A soil conditioner for preventing crop roots from absorbing cadmium and a preparation method thereof

Abstract

A soil conditioner that blocks the absorption of cadmium by the roots of crops and a preparation method thereof, relating to the technical field of soil remediation. The aforementioned soil conditioner that blocks the absorption of cadmium by the roots of crops is mainly composed of sawdust compost and calcium carbonate igneous rock, supplemented by silicon fertilizer, calcium magnesium phosphate fertilizer, potassium sulfate, boric acid, and sodium selenite, wherein the weight of sawdust compost and calcium carbonate igneous rock accounts for more than 70%. The aforementioned soil conditioner that blocks the absorption of cadmium by the roots of crops can significantly inhibit the absorption of cadmium by crops such as water spinach, peppers, sweet potatoes, and rice, thereby reducing the cadmium content in the corresponding agricultural products.

Description

Technical Field

[0001] The invention relates to the technical field of soil remediation, and in particular to a soil conditioner for blocking crop roots from absorbing cadmium and a preparation method thereof. Background Art

[0002] The quality of agricultural products is closely related to soil. At present, factors such as wastewater, waste gas, and waste residue emissions from non-ferrous metal mining and smelting have caused cadmium pollution in large areas of cultivated land, resulting in excessive cadmium content in vegetables and grain crops. Long-term intake of cadmium-contaminated agricultural products can easily cause chronic poisoning of the kidneys, leading to symptoms such as proteinuria, aminoaciduria, and diabetes, which in turn cause great harm to human health. Most of the existing methods for reducing the cadmium content of agricultural products are to increase the soil pH or apply adsorption materials to reduce the effective cadmium content in the soil, so as to achieve the purpose of reducing the cadmium content of agricultural products. These cadmium reduction methods have the following disadvantages in practical application: 1. The adsorption capacity of soil for cadmium will be affected by the external environment. For example, changes in soil temperature, humidity, acidity, alkalinity, redox properties, etc. will cause changes in the adsorption capacity of soil for cadmium, and the timeliness and stability of adsorption need to be improved. 2. Increasing the soil pH value will reduce the effectiveness of other metal elements necessary for crops. After long-term application, it will change the properties of the soil, leading to soil compaction and reduced crop yield and quality.

[0003] Studies have found that not only is soil cadmium pollution widespread in southern my country, but there is also a lot of precipitation and strong soil leaching, which leads to a lack of nutrients and beneficial elements such as potassium, boron, and selenium in the soil. In addition, the soil has low organic matter content, poor water and fertilizer retention capacity, low effective silicon content, and crops are prone to lodging. Long-term heavy application of nitrogen fertilizers has led to a decrease in soil pH and an increase in the effectiveness of soil cadmium. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a soil conditioner that can block the absorption of cadmium by crop roots, reduce the activity of soil cadmium, promote the biosynthesis of crop root cell wall components, and thus prevent the absorption and accumulation of cadmium by crops such as water spinach, pepper, sweet potato, and rice.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a soil conditioner for blocking the roots of crops from absorbing cadmium, mainly composed of sawdust compost and calcium carbonate igneous rock, supplemented by silicon fertilizer, calcium magnesium phosphate fertilizer, potassium sulfate, boric acid, and sodium selenite, wherein the weight of the sawdust compost and calcium carbonate igneous rock accounts for more than 70%.

[0006] The soil conditioner for preventing crop roots from absorbing cadmium comprises the following components by weight:

[0007]

[0008] The soil conditioner for preventing crop roots from absorbing cadmium comprises the following components by weight:

[0009]

[0010] For example, the soil conditioner may include the following components: wood chip compost (80-100kg); silicon fertilizer (25-50kg); calcium carbonate igneous rock (80-120kg), calcium magnesium phosphate fertilizer (15-25kg); potassium sulfate (10-15kg); boric acid (0.75-1.25kg); sodium selenite (75-90g).

[0011] The calcium carbonate igneous rock may contain manganese, and the weight content of manganese in the calcium carbonate igneous rock may be 0.10-0.12%, which can supplement the nutrient element manganese of soil crops.

[0012] In addition, the soil conditioner for blocking the absorption of cadmium by crop roots can be prepared by the following steps:

[0013] a. fermenting the sawdust to obtain sawdust compost;

[0014] b. Evenly mix silicon fertilizer, calcium carbonate volcanic rock, and calcium magnesium phosphate fertilizer to obtain inorganic nutrients;

[0015] c. Evenly mix the sawdust compost with potassium sulfate, boric acid and sodium selenite, dry and mix with inorganic nutrients, and add water to adjust the humidity to obtain a mixture;

[0016] d. Granulate the mixture, dry it and sieve it to obtain a soil conditioner.

[0017] Among them, in step a, the sawdust is fermented with white rot fungus liquid, which can make the fermentation effect of the sawdust better.

[0018] Wherein, in step a, the sawdust compost is obtained by fermenting sawdust with a diameter of 0.8 to 1.3 mm and a length of 5 to 8 mm.

[0019] Wherein, in step b, the silicon fertilizer, calcium carbonate volcanic rock, and calcium magnesium phosphate fertilizer are in powder form, which can make the mixing more uniform.

[0020] In addition, the above-mentioned soil conditioner that blocks the absorption of cadmium by crop roots can be used in crop planting.

[0021] The soil conditioner that blocks the root absorption of cadmium by crops not only provides nutrients by adding silicon fertilizer, calcium carbonate igneous rock, calcium magnesium phosphate fertilizer and sawdust compost, but more importantly, it can reduce the bioavailability of soil cadmium and reduce the absorption of cadmium by crops. In addition, the increase of nutrients such as silicon, calcium, manganese, phosphorus, magnesium, boron, potassium, selenium, etc. can promote the biosynthesis of root cell wall components, improve the ability of cell wall to fix cadmium, prevent cadmium from being transported into cells, thereby reducing cadmium absorption. The supplementation of these nutrients is also very beneficial for promoting the growth and development of crops and the increase of yield. Therefore, this soil conditioner can supplement the vast majority of elements required for crop growth, improve the health of soil, prevent the absorption and accumulation of cadmium from aspects such as rhizosphere soil and root system, and can also significantly increase the yield of agricultural products.

[0022] In summary, the soil conditioner provided by the present invention can effectively reduce the effectiveness of soil cadmium, improve the ability of crop roots to control cadmium absorption and transport, thereby significantly reducing the cadmium content of agricultural products. It has been tested that the application of the soil conditioner can make the cadmium content of water spinach and rice produced in cadmium-contaminated soil with a cadmium content of 3.0 mg / kg not exceed 0.15 mg / kg, which is far below the maximum limit of 0.2 mg / kg specified in the national food safety standard; the cadmium content of peppers does not exceed 0.03 mg / kg, which is far below the maximum limit of 0.05 mg / kg specified in the national food safety standard; the cadmium content of sweet potato tubers does not exceed 0.07 mg / kg, which is far below the maximum limit of 0.1 mg / kg specified in the national food safety standard. In addition, this soil conditioner can be applied to most crops in dry land and paddy fields contaminated with cadmium. DETAILED DESCRIPTION

[0023] The following examples are given to specifically describe the present invention. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements or adjustments made to the present invention by ordinary technicians in this field based on the examples still fall within the scope of protection of the present invention.

[0024] Example 1

[0025] The steps for preparing a soil conditioner that blocks cadmium absorption by crop roots are as follows:

[0026] a. Put sawdust into a fermentation tank, add an appropriate amount of white rot fungus liquid for fermentation, and obtain sawdust compost;

[0027] b. Crush 25 parts of silicon fertilizer, 80 parts of calcium carbonate igneous rock and 15 parts of calcium magnesium phosphate fertilizer, mix them evenly, and prepare inorganic nutrients;

[0028] c. 80 parts of air-dried sawdust compost were mixed with 10 parts of potassium sulfate, 0.75 parts of boric acid and 0.075 parts of sodium selenite, dried and mixed with inorganic nutrients, and water was added to obtain a mixture;

[0029] d. The mixture is granulated by a granulator, and then dried and sieved to finally obtain a soil conditioner.

[0030] Example 2

[0031] The steps for preparing a soil conditioner that blocks cadmium absorption by crop roots are as follows:

[0032] a. Put sawdust into a fermentation tank, add an appropriate amount of white rot fungus liquid for fermentation, and obtain sawdust compost;

[0033] b. Crush 40 parts of silicon fertilizer, 100 parts of calcium carbonate igneous rock and 20 parts of calcium magnesium phosphate fertilizer, mix them evenly, and prepare inorganic nutrients;

[0034] c. Mix 90 parts of air-dried sawdust compost with 12 parts of potassium sulfate, 1 part of boric acid and 0.08 parts of sodium selenite, dry them, mix them with inorganic nutrients, and add water to adjust the humidity to obtain a mixture;

[0035] d. The mixture is granulated by a granulator, and then dried and sieved to finally obtain a soil conditioner.

[0036] Example 3

[0037] The steps for preparing a soil conditioner that blocks cadmium absorption by crop roots are as follows:

[0038] a. Put sawdust into a fermentation tank, add an appropriate amount of white rot fungus liquid for fermentation, and obtain sawdust compost;

[0039] b. Crush 50 parts of silicon fertilizer, 120 parts of calcium carbonate igneous rock and 25 parts of calcium magnesium phosphate fertilizer, mix them evenly, and prepare inorganic nutrients;

[0040] c. 100 parts of air-dried sawdust compost were mixed with 15 parts of potassium sulfate, 1.25 parts of boric acid and 0.09 parts of sodium selenite, dried and mixed with inorganic nutrients, and water was added to obtain a mixture;

[0041] d. The mixture is granulated by a granulator, and then dried and sieved to finally obtain a soil conditioner.

[0042] Pot test.

[0043] (a) Treat the soil with amendments.

[0044] Flower pot specifications: upper diameter × lower diameter × height = 25cm × 18cm × 26cm, a total of 72 flower pots, each pot is filled with 4.75kg of soil.

[0045] Test group: a total of 36 flower pots, numbered 1-36 in sequence. The total cadmium content in the soil of flower pots 1-12 was 1.0 mg / kg, and the modifier prepared in Example 1 was applied; the total cadmium content in the soil of flower pots 13-24 was 2.0 mg / kg, and the modifier prepared in Example 2 was applied; the total cadmium content in the soil of flower pots 25-36 was 3.0 mg / kg, and the modifier prepared in Example 3 was applied. The dosage of the above modifiers was 1 / 19 of the soil mass, that is, the mass of organic fertilizer applied to each flower pot was 0.25 kg.

[0046] Control group: a total of 36 flower pots, numbered 1-36 in sequence, among which the total cadmium content in the soil of flower pots 1-12 was 1.0 mg / kg, the total cadmium content in the soil of flower pots 13-24 was 2.0 mg / kg, and the total cadmium content in the soil of flower pots 25-36 was 3.0 mg / kg. No amendments were applied to the above flower pots.

[0047] (2) Crop planting.

[0048] Water spinach, rice and pepper seeds were sterilized with 5% sodium hypochlorite solution for 15 minutes, then germinated in moist sterilized quartz sand. After 3 weeks, seedlings of roughly the same size were transplanted into flower pots, one plant per pot. Sweet potato seedlings 15 cm long were cut into flower pots, one plant per pot. In the experimental and control groups, each crop was replicated three times under each treatment. All flower pots were randomly placed in a greenhouse, and rice was flooded with water about 3 cm above the soil surface.

[0049] (3) Cadmium content in edible parts of crops.

[0050] 1. After the rice is mature, it is air-dried and husked with a rice husker to obtain brown rice. Water spinach stems and leaves, pepper fruits and sweet potato tubers are sampled when they can be picked, rinsed 3 times with tap water, and washed 3 times with deionized water. All samples are dried at 70°C to constant weight, crushed to obtain samples, placed in a digestion tank, and HNO3 and H2O2 are added, then placed in a microwave digester for digestion, and the cadmium content in the digestion solution is detected by a flame atomic absorption spectrometer (AA-6300C, Shimadzu), and the test results are recorded in Table 1 below.

[0051] Table 1 Cadmium content of agricultural products produced by the experimental group and the control group

[0052]

[0053]

[0054] 2. The soils of all control groups and test groups were extracted with diethylenetriaminepentaacetic acid (DTPA), and the cadmium content of the extracts was determined using a flame atomic absorption spectrometer (AA-6300C, Shimadzu), and the determination results were recorded in Table 2 below.

[0055] Table 2 Soil cadmium bioavailability in the experimental and control groups

[0056]

[0057] 3. The root tips of all crops in the control group and the experimental group were collected, and the contents of cellulose, hemicellulose, pectin and lignin were determined using a test kit, and the results were recorded in Table 3 below.

[0058] Table 3 Content of crop root cell wall components in the experimental group and the control group (mg / g, dry weight)

[0059]

[0060] 4. The roots of all crops in the control group and the experimental group were collected and divided into two parts, one for determining the total cadmium content in the roots and the other for determining the cadmium content in the root cell walls. The determination results were recorded in Table 4 below.

[0061] Table 4 Total cadmium content in crop roots and cell wall in the experimental group and the control group (mg / g, fresh weight)

[0062]

[0063]

[0064] 5. Collect the edible parts of all crops in the control group and the experimental group, including the stems and leaves of water spinach, the fruits of pepper, the tubers of sweet potato and the seeds of rice, weigh the fresh weight, and record the results in Table 5 below.

[0065] Table 5 Edible biomass of crops in the experimental group and the control group (g, fresh weight)

[0066]

[0067]

[0068] The test found that the application of this soil conditioner can reduce the cadmium content of water spinach and rice produced in cadmium-contaminated soil with a cadmium content of 3.0 mg / kg to no more than 0.15 mg / kg, which is far below the maximum limit of 0.2 mg / kg specified in the national food safety standard; the cadmium content of peppers does not exceed 0.03 mg / kg, which is far below the maximum limit of 0.05 mg / kg specified in the national food safety standard; the cadmium content of sweet potato tubers does not exceed 0.07 mg / kg, which is far below the maximum limit of 0.1 mg / kg specified in the national food safety standard. Therefore, the above-mentioned soil conditioner can effectively reduce the effectiveness of soil cadmium and improve the ability of crop roots to control cadmium absorption and transport, thereby significantly reducing the cadmium content of agricultural products. In addition, this soil conditioner can be applied to almost all crops in dry land and paddy fields contaminated with cadmium.

[0069] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present technical solution is within the protection scope of the present invention.

[0070] Finally, it should be emphasized that in order to allow ordinary technicians in the field to more easily understand the improvements of the present invention over the prior art, some descriptions of the present invention have been simplified, and for the sake of clarity, some other elements are omitted in this application document. Those skilled in the art should realize that these omitted elements may also constitute the content of the present invention.

Claims

1. A soil conditioner for preventing crop roots from absorbing cadmium, characterized in that: The method is mainly composed of sawdust compost and calcium carbonate igneous rock, supplemented by silicon fertilizer, calcium magnesium phosphate fertilizer, potassium sulfate, boric acid, and sodium selenite, wherein the weight of the sawdust compost and calcium carbonate igneous rock accounts for more than 70%, the calcium carbonate igneous rock contains manganese with a weight content of 0.10-0.12%, and the sawdust compost is obtained by fermenting sawdust with white rot fungus liquid; The soil conditioner consists of the following components by weight: 80-100 parts of sawdust compost; Silicon fertilizer 25-50 parts; 80-120 parts of calcium carbonate igneous rock; 15-25 parts of calcium magnesium phosphate fertilizer; 10-15 parts of potassium sulfate; Boric acid 0.75-1.25 parts; Sodium selenite 0.075-0.09 parts.

2. The soil conditioner for preventing crop roots from absorbing cadmium according to claim 1, characterized in that: The soil conditioner consists of the following components by weight: 80 portions of sawdust compost; Silicon fertilizer 25 parts; 80 parts of calcium carbonate igneous rock; 15 parts of calcium magnesium phosphate fertilizer; 10 parts of potassium sulfate; 0.75 parts of boric acid; 0.075 parts of sodium selenite.

3. The method for preparing the soil conditioner for preventing crop roots from absorbing cadmium according to claim 1 or 2, characterized in that: The following steps are involved: a. fermenting the sawdust to obtain sawdust compost; b. Evenly mix silicon fertilizer, calcium carbonate volcanic rock, and calcium magnesium phosphate fertilizer to obtain inorganic nutrients; c. Evenly mix the sawdust compost with potassium sulfate, boric acid and sodium selenite, dry and mix with inorganic nutrients, and add water to adjust the humidity to obtain a mixture; d. Granulate the mixture, dry it and sieve it to obtain a soil conditioner.

4. The method for preparing the soil conditioner for preventing crop roots from absorbing cadmium according to claim 3, characterized in that: In step a, the wood chips are fermented using white rot fungus liquid.

5. The method for preparing the soil conditioner for preventing crop roots from absorbing cadmium according to claim 3, characterized in that: In step a, the sawdust compost is obtained by fermenting sawdust with a diameter of 0.8 to 1.3 mm and a length of 5 to 8 mm.

6. The method for preparing the soil conditioner for preventing crop roots from absorbing cadmium according to claim 3, characterized in that: In step b, the silicon fertilizer, calcium carbonate volcanic rock and calcium magnesium phosphate fertilizer are in powder form.

7. Use of the soil conditioner for preventing crop roots from absorbing cadmium as claimed in claim 1 or 2 in crop planting.

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