CN110387239B

CN110387239B - Soil conditioner for fly ash land and preparation method and soil conditioning method thereof

Info

Publication number: CN110387239B
Application number: CN201910516440.5A
Authority: CN
Inventors: 黄占斌; 李昉泽; 母振庆; 黄娟; 马妍; 李小华; 濮阳雪华; 杜林峰; 王平; 王惠芳
Original assignee: Beijing Beilin Advanced Ecological Environmental Protection Technology Institute Co ltd; Shenzhen Techand Ecology and Environment Co Ltd
Current assignee: Beijing Beilin Advanced Ecological Environmental Protection Technology Institute Co ltd; Shenzhen Techand Ecology and Environment Co Ltd
Priority date: 2019-06-14
Filing date: 2019-06-14
Publication date: 2021-05-14
Anticipated expiration: 2039-06-14
Also published as: CN110387239A

Abstract

The invention relates to a soil conditioner for a fly ash field, a preparation method thereof and a soil conditioning method. The soil conditioner for the fly ash land mainly comprises the following components in percentage by mass: 70-75% of modified humic acid, 0.4-0.8% of water-retaining agent, 20-25% of zeolite and 2-6% of black alum; the modified humic acid is at least one of ammoniated humic acid, potassium humate and sodium humate. The soil conditioner for the fly ash land provided by the invention takes the modified humic acid, the water-retaining agent, the melanterite and the zeolite as main components, improves the soil volume weight, the specific gravity, the water content and the void structure of the fly ash land, can effectively solve the problems of low soil volume weight, loose soil quality and poor water and fertilizer retention capability of the fly ash soil, promotes the formation of a water-stable granular structure, improves the soil structure, promotes the mineralization of nutrient elements, reduces the pH value of the soil and finally realizes the improvement of the crop yield.

Description

Soil conditioner for fly ash land and preparation method and soil conditioning method thereof

Technical Field

The invention belongs to the field of soil conditioners, and particularly relates to a soil conditioner for a coal ash field, a preparation method of the soil conditioner and a soil conditioning method.

Background

The fly ash is a silver gray and gray granular body with different sizes and irregular shapes, the mass percentage of mineral mullite in the fly ash is 50-80%, and the mass percentage of alpha-quartz is about 20%. The fly ash is rich in Si, Ca, Fe, Mg elements and some trace elements such as S, B, Zn, Cu and the like.

Fly ash from fly ash sites originates from coal fired power plants. The fly ash land is a land covered by pure fly ash or the soil with the fly ash accounting for more than 80 percent of the soil weight. Compared with natural farmland, the fly ash land has the outstanding problem of low volume weight (often 1 g/cm)³Below), less than the recommended soil volume weight requirement (1-1.25 g/cm) for agricultural land³) Moreover, the soil water retention capacity of the fly ash is extremely poor, and water can rapidly seep downwards, so that crops cannot be fully utilized; second is the diameter of the soil aggregate>The water-stable aggregate with the thickness of 0.25mm accounts for a lower proportion, and influences the normal growth and reproduction of soil microorganisms; more importantly, the soil fertility of the fly ash is lower than the normal soil fertility; in addition, the soil of the fly ash land has the problem of heavy metal pollution. In conclusion, the fly ash land has low soil productivity, poor water and fertilizer retention capacity, weak drought resistance and stress resistance, low crop yield and heavy harvested productsThe content of metal exceeds the standard.

The existing soil conditioner is mostly applied to soil such as a tailing pond, and for example, the application publication number of the Chinese patent application with the Chinese patent application No. CN106365908A discloses a tailing pond soil conditioner and an application method thereof. The tailing pond soil is sandy soil, and has high volume weight, tight soil adhesion, poor air permeability and low organic matter content. In contrast, the improvement strategy of the tailings pond soil mainly reduces the volume weight of the soil and improves the permeability of the soil. The soil (fly ash soil) characteristics of the fly ash land are greatly different from those of the soil of the tailing pond, and the prior art also lacks a soil conditioning method for the fly ash land.

Disclosure of Invention

The invention aims to provide a soil conditioner for a coal ash field, which solves the problem that the existing soil conditioner cannot improve the soil structure of the coal ash field.

The second purpose of the invention is to provide a preparation method of the soil conditioner for the coal ash land, which is used for solving the problem that the existing soil conditioner cannot improve the soil structure of the coal ash land.

The third purpose of the invention is to provide a method for conditioning soil in the fly ash field, so as to solve the problem that the soil conditioning effect of the existing method on the fly ash field is poor.

In order to achieve the purpose, the technical scheme of the soil conditioner for the fly ash field is as follows:

a soil conditioner for a coal ash field mainly comprises the following components in percentage by mass: 70-75% of modified humic acid, 0.4-0.8% of water-retaining agent, 20-25% of zeolite and 2-6% of black alum; the modified humic acid is at least one of ammoniated humic acid, potassium humate and sodium humate.

In the soil conditioner, the sum of the mass percentages of the modified humic acid, the water-retaining agent, the zeolite and the melanterite is 100 percent.

The soil conditioner for the fly ash land provided by the invention takes the modified humic acid, the water-retaining agent, the melanterite and the zeolite as main components, improves the soil volume weight, the specific gravity, the water content and the void structure of the fly ash land, can effectively solve the problems of low soil volume weight, loose soil quality and poor water and fertilizer retention capability of the fly ash soil, promotes the formation of a soil water-stable granular structure, improves the soil structure, promotes the mineralization of organic nutrient elements, reduces the pH value of the soil and finally realizes the improvement of the crop yield.

In the aspect of soil improvement of the fly ash land, the modified humic acid can activate functional groups in the humic acid, and hydroxyl and carboxyl in the functional groups are easy to generate condensation reaction with calcium ions in soil, so that the formation of a soil aggregate structure can be promoted; in addition, the modified humic acid is a high-efficiency organic fertilizer, can improve the content of quick-acting potassium and nitrogen in soil, increase the nutrient absorption and utilization rate of crops, and promote the growth of the crops. The water-retaining agent can increase the water content of the soil through two modes of water absorption, swelling and the like, can effectively improve the water environment of the rhizosphere of crops, directly provides the water stored by the water-retaining agent for the crops, promotes the formation of a soil aggregate structure, particularly quickly increases macro aggregate, and increases the volume weight of the soil while maintaining the high porosity of the soil; the black alum generates Fe (OH) after being added into soil₃Precipitation and CO₂，CO₂After formation, the soil can be swelled and loosened, and Fe³⁺And CaSO₄All have certain adhesiveness, and clay grains of the soil are adhered together to promote the formation of a new soil structural unit. The zeolite is a porous material with large specific surface area, has good ion exchange and exchange selectivity, can loosen soil, improve the utilization effect of fertilizer, improve the fertilizer retention capacity of the soil and improve the soil structure; the fertilizer has the effects of controlling nitrogen and releasing phosphorus on soil nutrients, can better promote the water and fertilizer retention capacity of the fly ash soil after soil dressing is added, and simultaneously has the effects of adsorbing and passivating harmful metal elements such as cadmium and lead in the fly ash soil and reducing heavy metal pollution. The components are reasonably matched, and the synergistic promotion effect is realized on the formation of the fly ash soil aggregate and the improvement of the soil structure.

In the aspect of influence on the pH value of the fly ash soil, the modified humic acid, the water-retaining agent and the melanterite can reduce the pH value of the fly ash soil through acid-base neutralization or exchange action, so that the activity of soil microorganisms and related enzymes is directly or indirectly improved.

In the aspect of passivation of heavy metals, the humic acid, the water-retaining agent and the zeolite can adsorb the heavy metals in the soil through the actions of hydrogen bonds or pi-pi bonds and the like, so that the content of the heavy metals in the soil is reduced.

In order to further improve the conditioning effect of the ammoniated humic acid on the soil structure, the ammoniated humic acid is preferably prepared by a method comprising the following steps: and (3) crushing weathered coal, uniformly mixing the weathered coal with ammonia water, sealing and curing for more than one week to obtain the finished product.

The technical scheme of the preparation method of the soil conditioner for the fly ash land is as follows:

a preparation method of a soil conditioner for a coal ash field comprises the following steps: mixing the water-retaining agent and the zeolite powder to obtain a premix; and mixing the premix with modified humic acid and black alum to obtain the finished product.

According to the preparation method of the soil conditioner for the fly ash land, provided by the invention, the premix, the modified humic acid and the melanterite are mixed, so that the agglomeration phenomenon caused by the mixing of the water-retaining agent and the raw materials possibly containing water (the modified humic acid and the melanterite) can be avoided, and the raw materials are mixed more uniformly. The obtained soil conditioner has good improvement effect on the soil structure of the fly ash soil.

In order to further promote the uniform mixing of the raw materials, preferably, the premix, the modified humic acid and the black alum are mixed to obtain a mixture, and the mixture is ground. The particle sizes of various ground raw materials are close to each other and are uniformly mixed, so that the raw materials are prevented from being separated in a layered manner, and the soil conditioning effect can be quickly exerted.

The technical scheme of the soil conditioning method of the fly ash land is as follows:

a soil conditioning method for a coal ash field comprises the following steps: uniformly spreading the soil conditioner on the soil surface, and ploughing; the soil conditioner mainly comprises the following components in percentage by mass: 70-75% of modified humic acid, 0.4-0.8% of water-retaining agent, 20-25% of zeolite and 2-6% of black alum; the modified humic acid is at least one of ammoniated humic acid, potassium humate and sodium humate.

The soil conditioning method for the fly ash land provided by the invention promotes the fly ash soil to be rapidly changed into the soil available for the cultivated land to the maximum extent, not only can preserve water and fertilizer and promote plant growth, but also can reduce the content of heavy metal in the soil, and the soil conditioner and the heavy metal reach a reaction stable state after being improved by the soil conditioner for about one month, and the content of the soil exceeding the standard heavy metal in an effective state is reduced to be within the standard; can also adjust the micro-ecological environment of the soil, improve the species of soil microorganisms and promote the growth and the propagation of the soil microorganisms. Meanwhile, the soil conditioning method has the advantages of simple process, low energy consumption, low cost, lasting stability, easiness in industrial production and better economic and environmental benefits.

In order to further improve the granular structure and the water and fertilizer retention capacity of the fly ash soil, preferably, the soil conditioner is applied by adding additional soil to the fly ash land and ploughing.

In order to further improve the conditioning effect on the soil structure, it is preferable to add the alien soil in an amount of 10 to 40 wt% based on the weight of the soil at a depth of 30cm in the fly ash field. The method for calculating the soil weight of the fly ash land with the depth of 30cm comprises the following steps: the volume weight of soil with the acre multiplied by 30cm depth obtains the weight of the added alien soil according to 10-40 wt% of the soil weight, and then obtains the addition amount of the alien soil according to the volume weight of the alien soil.

From the aspects of cost and conditioning effect on soil, the dosage of the soil conditioner is preferably 600-1200kg per mu. In order to further increase the soil fertility of the fly ash field, the soil conditioner preferably further comprises a chemical fertilizer, and the dosage of the chemical fertilizer is 100-200kg per mu.

In order to promote the physicochemical reaction of the soil conditioner and the soil, preferably, the soil conditioner is irrigated after ploughing to promote the soil conditioning reaction, and then agricultural planting is carried out for more than 10 days.

Detailed Description

The following examples are provided to further illustrate the practice of the invention. In the following examples, the water-retaining agent is selected to satisfy the agricultural department standard NY/T886-Has hydrophilic functional groups such as carboxyl, hydroxyl, quaternary ammonium salt and the like, and has good water absorption and swelling effects. The zeolite powder meets the national standard GB/T21695-. In ferrous sulfate, FeSO₄·7H₂The mass content of O is more than 90 percent. The potassium humate meets the national standard GB/T33804-2017.

The ammoniated humic acid is prepared by the following method: drying and crushing weathered coal (which is sieved by a 60-mesh sieve and has the moisture content of less than or equal to 15%) to obtain weathered coal powder; spraying 15% ammonia (containing ammonia (NH)) to the weathered coal powder₃) 15-25 percent) and the mass ratio of ammonia water to weathered coal powder is 1:2, and the mixture is sealed and cured for 7 days to obtain the air-dried pulverized coal.

The concrete examples of the soil conditioner for the fly ash land of the invention are as follows:

example 1

The soil conditioner for the fly ash field in the embodiment comprises the following components in percentage by mass: 72.4 percent of potassium humate, 0.6 percent of polymer water-retaining agent, 23 percent of zeolite powder and 4 percent of black alum.

Example 2

The soil conditioner for the fly ash field in the embodiment comprises the following components in percentage by mass: 72.4 percent of ammoniated humic acid, 0.6 percent of polymer water-retaining agent, 23 percent of zeolite powder and 4 percent of black alum.

Example 3

The soil conditioner for the fly ash field in the embodiment comprises the following components in percentage by mass: 73.6 percent of ammoniated humic acid, 0.4 percent of polymer water-retaining agent, 20 percent of zeolite powder and 6 percent of black alum.

Example 4

The soil conditioner for the fly ash field in the embodiment comprises the following components in percentage by mass: 72.2 percent of ammoniated humic acid, 0.8 percent of polymer water-retaining agent, 25 percent of zeolite powder and 2 percent of black alum.

In other embodiments of the soil conditioner for fly ash fields of the invention, auxiliary materials such as chemical fertilizers (the adding amount of the chemical fertilizers is 100 plus 200 kg/mu) and the like can be further added on the basis of the components of the soil conditioner embodiments so as to accelerate the conditioning process of the soil.

The concrete embodiment of the preparation method of the soil conditioner for the fly ash land of the invention is as follows:

example 1

This example illustrates the preparation of soil conditioner example 1, which specifically includes the following steps: mixing the water-retaining agent and the zeolite powder, adding potassium humate and black alum, and mixing to obtain a mixture; and grinding the mixture, and sieving the mixture by a 100-mesh sieve to obtain the powder.

Example 2

This example illustrates the preparation of soil conditioner example 2, which specifically includes the following steps: mixing the water-retaining agent and the zeolite powder uniformly, and then adding ammoniated humic acid and black alum and mixing uniformly to obtain a mixture; and grinding the mixture, and sieving the mixture by a 100-mesh sieve to obtain the powder.

Examples 3 to 4

Examples 3 to 4 of the method for preparing the soil conditioner for fly ash fields, reference is made to the method for preparing the soil conditioner example 2 of preparing the soil conditioner examples 3 to 4, respectively.

The concrete embodiment of the soil conditioning method of the fly ash land of the invention is as follows:

example 1

The soil conditioning method for the fly ash field comprises the following steps: uniformly spreading the soil conditioner on the surface of the soil to be conditioned, and then carrying out rotary tillage by using a rotary cultivator to fully mix the soil and the soil conditioner, wherein the rotary tillage depth is 20-30 cm; the land surface is finished, the ridge is drawn, the irrigation is carried out (the physical and chemical reaction of the conditioner and the soil is accelerated), and the irrigation water amount is 60-80m per mu³The conditioner and the soil are subjected to physicochemical reaction for more than 10 days, and then the farming operation can be carried out.

In this example, the soil conditioner includes a main material and an auxiliary material, the main material and the soil conditioner in example 1 have the same composition and ratio, and the auxiliary material is a chemical fertilizer. The addition amount of the main material is 900 kg/mu, and the addition amount of the auxiliary material is 120 kg/mu.

Example 2

The soil conditioning method for the fly ash field comprises the following steps: adding loess (volume weight of 1.6-1.8 g/cm) into the soil surface of the fly ash field³) In an amount ofThe soil with the depth of 30cm is 10 percent of the weight of the soil, a rotary cultivator is used for rotary tillage after the soil is manually paved, and the rotary tillage depth is 20-30 cm; then uniformly spreading the soil conditioner on the surface of the soil, and carrying out rotary tillage by using a rotary cultivator to fully mix the soil and the soil conditioner, wherein the rotary tillage depth is 20-30 cm; the land surface is finished, the ridge is drawn, the irrigation is carried out (the physical and chemical reaction of the conditioner and the soil is accelerated), and the irrigation water amount is 60-80m per mu³The conditioner and the soil are subjected to physicochemical reaction for more than 10 days, and then the farming operation can be carried out.

In this example, the composition of the main material and the auxiliary material of the soil conditioner was the same as that of example 1 of the soil conditioning method.

Example 3

The method for conditioning soil in fly ash field of this example is substantially the same as the soil conditioning method of example 2 except that loess (extra soil) is added in an amount of 30% by weight based on the soil at a depth of 30cm in the field.

Example 4

The method for conditioning soil in fly ash field of this example is substantially the same as the soil conditioning method of example 2 except that loess (extra soil) is added in an amount of 40% by weight based on the soil at a depth of 30cm in the field.

Example 5

The soil conditioning method of the fly ash land in the embodiment is basically the same as the soil conditioning method in the embodiment 2, and the difference is only that (1) the soil conditioner comprises a main material and an auxiliary material, the main material and the soil conditioner in the embodiment 2 have the same components and proportion, and the auxiliary material is a chemical fertilizer. The addition amount of the main material is 900 kg/mu, and the addition amount of the auxiliary material is 120 kg/mu. (2) The addition amount of loess (extra soil) is 20% of the weight of soil with a depth of 30cm in the land.

Example 6

The soil conditioning method of the fly ash field in the embodiment is basically the same as the soil conditioning method in embodiment 2, and the difference is that (1) the soil conditioner comprises a main material and an auxiliary material, wherein the addition amount of the main material is 600 kg/mu, and the addition amount of the auxiliary material is 120 kg/mu. (2) The addition amount of loess (extra soil) is 20% of the weight of soil with a depth of 30cm in the land.

Example 7

The method for conditioning soil in fly ash field of this example is substantially the same as the soil conditioning method of example 2 except that loess (extra soil) is added in an amount of 20% by weight based on the soil at a depth of 30cm in the field.

Example 8

The soil conditioning method of the fly ash field in the embodiment is basically the same as the soil conditioning method in embodiment 2, and the difference is that (1) the soil conditioner comprises a main material and an auxiliary material, wherein the addition amount of the main material is 1200 kg/mu, and the addition amount of the auxiliary material is 120 kg/mu. (2) The addition amount of loess (extra soil) is 20% of the weight of soil with a depth of 30cm in the land.

Examples of the experiments

The present experimental example explains the practical application effect of the soil conditioner and the soil conditioning method of the present invention.

The experimental fly ash land is located on a belt of Handan City concerned with county and village in Hebei province, large-area fly ash land parcels are distributed in a local agricultural land, the thickness of the fly ash is more than 20cm, 4 villages related to Zhuang, Huyu, Shigang and lianquan are involved, and the area of the range is about 3500 mu. The fly ash soil in the experimental area has high content of harmful elements Cd, Pb and Hg, the content of water-soluble salt in the fly ash soil is generally high, the pH value is alkaline, beneficial elements Se and B are rich, the soil structure is loose, and the soil energy-holding capacity is poor.

In the experimental area, a land sample with the length of 31m and the width of 22m is divided into 9 groups, each group is divided into 3 parallel groups, the total number of the groups is 27, each group is 7.6m in length and 3.4m in width, and the basic properties of the experimental land are shown in the table 1.

TABLE 1 basic Properties of the soil tested

The differences between the treatments are shown in Table 2, soil conditioning was carried out according to the method of example, and soil samples were collected 10 days after the physicochemical reaction for analysis. In Table 2, the A0 treatment is to add fertilizer only to the soil of the fly ash field, and the treatments such as rotary tillage and irrigation are consistent with other soil conditioning method examples.

TABLE 2 soil conditioning experiment on fly ash land according to different soil conditioning method embodiments

(1, A1-A8 treatments correspond to soil conditioning method examples 1-8, respectively, and A1-A8 treatments in tables 3-7 have the same meaning.2. soil conditioner G1, soil conditioner G2 correspond to the components of soil conditioner example 1, soil conditioner example 2, respectively.)

The physical properties of the conditioned soil were measured and the results are shown in table 3.

TABLE 3 Effect of different treatments on soil bulk weight, specific gravity and porosity

From the results in table 3, it can be seen that the addition of the soil conditioner and the soil conditioner has an obvious effect on the volume weight, specific gravity and porosity of the soil, and the addition of the soil conditioner alone can increase the volume weight and specific gravity of the soil, reduce the porosity of the soil and increase the capillary porosity of the soil (the part of the soil that is effective for plants to store water). In the treatment of simultaneously adding the soil conditioner and the alien soil, the A5 treatment effect is best, the volume weight of the soil is increased to the maximum, the growth rate of the comparison blank group is 102%, the specific gravity growth rate is 20.8%, the porosity of the capillary is also the maximum, and the improvement on the water retention capacity of the soil is strongest.

The results of the different treatments optimized for soil water stable agglomerates are shown in table 4.

TABLE 4 Effect of different treatments on soil Water-stable agglomerates

From the results in table 4, it can be seen that the content of macro aggregates with a diameter of >2mm in the soil is increased after the soil conditioner is added to the fly ash land, and the content of the macro aggregates is increased more obviously by the alien soil. The soil aggregate improvement effect in all treatments was best the A5 treatment, with a 517.5% increase in large aggregates with a diameter >2mm compared to the A0 blank; agglomerates >0.25mm in diameter, with a growth rate of 4.8%.

The effect of the different treatments on soil chemistry is shown in table 5.

TABLE 5 Effect of different treatments on soil chemistry

As can be seen from Table 5, after soil conditioning is performed by adding the alien soil and the soil conditioner, the pH of the soil is not changed obviously, and other chemical components of the soil are changed differently. The addition of only the soil conditioner, a1, compared to the a0 treatment, reduced the overall total nutrients (total N, P, K and organic matter) of the soil, but increased the available P and K. Meanwhile, soil dressing and a soil conditioner are added for soil conditioning, the increase of alkaline hydrolysis N is obvious, wherein A3 and A4 are experimental areas with soil dressing amount of 30% and 40% respectively, the content of alkaline hydrolysis N is obviously reduced due to the fact that the soil dressing amount is higher than that of other processing areas, the soil conditioner added in the A8 processing is 1200 kg/mu, due to the fact that the content of ammoniated humic acid is increased, the slow release effect is achieved on the release of nitrogen in the soil, the application amount of ammoniated humic acid in the A8 processing is the largest, the release of alkaline hydrolysis nitrogen is slow, and therefore the content of alkaline hydrolysis nitrogen is the lowest.

Compared with the contrast, the organic matter content of each treatment is reduced in different degrees, which shows that the soil conditioner promotes the mineralization of organic nutrient elements in the fly ash soil, promotes the release of N, P, K and improves the absorption and utilization of crops.

The contents of heavy metal elements Cd, Pb, and Hg in the conditioned soil were measured, and the results are shown in table 6.

TABLE 6 Effect of different treatments on heavy metals in the soil (unit: g/kg)

From the results in table 6, it can be seen that the conditioning method of the example is effective in reducing the heavy metal content in the soil compared to the a0 treatment, wherein the maximum reduction in Pb is 66%, the maximum reduction in Cd is 74%, and the maximum reduction in Hg is 92%. The best effect for reducing the heavy metal content is A5 treatment, which can realize 58% reduction of Pb, 74% reduction of Cd and 92% reduction of Hg. The reason for the reduction of the content of heavy metal elements is that: firstly, the content concentration of the fly ash soil is diluted by adding the soil dressing, and secondly, the heavy metal in the soil is conditioned by the soil conditioner, so that part of the heavy metal leaks into the deep layer of the soil.

Corn is planted on the conditioned soil, the planting density is 5500 plants/mu, the row spacing of the plants is 40 multiplied by 30cm, after the corn is mature, the corn in each cell is taken, the dry weight and the hundred-grain weight of the corn are measured and calculated, and the result is shown in table 7.

TABLE 7 Effect of different treatments on corn yield

From the results in table 7, it can be seen that the addition of a soil conditioner significantly improved the yield of corn compared to the treatment with a0 and a 1; the comparison of the treatments A2, A3, A4 and A7 shows that the weight of the corn grains is increased after the soil dressing is increased, the yield is increased, and the yield of the A7 treatment (the soil dressing amount is 20 percent) is increased to the highest extent and is increased by 94.52 percent compared with the A0; compared with the treatment of A7, the soil conditioner G2 has better effect than G1 and has high growth rate on the corn yield; by combining the treatments, the yield of the corn is increased to the highest level by the A5 treatment, and the yield reaches 116.81%.

An economic analysis of soil conditioning on fly ash fields is shown in table 8.

TABLE 8 statistical results of the economics of soil conditioning of fly ash fields

The experimental results show that the method of 'foreign soil plus soil conditioner' for conditioning the soil in the fly ash field has the characteristics of short conditioning period, quick response, low cost, obvious soil conditioning effect, obvious crop promotion effect and the like. The method provided by the invention has the advantages that the volume weight of the soil in the fly ash field is obviously improved, the proportion of large aggregates in the fly ash soil is increased, the physical structure of the fly ash soil is improved, the maintenance of water and fertilizer is facilitated, the passivation effect on excessive heavy metals such as Pb, Cd and Hg in the fly ash soil is obvious, the national use standard is reached, the crops grow well after being planted with the crops, and the yield is increased.

Claims

1. The method for improving the coal ash land by using the soil conditioner is characterized in that the soil conditioner mainly comprises the following components in percentage by mass: 70-75% of modified humic acid, 0.4-0.8% of water-retaining agent, 20-25% of zeolite and 2-6% of black alum; the modified humic acid is at least one of ammoniated humic acid, potassium humate and sodium humate; the improvement method comprises the following steps: uniformly spreading the soil conditioner on the soil surface, and ploughing; before the soil conditioner is spread, the volume weight of the soil conditioner is added into the fly ash land and is 1.6-1.8g/cm³Ploughing the loess; adding loess according to 10-40 wt% of soil weight at 30cm depth of the fly ash field; the dosage of the soil conditioner is 600-1200kg per mu.

2. The method according to claim 1, wherein the ammoniated humic acid is produced by a process comprising the steps of: and (3) crushing weathered coal, uniformly mixing the weathered coal with ammonia water, sealing and curing for more than one week to obtain the finished product.

3. The method of claim 1, wherein the soil conditioner further comprises a fertilizer, and the fertilizer is used in an amount of 100 kg/mu.

4. The method of claim 1, wherein the cultivation is followed by irrigation to promote soil conditioning and further agricultural planting is carried out over 10 days.