A boron-phosphorus-containing agricultural fiber and a method for preparing the same

Abstract

The application provides a boron-phosphorus-containing agricultural fiber and a preparation method thereof, which comprises the following components in mass fraction: 50-72% of SiO2, 2-7% of MgO, 23-31% of CaO, 0.02-8% of B2O3, 0.03-8% of P2O5, 0-3% of Na2O, 0-3% of K2O, Al2O3<3%, and Fe2O3<=3%; the mass content ratio of P2O5 and Fe2O3 is 1.5-2.5; and the molar ratio of O / Si is 2.2-3.0. The B2O3 and P2O5 are introduced into the agricultural fiber, so that the fiber quality is high, the fiber index is high, the fiber diameter is low, the specific surface area is high, the content of effective silicon, effective calcium, effective magnesium, effective boron and effective phosphorus in the soil is effectively improved, and no organic adhesive / binder and other substances are used, which cannot be further absorbed by plants and thus cannot cause harm to human bodies.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of agricultural fibers, and particularly relates to a boron-phosphorus-containing agricultural fiber and a preparation method thereof. BACKGROUND

[0002] The existing inorganic fibers used in agriculture only serve as a base material, without considering the harmful effects of the fibers on soil and the promotion of plant absorption and growth. Meanwhile, the production of the existing inorganic fibers only considers the temperature resistance and practicability in the industrial field, without considering the cost and environmental protection solubility, and the melting temperature is high, increasing the cost.

[0003] Meanwhile, in the products in the prior art using inorganic fiber materials as a culture medium, organic adhesives / binders and the like need to be added, and these organic adhesives / binders contain toxic substances such as phenol and formaldehyde, which are harmful to soil, cause persistent damage to soil, and are further absorbed by plants, and then possibly absorbed by human bodies, causing permanent damage to human bodies. SUMMARY

[0004] Therefore, the present application aims to provide a boron-phosphorus-containing agricultural fiber and a preparation method thereof, the fiber has a high fiber index and a high specific surface area, can increase the effective silicon, effective calcium and effective magnesium in soil, increase the contents of effective boron and effective phosphorus, improve the absorption of these elements by roots of plants, and thus improve the yield and quality of crops.

[0005] The present application provides a boron-phosphorus-containing agricultural fiber, which comprises the following components in mass fraction:

[0006] 50-72% of SiO2, 2-7% of MgO, 23-31% of CaO, 0.02-8% of B2O3, 0.03-8% of P2O5, 0-3% of Na2O, 0-3% of K2O, Al2O3<3%, and Fe2O3≤3%;

[0007] The mass content ratio of P2O5 and Fe2O3 is 1.5-2.5.

[0008] The molar ratio of O / Si in the agricultural fiber is 2.2-3.0.

[0009] In the present application, the mass content ratio of P2O5 and Fe2O3 is 1.6-2.5.

[0010] In the present application, the molar ratio of O / Si in the agricultural fiber is 2.4-2.8.

[0011] In the present application, B2O3 is 0.5-6%, and P2O5 is 3-5%. Al2O3 in the agricultural fiber is <1 wt%, 0-2% of Na2O, and 0-2% of K2O.

[0012] In the present application, the proportion of fibers with a diameter of 1-2 μm in the agricultural fibers is 10-20 wt%, the proportion of fibers with a diameter of 2-3 μm is 70-80 wt%, the proportion of fibers with a diameter of 3-4 μm is 5-10 wt%, and the proportion of fibers with a diameter of 4-5 μm is 1-5 wt%. If the proportion of fibers with a diameter of 4-5 μm is too high, the bulk density of the fiber product is too large, the air permeability is poor, and the water absorption rate is reduced.

[0013] In the present application, the content of available silicon in the agricultural fibers is 300-2000 mg / kg, the content of available calcium is 150-500 mg / kg, the content of available magnesium is 30-100 mg / kg, the content of available iron is 10-80 mg / kg, the content of available boron is 0.01-5 mg / kg, and the content of available phosphorus is 5-150 mg / kg. In the present application, the test method for available silicon is "NY / T1121.15-2006 Soil Testing Series Standards", the test method for available calcium and magnesium is "LY / T 2445-2015 Specification for Soil Protection for Greening", and the test methods for available boron and available phosphorus are based on "GB 12298-1990 Soil Available Boron Determination Method" and "Soil Available Phosphorus Determination Sodium Bicarbonate Extraction-Molybdenum Antimony Anti-Spectrophotometric Method".

[0014] In the present application, the pH value of the agricultural fibers is 5.6-7.2; the thermal conductivity coefficient at 25°C is 0.03-0.06 W / m.K; and the specific surface area is 300-600 m 2 / kg.

[0015] The bulk density of the agricultural fibers is 48-128 kg / m 3 , which needs to be 48 kg / m 3 to maintain the water and fertilizer requirements of plant-level crops; a bulk density that is too low is not conducive to water retention and the ability to provide support for plant growth.

[0016] The introduction of B2O3 and P2O5 can improve the fiber formation quality of the fibers, the bulk density is lower, and the diameter of the fibers can be finer (see Figure 1 ), the specific surface area of the fibers is higher, the contact area between the plant and the fibers is increased, the contents of available silicon, available calcium, and available magnesium in the soil are effectively improved, the contents of available boron and available phosphorus are increased, and thus the absorption of these elements by the roots of the plant is improved, thereby improving the yield and quality of the crops.

[0017] In the present application, the porosity of the agricultural fibers is 50-90%; it has a porous performance to provide sufficient water and air for the germination and root growth of plants in the growth medium.

[0018] The water retention rate of the agricultural fiber is 100-1000%, and the agricultural fiber should have good water retention capacity. After the agricultural fiber is fully absorbed, it is weighed, and then the soil is dried in an oven at 105±2℃. By measuring the weight change before and after drying, the water retention capacity is obtained, which can be used as an indicator of soil water retention.

[0019] The application provides a preparation method of the agricultural fiber containing boron and phosphorus.

[0020] The calcium stone powder, the silicon stone powder, the magnesite, the phosphorus-containing material and the boron-containing material are melted, spun or sprayed into fibers, and then heat-treated to obtain the agricultural fiber containing boron and phosphorus.

[0021] In the application, the melting temperature is 1400-1850℃, preferably 1700-1850℃. During the preparation process, B2O3 and P2O5 are introduced, which can reduce the melting temperature of the melt of the raw materials in the melting process to 1800-2000℃, so that the melting can be carried out at 1400-1850℃.

[0022] In the application, the calcium stone powder is selected from one or more of lime containing CaO, light-burned dolomite, heavy-burned dolomite, wollastonite and calcium-containing minerals.

[0023] The silicon stone powder is selected from one or more of silica containing SiO2, quartz sand and silicon-containing minerals.

[0024] The magnesite is selected from one or more of fused magnesite containing MgO, light-burned magnesite, light-burned dolomite, heavy-burned dolomite, forsterite and magnesium-containing minerals.

[0025] The boron-containing material is selected from one or more of borax, boric acid, boromagnesite, silicocalciteborite and boron-containing minerals.

[0026] The phosphorus-containing material is selected from one or more of sodium dihydrogen phosphate (NaH2PO3), P2O5 and phosphorus-containing minerals.

[0027] In the application, the preparation raw materials preferably further include iron-containing raw materials and aluminum-containing raw materials; the iron-containing raw materials are selected from one or more of magnetite (Fe3O4), hematite (Fe2O3) and iron-containing minerals.

[0028] In the application, the natural minerals are treated by melting and then fiberized by a specific preparation process through artificial intervention. No organic binder / binder and other substances are used in the preparation process, and the organic binder / binder is not further absorbed by plants, so as to not cause harm to the human body. The natural minerals are treated by melting and then fiberized to accelerate the process from rock to soil. In addition, the fibers will be dissolved, peeled and powdered during use. Figure 2), release the silicon, calcium, magnesium and other elements required for plant growth, and make the fiber structure gradually change during use, thereby making the soil loose and ventilated. The fiber has a large specific surface area, accelerates the fiber dissolution in the soil, and is beneficial to the development of the plant root system. Meanwhile, the fiber can also provide silicon, calcium, magnesium, iron, boron, phosphorus and other elements required for the growth of different plants due to the bio-dissolubility.

[0029] In the present application, the spinning or fiber blowing temperature is 1570-1600 DEG C.

[0030] In the present application, the heat treatment temperature is 400-700 DEG C, and the heat treatment time is 3-10 min.

[0031] The present application provides an agricultural fiber containing boron and phosphorus, which comprises the following components in mass fraction: 50-72% of SiO2, 2-7% of MgO, 23-31% of CaO, 0.02-8% of B2O3, 0.03-8% of P2O5, 0-3% of Na2O, 0-3% of K2O, <3% of Al2O3, and <=3% of Fe2O3; the mass content ratio of P2O5 and Fe2O3 is 1.5-2.5; and the molar ratio of O / Si in the agricultural fiber is 2.2-3.0. The present application introduces B2O3 and P2O5 into the agricultural fiber, so that the fiber has high fiber-forming quality and high fiber index, the fiber has low diameter and high specific surface area, the contents of effective silicon, effective calcium, effective magnesium, effective boron and effective phosphorus in the soil are effectively increased, the absorption of these elements by the plant root is improved, and thus the yield and quality of crops are improved. The agricultural fiber is prepared without using organic adhesives / binders and other substances, and the organic adhesives / binders are not further absorbed by the plant, so that the harm to the human body is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 SEM image of the agricultural fiber containing boron and phosphorus provided in the present application;

[0033] Figure 2 SEM image of the fiber after water dissolution provided in the present application. DETAILED DESCRIPTION

[0034] In order to further illustrate the present application, the agricultural fiber containing boron and phosphorus and the preparation method thereof provided in the present application are described in detail below in combination with examples, but they should not be understood as limiting the protection scope of the present application.

[0035] Example 1

[0036] The required raw materials, calcite powder, silica powder, magnesite, borax and phosphorus pentoxide, are mixed uniformly in a ratio of 27.5:65.0:5.0:1.3:1.2 by mass percentage, and then continuously melted at a temperature ranging from 1700 to 1850°C. The fiber is formed by spinning at a temperature of 1570 to 1600°C and a spinning speed of 170 m / s. The obtained agricultural fiber containing boron and phosphorus is heat treated at a temperature of 610°C for 5 minutes.

[0037] The agricultural fiber obtained in this example has the following composition: SiO2: 64.6 wt%; MgO: 5.01 wt%; CaO: 27.3 wt%; Al2O3: 0.645 wt%; Fe2O3: 0.58 wt%; B2O3: 1.04 wt%; P2O5: 1.3 wt%; Na2O: 0.5 wt%; K2O: 0.2 wt%; and a molar ratio of O / Si of 2.8, a P2O5 / Fe2O3 ratio of 2.24, a bulk density of 64 kg / cm 3 , an average fiber diameter of 2.9 microns, a fiber diameter of 1 to 2 microns accounting for 19 wt%, a fiber diameter of 2 to 3 microns accounting for 75 wt%, a fiber diameter of 3 to 4 microns accounting for 4 wt%, a fiber diameter of 4 to 5 microns accounting for 2 wt%, an average thermal conductivity of 0.031 W / m.k at 25°C, a pH value of 7.04, a water absorption of 820%, a porosity of 75%, a specific surface area of 459 m 2 / kg, and no excessive amounts of cadmium, mercury, arsenic, lead, chromium, etc.

[0038] The contents of effective silicon, effective calcium, effective magnesium, effective iron, effective boron and effective phosphorus in the agricultural fiber containing boron and phosphorus are 1580 mg / kg, 308 mg / kg, 69 mg / kg, 20 mg / kg, 1.2 mg / kg and 29 mg / kg, respectively.

[0039] Comparative Example 1

[0040] The required raw materials, calcite powder, silica powder, magnesite, borax and phosphorus pentoxide, are mixed uniformly in a ratio of 27.5:65.0:5.0:1.3:1.2 by mass percentage, and then continuously melted at a temperature ranging from 1700 to 1850°C. The fiber is formed by spinning at a temperature of 1570 to 1600°C and a spinning speed of 170 m / s. The obtained agricultural fiber containing boron and phosphorus is heat treated at a temperature of 610°C for 5 minutes.

[0041] The agricultural fiber obtained in this comparative example has the following composition: SiO2: 64.2 wt%; MgO: 4.56 wt%; CaO: 27.03 wt%; Al2O3: 0.345 wt%; Fe2O3: 0.82 wt%; B2O3: 0.9 wt%; P2O5: 1.2 wt%; Na2O: 0.1 wt%; K2O: 0.2 wt%; O / Si molar ratio: 2.58; P2O5 / Fe2O3: 1.46; and bulk density: 64 kg / cm³. 3 The average fiber diameter is 2.8 micrometers, with fibers of 1–2 μm diameter accounting for 18 wt%, 2–3 μm diameter fibers accounting for 72 wt%, 3–4 μm diameter fibers accounting for 7 wt%, and 4–5 μm diameter fibers accounting for 3 wt%. The average thermal conductivity at 25℃ is 0.032 W / mK, the pH value is 7.02, the water absorption rate is 820%, the porosity is 76%, and the specific surface area is 476 m². 2 / kg, cadmium, mercury, arsenic, lead and other substances do not exceed the standard.

[0042] The contents of available silicon, available calcium, available magnesium, available iron, available boron and available phosphorus in agricultural fibers are 520 mg / kg, 148 mg / kg, 28 mg / kg, 4 mg / kg, 0.0 mg / kg and 4 mg / kg, respectively.

[0043] Example 2

[0044] The required raw materials, calcium silicate powder, silica powder, magnesia, borax, and phosphorus pentoxide, are mixed evenly in a weight percentage ratio of 26.5:62.5:3.5:6.3:1.2. The mixture is continuously melted in the range of 1700-1850℃, and then spun into fibers at a spinning temperature of 1570-1600℃ and a spinning speed of 170m / s. The heat treatment temperature is 490℃ and the time is 8min to obtain boron-phosphorus-containing agricultural fibers.

[0045] The agricultural fiber obtained in this example has the following composition: SiO2: 62.5 wt%; MgO: 4.07 wt%; CaO: 26.9 wt%; Al2O3: 0.47 wt%; Fe2O3: 0.8 wt%; B2O3: 4.2 wt%; P2O5: 1.3 wt%; Na2O: 0.2 wt%; K2O: 0.1 wt%; O / Si molar ratio: 2.7; P2O5 / Fe2O3: 1.63; and bulk density: 64 kg / cm³. 3 The average fiber diameter is 2.8 micrometers, with fibers of 1–2 μm accounting for 20 wt%, 2–3 μm for 74 wt%, 3–4 μm for 4 wt%, and 4–5 μm for 2 wt%. The average thermal conductivity at 25℃ is 0.030 W / mK, the pH value is 7.04, the water absorption rate is 860%, the porosity is 76%, and the specific surface area is 490 m². 2 / kg, cadmium mercury arsenic lead and other do not exceed the standard.

[0046] The contents of effective silicon, effective calcium, effective magnesium, effective iron, effective boron and effective phosphorus in the agricultural fiber are 280 mg / kg, 132 mg / kg, 28 mg / kg, 5 mg / kg, 0 mg / kg and 1 mg / kg respectively.

[0047] Comparative Example 2

[0048] The required raw materials, calcium stone powder, silica powder, magnesia, phosphorus pentoxide, are mixed uniformly according to the proportion of 27.3:65.4:5.1:2.2 by weight percentage, continuously melt in the range of 1500-1650°C, and then fiberize by spinning, the fiberizing temperature is 1410-1480°C, the spinning line speed is 170 m / s, the heat treatment temperature is 610°C, and the time is 5 min, to obtain the agricultural fiber.

[0049] The agricultural fiber obtained in the comparative example has the following contents: SiO2: 63.8 wt%; MgO: 5.01 wt%; CaO: 26.12 wt%; Al2O3: 0.415 wt%; Fe2O3: 0.88 wt%, B2O3: 0%, P2O5: 1.8 wt%, Na2O: 0.61 wt%, K2O: 0.2 wt%, the molar ratio of O / Si is 2.6, P2O5 / Fe2O3 is 2.05, the bulk density is 64 kg / cm 3 , the average diameter of the fiber is 3.9 microns, the fiber with a diameter of 1-2 μm accounts for 15 wt%, the fiber with a diameter of 2-3 μm accounts for 65 wt%, the fiber with a diameter of 3-4 μm accounts for 15 wt%, the fiber with a diameter of 4-5 μm accounts for 5 wt%, the average thermal conductivity at 25°C is 0.036 W / m.k, the pH value is 7.02, the water absorption is 340%, the porosity is 70%, the specific surface area is 176 m 2 / kg, cadmium mercury arsenic lead and other do not exceed the standard.

[0050] The contents of effective silicon, effective calcium, effective magnesium, effective iron, effective boron and effective phosphorus in the agricultural fiber are 280 mg / kg, 132 mg / kg, 28 mg / kg, 5 mg / kg, 0 mg / kg and 1 mg / kg respectively.

[0051] Comparative Example 3

[0052] The required raw materials, calcium stone powder, silica powder, magnesia, borax, phosphorus pentoxide, are mixed uniformly according to the proportion of 26.5:63.8:4.7:5.0:0 by weight percentage, continuously melt in the range of 1700-1850°C, and then fiberize by spinning, the fiberizing temperature is 1570-1600°C, the spinning line speed is 170 m / s, the heat treatment temperature is 650°C, and the time is 4 min, to obtain the agricultural fiber.

[0053] The agricultural fiber obtained in this comparative example has SiO2: 57.2 wt%; MgO: 4.08 wt%; CaO: 26.7 wt%; Al2O3: 3.2 wt%; Fe2O3: 0.58 wt%, B2O3: 6.2 wt%, P2O5: 1.2 wt%, Na2O: 0.1 wt%, K2O: 0.2 wt%, and a molar ratio of O / Si of 3.06, P2O5 / Fe2O3 = 2.06, a bulk density of 64 kg / cm3, an average fiber diameter of 2.0 micrometers, fibers having a diameter of 1-2 μm accounting for 33 wt%, fibers having a diameter of 2-3 μm accounting for 64 wt%, fibers having a diameter of 3-4 μm accounting for 3 wt%, fibers having a diameter of 4-5 μm accounting for 0 wt%, an average thermal conductivity of 0.030 W / m.k at 25°C, a pH of 7.04, a water absorption of 560%, a porosity of 70%, a specific surface area of 580 m2 / g, and no excessive amounts of cadmium, mercury, arsenic, lead, and chromium. 3 , the average fiber diameter is 3.0 micrometers, fibers having a diameter of 1-2 μm account for 20 wt%, fibers having a diameter of 2-3 μm account for 68 wt%, fibers having a diameter of 3-4 μm account for 8 wt%, fibers having a diameter of 4-5 μm account for 4 wt%, the average thermal conductivity is 0.035 W / m.k at 25°C, the pH is 7.04, the water absorption is 860%, the porosity is 70%, the specific surface area is 280 m 2 2 / g, and no excessive amounts of cadmium, mercury, arsenic, lead, and chromium.

[0054] The contents of effective silicon, effective calcium, effective magnesium, effective iron, effective boron, and effective phosphorus in the agricultural fiber are 380 mg / kg, 119 mg / kg, 32 mg / kg, 3 mg / kg, 2 mg / kg, and 0 mg / kg, respectively.

[0055] Comparative Example 4

[0056] The required raw materials, calcium stone powder, silica powder, magnesia, borax, diaphosphorus pentoxide, and industrial alumina, are mixed uniformly in a ratio of 26.5:57.6:4.1:6.4:1.4:4 by weight percentage, and are continuously melted at a temperature of 1700-1850°C, and are formed into fibers by spinning, the fiber forming temperature is 1570-1600°C, the spinning line speed is 170 m / s, the heat treatment temperature is 550°C, and the time is 7 min, to obtain the agricultural fiber.

[0057] The agricultural fiber obtained in this comparative example has SiO2: 57.2 wt%; MgO: 4.08 wt%; CaO: 26.7 wt%; Al2O3: 3.2 wt%; Fe2O3: 0.58 wt%, B2O3: 6.2 wt%, P2O5: 1.2 wt%, Na2O: 0.1 wt%, K2O: 0.2 wt%, and a molar ratio of O / Si of 3.06, P2O5 / Fe2O3 = 2.06, a bulk density of 64 kg / cm3, an average fiber diameter of 2.0 micrometers, fibers having a diameter of 1-2 μm accounting for 33 wt%, fibers having a diameter of 2-3 μm accounting for 64 wt%, fibers having a diameter of 3-4 μm accounting for 3 wt%, fibers having a diameter of 4-5 μm accounting for 0 wt%, an average thermal conductivity of 0.030 W / m.k at 25°C, a pH of 7.04, a water absorption of 560%, a porosity of 70%, a specific surface area of 580 m2 / g, and no excessive amounts of cadmium, mercury, arsenic, lead, and chromium. 3 , the average fiber diameter is 3.0 micrometers, fibers having a diameter of 1-2 μm account for 20 wt%, fibers having a diameter of 2-3 μm account for 68 wt%, fibers having a diameter of 3-4 μm account for 8 wt%, fibers having a diameter of 4-5 μm account for 4 wt%, the average thermal conductivity is 0.035 W / m.k at 25°C, the pH is 7.04, the water absorption is 860%, the porosity is 70%, the specific surface area is 280 m 2 / kg, cadmium mercury arsenic lead chromium and the like are not over standard.

[0058] The contents of effective silicon, effective calcium, effective magnesium, effective iron, effective boron and effective phosphorus in the agricultural fiber are 280 mg / kg, 129 mg / kg, 28 mg / kg, 3 mg / kg, 1 mg / kg and 0 mg / kg respectively.

[0059] It can be seen from the above examples that the agricultural fiber containing boron and phosphorus comprises the following components in mass fraction: 50-72% of SiO2, 2-7% of MgO, 23-31% of CaO, 0.02-8% of B2O3, 0.03-8% of P2O5, 0-3% of Na2O, 0-3% of K2O, Al2O3<3%, and Fe2O3≤3%; the mass content ratio of P2O5 and Fe2O3 is 1.5-2.5; and the molar ratio of O / Si in the agricultural fiber is 2.2-3.0. By introducing B2O3 and P2O5 into the agricultural fiber, the fiber forming quality and fiber index of the fiber are high; the diameter of the fiber is low, and the specific surface area of the fiber is high; the contents of effective silicon, effective calcium, effective magnesium, effective boron and effective phosphorus in the soil are effectively improved; the absorption of the plant roots to these elements is improved, so that the yield and quality of crops are improved. The agricultural fiber is prepared without using organic adhesives / binders and the like, and the agricultural fiber is not further absorbed by the plant due to the presence of the organic adhesives / binders, so that the harm to the human body is avoided.

[0060] The above only describes the preferred embodiments of the present application, and it should be noted that some improvements and refinements can be made by those skilled in the art without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1.A method for preparing a boron-phosphorus-containing agricultural fiber, comprising the following steps: melting calcium stone powder, silica powder, magnesia, phosphorus-containing material and boron-containing material at 1400-1850 ℃, spinning or blowing into fibers, and heat treating to obtain the boron-phosphorus-containing agricultural fiber; the calcium stone powder is selected from one or more of lime, light-burned dolomite, heavy-burned dolomite and wollastonite containing CaO; the silica powder is selected from one or more of silica stone and quartz sand containing SiO 2; the magnesia is selected from one or more of fused magnesia, light-burned magnesia, light-burned dolomite, heavy-burned dolomite and forsterite containing MgO; the boron-containing material is selected from one or more of borax, boric acid, borymage and colemanite; the phosphorus-containing material is selected from one or more of sodium dihydrogen phosphate and P 2 O 5; the boron-phosphorus-containing agricultural fiber comprises the following components in mass fraction: 50-72% SiO 2, 2-7% MgO, 23-31% CaO, 0.5-6% B 2 O 3, 0.03-8% P 2 O 5, 0-3% Na 2 O, 0-3% K 2 O, Al 2 O 3 < 3%, Fe 2 O 3 ≤ 3%; the mass content ratio of P 2 O 5 and Fe 2 O 3 is 1.6-2.5; the molar ratio of O / Si in the agricultural fiber is 2.4-2.8; the proportion of fibers with a diameter of 1-2 μm in the agricultural fiber is 10-20 wt%, the proportion of fibers with a diameter of 2-3 μm is 70-80 wt%, the proportion of fibers with a diameter of 3-4 μm is 5-10 wt%, and the proportion of fibers with a diameter of 4-5 μm is 1-5 wt%; the content of available silicon in the agricultural fiber is 300-2000 mg / kg, the content of available calcium is 150-500 mg / kg, the content of available magnesium is 30-100 mg / kg, the content of available iron is 10-80 mg / kg, the content of available boron is 0.01-5 mg / kg, and the content of available phosphorus is 5-150 mg / kg; the pH value of the agricultural fiber is 5.6-7.2; and the thermal conductivity of the agricultural fiber at 25 ℃ is 0.03-0.06 W / m·K. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The specific surface area of the agricultural fiber is 300~600m 2 / kg; The agricultural fiber has a bulk density of 48-128 kg / m 3 , a porosity of 50-90%, and a water retention rate of 100-1000%.

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