CN102504826A - a soil conditioner - Google Patents

Abstract

The invention provides a soil conditioner, which comprises: 55% to 65% of bimetallic oxides of magnesium and aluminum, 20% to 30% of straw biomass coke, and 10% to 20% of iron phosphate . Among them, 20%-30% of the biomass coke is produced by carbonizing 40-50% of crop straws, and the crop straws include one or more of rice, millet and corn straws. The conditioner of the invention can fix the arsenic in the soil and reduce the toxicity of the arsenic, so as to reduce the arsenic absorption by crops. At the same time, the conditioner contains more nutrients such as calcium, magnesium and phosphorus, which can indirectly supplement the necessary nutrients for the crops in the soil.

Description

a soil conditioner

technical field

The invention relates to a soil conditioner, in particular to a conditioner capable of reducing excessive arsenic toxicity in soil.

Background technique

Arsenic (As) is a toxic metalloid element of global concern. For a long time, various production activities such as mineral mining and smelting, coal combustion, use of arsenic-containing pesticides, veterinary drugs, and preservatives, etc., can accelerate the transfer of arsenic to soil, water and other environments to a certain extent, thereby threatening Environmental safety and human health, and the resulting arsenic pollution in soil and water have also received widespread attention. Grain crops are an important way for arsenic to enter the human food chain. Therefore, planting crops on farmland with excessive arsenic has a high risk of arsenic accumulation in agricultural products. How to reduce the absorption of arsenic by crops has also attracted widespread attention.

At the same time, arsenic in farmland can also infiltrate through surface runoff or with irrigation water, which may cause secondary pollution of rivers, lakes and groundwater. How to reduce the availability of arsenic in the soil and make it into a relatively stable state, not only make it fixed in situ and not discharge to the environment, but also make it difficult for crops to absorb and utilize it. While this cannot fundamentally solve the problem of soil arsenic pollution, it is also an effective way to reduce the absorption of arsenic by crops in the soil exceeding the standard and reduce its toxicity.

Arsenic exists in various forms in soil, but generally exists in the form of inorganic compounds, such as pentavalent arsenic and trivalent arsenic; sometimes it also exists in the form of organic compounds, such as monomethyl arsenic (MMA), Dimethylarsenic (DMA), trimethylarsenic (TMA), etc. Studies have found that the content of organic arsenic in the natural state is usually very low, while the content and toxicity of inorganic arsenic are greater than that of arsenic in the organic state, and the toxicity of trivalent arsenic is 60 times that of pentavalent arsenic. (MMA, DMA) 70 times the toxicity. Therefore, inorganic arsenic is listed as the number one environmental pollutant by the Environmental Protection Agency of the United States, and a series of thresholds for arsenic content in soil, water and agricultural products have been established. Therefore, in a sense, reducing the toxicity and availability of arsenic in soil mainly refers to reducing the availability of inorganic arsenic to crops, reducing its absorption by crops, and reducing its toxicity.

At present, chemical methods are mainly used to reduce the effectiveness of arsenic in soil and reduce its toxicity regulation at home and abroad, that is, adding chemical conditioners to soil to reduce the toxicity of arsenic contained in it and reduce the absorption of arsenic by crops. Although many conditioners have been developed successively, due to various reasons, their practical application effects are poor, especially less research related to reducing the absorption of arsenic by crops, or less related to this aspect. practical application. There is no report on a conditioner that can reduce the toxicity of arsenic in the soil, reduce the absorption of arsenic by crops, and have a lower production cost.

Contents of the invention

The technical problem to be solved by the present invention is to provide a soil conditioner that can reduce the toxicity of arsenic in the soil.

In order to solve the above technical problems, the present invention provides a soil conditioner, which includes: 55% to 65% magnesium and aluminum bimetallic oxides, 20% to 30% straw biomass coke, and 10% ~20% iron phosphate.

Preferably,

20% to 30% of the biomass coke is produced by carbonizing 40 to 50% of the crop straw, which includes one or more of rice, millet and corn straw.

Preferably,

55%-65% of magnesium and aluminum bimetallic oxides are obtained through 55%-65% of finely ground magnesium-aluminum hydrotalcite.

In order to solve the problems of the technologies described above, the invention provides a kind of preparation method of soil conditioner as described above, comprising the steps:

According to the calculation of the soil conditioner with a total weight of 100 kg, the following materials are weighed: 55-65 kg of ground hydrotalcite, 40-50 kg of ground corn stalks, 10-20 kg of ground iron phosphate; Mix evenly and moisten it with water until the water comes out when grasping to form a mixed material;

Cover the mixed material with a plastic film and stack it indoors for 3 to 4 days, then place it in a carbonization furnace, heat it slowly to 490-520°C in a relatively sealed state, and keep it for 2.8-3.2 hours before stopping the heating. The slowly heated mixed material is gradually cooled, taken out, ground and passed through a 0.20-0.30mm sieve to obtain a soil conditioner.

In order to solve the above-mentioned technical problems, the present invention provides an application of the aforementioned soil conditioner in reducing arsenic toxicity in soil.

In order to solve the above-mentioned technical problems, the present invention provides an application of the aforementioned soil conditioner in reducing the absorption of arsenic by crops in the soil.

The conditioner of the invention can fix the arsenic in the soil and reduce the toxicity of the arsenic, so as to reduce the arsenic absorption by crops. At the same time, the conditioner contains more nutrients such as calcium, magnesium and phosphorus, which can indirectly supplement these necessary nutrients for crops in the soil. Moreover, after the hydrotalcite in the conditioner is treated at high temperature, the water molecule and the carbonate anion layer disappear, the original structure is destroyed, the sheets are stacked closely, and the space channel is small, and there is magnesium oxide with good crystallinity. And the formation of microcrystalline alumina, so that it can have a strong adsorption and fixation capacity for arsenate ions in the soil.

Description of drawings

Fig. 1 is the variation curve graph of soil conditioner of the present invention and hydrotalcite respectively to the adsorption capacity of pentavalent arsenic in the solution over time;

Fig. 2 is a graph showing the variation curve of the adsorption amount of pentavalent arsenic by the soil conditioner and hydrotalcite of the present invention with the concentration in the solution.

Detailed ways

The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and preferred embodiments. It should be understood that the following examples are only used to illustrate and explain the present invention, but not to limit the technical solution of the present invention.

Example 1

The soil conditioner provided by the invention comprises: 55% to 65% of magnesium and aluminum double metal oxides, 20% to 30% of straw biomass coke and 10% to 20% of iron phosphate.

In the above embodiments, 20%-30% of the biomass coke is produced by carbonizing 40-50% of crop straw (such as rice, millet or corn straw).

In the above embodiments, 55% to 65% of magnesium and aluminum bimetallic oxides are obtained through 55% to 65% of finely ground magnesium aluminum hydrotalcite (hereinafter referred to as hydrotalcite).

Example 2

The method embodiment of preparing above-mentioned soil conditioner, comprises the steps:

According to the calculation of the soil conditioner with a total weight of 100 kg, the following materials are weighed: 55 kg of ground magnesium aluminum hydrotalcite, 45 kg of ground corn stalks, 20 kg of ground iron phosphate; the weighed materials are evenly mixed, and Wet it with water until water can come out when grasping it, forming a mixed material;

Cover the mixed material with a plastic film, and stack it indoors for 3 to 4 days, then place it in a carbonization furnace, heat the mixed material slowly to 490°C in a relatively sealed state, and keep it for 2.8 hours, then stop heating, and let the carbonization process slowly The heated mixed material is taken out after gradually cooling, ground and passed through a 0.20mm sieve to obtain the soil conditioner of the present invention.

Example 3

The method embodiment of preparing above-mentioned soil conditioner, comprises the steps:

According to the calculation of the soil conditioner with a total weight of 100 kg, the following materials are weighed: 60 kg of ground magnesium aluminum hydrotalcite, 50 kg of ground corn stalks, 10 kg of ground iron phosphate; the weighed materials are evenly mixed, and Wet it with water until water can come out when grasping it, forming a mixed material;

Cover the mixed material with a plastic film, and stack it indoors for 3 to 4 days, then place it in a carbonization furnace, heat the mixed material slowly to 500°C in a relatively sealed state, and keep it for 3 hours, then stop heating, and let the carbonization process slowly The heated mixed material is taken out after gradually cooling, ground and passed through a 0.25mm sieve to obtain the soil conditioner of the present invention.

Example 4

The method embodiment of preparing above-mentioned soil conditioner, comprises the steps:

According to the calculation of the soil conditioner with a total weight of 100 kg, weigh the following materials: 65 kg of ground hydrotalcite, 40 kg of ground corn stalks, and 15 kg of ground iron phosphate; mix the weighed materials evenly, and moisten with water Until the water can come out when grasped by hand, a mixed material is formed;

Cover the mixed material with a plastic film, and stack it indoors for 3 to 4 days, then place it in a carbonization furnace, heat the mixed material slowly to 520°C in a relatively sealed state, and keep it for 3.2 hours, then stop heating, and let the carbonization process slowly The heated mixed material is taken out after gradually cooling, ground and passed through a 0.30mm sieve to obtain the soil conditioner of the present invention.

test 1

Take by weighing 50 mg of the soil conditioner of the embodiment of the present invention 1 (hereinafter referred to as soil conditioner 1) and 24 parts of each 50mg hydrotalcite conditioner, place respectively in 48 plastic centrifuge tubes of 100ml, every three pairs are filled with soil conditioner 1 and the centrifuge tube containing hydrotalcite to form a group, a total of 8 groups; add 25ml of pentavalent arsenic solution with a concentration of 50mg/L prepared in advance with sodium arsenate to each centrifuge tube;

Place the 8 groups of centrifuge tubes added with the pentavalent arsenic solution in a reciprocating shaker, shake at a constant speed of 150r/min at room temperature, and shake for 0.5, 1, 1.5, 3, 6, 12, 18, 24 hours respectively Finally, take out one group (i.e. three pairs) of centrifuge tubes from the oscillator and carry out centrifugation, get the supernatant after centrifugation, and measure the concentration of pentavalent arsenic in the supernatant with an atomic fluorescence spectrometer;

Taking the adsorption time (i.e. oscillation time) as the abscissa, and taking the adsorption amount of pentavalent arsenic as the ordinate, the adsorption amount-adsorption time curve is drawn, as shown in Figure 1; it can be seen that the soil conditioner 1 and The adsorption capacity of each hydrotalcite to pentavalent arsenic in the solution.

In the above test, the adsorption tests of soil conditioner 1 and hydrotalcite were repeated three times at different times, that is, three centrifuge tubes of soil conditioner 1 and hydrotalcite were taken for each treatment and measured at the same time to eliminate the test error.

As can be seen from the results in Figure 1, when the adsorption time is short (within 1.5 hours), the absorption of pentavalent arsenic by the two substances tested increases rapidly with time, and gradually tends to be gentle thereafter. After the adsorption time reaches 12 hours, the change becomes more gentle, that is, the adsorption of the two substances to pentavalent arsenic has a process of fast reaction and slow reaction, but hydrotalcite has a small adsorption amount of pentavalent arsenic, so its change The overall trend is very flat.

By comparison, it can be seen that the adsorption capacity of soil conditioner 1 to pentavalent arsenic in the solution is much higher than that of hydrotalcite, and its adsorption capacity is 35.1 times that of hydrotalcite on average. The gap tends to narrow slightly with the extension of adsorption time. Calculate the effect of soil conditioner 1 on the removal of pentavalent arsenic in the solution under the experimental conditions. It is found that the adsorption time is 45.5% when the adsorption time is 0.5h, reaches 70.2% when the adsorption time is 6h, and reaches 91.2% when the adsorption time is 12h. 97.3% at 18 hours, and 98.5% at 24 hours, that is, the pentavalent arsenic in the solution has been basically removed after 24 hours of treatment. This result provides an important basis for the next design of the adsorption test, etc., and also shows that the conditioning agent of the present invention has a significant effect on removing arsenic in the solution.

test 2

Take by weighing 50mg of the soil conditioner of the embodiment of the present invention 2 (hereinafter referred to as soil conditioner 2), each 27 parts of 50mg hydrotalcite conditioner, place respectively in 54 plastic centrifuge tubes of 100ml, then, respectively in each centrifuge tube Add 25ml of pentavalent arsenic solutions of different concentrations prepared in advance with sodium arsenate. The concentrations of the pentavalent arsenic solutions prepared in the test are 0, 1, 2.5, 5, 10, 25, 50, 100, 150 mg/L, Place the centrifuge tubes added with different concentrations of pentavalent arsenic solutions in a centrifuge, centrifuge and shake at a constant speed of 150r/mim for 24 hours at room temperature, take the supernatant, and measure the concentration of pentavalent arsenic in the supernatant with an atomic fluorescence spectrometer. Based on this, the adsorption amount of pentavalent arsenic in the solution by soil conditioner 2 and hydrotalcite was calculated.

Taking the initial concentration of pentavalent arsenic solution as the abscissa, and the adsorption amount of pentavalent arsenic by the added soil conditioner 2 and hydrotalcite as the ordinate, draw the isotherm adsorption curve. In this test, the adsorption tests of soil conditioner 2 and hydrotalcite at different concentrations were repeated three times.

In this test, the adsorption amount of pentavalent arsenic by soil conditioner 2 and hydrotalcite varies with the concentration in the solution as shown in Figure 2.

It can be seen from the results in Figure 2 that the adsorption capacity of soil conditioner 2 to pentavalent arsenic in the solution is significantly higher than that of hydrotalcite, and its adsorption capacity at different solution concentrations is 24.2 times that of hydrotalcite on average. Wherein, when the concentration of pentavalent arsenic in the solution was 10 mg/L, the adsorption capacity of soil conditioner 2 was 12.7 times that of hydrotalcite, and the removal rate of pentavalent arsenic in the solution was 98.26%; the concentration of pentavalent arsenic in the solution was When the concentration of pentavalent arsenic in the solution was 150mg/L, the adsorption capacity of soil conditioner 2 was 32.3 times that of hydrotalcite, and the removal rate of pentavalent arsenic in the solution was 150mg/L. The adsorption capacity is 24.0 times that of hydrotalcite, and the removal rate of pentavalent arsenic in the solution is 79.10%. The results show that the application of soil conditioner 2 has a good adsorption effect on pentavalent arsenic in water, and can be used to remove pentavalent arsenic in aqueous solution. Under the test conditions, when the concentration of pentavalent arsenic in the solution was lower than 50mg/L, the removal rate of the application of soil conditioner 2 reached more than 96%, and the concentration of pentavalent arsenic in the solution was reduced to below 2mg/L, while the solution The removal rate decreased slightly when the concentration of pentavalent arsenic in medium continued to increase; but the removal effect was poor when the untreated hydrotalcite was applied, and the removal rate was only 2.70%.

Test 3

The red soil was collected in the area around the arsenic mine in Shimen County, Hunan Province. The soil was developed from Quaternary red soil parent material. Its basic physical and chemical properties are: pH 6.03, organic matter 40.8g/kg, CEC 17.1cmol/kg, total nitrogen 2.26g/kg , total phosphorus 0.58g/kg, total potassium 16.21g/kg, total arsenic 45.10mg/kg.

The soil was cultivated under constant temperature and humidity to simulate normal temperature conditions. Take by weighing 10g air-dried and ground the soil sample of 1mm sieve to 50mL centrifuge tube, add the soil conditioner (hereinafter referred to as soil conditioner 3) of the embodiment of the present invention 3, after mixing with soil, according to 70% of the field water holding capacity Add ultrapure water; then, put them into a constant temperature and humidity box with a temperature of 25°C and a humidity of 70% for cultivation.

In this test, 7 groups of soil conditioner 3 (3 centrifuge tubes in each group) were treated with different addition amounts, which were respectively: 1) control CK (0.0% w/w); 2) addition amount of 0.5% (w/w); /w); 3) The addition amount is 1% (w/w); 4) The addition amount is 2% (w/w); 5) The addition amount is 3% (w/w); 6) The addition amount is 4% (w/w); 7) The addition amount is 5% (w/w). For each treatment, the montmorillonite, which has a weak ability to adsorb and fix arsenic, was air-dried and ground through a 1mm sieve, was supplemented to a total addition of 5%, to eliminate the possible impact of different additions of soil conditioner 3.

During the test period, the centrifuge tubes were taken out and weighed every day to replenish water, and the soil water content was kept at about 70% of the field water capacity. After uniform cultivation for 8 weeks, a group of centrifuge tubes were taken out and tested for the content of different forms of arsenic and total arsenic in the soil of each treatment. Each treatment in this experiment was repeated three times, that is, a total of three groups of centrifuge tubes were taken out in sequence, and the content of different forms of arsenic and total arsenic in the soil of each treatment were tested.

In this study, the change ratio of each bound arsenic was calculated by the following formula: the change ratio of each bound arsenic (%)=(CC ₀ )/C ₀ ×100. In the formula, C is the content of a certain form of arsenic under the addition of soil conditioner 3, and _C0 is the content of the corresponding form of arsenic in the control treatment. A positive value of the calculated percentage means that the soil bound arsenic increases after adding soil conditioner 3, while a negative value means that the soil bound arsenic decreases after adding soil conditioner 3.

The graded determination of soil arsenic form is carried out according to the method of Samuel V H etc. (2003), and concrete operation steps are:

Soluble arsenic (A-As): Accurately weigh 1.0000g air-dried soil sample into a 100mL centrifuge tube, add 50mL NH ₄ Cl with a concentration of 1mol/L, shake well, shake at 20-25°C for 0.5h, at 4000rpm After centrifugation for 3 minutes, filter and test.

Aluminum-type arsenic (Al-As): Add 50 mL of NH ₄ F with a concentration of 0.5 mol/L, shake at 20-25°C for 1 hour, centrifuge at 4000 rpm for 3 minutes, filter, and wait for the test.

Iron-type arsenic (Fe-As): add 50mL NaOH with a concentration of 0.1mol/L, shake at 20-25°C for 2h, let stand for 16h, shake again for 2h, centrifuge at 4000rpm for 5-15min, filter, and test.

Calcium-type arsenic (Ca-As): Add 50 mL of H ₂ SO ₄ with a concentration of 0.25 mol/L, shake at 20-25°C for 1 hour, centrifuge at 4000 rpm for 3 minutes, filter, and test.

Residual arsenic (O-As): Dry the above extracted soil, transfer it to a digestion tube, first add 9mL of analytically pure concentrated hydrochloric acid, then add 3mL of superior pure concentrated nitric acid, and finally add 3mL of perchloric acid , shake gently, cover with membrane, and leave overnight at room temperature. Cover the small funnel the next day, and heat to a slight boil (140-170°C) at low temperature in a fume hood. Cook until off-white, and after cooling, dilute to 50mL, filter, and wait for test.

In this experiment, the changes (mg/kg) of different forms of arsenic in the soil after adding different proportions of soil conditioner 3 are shown in Table 1.

From the results in Table 1, it can be found that adding soil conditioner 3 to the soil with excessive arsenic content significantly reduces the content of soluble arsenic and iron-type arsenic. content decreased by 76.8% and iron-type arsenic content decreased by 84.0%; calcium-type arsenic and residual arsenic content increased significantly, especially the calcium-type arsenic content increased significantly. The content of type arsenic increased by 105.0%, and the content of residual arsenic increased by 12.4%, while the content of aluminum type arsenic did not change much. It is generally believed that from soluble arsenic to aluminum-type arsenic, iron-type arsenic, calcium-type arsenic, and residual arsenic, its

Table 1

The bioavailability ranges from high to low, especially the soluble arsenic is generally considered to be the form that can be easily absorbed and utilized by crops, while the residue state is generally considered to be the form that is difficult to be absorbed and utilized by crops. Obviously, after adding a certain proportion of soil conditioner 3 to the soil, the increase of soil calcium-type arsenic and residual arsenic content also means to a certain extent that the crop availability of soil arsenic has decreased to some extent, That is, the expected purpose of passivating soil arsenic has been achieved. Of course, the final passivation effect needs to be proved by the absorption and utilization of crops.

Test 4

The above-mentioned red soil developed from Quaternary laterite parent material around the Shimen Arsenic Mine in Hunan was collected, dried naturally, crushed, and passed through a 2mm sieve for later use. Apply 0.15g nitrogen, 0.18g P ₂ O ₅ , 0.12g K ₂ O to the spare soil, add urea, KH ₂ PO ₄ and K ₂ SO ₄ respectively, 2kg per pot After the above-mentioned soil that added nitrogen, phosphorus and potassium nutrients was potted, then in each pot, add the soil conditioner of the embodiment of the present invention 3 (hereinafter referred to as soil conditioner 3) in the proportion of 0%, 2.5%, and 5% of the soil weight. ) and hydrotalcite, that is, 5 treatments were set in this test, which were respectively (1) control CK (i.e. without adding soil conditioner 3); (2) adding hydrotalcite by 2.5% of soil weight; (4) add soil conditioner 3 by 2.5% of soil weight; (5) add soil conditioner 3 by 5% of soil weight; each treatment is repeated 4 times in this test. After mixing the added conditioner and soil evenly, moisten it with an appropriate amount of deionized water, and let it stand for 1 week.

Select small rapeseed seedlings with basically the same growth (the variety is "Specially Selected Beijing Oil", bred by the Vegetable and Flower Research Institute of the Chinese Academy of Agricultural Sciences), and transplant them into the prepared pots of the aforementioned treatments. 6 plants were planted inside, and the pots and pots were moved to the greenhouse as a whole, and managed according to conventional planting. After the seedlings survived (1 week after transplanting), select the size and the growth situation according to the growth of rapeseed, pull out 3 of them, and leave 3 seedlings with the same size and growth to continue cultivation and management. After 60 days of cultivation, Rapeseed rape was harvested and washed with clean water for different treatments, killed at 105°C, and then dried under reduced pressure at 60°C. The weights were weighed and used as the biomass of each treatment. At the same time, the samples of each treatment were pulverized with a plant grinder and reserved for the determination of arsenic content. After the plants were harvested, soil samples from each pot were taken at the same time to analyze the content and form of arsenic.

After adding two conditioners and two kinds of ratios in this experiment, the results of rapeseed yield and arsenic content in plants of each treatment are shown in Table 2.

Table 2

From the results in Table 2, it can be found that under the premise of high soil arsenic content in this test, the addition of hydrotalcite has little effect on crop yield, and has little effect on the arsenic content of crop plants, that is, it has little effect on crop growth and Absorption of arsenic has essentially no effect. However, after adding soil conditioner 3, the crop yield increased significantly under the same conditions. Compared with CK, when the addition amount was 2.5% and 5%, it increased by 32.86% and 6.15%, respectively, that is, the soil conditioner 3 The effect of increasing production is better when the addition amount is 2.5%. From the comparison of the arsenic content in the plants, the addition of hydrotalcite in this experiment has almost no effect on the arsenic content of the rapeseed plants, that is, its conditioning effect is very limited; but the arsenic content of the rapeseed plants has dropped significantly after adding soil conditioner 3 , when the addition amount was 2.5%, it decreased by 0.229mg/kg, and decreased by 31.33%, and when the addition amount was 5%, it decreased by 0.274mg/kg, and decreased by 37.48%. Comparing the situation of arsenic absorption by crops, the addition of hydrotalcite also has no effect on the amount of arsenic absorbed by crops, while the amount of arsenic absorbed by the crops is significantly reduced when the soil conditioner 3 is added, and when the addition amount is 2.5%, it decreases by 0.63ug/pot, which is a decrease of 8.69%. , when the addition amount was 5%, it decreased by 2.44ug/pot, a decrease of 33.66%. This result shows that after applying the soil conditioner of the present invention in soil with higher arsenic content, the arsenic content of plants can be reduced, and the absorption of arsenic by crops can be reduced, so that it becomes safe to plant crops in soil with arsenic content slightly exceeding the standard. possible.

The prepared product contains rich oxides of Mg, Al and Fe, etc., which has a strong ability to fix arsenic and a large fixing capacity, and can fix arsenic in solution and soil and lose its activity. However, after corn stalks are turned into biomass coke by carbonization, the stability in the soil is very strong, and in the early stage of the present invention, after being mixed with hydrotalcite and iron phosphate for 3-4 days, the cellulose of corn stalks can be made under alkaline conditions. Softening, partial mineral dissolution, etc., so its specific surface area is larger than that of direct preparation of biomass char, which greatly increases the surface area of the prepared product, making it more capable of absorbing and fixing arsenic plasma in the soil. According to the results of the preliminary test, the conditioner prepared by the method of the present invention has a 5-10 times higher ability to fix arsenic in water than that before simple mixing of the above substances, and the fixed arsenic is difficult to be desorbed. The application of the conditioning agent of the present invention has better arsenic passivation function on farmlands with excessive arsenic content, can effectively reduce the absorption and conversion of arsenic by crops, and achieve the purpose of high-quality and safe production of crops.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any skilled person may make some changes and modifications without departing from the spirit and scope of the present invention.

Claims (6)

1. a soil conditioner is characterized in that, counts by weight percentage to comprise: 55%～65% magnesium, Al bimetal oxide compound, 20%～30% straw biomass is burnt, and 10%～20% tertiary iron phosphate.

2. according to the described soil conditioner of claim 1, it is characterized in that,

Said 20%～30% biomass char is that 40～50% agricultural crop straws are generated through carbonization, and said agricultural crop straw comprises one or more in paddy rice, millet and the corn straw.

3. according to the described soil conditioner of claim 1, it is characterized in that,

Said 55%～65% magnesium, Al bimetal oxide compound obtain through 55%～65% levigated magnesium aluminum-hydrotalcite.

4. the preparation method of a soil conditioner as claimed in claim 1 is characterized in that, comprises the steps:

By the preparation gross weight is the soil conditioner calculating of double centner altogether, takes by weighing following material: 55～65kg levigated hydrotalcite, the corn straw that 40～50kg pulverizes, 10～20kg levigated tertiary iron phosphate; With the material uniform mixing that takes by weighing, and water is moistening can water outlet when holding in hand till, form mixture;

Said mixture is covered with plastics film; And be deposited in indoor 3 to 4 days, and place charring furnace then, under the state of sealing relatively, slowly be heated to 490～520 ℃; And keep stopping after 2.8～3.2 hours heating; Make after the mixture of slow heating cools off gradually and take out, levigate and mistake 0.20～0.30mm sieve makes said soil conditioner.

5. the application aspect the arsenic toxicity of a soil conditioner as claimed in claim 1 in reducing soil.

A soil conditioner as claimed in claim 1 in reducing soil crop to the application aspect the arsenic absorption.

Therefore protection scope of the present invention when with aforementioned claims the person of being defined be as the criterion.

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