Selenium-rich nutrient solution and preparation method thereof

Abstract

The invention discloses a selenium-rich nutrient solution and a preparation method thereof.The selenium-rich nutrient solution is prepared from, by use amount per mu, 6-10 g of sodium selenite, 80-120 g of monopotassium phosphate, 10-20 g of organic silicon surfactant and 150-250 mL of tea water; alkaline sodium selenite providing a selenium source balances the pH value of the selenium-rich nutrient solution to be neutral under the neutralization of tea water with the pH value of 5-6 and the action of monopotassium phosphate serving as a nutrient component and a buffer solution, so that the selenium-rich nutrient solution can be stored for a long time; the selenium-rich nutrient solution is sprayed on leaves once, and by taking rice as an example, the selenium content in the rice can be increased to 0.5 mg / kg or above, meanwhile, photosynthesis of crops can be promoted, the stress resistance of the crops can be improved, premature senility can be delayed, and the yield can be increased.

Description

Technical Field

[0001] This invention belongs to the field of plant nutrient solution technology, specifically relating to a selenium-enriched nutrient solution and its preparation method. Background Technology

[0002] Selenium is an essential micronutrient for the human body, playing a vital role in maintaining normal physiological functions. It participates in the synthesis and metabolism of various enzymes, and possesses physiological functions such as enhancing immunity, anti-oxidation, and delaying aging. It also shows positive effects on cardiovascular health, bone development, and tumor prevention. In most parts of my country, the soil selenium content is low, resulting in generally insufficient selenium content in crops produced in these regions, failing to meet the body's normal selenium requirements. Therefore, increasing the selenium content of crops through agricultural production techniques and developing selenium-enriched agricultural products is an effective way to address the problem of insufficient selenium intake, possessing significant social value and market potential.

[0003] Currently, the main technologies for increasing the selenium content of crops include soil application and foliar spraying. Soil application typically involves directly applying selenium fertilizer into the soil, allowing the crop roots to absorb and convert it for selenium enrichment. However, this method has significant drawbacks: firstly, selenium in the soil is easily adsorbed and fixed by soil metals and colloids, transforming into forms that are difficult for crops to absorb, resulting in extremely low selenium fertilizer utilization, typically less than 2%. This not only increases production costs but may also lead to environmental risks due to soil selenium accumulation; secondly, soil application is affected by various factors such as soil texture, pH value, and organic matter content, making the selenium enrichment effect unstable and difficult to precisely control the selenium content of crops.

[0004] Compared to soil application of selenium, foliar spraying of selenium fertilizer, because it acts directly on the above-ground parts of crops and is absorbed through the stomata and cuticle of leaves, has advantages such as rapid absorption, high utilization rate, and direct action, making it the current mainstream technology for producing selenium-enriched agricultural products. However, existing selenium nutrient solutions used for foliar spraying still have many problems: Currently, the market uses sodium selenite as the selenium source in selenium nutrient solutions. However, sodium selenite aqueous solution alone is an alkaline substance that is easily blocked by the waxy layer on the surface of crop leaves, resulting in limited absorption efficiency and making it difficult to significantly increase selenium content; although some products add auxiliary ingredients, they are not neutralized. Due to unreasonable formula design, either the type and amount of surfactant are inappropriate, which cannot effectively reduce the surface tension of the nutrient solution, resulting in poor spreadability and easy loss of selenium fertilizer nutrient solution on the leaf surface. More importantly, sodium selenite solution is an alkaline solution, and excessive use can cause crop burning and scorching, seriously affecting crop yield. Either they lack synergistic nutritional components, failing to meet both selenium absorption and crop growth needs, resulting in poor selenium content enhancement in crops, making it difficult to consistently achieve the selenium enrichment standard of 0.2 mg / kg with a single foliar spray; or they themselves suffer from poor stability, easily undergoing reduction reactions during storage, leading to precipitation and stratification, and becoming ineffective, making them difficult to store for long periods. This limits the large-scale production of selenium-enriched fertilizer products, seriously affecting production costs and hindering their widespread application in agricultural production. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a selenium-enriched nutrient solution and its preparation method. A single foliar spray of the selenium-enriched nutrient solution, taking rice as an example, can increase the selenium content in rice to over 0.5 mg / kg. Simultaneously, it can promote photosynthesis in crops, enhance their resistance to adverse conditions, delay premature aging, and increase yield.

[0006] The technical solution adopted in this invention is as follows:

[0007] This invention provides a selenium-enriched nutrient solution, which, based on the usage per acre, contains: 6-10 g sodium selenite, 80-120 g potassium dihydrogen phosphate, 10-20 g organosilicon surfactant, and 150-250 mL tea water. The pH of the selenium-enriched nutrient solution prepared according to this formula is between 7 and 7.5.

[0008] The silicone surfactant is any one or more of the following grades: RH-208, RH-288, RH-209, BD-3077, ASS8211, ASS8277, ASS8309, H-8408, and H-8806.

[0009] The pH of the tea water is 5-6.

[0010] The method for preparing the tea is as follows: steep the tea leaves in warm water at a temperature of 80-100℃ for 10-30 minutes.

[0011] The mass-to-volume ratio of the tea leaves to the warm water is 1 g: 10~20 mL.

[0012] The tea leaves can be any commercially available tea, or can be prepared by the following method: stir-frying leaves from any tea tree at 120-150℃ for 5-8 minutes, then kneading them in a kneading machine for 3-5 minutes, and finally drying them at 60-80℃ for 2-3 hours; or tea leaves harvested by a tea-picking machine, stir-frying them at 120-150℃ for 5-8 minutes, then kneading them in a kneading machine for 3-5 minutes, then drying them at 60-80℃ for 2-3 hours, and finally using the sieved material after screening as the raw material for tea.

[0013] When using an electric small backpack sprayer to apply selenium-enriched nutrient solution, the selenium-enriched nutrient solution is diluted 200 times with water before spraying.

[0014] When using an electric water pump to spray the selenium-enriched nutrient solution, the selenium-enriched nutrient solution is diluted 200 times with water before spraying.

[0015] When using drones to spray selenium-enriched nutrient solution, the selenium-enriched nutrient solution is diluted 20 times with water before spraying.

[0016] The present invention also provides a method for preparing the selenium-enriched nutrient solution, the method comprising the following steps: adding sodium selenite to tea water, stirring until completely dissolved, adding potassium dihydrogen phosphate, stirring until completely dissolved again, adding an organosilicon surfactant, and then stirring evenly. This preparation method is suitable for situations where the selenium-enriched nutrient solution is prepared and used immediately or within 12 months.

[0017] The preparation method further includes: freezing the well-stirred selenium-enriched nutrient solution into ice blocks, packaging them, and then refrigerating and transporting them. This preparation method is suitable for situations where the prepared selenium-enriched nutrient solution needs to be stored and transported for a long time.

[0018] Furthermore, the freezing temperature is -20 to -30°C.

[0019] The selenium-enriched nutrient solution provided by this invention uses sodium selenite as a high-quality selenium source. The dosage of 6-10 g / mu in the formula is precisely proportioned, which can provide crops with sufficient selenium. Taking rice as an example, a single spraying can ensure that the selenium content in the rice is stably increased to more than 0.5 mg / kg. At the same time, it can avoid crop poisoning, growth inhibition or soil selenium residue pollution caused by excessive selenium source, thus taking into account both safety and effectiveness.

[0020] Potassium dihydrogen phosphate not only supplements crops with phosphorus and potassium, promoting photosynthesis and nutrient metabolism, but also regulates the osmotic pressure of crop cells, providing a physiological basis for the absorption and transport of selenium. This solves the problem of crop growth imbalance caused by single selenium-enriched fertilizers that only supplement selenium without providing additional nutrients, thus simultaneously improving crop yield and quality. At the same time, potassium dihydrogen phosphate also acts as a buffer, balancing the pH of the selenium-enriched nutrient solution, keeping the pH within the neutral range. This facilitates long-term storage, avoids irritation to plant leaves during spraying, improves the efficiency of selenium conversion, and extends the storage time of the selenium-enriched nutrient solution.

[0021] Organosilicon surfactants can reduce the surface tension of selenium-enriched nutrient solutions, improve their adhesion, wettability and penetration on crop leaf surfaces, reduce selenium source loss due to rain or evaporation after spraying, and make selenium more easily absorbed by crops through leaf stomata or cuticle, thus significantly reducing selenium source waste.

[0022] Tea water contains natural components such as tea polyphenols and amino acids. On the one hand, it can enhance the compatibility of sodium selenite, potassium dihydrogen phosphate, and organosilicon, adjust the selenium-enriched nutrient solution to neutrality, prevent component precipitation and stratification, and ensure the homogeneity of the nutrient solution. On the other hand, it can gently regulate the microenvironment on the surface of crop leaves, reduce the irritation of chemical reagents to crops, and lower the risk of leaf burn. At the same time, tea water is widely available and inexpensive, taking into account both environmental protection and economy. Meanwhile, the selenium provided by sodium selenite, after being absorbed by crops, can participate in the synthesis of glutathione peroxidase. This enzyme can remove reactive oxygen species produced during photosynthesis, preventing oxidative damage to chloroplast membranes and photosynthetic pigments by reactive oxygen species, and maintaining stable chlorophyll content.

[0023] This invention provides a method for preparing selenium-enriched nutrient solution that addresses the shortcomings of sodium selenite solution, which is easily reduced and loses its activity, and traditional liquid selenium-enriched fertilizers, which suffer from reduced selenium source activity during room temperature storage or transportation, leading to a decline in selenium enrichment effects. By employing a process of orderly mixing and stirring → freezing into ice blocks → refrigerated storage and transportation, the nutrient solution is solidified into ice block form. The low-temperature environment effectively inhibits the reduction reaction of sodium selenite, preventing component precipitation and significantly extending the shelf life of the nutrient solution. This ensures that the product maintains a stable selenium enrichment effect even after transportation and storage. Furthermore, the ice block form facilitates quantitative application: a fixed amount of ice blocks corresponds to each acre of land, eliminating the need for farmers to weigh or dilute the solution. Farmers can simply melt the ice blocks and spray directly, avoiding poor selenium enrichment effects or crop damage due to improper proportions. This method is particularly suitable for large-scale, high-efficiency operations. Thorough stirring before freezing ensures uniform mixing of all components, preventing stratification and precipitation during freezing. The ice blocks maintain a stable concentration ratio after melting, ensuring uniform selenium absorption in all parts of the crop and avoiding excessively high or low selenium content in certain areas, thus improving the consistency of the quality of selenium-enriched agricultural products. Ice blocks are less prone to leakage during refrigerated transport. Compared to liquid nutrient solutions, they have lower packaging requirements, reducing the cost of specialized sealed packaging. At the same time, the solidified ice blocks have a uniform density, resulting in higher space utilization during stacking and transport, which can reduce losses during transportation. They are especially suitable for large-scale production scenarios with cross-regional supply.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The raw materials used in the selenium-enriched nutrient solution provided by this invention are all low-toxicity and easily degradable components commonly used in agricultural production, with no heavy metals or difficult-to-degrade pollutants added; the amount of organosilicon surfactant is controlled at 10~20 g / mu, which meets the safety standards for agricultural chemicals and will not damage the soil microbial community or groundwater environment; the natural properties of tea further reduce the environmental residue risk of chemical reagents, which is in line with the development trend of green and organic agriculture.

[0026] The selenium-enriched nutrient solution provided by this invention utilizes a scientifically synergistic formula. The alkaline sodium selenite, providing the selenium source, is neutralized by tea at a pH of 5-6, and potassium dihydrogen phosphate, acting as both a nutrient and a buffer, balances the pH of the solution to neutral, allowing for long-term preservation. Simultaneously, it is used in conjunction with an organosilicon surfactant that promotes absorption, along with an innovative freeze-drying preparation process. This achieves multiple advantages, including precise selenium enrichment, improved component stability, convenient operation, and environmental safety. It addresses the shortcomings of traditional selenium-enriched fertilizers, such as low absorption efficiency, short shelf life, and complex operation, while also considering crop yield, quality, and agricultural environmental friendliness. Suitable for selenium-enriched cultivation of various crops such as wheat, rice, vegetables, and fruits, it possesses significant economic value and promising prospects for widespread application.

[0027] Instruction manual illustrations

[0028] Figure 1 The growth of rice after being sprayed with the selenium-enriched nutrient solution in Example 1;

[0029] Figure 2 The growth of rice after being sprayed with the selenium-enriched nutrient solution in Comparative Example 5. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the embodiments.

[0031] Example 1

[0032] A selenium-enriched nutrient solution, based on the usage per acre, contains: 6 g sodium selenite, 80 g potassium dihydrogen phosphate, 10 g organosilicon RH-208, and 200 mL tea water; the tea water is obtained by soaking commercially available Huangshan Maofeng tea in warm water at 85°C for 15 min at a mass-volume ratio of 1 g: 15 mL.

[0033] The preparation method includes the following steps: adding sodium selenite to tea water, stirring until completely dissolved, then adding potassium dihydrogen phosphate, stirring until completely dissolved again, then adding an organosilicon surfactant, and then stirring evenly. The resulting selenium-enriched nutrient solution has a pH of 7.2.

[0034] Example 2

[0035] A selenium-enriched nutrient solution, based on the usage per acre, contains: 8g sodium selenite, 100g potassium dihydrogen phosphate, 15g organosilicon BD-3077, and 200mL tea. The tea is obtained by soaking byproducts from the processing of Taiping Houkui tea in warm water at 85℃ for 15 minutes at a mass-to-volume ratio of 1g:15mL.

[0036] The preparation method includes the following steps: adding sodium selenite to tea water, stirring until completely dissolved, then adding potassium dihydrogen phosphate, stirring until completely dissolved again, then adding an organosilicon surfactant, and then stirring evenly. The resulting selenium-enriched nutrient solution has a pH of 7.3.

[0037] Example 3

[0038] A selenium-enriched nutrient solution, based on the usage per acre, contains: 10 g sodium selenite, 120 g potassium dihydrogen phosphate, 20 g organosilicon ASS8309, and 250 mL tea. The tea is obtained by steeping commercially available Anji white tea in warm water at 85°C for 15 minutes at a mass-to-volume ratio of 1 g: 15 mL.

[0039] The preparation method includes the following steps: adding sodium selenite to tea water, stirring until completely dissolved, then adding potassium dihydrogen phosphate, stirring until completely dissolved again, then adding an organosilicon surfactant, and then stirring evenly. The resulting selenium-enriched nutrient solution has a pH of 7.0.

[0040] Example 4

[0041] A selenium-enriched nutrient solution, based on the usage per acre, contains: 10 g sodium selenite, 120 g potassium dihydrogen phosphate, 20 g organosilicon ASS8309, and 250 mL tea. The tea is obtained by steeping commercially available Anji white tea in warm water at 85°C for 15 minutes at a mass-to-volume ratio of 1 g: 15 mL.

[0042] The preparation method includes the following steps: adding sodium selenite to tea water, stirring until completely dissolved, then adding potassium dihydrogen phosphate, stirring until completely dissolved again, then adding an organosilicon surfactant, stirring evenly, and finally freezing into ice cubes at -20℃ and storing at -20℃ for 72 months.

[0043] Comparative Example 1

[0044] The rest is the same as in Example 1, except that the tea was replaced with tap water, and the pH of the resulting selenium-enriched nutrient solution was 8.0.

[0045] Comparative Example 2

[0046] The rest is the same as in Example 2, except that potassium dihydrogen phosphate is replaced with potassium sulfate, and the pH of the resulting selenium-enriched nutrient solution is 9.5.

[0047] Comparative Example 3

[0048] The rest is the same as in Example 2, except that the use of organosilicon BD-3077 is omitted.

[0049] Comparative Example 4

[0050] The rest is the same as in Example 4, except that during preparation: sodium selenite is added to tea water and stirred until completely dissolved, then potassium dihydrogen phosphate is added and stirred until completely dissolved, then an organosilicon surfactant is added, and then stirred evenly. Then it is stored at room temperature for 72 months.

[0051] Comparative Example 5

[0052] The rest is the same as in Example 3, except that the amount of sodium selenite used is 12 g / mu.

[0053] Test Example 1

[0054] The same paddy field was divided into 10 equal areas. Under the same conditions, the same variety of rice was planted. When the rice reached the grain-filling stage, drones were used to spray the selenium-enriched nutrient solution from each embodiment and comparative example in each area. One area was set up as a blank control.

[0055] The selenium-enriched nutrient solutions in Examples 1-3 and Comparative Examples 1-3 and 5 were prepared and used immediately, while the selenium-enriched nutrient solutions in Example 4 and Comparative Example 4 were used after being stored for 72 months. Before spraying, the selenium-enriched nutrient solutions in each example and comparative example were diluted 20 times with tap water. The growth of the rice was observed and recorded after spraying. After the rice matured, the selenium content in the rice was tested using Method 1 of GB5009.93-2017 "National Food Safety Standard - Determination of Selenium in Food". The results are shown in Table 1.

[0056] Table 1

[0057]

[0058] The results above show that the selenium-enriched nutrient solution provided by this invention can increase the selenium content of crops to more than 0.5 mg / kg.

[0059] In Comparative Example 1, the selenium content in the rice decreased significantly and leaf burn occurred because tea was not used to prepare the selenium-enriched nutrient solution. This shows that the combined use of tea with potassium dihydrogen phosphate and organosilicon can change the microenvironment of the leaves, promote the absorption of nutrient solution by the leaves, and significantly reduce the risk of leaf burn.

[0060] In Comparative Example 2, although potassium sulfate was also used as a nutrient supplement, it could not play a buffering role and could not balance the pH of the selenium-enriched nutrient solution. When sprayed, it irritated the plant leaves, resulting in a decrease in the efficiency of selenium conversion.

[0061] In Comparative Example 3, the absence of organosilicon BD-3077 failed to reduce the surface tension of the selenium-enriched nutrient solution, thus reducing its adhesion, wetting, and penetration on the crop leaf surface, which in turn affected the absorption of selenium.

[0062] In Comparative Example 4, after the selenium-enriched nutrient solution was stored at room temperature for 6 months, the sodium selenite in its components was reduced and lost its activity, thus becoming ineffective. The activity of the selenium source was easily reduced, resulting in a significantly worse selenium enrichment effect compared to Example 4.

[0063] In Comparative Example 5, the amount of sodium selenite used was too high, which caused leaf burn on the rice after spraying and poor growth of the rice. Although the amount of sodium selenite used in this comparative example was increased compared to Example 3, the selenium content in the rice was not significantly increased compared to Example 3.

[0064] Test Example 2

[0065] The same paddy field was divided into 6 equal areas. Under the same conditions, the same variety of rice was planted. When the rice grew to the grain-filling stage, drones were used to spray the selenium-enriched nutrient solution of Examples 1-3 and Comparative Examples 1-2 in each area, and one area was set up as a blank control.

[0066] In Examples 1-3 and Comparative Examples 1-2, the selenium-enriched nutrient solutions were stored for 12 months after preparation, and their properties were observed after 12 months. Before spraying, the selenium-enriched nutrient solutions in all examples and comparative examples were diluted 20 times with tap water. The growth of the rice was observed and recorded after spraying. After the rice matured, the selenium content in the rice was tested using Method 1 of GB 5009.93-2017 "National Food Safety Standard - Determination of Selenium in Food". The results are shown in Table 2.

[0067] Table 2

[0068]

[0069] The results above show that the selenium-enriched nutrient solution provided by this invention, even after being stored for 12 months, can still stably increase the selenium content of crops to more than 0.5 mg / kg. This demonstrates that the selenium-enriched nutrient solution formula provided by this invention can significantly improve the storage time of the selenium-enriched nutrient solution.

[0070] In contrast, in Comparative Examples 1 and 2, the lack of tea and potassium dihydrogen phosphate, respectively, resulted in poor storage stability, which in turn affected the effectiveness of the selenium-enriched nutrient solution.

[0071] The above detailed description of a selenium-enriched nutrient solution and its preparation method, with reference to the embodiments, is illustrative rather than limiting. Several embodiments may be listed within the defined scope. Therefore, variations and modifications that do not depart from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A selenium-enriched nutrient solution, characterized in that, The selenium-enriched nutrient solution, calculated per acre, contains: 6-10 g sodium selenite, 80-120 g potassium dihydrogen phosphate, 10-20 g organosilicon surfactant, and 150-250 mL tea.

2. The selenium-enriched nutrient solution according to claim 1, characterized in that, The silicone surfactant is any one or more of the following grades: RH-208, RH-288, RH-209, BD-3077, ASS8211, ASS8277, ASS8309, H-8408, and H-8806.

3. The selenium-enriched nutrient solution according to claim 1, characterized in that, The pH of the tea water is 5-6.

4. The selenium-enriched nutrient solution according to claim 1, characterized in that, The method for preparing the tea is as follows: soak the tea leaves in warm water at 80-100℃ for 10-30 minutes.

5. The selenium-enriched nutrient solution according to claim 4, characterized in that, The mass-to-volume ratio of the tea leaves to the warm water is 1g:10~20mL.

6. The selenium-enriched nutrient solution according to claim 1, characterized in that, When using an electric small backpack sprayer to apply selenium-enriched nutrient solution, the selenium-enriched nutrient solution is diluted 200 times with water before spraying.

7. The selenium-enriched nutrient solution according to claim 1, characterized in that, When using an electric water pump to spray the selenium-enriched nutrient solution, the selenium-enriched nutrient solution is diluted 200 times with water before spraying.

8. The selenium-enriched nutrient solution according to claim 1, characterized in that, When using drones to spray selenium-enriched nutrient solution, the selenium-enriched nutrient solution is diluted 20 times with water before spraying.

9. The method for preparing selenium-enriched nutrient solution according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: adding sodium selenite to tea water, stirring until completely dissolved, then adding potassium dihydrogen phosphate, stirring until completely dissolved again, then adding an organosilicon surfactant, and finally stirring evenly.

10. The method for preparing selenium-enriched nutrient solution as described in claim 9, characterized in that, The preparation method further includes: freezing the well-stirred selenium-enriched nutrient solution into ice blocks, packaging them, and then storing and transporting them under cold storage.

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