and then plow it;

[0074] (3) Treatment 3: In addition to the conventional compound fertilizer (B0), 160 kg / 667 m3 of bio-organic fertilizer (B2) was applied. 2 , spread it in the plot before planting and then plow it.

[0075] Sweet potato seedlings were planted manually on May 25; samples were taken separately from each plot at harvest time, and other cultivation and management were consistent with local management practices.

[0076] 4. Results and Analysis

[0077] (1) Effects of different treatments on sweet potato yield

[0078] When the sweet potatoes were harvested, the weight and yield of the sweet potatoes in each plot were measured and the data were compiled in Table 4.

[0079] Table 4

[0080]

[0081] (2) Effects of different treatments on selenium and cadmium contents in sweet potato roots

[0082] When the sweet potatoes were ripe and ready for harvest, samples were collected from each plot. After processing, the samples were tested for selenium and cadmium content, and the measured data were recorded separately. The results showed that adding a selenium-rich, cadmium-blocking bio-organic fertilizer (B1) to conventional fertilization had significant differences in the selenium and cadmium content of sweet potato roots compared to applying no organic fertilizer (B0) or adding commercial organic fertilizer (B2), as shown in Table 5 below.

[0083] Table 5

[0084]

[0085] 5. Conclusion

[0086] (1) The selenium-rich cadmium-blocking bio-organic fertilizer of the present invention can increase the yield of sweet potatoes. On the basis of conventional fertilization, the average yield per mu of the selenium-rich cadmium-blocking bio-organic fertilizer is increased by 117 kg compared with the average yield per mu of no organic fertilizer, and is increased by 116.2 kg compared with the average yield per mu of commercial organic fertilizer, which is a significant increase in yield.

[0087] (2) The selenium-rich cadmium-blocking biological organic fertilizer of the present invention can significantly increase the selenium content of sweet potatoes and reduce their cadmium content. On the basis of conventional fertilization, the sweet potato tubers treated with the selenium-rich cadmium-blocking biological organic fertilizer (B1) were compared with the sweet potato tubers not treated with organic fertilizer. The selenium content of the sweet potato tubers treated with the present invention increased by 0.0124 mg / kg, an increase of 43.06%; the cadmium content decreased by 0.0143 mg / kg, a decrease of 46.28%. The sweet potato tubers treated with the selenium-rich cadmium-blocking biological organic fertilizer (B1) were compared with the sweet potato tubers treated with the bamboo charcoal organic fertilizer (B2). The selenium content of the sweet potato tubers treated with the present invention increased by 0.0129 mg / kg, an increase of 45.58%; the cadmium content decreased by 0.0051 mg / kg, a decrease of 30.72%.

[0088] Example 3

[0089] The selenium-rich, cadmium-blocking biological organic fertilizer (denoted as C1) prepared above was applied to edamame. The specific process and results are as follows.

[0090] 1. Test varieties

[0091] Hainan 64.

[0092] 2. Test fertilizer

[0093] Selenium-rich cadmium-blocking bio-organic fertilizer (C1), bio-organic fertilizer (C2, purchased from Jiangxi Kangrun Biotechnology Co., Ltd.) and conventional compound fertilizer (N:P2O5:K2O=15:15:15) (C0, purchased from Jiangxi Huaxin Fertilizer Co., Ltd.).

[0094] 3. Experimental Design

[0095] A field fertilizer efficiency test for edamame was conducted from August to November 2024. The soil type of the test site was brown soil, previously used for rice cultivation, with sufficient fertility and good irrigation and drainage conditions. Before the test, the soil selenium content was 0.33 mg / kg and the cadmium content was 0.15 mg / kg.

[0096] The experiment was conducted with three treatments and three replicates, and the plot area was 66.7 m 2 , randomly arranged, and a protection row of 1m is set up in the cell. The specific treatment is as follows:

[0097] (1) Treatment 1: Conventional compound fertilizer (C0) fertilization treatment, basal fertilizer application on August 3, every 667m 2 Use 60kg of 45% compound fertilizer;

[0098] (2) Treatment 2: On the basis of conventional compound fertilizer (C0), 80 kg / 667 m3 of selenium-rich and cadmium-blocking biological organic fertilizer (C1) was added. 2 , spread it in the plot before planting and then plow it;

[0099] (3) Treatment 3: On the basis of conventional compound fertilizer (C0), bio-organic fertilizer (C2) was added at 160 kg / 667 m 2 , spread it in the plot before planting and then plow it.

[0100] On August 15, edamame was sown in holes; samples were taken from each plot separately during harvest, and other cultivation and management were consistent with local management practices.

[0101] 4. Results and Analysis

[0102] (1) Effects of different treatments on edamame yield

[0103] When the edamame was harvested, the weight and yield of the edamame in each plot were measured and the data were compiled in Table 6.

[0104] Table 6

[0105]

[0106] (2) Effects of different treatments on selenium and cadmium content in edamame fruit

[0107] After edamame matured, samples were collected from each plot and, after appropriate processing, tested for selenium and cadmium content. The data were recorded. This indicates that the effects of adding a selenium-rich, cadmium-blocking bio-organic fertilizer (C1) to conventional fertilization, no organic fertilizer (C0), and additional bio-organic fertilizer (C2) on the selenium and cadmium content of edamame fruit were significantly different, as shown in Table 7 below.

[0108] Table 7

[0109]

[0110] 5. Conclusion

[0111] (1) The selenium-rich, cadmium-blocking bio-organic fertilizer of the present invention can increase the yield of edamame. On the basis of conventional fertilization, the average yield per mu of the selenium-rich, cadmium-blocking bio-organic fertilizer is increased by 192.9 kg compared with the average yield per mu of no organic fertilizer, and is increased by 151.55 kg compared with the average yield per mu of the bio-organic fertilizer, which is a significant increase in yield.

[0112] (2) The selenium-rich cadmium-blocking bio-organic fertilizer of the present invention can significantly increase the selenium content and reduce the cadmium content of edamame fruit. On the basis of conventional fertilization, the edamame fruit treated with the selenium-rich cadmium-blocking bio-organic fertilizer (C1) was compared with the edamame fruit not treated with organic fertilizer. The selenium content of the edamame fruit treated with the selenium-rich cadmium-blocking bio-organic fertilizer of the present invention increased by 0.2243 mg / kg, an increase of 594.96%; the cadmium content decreased by 0.0467 mg / kg, a decrease of 32.21%. The edamame fruit treated with the selenium-rich cadmium-blocking bio-organic fertilizer (C1) was compared with the edamame fruit treated with the bio-organic fertilizer (C2). The selenium content of the edamame fruit treated with the selenium-rich cadmium-blocking bio-organic fertilizer of the present invention increased by 0.1931 mg / kg, an increase of 280.26%; the cadmium content decreased by 0.0187 mg / kg, a decrease of 15.98%.

[0113] The above embodiments provide detailed descriptions of the implementation methods of the present invention. However, the present invention is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. The above descriptions are merely preferred embodiments of the present invention and do not limit the scope of the present invention. Any equivalent structural changes made using the contents of the present invention description are included within the scope of the present invention.

Claims

1. A selenium-rich cadmium-blocking biological organic fertilizer, characterized in that The bio-organic fertilizer contains the following components by weight: 10-15 parts of functional components and 85-90 parts of decomposed materials; The functional components are composed of iron powder, sodium selenite, zinc sulfate monohydrate, calcium peroxide, calcium sulfate, and potassium fulvate in a weight ratio of 1.0: 0.1: 1.0: 1.0: 1.0: 1.0; The decomposed material consists of walnut residue, mushroom residue and a decomposing agent, wherein the weight ratio of the walnut residue to the mushroom residue is (5-6):(4-5), and the weight of the decomposing agent is 0.2% of the total weight of the walnut residue and the mushroom residue.

2. A selenium-rich cadmium-blocking biological organic fertilizer according to claim 1, characterized in that: The mesh number of the iron powder is 200 meshes.

3. A kind of selenium-rich cadmium-blocking biological organic fertilizer according to claim 1, it is characterized in that: The effective component of the sodium selenite accounts for 98%.

4. A selenium-rich cadmium-blocking biological organic fertilizer according to claim 1, characterized in that: The effective component of the calcium peroxide accounts for 60%.

5. A selenium-rich cadmium-blocking biological organic fertilizer according to claim 1, characterized in that: The effective component of the zinc sulfate monohydrate accounts for 98%.

6. A selenium-rich cadmium-blocking biological organic fertilizer according to claim 1, characterized in that: The effective component of the calcium sulfate accounts for 98%.

7. A selenium-rich cadmium-blocking biological organic fertilizer according to claim 1, characterized in that The technical indicators of the potassium fulvic acid are: fulvic acid ≥52%, potassium chloride ≥12%, humic acid ≥50%, and organic matter ≥80%.

8. The method for preparing a selenium-rich cadmium-blocking bio-organic fertilizer as described in any one of claims 1 to 7, wherein Here are the steps: 1) uniformly mixing iron powder, sodium selenite, zinc sulfate monohydrate, calcium peroxide, calcium sulfate, and potassium fulvate to obtain a functional component; 2) After the walnut residue, mushroom residue and decomposing agent are evenly mixed, the composting is carried out in a windrowing manner. After the composting temperature rises to 50-55° C., the compost is turned over. The first fermentation lasts for 25 days, and the compost is turned over every 7-8 days. After the first fermentation is completed, the compost is transported to a secondary fermentation workshop and statically fermented for 20-25 days to obtain a decomposed material. 3) Evenly mixing the functional components and the decomposed materials to obtain the selenium-rich and cadmium-blocking biological organic fertilizer.

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