Is it toxic to use too much boron fertilizer?

A substance containing a lot of boron, whose main function is to provide plant nutrition. Boron fertilizers mainly include boric acid and borax. Boron is one of the essential nutrients for plants. Boron is absorbed and utilized by plants in the form of boric acid molecule (H3BO3), which is not easy to move in plants. Boron can promote the growth of roots, play an important role in the synthesis and transportation of carbohydrates, the products of photosynthesis, and play a special role in the normal fertilization process. Therefore, it has obvious control ability to rape "flower without fruit", cotton "bud without flower", fruit tree "flower without fruit" and wheat "barnyard grass" If leguminous crops are short of boron, the nodules will develop poorly and even lose their nitrogen fixation ability. Boron application in rape, cotton, soybean, beet, apple and citrus all significantly increased yield and improved quality. There are boron-deficient soils in both the south and the north of China, so rational application of boron fertilizer is of great significance to China's agricultural development. Boron-based foliar fertilizer Biostadt Does liquid boron fertilizer Biostadt contain liquido10.9% (150g/l)? N- boron nitrogen content: 18%, boron content: 3.9%. Biostadt containing controlled release nitrogen fertilizer (urea-formaldehyde)? OK potassium content: 20%, boron content: 19.4% Biostadt? Boron and nitrogen content: 6%, sulfur content: 22.5%, magnesium content: 5%, boron content: 8%, manganese content: 2.5% Edit the technical problems of conventional boron fertilizer varieties in this paragraph. Conventional boron fertilizer refers to boron chemical products with borax, boric acid and boron-magnesium fertilizer as the main components, which are used as trace element fertilizers for agriculture. In the popularization and application of these conventional boron fertilizers, some insurmountable technical problems are also exposed: 1 boron fertilizer has poor solubility. Because the boron fertilizer used in Anhui Province is mainly industrial borax purchased from Liaoning, China, and its chemical molecular formula is Na2B4O7. 10H2O, which is generally used in industrial ceramics, glass, etc. But it is difficult to dissolve in agriculture. Generally, the solubility is 4.8% at 20℃, and it can slowly dissolve in warm water at 40℃, but it will solidify after cooling. Most farmers in boron-deficient areas such as Anhui sprayed boron fertilizer before rape flowering. This period is mostly around the Spring Festival, which is a low temperature period. Often borax has just dissolved here, and the acre of land has not been sprayed, and borax has returned to its crystal shape. Therefore, in the process of use, farmers often encounter the phenomenon that boron fertilizer crystals block the nozzle, which affects the application effect of boron fertilizer. When spraying boron fertilizer in spring, farmers should carry not only boron fertilizer, but also thermos bottles. The utilization rate of boron is low, which is easy to cause poison to the following crops. Because rape is an overwintering crop, the temperature is low during vegetative growth, and borax base is difficult to dissolve after being applied to soil, and a considerable part of it is adsorbed and fixed by soil. For borax, the utilization rate of basic application is low, and 70 ~ 80% boron remains in the soil. Under the rotation of rape and other crops, if borax is applied for several years or excessively in the current season, the boron content in the soil will increase rapidly, which is harmful to the following crops, especially rice. When borax was applied in the rape base in the first year, the temperature was high and the climate was rainy and humid in the rice growing period in the second year. Undissolved boron in arid soil gradually dissolves, and boron adsorbed in soil is replaced by the enhancement of soil cation exchange ability. With the increase of boron concentration in soil aqueous solution, rice is easy to produce excessive boron after absorption. According to Li Jionghui's experiment in Jiangxi Yichun Agricultural College, the response of rice to boron fertilizer is related to the available boron content. When the soil available boron content was 0. 1 1mg/kg, the yield increase rate of rice was 13%. When the soil available boron increased to 0. 1.7 mg/kg, the rice yield increased by 7%. Therefore, the critical value of boron deficiency in rice does not seem to exceed about 0. 1.5 mg/kg soil available boron. For Anhui soil, when planting rice, the soil is not short of boron. When the concentration of boron solution in soil increases, boron poisoning is easy to occur, which leads to rice yield reduction. Generally speaking, the suitable range of crop boron is small. When the boron concentration in soil is above 5mg/kg, the seed germination is blocked, and when the boron concentration in gramineous crops is above 10mg/kg, excessive symptoms are easy to appear. 3 Boron fertilizer is low in boron content and poor in commercialization, such as boron magnesium fertilizer and boron mud. Although it is cheap, it is poor in quality when used as boron fertilizer, and the boron content is only 0.5-6544. When planting rape, the application amount per mu of base must be above 10 kg to meet the needs of rape growth. On the one hand, the transportation cost increases, on the other hand, the commodity rate is low, so it is difficult to process and repackage, and it is difficult for farmers to buy it in the market. Even if boron magnesium fertilizer is purchased, it is often sold as borax by illegal traders. Most of the dosage on the label can't meet the needs of crops, and farmers are easily deceived. The nutritional function of boron in this period has three major effects on the physiological process of crops: first, boron can promote the operation of carbohydrates, and plants contain appropriate amount of boron, which can improve the supply of organic matter in various organs of crops, make crops grow normally, and improve the seed setting rate and fruit setting rate. Secondly, boron has a special effect on the fertilization process. Its content in pollen is the largest in stigma and ovary, which can stimulate pollen germination and pollen tube elongation, and make pollination go smoothly. When crops are short of boron, anthers and filaments contract and cannot form pollen, which shows the disease of "flowering without fruit". The third is regulation. Boron can regulate the formation and movement of organic acids in plants. Under the condition of boron deficiency, organic acids accumulate in roots, cell differentiation and apical meristem elongation are inhibited, and cork occurs, causing root necrosis. Boron can also enhance the drought and disease resistance of crops and promote the early maturity of crops. In addition, the application of boron fertilizer in rice hybrid seed production can make the maturity of reproductive organs of male and female plants tend to be the same, and promote the seed yield to increase greatly; At the same time, it can also improve the seed setting rate of distant hybrid varieties. Therefore, boron can also play an important role in breeding. As economic crops with high demand for boron, such as rape, cotton, peanuts, fruit trees and vegetables, boron deficiency will seriously affect the normal growth of crops, and boron deficiency has become the main limiting factor to hinder the improvement of crop yield and quality. This section edits the status and availability of boron in soil. The boron absorbed by plants mainly comes from soil, and the boron content in soil is very important to plants. The boron content in soil is closely related to parent material, soil type and climatic conditions. Boron exists widely in nature, and animal and plant residues, rainfall and minerals are all sources of boron in soil. Among them, minerals are the most important, so the content of boron in soil is related to soil-forming parent material. The soil developed by sedimentary rocks contains more boron than that developed by igneous rocks. The boron content of soil in arid areas is higher than that in warm areas, and that in coastal areas is higher than that in inland areas. The boron content of different soil types in the same area is also different. The more sand the soil, the lower the boron content. According to relevant data, the total boron content in soil in China ranges from 0 to 500 mg/kg, with an average of 64 mg/kg. The distribution law of soil total boron in China is gradually decreasing from north to south and from west to east, with the lowest in the southeastern provinces. Boron in soil can be simply divided into total boron and available boron. Soil total boron refers to the sum of boron existing in soil, including boron available to plants and boron unavailable. Soil available boron (about 5% of total boron) refers to boron that plants can absorb and utilize from soil. Therefore, whether the soil is short of boron depends entirely on the content of available boron in the soil. The content of available boron in soil is not only related to parent material, but also directly affected by soil pH value, farming system, cultivation management, climate and ecological conditions. The distribution trend of soil available boron content is consistent with that of soil total boron content. The content of available boron in different types of soil varies greatly, and the main factor of boron transformation from shadow ⅱ to soil is: soil pH value. In general soil, the availability of boron is the highest at pH5-7. Soil with pH-GT7%, especially strongly calcareous soil, is adsorbed and fixed by trivalent oxides and clay minerals because of its high pH value. Although there is a lot of available boron in acidic soil, it is easy to leach out, so the acidic soil with serious leaching in the south, especially sandy soil, is also easy to lack boron. Organic matter content. When there is more organic matter in the soil, the content of available boron is also higher, because the content of boron combined with or fixed by organic matter is also higher, which can be released for crops to use when organic matter is decomposed. Climatic conditions. Drought or rainy weather will reduce the available boron content in soil, and drought will strengthen boron fixation. Drought is accompanied by high temperature, boron generates insoluble compounds, and available boron decreases; During rainy season and flood, water-soluble boron is leached out, which reduces the available boron in soil. However, in coastal areas, because each liter of seawater contains 4 7 mg of boron, rainfall can supplement soil boron. The critical value of available boron in soil is 0.5 mg/kg, and the soil below 0.25 mg/kg is seriously deficient in boron. According to the statistics of the second national soil survey in 1 982 ~ 1 986, the boron-deficient area of cultivated land in China exceeds 500 million mu. The proportion of boron deficiency in cultivated land in Guizhou, Sichuan, Hubei, Hunan, Anhui, Jiangsu, Jiangxi, Yunnan, Henan, Shaanxi, Guangdong, Fujian, Guangxi, Jilin, Hebei, Shandong and Shanxi is all greater than 60%. When planting crops in these areas, the use of boron fertilizer should not be ignored. In this section, the varieties and resources of boron fertilizer in China are edited. Boron fertilizer refers to trace element fertilizer containing boron (B), which can promote crop growth, enhance crop stress resistance and facilitate flowering and fruiting, also known as boron fertilizer. At present, the common varieties of boron fertilizer in the market are: borax: chemical name disodium tetraborate decahydrate (Na2B4 10H2O), which is the raw material for extracting boron and boron compounds. The main content of the national standard first-class product (Na2B4. LOH. O)≥95.0%, corresponding to boron (b) content of 1. 1%. Boric acid: the content of molecular formula H3BO3 (national standard) is ≥ 99.5%, which is equivalent to about 17% of boron (b). It is formed by reaction of magnesite with sulfuric acid, filtration, concentration, crystallization and drying. Boric acid is a colorless triclinic scale-like crystal with pearl luster or white fine crystals, which is soluble in water. It is a chemical raw material of inorganic compound boron and one of the traditional boron fertilizers. Boron-magnesium fertilizer: It is a by-product of industrial boric acid production, and its main components are magnesium sulfate (MgSO4 7H2O) and boric acid (H3BO3), with the main content of about 85-93%, of which magnesium sulfate accounts for about 80-90% and boric acid accounts for 3.6%, which is equivalent to 0.5- 1% of boron (B), and its appearance is white or grayish white crystal particles or powder. New efficient boron fertilizer: Since the end of the 20th century, Anhui Soil Fertilizer Workstation began to develop refined polymeric boron fertilizer-instant boron fertilizer, which was industrialized in 2003. The main component is sodium octaborate tetrahydrate, and the content of boron (B) is as high as 2 1%. It has the characteristics of good water solubility, low dosage, high plant absorption and utilization rate and less soil residue, and won the second prize of Anhui Science and Technology in 2003. It is a new special boron fertilizer variety suitable for crop boron supplement jointly developed by Anhui Soil and Fertilizer General Station and Anhui Fertilizer Corporation. Boron fertilizer resource is a boron-containing mineral-borate mineral. China is rich in boron resources, and there are boron mines in 14 provinces (regions). There are 63 mining areas with proven reserves, with total reserves of1000 billion cubic meters of 46.706 million tons, ranking fifth in the world. As far as provinces (regions) are concerned, Liaoning has the largest boron reserves, accounting for 57% of the national reserves; Followed by Qinghai, accounting for 24.7%. Boron deposits are mainly Proterozoic sedimentary metamorphic deposits, such as those in Yingkou and Kuandian, Liaoning Province, which are the main sources of boron resources in China. Modern salt lake boron deposits are also very important, such as some salt lake boron deposits in Qinghai and Tibet. China's boron mine production capacity is about 487,000 tons/year, equivalent to B.O. standard ore capacity 12%). In recent years, the output of boron ore and its related products in China has been increasing continuously. Internationally, the United States and Turkey have always been the two largest producers, accounting for more than 40% of the world's total output respectively. China's output accounts for a small share of the world. There are about 30 large-scale chemical plants that produce borax and boric acid, with a production capacity of about 200,000 tons and 30,000 tons respectively. Application of Boron Fertilizer Before liberation, the research and application of boron fertilizer in China was blank. Since 1950s, it has mainly been the fertilizer efficiency test of some crops. In the mid-1960s, the Institute of Oilseed Crops of Chinese Academy of Agricultural Sciences found that the disease of "flowering without fruit" occurred in Brassica napus, which was proved to be boron deficiency by research. The application of boron fertilizer can be effectively controlled. This is a major breakthrough in the research and application of boron fertilizer in China. Since the mid-1970s, cotton "bud but not flower" disease in Xinzhou County, Hubei Province, barnyard grass disease in wheat in Gannan, Heilongjiang Province, apple, citrus "false fruit" disease and olive "multiple head" disease in some places have been discovered one after another, all of which belong to boron deficiency disease. Since then, the research and application of boron fertilizer has attracted the attention of scientific and technological workers. With the support of relevant state departments, boron fertilizer work has entered a new stage of extensive development. In recent years, according to the test results of domestic soil fertilizer workers, applying boron fertilizer to rape, cotton, peanuts, grapes, fruits, chestnuts, vegetables, beans and other crops has achieved remarkable results in increasing production. The experiment of boron application on 468 cotton plants in Hubei, Zhejiang, Shandong, Jiangsu, Shanghai, Hebei, Shaanxi and other provinces (cities)/kloc-0 showed that compared with the control average mu, boron application increased lint yield by 6.5 kg (weighted average), and the yield increase rate was 10.3%. The results of Zhejiang experiment showed that the application of boron fertilizer in soil with water-soluble boron content of 0. 1.7 mg/kg, 0. 1.8mg/kg, 0.28mg/kg and 0.36mg/kg increased the yield of rapeseed by 276%, 284% and1.94 respectively. According to the investigation in Anhui, the yield per mu of rape without boron fertilizer is 50- 1.00 kg, and that of rape with boron fertilizer is more than 1.50 kg. Therefore, farmers can increase their income by 1.20 yuan -200 yuan per mu, while the cost of purchasing boron fertilizer (1 double base fertilizer and twice spraying) is only 6 yuan per mu. Therefore, the importance of applying boron fertilizer is more and more recognized by farmers, especially applying boron fertilizer to rape and cotton has become farmers' conscious behavior. Scientific and rational use of boron fertilizer in this period can not only obtain the best yield-increasing effect with the minimum investment, but also improve the quality of agricultural products and increase income. When using boron fertilizer, we should pay attention to the following aspects: selecting excellent varieties. Boron fertilizer with boron (B) content greater than 10% and without other medium and trace elements should be selected to supplement boron to plants, so as to achieve the purpose of boron deficiency and boron supplement. At present, in addition to the traditional boron fertilizer borax, new boron fertilizers such as "Jindilai" boron fertilizer introduced by Anhui Fertilizer Corporation and Su Le boron in the United States all have boron content ≥ 20%, which is soluble in water at room temperature, and the crop absorption and utilization rate is high. Rational application of boron fertilizer. Basic application: Borax can be used as basic fertilizer for soil with serious boron deficiency, which can prolong the time of boron supply in soil. The dosage per mu is 0.5- 1 kg. When sowing crops, the selected boron fertilizer should be fully mixed with farmyard manure, chemical fertilizer or appropriate amount of dry fine soil, and used as bottom fertilizer for hole application or strip application, and contact with seeds should be avoided as far as possible. Borax should be applied in areas where boron deficiency is not serious and the soil is sticky, so as to prevent the residual borax from causing soil acidification and poisoning crops. It can be considered to be applied twice a year. Special attention should be paid to the application of borax in greenhouse crops. It is more effective to mix boron fertilizer with human and animal manure, water fertilizer or chemical fertilizer solution and irrigate points at seedling stage as base fertilizer or topdressing than dry application. When boron deficiency is common or not serious in foliar spraying soil, foliar spraying boron can replenish boron flexibly and timely according to crop growth, and the effect is remarkable. It has the characteristics of saving fertilizer, reducing pollution and quick absorption by plants. It is the most commonly used method of boron application, which can be sprayed on both the front and back of the leaf, but the effect of spraying on the back is better because the pores are on the back of the leaf. Foliar spraying of boron fertilizer should be timely and appropriate according to the vegetative growth or reproductive growth characteristics of the crops (see table 1). The spraying period should be sooner rather than later, and the spraying effect after flowering is not significant; It is best to spray it more than twice; After basal application of boron fertilizer, boron fertilizer should also be sprayed in the key period of reproductive growth, such as spraying boron once in the bud stage of rape, to ensure adequate supply of boron at the peak of reproductive growth. Appropriate dosage. According to the situation of boron deficiency in soil and applied crops, combined with the selected varieties, appropriate application should be made, neither too little nor too much. Generally, crops with heavy boron deficiency or high boron need to use the upper limit, and vice versa; The upper limit is for sandy soil where boron is easily leached, and the lower limit is for cohesive soil (see Table 2). At present, there is still a big gap between the application level of boron fertilizer in China and developed countries. The main manifestations are as follows: First, the application of boron fertilizer in crops is still limited to rape and cotton, but less in vegetables, fruit trees, grain, tobacco, peanuts, hemp and other crops that need more boron. Secondly, borax is still the main variety of boron fertilizer at present. Because borax is insoluble and its utilization rate is low, most of it can't play its role after being fixed by soil, which is easy to cause boron damage to the next crop. Therefore, it is necessary to intensify propaganda, popularize the knowledge of boron fertilizer and improve the application area and level of boron fertilizer. At the same time, combined with many factors such as agricultural product quality, safety, ecological environment, resource conservation, etc., it is of great significance to vigorously promote new boron fertilizers with high efficiency and high absorption rate, such as "Jindilai" instant boron fertilizer produced in Anhui and Su Le boron fertilizer produced in the United States, which have high content and high utilization rate.