1. The salinized soil composite improver produced by utilizing the agricultural waste is characterized by comprising the following components in percentage by mass:

50-60% of sludge of the agricultural sewage facility, 30-40% of crop production waste, 5-10% of fly ash and 0.03-0.05% of PAM.

2. The compound saline soil conditioner produced by using agricultural waste is characterized in that the sludge of the agricultural waste is waste and/or residual sludge produced by rural domestic sewage treatment facilities, the water content is 60-80 wt%, the waste produced by crops is straw particles cut into the length of 2-3mm, the particle size of the fly ash is 0.03-0.05 mm, the molecular weight of PAM is 1200 ten thousand, and the hydrolysis degree is 30%.

3. The compound improver for salinized soil produced by using agricultural and sewage wastes according to claim 2, wherein the fly ash is fine ash formed after coal used in a thermal power plant is combusted in a boiler and is carried out of a hearth by smoke.

4. The preparation method of the salinized soil composite improver produced by utilizing the agricultural waste is characterized by uniformly mixing 50-60% of agricultural waste facility sludge, 30-40% of crop production waste and 5-10% of fly ash by mass, then carrying out aerobic composting for 15 days at normal temperature, then carrying out anaerobic composting fermentation for 40-50 days to obtain humus, adding 0.03-0.05% of PAM into the humus, and stirring and uniformly mixing to obtain the soil composite improver.

5. The preparation method of the salinized soil composite improver produced by utilizing the agricultural waste, according to claim 4, is characterized in that the agricultural waste is waste and/or excess sludge produced by rural domestic sewage treatment facilities, the water content is 60-80 wt%, the crop production waste is straw particles cut into the length of 2-3mm, the particle size of the fly ash is 0.03-0.05 mm, the molecular weight of PAM is 1200 ten thousand, and the hydrolysis degree is 30%.

6. The method for preparing the saline soil composite improver produced by utilizing the agricultural waste, according to claim 4, is characterized in that the waste and/or the excess sludge produced by the rural domestic sewage treatment facility are dehydrated by a plate-frame filter pressing system, and the carbon-nitrogen ratio of the mixed sludge of the agricultural waste facility, the crop production waste and the fly ash is 30-35.

7. The method for preparing the saline soil composite improver produced by utilizing the agricultural waste, according to claim 5, is characterized in that the fly ash is fine ash which is formed after coal used in a thermal power plant is combusted in a boiler and is carried out of a hearth by flue gas.

8. A preparation method of a salinized soil composite modifier produced by utilizing agricultural wastes is characterized by comprising the following steps:

step 1, sludge dewatering, namely, uniformly collecting waste or excess sludge generated by rural domestic sewage treatment facilities, dewatering by adopting a mechanical dewatering mode to finally obtain an organic material with the water content of 60-80 percent to obtain agricultural operation and maintenance waste,

step 2, preparing auxiliary materials, collecting the waste generated in the agricultural production system, crushing the waste into 2-3mm particles by using a crusher for later use to obtain the agricultural production waste,

step 3, obtaining fly ash, collecting the fly ash produced by a thermal power plant, wherein the particle size of the fly ash is about 0.03-0.05 mm,

step 4, composting is mixed, namely, the agricultural and sewage transport and maintenance waste in the step 1, the agricultural production waste in the step 2 and the fly ash in the step 3 are mixed uniformly according to the weight ratio of 5:3:1, aerobic composting is carried out for 15 days at normal temperature, and then anaerobic composting fermentation is carried out for 40-50 days to obtain humus,

and 5, adding PAM, namely adding the PAM with the molecular weight of 1200 ten thousand and the hydrolysis degree of 30% into the humus obtained in the step 4 according to the proportion of 0.05 wt%, and uniformly mixing to obtain the final soil composite improver.

9. The compound saline soil conditioner produced by using agricultural waste according to claim 1, wherein the waste and/or excess sludge produced by the rural domestic sewage treatment facility is dewatered by a plate-and-frame filter pressing system, the carbon-nitrogen ratio of the mixed sludge of the agricultural waste facility, the crop production waste and the fly ash is 30-35, and the fly ash in the step 3 is fine ash which is formed after coal used in a thermal power plant is combusted in a boiler and is carried out of a hearth by smoke.

10. The application of the soil composite modifier produced by using the agricultural waste in the saline soil according to any one of claims 1 to 9 is characterized in that:

step 1, selecting a salinized farmland, controlling the pH value of soil of the salinized land to be repaired to be 8.5-9.0,

and 2, spreading the composite soil conditioner for repairing the salinized farmland, wherein the mass of the soil composite conditioner spread in each mu of soil is 7.5-15 tons.

Background

The agricultural waste is a general term of waste discharged in agricultural production, agricultural product processing, livestock and poultry breeding industry and rural residents. If the untreated agricultural waste is directly discarded, the environment can be polluted. If untreated animal wastes are discharged into rivers and lakes, the water quality is polluted, the Biochemical Oxygen Demand (BOD) load is increased, the anaerobic decay or eutrophication phenomenon is formed, and the survival of fishes, shellfishes and algae is threatened; diseases can be infected, and the health of residents is affected; if the fertilizer is properly treated, the fertilizer can become an important organic fertilizer source. Therefore, effective disposal and utilization of agricultural waste is a major issue in the field of ecological environment protection.

On the other hand, soil is the foundation of agricultural production and is also the most important natural resource of human life, but if the use mode of human is improper, such as the planting age of crops is continuously prolonged, and a large amount of fertilizer is input blindly, the salt content in the soil is continuously increased, and further the problem of secondary salinization of the soil is caused. The salinized soil contains a large amount of Na⁺、Cl^-、HCO₃ ^-Plasma, which causes a decrease in air and water permeability of the soil, a decrease in nutrient availability, and hardening of the soil more easily, and also a deterioration in the tiltability of the soil. In addition, the saline soil contains excessive soluble salts, which can cause the osmotic pressure of the soil solution to be high and the water potential to be reduced, and directly affect the normal absorption of the crops to the water, and on the other hand, the crops can cause the excessive absorption of partial ions to inhibit the absorption of other nutrient ions, thereby affecting the normal growth and reproduction of the crops and finally causing the reduction of the yield and the quality of the crops. At present, the salinized farmland of 7.60 multiplied by 10 exists in China⁶hm²The land-based cultivation method for the agricultural crops occupies 20.0% of the total land cultivation area in China, and has a growing trend in the future, and along with the fact that the demand of people for grain safety is higher and higher in recent years, the demand for land resources is expanded. In order to meet the requirement, the large amount of salinized soil in China is in urgent need of repair and utilization, and the research and development of an efficient salinized soil repair technology is one of important ways for solving the problem.

Aiming at the characteristics of high salinity, low nutrient content, poor structure and the like of the salinized soil, the current main repairing methods comprise a microorganism repairing method, a biochar repairing method, a biological organic fertilizer repairing method and the like. The biological organic fertilizer contains various functional microorganisms, the microorganisms play a role in promoting the formation of soil granular structures, the total amount of water-soluble salt and the pH value of the salinized soil can be obviously reduced, the soil fertility can be effectively improved, and therefore the biological organic fertilizer has a better repairing effect on the salinized soil. If researches show that the biological organic fertilizer is applied to the saline soil, the activities of spike leaf catalase, superoxide dismutase and peroxidase in each growth period of the corn can be improved, the salt resistance of the corn is improved, and the yield of the corn is further improved. In addition, the technology for improving the soil fertility by using nutrient substances contained in the sludge is also available at present, the technology can improve the microbial activity and further promote the plant growth, and the sludge is recycled while the sludge disposal problem is solved. In addition, the sludge recycling can reduce the dependence of agriculture on chemical fertilizers to a certain extent, is beneficial to solving the problems of soil hardening, salinization, surface runoff and underground water pollution and the like caused by long-term application of the chemical fertilizers, and conforms to the concept of green sustainable development in the new era of China.

For example, the invention patent in China, which has the patent application number of 201710101917.4 and is named as 'an organic matter soil repairing agent, a preparation method and application thereof in sludge digestion', discloses a preparation method of the organic matter soil repairing agent. The preparation method comprises the following steps: 1) pretreating a sludge raw material; 2) preparing a compound microbial agent; 3) fermenting the compound microbial agent; 4) preparing organic matter degrading bacteria group. The specific implementation scheme is as follows: the method is used for carrying out innocent treatment on the urban sewage sludge in the early stage. After the sludge repairing agent is used for 1-6 months through experiments, the proportion effective removal rate of various pollutants in the soil reaches more than 95% and meets the national standard, and meanwhile, the fermentation product can acidify hardened saline land and is also a good organic fertilizer, so that the use of chemical reagents and chemical fertilizers in agricultural production is facilitated, and pollution sources and secondary pollution are avoided from the source. However, the technical scheme has the following disadvantages: although the soil remediation scheme taking the municipal sludge as the main substrate can improve the physicochemical properties of soil and increase the soil fertility, the application of the municipal sludge in salinized land is restricted by the potential ecological environment risk of heavy metals contained in the sludge due to the overhigh content of the heavy metals in the municipal sludge, and the higher pH of the salinized soil can promote the dissolution of organic matters in sludge compost products and the release of the heavy metals, thereby increasing additional environmental risks.

Disclosure of Invention

The invention aims to solve the problems and provides a salinized soil composite modifier produced by utilizing agricultural waste.

The invention also aims to provide a preparation method of the salinized soil composite modifier produced by utilizing the agricultural waste.

The invention further aims to provide application of the soil composite improver produced by utilizing the agricultural waste in salinized soil.

In order to achieve the purpose, the invention adopts the following technical scheme:

a saline soil composite modifier produced by utilizing agricultural wastes comprises the following components in percentage by mass: 50-60% of sludge of the agricultural sewage facility, 30-40% of crop production waste, 5-10% of fly ash and 0.03-0.05% of PAM.

In the salinized soil composite modifier produced by utilizing the agricultural waste, the sludge of the agricultural waste is waste and/or residual sludge produced by rural domestic sewage treatment facilities, the water content is 60-80 wt%, the waste produced by crops is straw particles cut into the length of 2-3mm, the particle size of the fly ash is 0.03-0.05 mm, the molecular weight of PAM is 1200 ten thousand, and the hydrolysis degree is 30%.

In the salinized soil composite modifier produced by utilizing the agricultural waste, the fly ash is fine ash which is formed after coal used in a thermal power plant is combusted in a boiler and is carried out of a hearth by smoke.

A preparation method of a salinized soil composite improver produced by utilizing agricultural waste comprises the steps of uniformly mixing 50% -60% of agricultural waste facility sludge, 30% -40% of crop production waste and 5% -10% of fly ash by mass, then carrying out aerobic composting for 15 days at normal temperature, then carrying out anaerobic composting fermentation for 40-50 days to obtain humus, adding 0.03-0.05% of PAM into the humus, and stirring and uniformly mixing to obtain the soil composite improver.

In the preparation method of the salinized soil composite modifier produced by utilizing the agricultural waste, the sludge of the agricultural waste is waste and/or residual sludge produced by rural domestic sewage treatment facilities, the water content is 60-80 wt%, the waste produced by crops is straw particles cut into the length of 2-3mm, the particle size of the fly ash is 0.03-0.05 mm, the molecular weight of PAM is 1200 ten thousand, and the hydrolysis degree is 30%.

In the preparation method of the salinized soil composite improver produced by utilizing the agricultural waste, the waste and/or residual sludge produced by the rural domestic sewage treatment facility is dehydrated by a plate-frame filter pressing system, and the carbon-nitrogen ratio of the mixed sludge of the agricultural waste facility, the crop production waste and the fly ash is 30-35.

In the preparation method of the salinized soil composite modifier produced by utilizing the agricultural waste, the fly ash is fine ash which is formed after coal used in a thermal power plant is combusted in a boiler and is carried out of a hearth by smoke.

A preparation method of a salinized soil composite modifier produced by utilizing agricultural wastes comprises the following steps:

step 1, sludge dewatering, namely, uniformly collecting waste or excess sludge generated by rural domestic sewage treatment facilities, dewatering by adopting a mechanical dewatering mode to finally obtain an organic material with the water content of 60-80 percent to obtain agricultural operation and maintenance waste,

step 2, preparing auxiliary materials, collecting the waste generated in the agricultural production system, crushing the waste into 2-3mm particles by using a crusher for later use to obtain the agricultural production waste,

step 3, obtaining fly ash, collecting the fly ash produced by a thermal power plant, wherein the particle size of the fly ash is about 0.03-0.05 mm,

step 4, composting is mixed, namely, the agricultural and sewage transport and maintenance waste in the step 1, the agricultural production waste in the step 2 and the fly ash in the step 3 are mixed uniformly according to the weight ratio of 5:3:1, aerobic composting is carried out for 15 days at normal temperature, and then anaerobic composting fermentation is carried out for 40-50 days to obtain humus,

and 5, adding PAM, namely adding the PAM with the molecular weight of 1200 ten thousand and the hydrolysis degree of 30% into the humus obtained in the step 4 according to the proportion of 0.05 wt%, and uniformly mixing to obtain the final soil composite improver.

In the salinized soil composite modifier produced by utilizing the agricultural waste, the waste and/or residual sludge produced by the rural domestic sewage treatment facility is dehydrated by a plate-and-frame filter pressing system, the carbon-nitrogen ratio of the mixed sludge of the agricultural waste, the crop production waste and the fly ash is 30-35, and the fly ash in the step 3 is fine ash which is formed after coal used by a thermal power plant is combusted in a boiler and is carried out of a hearth by smoke.

The application of the soil composite improver produced by utilizing the agricultural waste in the salinized soil comprises the steps of 1, selecting salinized farmland, wherein the pH of the soil of the salinized land to be repaired is 8.5-9.0, and 2, spreading the composite soil improver to repair the salinized farmland, wherein the mass of the composite soil improver spread in each mu of soil is 7.5-15 tons.

Compared with the prior art, the invention has the advantages that:

1. the composite soil conditioner has the advantages of easily available raw materials and low cost, organic materials are produced by taking the operation and maintenance wastes of the agricultural waste treatment facilities, the agricultural production wastes and the residues of industrial production as raw materials, and the soil conditioner is produced by adding PAM (polyacrylamide), so that the wastes generated by the agricultural waste operation and maintenance facilities and the agricultural production are properly treated while the salinized soil is efficiently repaired, the pollution to the rural environment is prevented, and the resource utilization of the wastes is realized.

2. The preparation method of the soil conditioner has the advantages of easily obtained raw materials, low price, simple preparation process, high controllability, lower total preparation cost and better economic benefit when being applied to the restoration of the salinized soil.

3. Because the heavy metal content of the sludge of the agricultural sewage facility is lower, the sludge can effectively avoid the generation of heavy metal pollution when being applied to soil, and the ecological safety is better.

4. The composite soil conditioner contains various effective components, can comprehensively utilize physical repair and chemical repair measures to effectively neutralize alkali in soil, reduce the ESP value of the soil and restore the pH value of the soil to a normal range, and the fly ash in the soil can also replace sodium adsorbed on the surface of a soil colloid, reduce the salt content of the salinized soil, and simultaneously can also effectively improve the organic matter content of the soil, improve the porosity of the soil, reduce the volume weight, effectively improve the soil structure, indirectly improve the activity of microorganisms and enzymes in the soil and promote the growth and the propagation of the microorganisms in the soil.

5. The soil conditioner can improve the salinized soil structure through various reactions, and improve the water retention rate and the fertility of the soil. After soil amendment is applied into soil, on the one hand, the organic matter that contains in the amendment, polymer PAM can interact with soil particles, form the very big wadding group of volume, reduce surface runoff and soil runoff, improve soil infiltration rate and then increase the water content of salinization soil, on the other hand, still can increase in the amendment and be used for through establishing and stabilizing water stability aggregate and adsorbing the effect in two aspects to fertilizer element, strengthen the absorption and the maintenance of salinization soil to the fertilizer, restrain fertilizer element and run off, improve the utilization ratio of soil to the fertilizer.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the following description will be clearly and completely described in conjunction with the technical solutions in the embodiments of the present invention.

Example 1

Firstly, collecting waste such as excess sludge generated by operation and maintenance of rural domestic sewage treatment facilities, and mechanically dehydrating the excess sludge by adopting a plate-and-frame filter pressing system to obtain dehydrated sludge with the water content of 60-80%; then, adding agricultural wastes (straws) which are crushed to 2-3mm and acidic coal ash with the particle size of 0.03-0.05 mm into the dewatered sludge, fully stirring and uniformly mixing, and controlling the proportion of the three materials to dewater the sludge: straw particle: the fly ash is 5:3:1, preferably, the C/N (carbon-nitrogen ratio) of the mixed material is controlled to be 30-35, the carbon-nitrogen ratio is controlled according to the selection of straws, the straws in the embodiment are rice straws, corn straws, weeds, soybean straws, sorghum straws and the like, and the control of the carbon-nitrogen ratio is convenient for subsequent fermentation; preferably, a proper amount of aerobic fermentation bacteria, such as composting fermentation bacteria of Microbiol technologies, Inc. in Guangzhou city, is added into the fully stirred material according to the proportion of 1kg of the material added into 10 tons of the material, then the material is placed in a composting place for aerobic composting for 15 days at normal temperature, and then anaerobic composting is carried out for 40 to 50 days under anaerobic conditions, so as to remove a large amount of harmful components in the material and obtain humus with loose appearance and stable components. And finally, adding Polyacrylamide (PAM) (with the molecular weight of 1200 ten thousand and the hydrolysis degree of 30%) purchased into the composted humus, wherein the adding amount is about 0.05 percent of the overall specific gravity of the humus, and uniformly stirring to obtain the composite soil conditioner.

The repairing principle of the soil repairing agent of the embodiment comprises the following steps:

(1) organic matters contained in the soil remediation agent can improve the fertilizer retention and buffering performance of the soil by adsorbing a large number of cations in the soil. One of the raw materials of the soil remediation agent is organic matter produced by agricultural and sewage facility operation and maintenance waste and crop production waste compound compost, the organic matter contains a large amount of protein, amino acid and humic acid, and after the soil remediation agent is applied to salinized soil, on one hand, the organic matter can adsorb a large amount of cations in the soil to effectively neutralize alkali in the soil, reduce the ESP and pH value of the soil, and on the other hand, the soil can be loosened and formed into a structure, so that the physical and chemical properties of the soil are obviously improved.

(2) The fly ash contained in the soil remediation agent can replace sodium adsorbed on the surface of soil colloid, and the salt content of the salinized soil is reduced. In addition, the modifier containing the fly ash can form water-insoluble hydroxide and hydrolysable acid through hydrolysis after being applied to the salinized soil, so that the pH value of the alkaline soil is effectively reduced, on the other hand, the modifier can improve the porosity of the soil, reduce the volume weight and effectively improve the soil structure through the ion exchange effect and the hard condensation reaction of the modifier, is beneficial to draining and washing the salt of a soil plough layer, and simultaneously cuts capillary tubes, reduces the evaporation of the water in the soil, so that the salt in the deep layer of the soil cannot be brought to the surface of the soil along with the evaporation of the water, and the harm of the salt and the alkali to crops can be reduced.

(3) The PAM contained in the soil remediation agent is used as a soil structure improver, and has the effects of increasing the cohesion among soil surface layer particles, maintaining a good soil structure, preventing soil crusting, preventing soil loss, inhibiting soil moisture evaporation and the like. PAM as soil structure improver can improve the structure of soil and increase the stability of aggregate in soil, and has better capability of inhibiting soil moisture evaporation. After the soil is treated by the polyacrylamide, the general sedimentation coefficient is increased, the dispersion coefficient is reduced, the structural coefficient is increased, the water-stable aggregate content is increased, the structural performance is enhanced, and the soil permeability is increased. These indexes prove that the material is one of better soil structure improving agents and plays an important role in preventing and controlling soil erosion.

Example 2

A preparation method of a salinized soil composite improver produced by utilizing agricultural waste comprises the steps of uniformly mixing 50% -60% of agricultural waste facility sludge, 30% -40% of crop production waste and 5% -10% of fly ash by mass, then carrying out aerobic composting for 15 days at normal temperature, then carrying out anaerobic composting fermentation for 40-50 days to obtain humus, adding 0.03-0.05% of PAM into the humus, and stirring and uniformly mixing to obtain the soil composite improver.

The agricultural sewage facility sludge is waste and/or excess sludge produced by rural domestic sewage treatment facilities, the water content is 60-80 wt%, the crop production waste is straw particles cut into 2-3mm long, the particle size of the fly ash is 0.03-0.05 mm, the molecular weight of the PAM is 1200 ten thousand, and the hydrolysis degree is 30%. And (3) dehydrating the waste and/or the residual sludge generated by the rural domestic sewage treatment facility by using a plate-frame filter pressing system, wherein the carbon-nitrogen ratio of the mixed sludge of the agricultural sewage facility, the crop production waste and the fly ash is 30-35. Fly ash is fine ash formed after coal used in thermal power plants is combusted in a boiler and is carried out of a hearth by flue gas.

Example 3

A saline soil composite modifier produced by utilizing agricultural wastes comprises the following components in percentage by mass: 50-60% of sludge of the agricultural sewage facility, 30-40% of crop production waste, 5-10% of fly ash and 0.03-0.05% of PAM.

Example 4

A saline soil composite modifier produced by utilizing agricultural wastes comprises the following components in percentage by mass: 50% of sludge of the agricultural sewage facility, 40% of crop production waste, 9.95% of fly ash and 0.03% -0.05% of PAM.

Example 5

A saline soil composite modifier produced by utilizing agricultural wastes comprises the following components in percentage by mass: 60% of sludge of the agricultural sewage facility, 30% of crop production waste, 9.97% of fly ash and 0.03% of PAM.

Example 6

A saline soil composite modifier produced by utilizing agricultural wastes comprises the following components in percentage by mass: 55% of sludge of the agricultural sewage facility, 39.7% of crop production waste, 5% of fly ash and 0.03% of PAM.

Example 7

A saline soil composite modifier produced by utilizing agricultural wastes comprises the following components in percentage by mass: 54.95 percent of sludge of the agricultural sewage facility, 35 percent of crop production waste, 10 percent of fly ash and 0.04 percent of PAM.

Application example 1

Selecting a piece of cultivated land which is salinized, taking a plurality of soil samples by adopting a multipoint sampling method, and measuring the main physicochemical properties of the soil in a laboratory, wherein the measuring results are shown in the following table

Table 1: main physicochemical properties of salinized land

And (4) supplementary notes: CEC-amount of cation exchange in soil; ESP-degree of alkalization of soil.

As can be seen from the table, the pH and exchangeable Na + concentration of the salinized farmland are high, and the alkalization degree of the soil is up to 51%; the soil has low air permeability and water retention porosity, low air-water ratio and poor integral water and air permeability; the CEC value of the soil cation exchange capacity which can directly reflect the soil fertility is only 11.0cmol/kg, which indicates that the fertility status of the cultivated land is not ideal.

2 blocks of 50m are divided in the salinized farmland²The soil remediation agent prepared by the invention (the soil remediation agent obtained in example 1) and a general conditioner are respectively added into soil to be restored, and the addition amount of the remediation agent in each land is 550 kg. The general modifier is rice straw pileAnd (4) a fertilized product. The main physicochemical properties of the soil tested are shown in table 1 in example 2. And (4) after the repairing agents are added into the two lands, ploughing in time, and ploughing again after one month. After two months, soil samples were taken by a multi-point sampling method, and the main physicochemical properties were measured and analyzed, and the measured data are shown in table 2.

Table 2: the soil physicochemical property of the composite soil conditioner and the general conditioner after being used as the soil conditioner

As can be seen from Table 2, after the repairing agent is used for 2 months, the main physical and chemical parameters of the salinized soil added with the composite soil conditioner are obviously improved compared with those of salinized cultivated land added with a common conditioner. The pH of the salinized farmland added with the composite soil conditioner is reduced from 8.6 to 7.5, and the salinized farmland has exchangeable Na⁺The concentration is reduced from 5.7cmol/kg to 4.2cmol/kg, the alkalization degree (ESP) is reduced from 51.8 to 32.1, the gas-water ratio is increased from 0.2 to 0.48, and the soil cation exchange capacity is increased from 11.8 to 13.2. In conclusion, the salinized farmland added with the composite soil conditioner provided by the invention has the advantages that the salinization degree of soil is obviously reduced, the water permeability and the air permeability are improved, the soil fertility is also improved, and the repairing effect is far better than that of the salinized farmland added with a common conditioner.

Application example 2

The effective plough layer thickness per mu of land is 20cm, and the soil volume weight is 1.1-1.20 g/cm³The weight of the plough layer soil of each mu of land is about 150 tons, and when the salinized farmland is repaired, the mass of the repairing materials (any soil conditioner in examples 1 to 7) applied to each mu of land is 5 to 10 percent of the mass of the soil, namely 7.5 to 15 tons/mu of land.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit of the invention.