A method for remediating arsenic-contaminated farmland

Abstract

This invention relates to a method for remediating arsenic-contaminated farmland; the method includes the following steps: applying base fertilizer to the farmland and tilling it evenly, wherein the base fertilizer includes organic fertilizer, and the amount of organic fertilizer applied is 200-500 kg / mu; transplanting cotton seedlings into the farmland and managing water; irrigating the cotton seedlings with a prepared sodium silicate solution; managing fertilizer and planting during the cotton growth process, and applying an activator that promotes the translocation of heavy metals into the cotton plants; harvesting the cotton when it matures and cutting the straw. This remediation method, through planting cotton and using organic fertilizer, irrigation with sodium silicate solution, and application of an activator, can promote the absorption of the heavy metal arsenic by plants, thereby reducing the arsenic content in the soil while ensuring the economic benefits of the farmland. The planting technique is simple, highly operable, and can effectively solve the problem of planting in arsenic-contaminated farmland.

Description

Technical Field

[0001] This invention relates to the field of soil pollution remediation technology, and in particular to a method for remediating arsenic-contaminated farmland. Background Technology

[0002] With social development, many small and medium-sized towns still suffer from incomplete separation of rainwater and sewage. Furthermore, in the past, surrounding enterprises discharged untreated industrial wastewater and domestic sewage directly into irrigation canals and rivers, exacerbating heavy metal pollution in farmland. Therefore, there is a necessity and urgency to carry out soil remediation and risk management for agricultural land in the region. Arsenic-contaminated soil not only reduces the productivity of farmland but also leads to excessive arsenic content in the edible parts of crops, exceeding food safety standards.

[0003] Common remediation techniques for arsenic-contaminated farmland include planting low-accumulation crops and agronomic regulation. Low-accumulation crops are those that can grow normally in contaminated soil, but whose edible parts have low or within acceptable limits for heavy metal content. Due to differences in genetic traits, there are significant differences in heavy metal accumulation among different crop species or even different varieties of the same crop. Low-accumulation crop substitution utilizes biological control techniques to reduce the risk of heavy metal contamination in crops, thereby preventing heavy metals from entering the human body through the food chain and causing health hazards. It is an economical and effective way to ensure the safe production of agricultural products in soils with mild to moderate heavy metal contamination. Agronomic regulation techniques mainly involve measures such as increasing the application of organic fertilizers, planting greenery, foliar spraying, and water management.

[0004] However, current technology only reduces the heavy metal content in the edible parts of crops, but does not eliminate the risk of heavy metals in the soil. Subsequent changes in conditions may lead to continued excessive levels of heavy metals in the edible parts of crops. Therefore, a remediation method for arsenic-contaminated farmland is urgently needed to address these issues. Summary of the Invention

[0005] To address the above problems, this invention provides a method for remediating arsenic-contaminated farmland, comprising the following steps:

[0006] S100: Apply base fertilizer to the farmland and till it evenly. The base fertilizer includes organic fertilizer, and the amount of organic fertilizer applied is 200-500 kg / mu.

[0007] S200: Transplant cotton seedlings to farmland and manage water usage;

[0008] S300: Irrigate cotton seedlings with a prepared sodium silicate solution;

[0009] S400: During the cotton growth process, fertilizer management and planting management are carried out, and activators that promote the translocation of heavy metals into cotton plants are applied.

[0010] S500: Cotton matures, cotton is harvested, and straw is cut.

[0011] Furthermore, the organic fertilizer in step S100 includes 7-10 parts humic acid, 30-40 parts rice straw, 20-30 parts pig manure, 5-15 parts diammonium hydrogen phosphate, and 20-30 parts kitchen waste.

[0012] Furthermore, the process of producing the organic fertilizer includes:

[0013] S101: Weigh out humic acid, rice straw, pig manure, diammonium hydrogen phosphate and kitchen waste according to the ratio, adjust the moisture content and mix them evenly;

[0014] S102: Ferment the mixed materials by piling them up;

[0015] S103: The fermented material is piled up and decomposed to obtain organic fertilizer.

[0016] Furthermore, the moisture content in step S101 is 20-35%.

[0017] Furthermore, the fermentation temperature in step S102 is 60-65℃.

[0018] Furthermore, the base fertilizer also includes compound fertilizer, and the application rate of the compound fertilizer is 20-30 kg / mu.

[0019] Furthermore, the sodium silicate solution pouring process in step S300 includes:

[0020] Apply 0.05–1.5 g of sodium silicate per kg of soil. Dissolve the sodium silicate in water according to the specified ratio to obtain a sodium silicate solution, and then irrigate each cotton seedling.

[0021] Furthermore, the activator includes phytic acid and / or sodium silicate.

[0022] Furthermore, in step S400, the fertilizer management includes topdressing, which uses urea and compound fertilizer, wherein the weight ratio of urea, compound fertilizer and activator is 3:5:2 to 10.

[0023] Furthermore, in step S500, the obtained straw is recycled in a biomass power plant.

[0024] The remediation method for arsenic-contaminated farmland provided by this invention uses pig manure, humic acid, rice straw, diammonium hydrogen phosphate, and kitchen waste to prepare organic fertilizer. This fertilizer provides trace elements and elements such as nitrogen and phosphorus necessary for plant growth. Applying the organic fertilizer increases the organic matter content in the soil, enhancing soil oxidation conditions and reducing arsenic toxicity. Simultaneously, the application of organic fertilizer raises the soil pH, increasing the content of exchangeable heavy metals in the soil and promoting the activation of arsenic. Irrigating with sodium silicate solution after cotton planting further promotes the activation of arsenic, allowing cotton roots and stems to absorb more arsenic. Additionally, irrigation with sodium silicate effectively promotes the absorption of phosphorus by cotton seedlings, which is beneficial for their growth. Phytic acid and sodium silicate are used as activators and chelating agents to activate heavy metals in the soil, improve their bioavailability, and promote plant absorption. Phytic acid has a multidentate ligand that can form heterocyclic chemical complexes with single metal ions. The chelating agent can desorb metal ions from organic matter such as Fe-Mn, increasing the solubility of heavy metals in the soil and promoting the translocation of heavy metals from the roots to the aboveground parts. In addition, sodium silicate is beneficial for plants to improve photosynthesis and increase biomass, promoting the absorption of arsenic. Phytic acid will enhance the plant's ability to accumulate arsenic, further strengthening the plant's ability to absorb arsenic, thereby effectively reducing the content of heavy metal arsenic in farmland and facilitating the planting of edible crops.

[0025] By employing the above technical solutions, this invention has the following advantages compared to existing technologies:

[0026] 1) The method for remediating arsenic-contaminated farmland provided by the present invention promotes the absorption of heavy metal arsenic by plants by planting cotton, applying organic fertilizer, irrigating with sodium silicate solution and applying activator. While ensuring the economic benefits of farmland, it reduces the arsenic content in the soil. The planting technology is simple, highly operable and can effectively solve the problem of planting in arsenic-contaminated farmland.

[0027] 2) The method for remediating arsenic-contaminated farmland provided by this invention uses pig manure, humic acid, rice straw, diammonium hydrogen phosphate and kitchen waste as raw materials for co-fermentation. It is environmentally friendly, stable and efficient, does not affect agricultural production, and is suitable for large-scale use. While ensuring the organic matter for plant growth, it can effectively reduce the bioavailability of arsenic in contaminated soil.

[0028] 3) The method for remediating arsenic-contaminated farmland provided by this invention employs planting techniques that do not cause farmland pollution during the planting process. The selected planting techniques are beneficial for guiding farmers in planting and are intended to provide a reference for the remediation of arsenic-contaminated soil in my country. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Although representative embodiments of the present invention have been described in detail, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0030] This invention provides a method for remediating arsenic-contaminated farmland, comprising the following steps:

[0031] S100: Apply base fertilizer to the farmland and till it evenly. The base fertilizer includes organic fertilizer, and the amount of organic fertilizer applied is 200-500 kg / mu.

[0032] S200: Transplant cotton seedlings to farmland and manage water usage;

[0033] S300: Irrigate cotton seedlings with a prepared sodium silicate solution;

[0034] S400: During the cotton growth process, fertilizer management and planting management are carried out, and activators that promote the translocation of heavy metals into cotton plants are applied.

[0035] S500: Cotton matures, cotton is harvested, and straw is cut.

[0036] The farmland mentioned in this invention can be either dry land or paddy field. To reduce arsenic pollution in rice-growing farmland and facilitate continued rice cultivation after the arsenic pollution in the paddy field has been reduced, the paddy field can be converted to dry land for cotton cultivation. Once the arsenic pollution has decreased to the agricultural land screening value, rice cultivation can resume. The method for reducing arsenic pollution in paddy fields is as follows:

[0037] (1) Converting paddy fields to dry land

[0038] 1.1 When there is less water in the paddy fields in spring, use machinery to dig drainage ditches in the fields to drain the remaining water. The drainage time is about one week. After the drainage is completed, use a rotary tiller to plow the fields to increase the looseness of the soil and turn the relatively compact bottom soil to the surface.

[0039] 1.2 After plowing, the surface soil moisture content decreases and the soil becomes loose. Then, the plot is finely prepared and the soil is rotary tilled in a timely manner to further improve the soil porosity and aeration. At the same time, weeds in the field are turned into the soil. The number of rotary tillages is generally 2 to 3 times.

[0040] (2) Land leveling

[0041] 2.1 After the paddy field is transformed, apply base fertilizer and plow and mix it with a tiller to improve soil fertility, which is conducive to the planting and growth of cash crops. The base fertilizer is mainly organic fertilizer, and at least one of compound fertilizer, urea and potassium fertilizer is applied appropriately. Preferably, the base fertilizer application rate is 200-500 kg / mu / year of organic fertilizer and 20-30 kg / mu / year of compound fertilizer.

[0042] 2.2 Before planting crops, the fields should be ridged and ditched according to the growth habits of the crops. The ridge height is generally about 15 to 20 cm. Irrigation and drainage ditches should be arranged in a reasonable manner. The direction of the irrigation ditches should be consistent with the direction of the irrigation ditches and ridges, and the spacing should be 50 to 80 meters.

[0043] (3) Cotton seedling raising

[0044] 3.1 Seedling raising

[0045] Cotton is planted using a seedling-first-transplanting method. In strictly controlled areas, 3 mu of farmland is selected as the seedling area, and small arched sheds are artificially erected for seedling cultivation. The seedling cultivation time is in early April.

[0046] 3.2 Transplanting

[0047] The optimal transplanting age is when the seedlings have 2 to 1-3 leaves and 1-1 heart. Transplanting is best done on a cloudy day; on a sunny day, transplant in the morning or after 4 pm. When transplanting, keep the soil around the seedling, hold the base of the stem and gently pull the seedling, trying to keep the root system intact. Use a small hoe or shovel to transplant directly, ensuring the roots are spread out and the seedling is upright. Ideally, maintain a plant spacing of 30cm and a row spacing of 66cm when transplanting cotton. Water thoroughly after transplanting to help the seedlings establish and survive.

[0048] (4) Sodium silicate irrigation

[0049] 4.1 Irrigation should be carried out using irrigation water prepared with sodium silicate, wherein sodium silicate is dissolved in water at a ratio of 0.05 to 1.5 g / kg (soil mass), and then each cotton seedling is irrigated. Irrigation with sodium silicate solution can effectively promote the absorption of phosphorus element in phosphorus-containing fertilizer by cotton seedlings, which is beneficial to the growth of cotton seedlings.

[0050] (5) Application of activator

[0051] 5.1 Seven to fourteen days after transplanting cotton seedlings, apply a light, early application of fertilizer to promote seedling growth on a sunny day. During the seedling stage, use primarily fast-acting fertilizers in small amounts to ensure stable and early growth. For fields with low basal fertilizer application, topdressing can be applied after the seedlings have recovered from transplanting. Topdressing can use urea, compound fertilizer, or organic fertilizer. During the cotton's growth period, apply an activator. Preferably, the weight ratio of urea, compound fertilizer, and activator is 3:5:2-10.

[0052] The activator includes phytic acid and / or sodium silicate, and is applied during the bud stage at a dosage of 2%.

[0053] (6) Cotton harvest

[0054] Cotton is picked manually or by machine, and after being picked and dried, it is sold on the market; straw is also harvested and dried.

[0055] (7) Post-straw disposal

[0056] After harvesting, the straw is dried, bundled, and then sent to a biomass power plant for resource utilization.

[0057] Preferably, the organic fertilizer includes 7-10 parts humic acid, 30-40 parts rice straw, 20-30 parts pig manure, 5-15 parts diammonium hydrogen phosphate, and 20-30 parts kitchen waste; wherein the kitchen waste can be discarded food, rotten vegetables and fruits, etc.

[0058] Specifically, the process of producing the organic fertilizer includes:

[0059] Weigh out humic acid, rice straw, pig manure, diammonium hydrogen phosphate, and kitchen waste according to the specified ratio, adjust the moisture content, and mix them evenly; pile the mixed materials for fermentation; stack the fermented materials to decompose and obtain organic fertilizer.

[0060] The moisture content is 20-35%; the fermentation temperature is 60-65℃.

[0061] Furthermore, the above-mentioned organic fertilizer and potting soil can be mixed in a 1:4 ratio, with a small amount of water added, insecticide sprayed on, covered with plastic film, and the gaps in the film sealed with soil. When fermentation is complete and there is no odor (about 2-3 months), it can be used directly as top dressing or base fertilizer.

[0062] The method for remediating arsenic-contaminated farmland according to the present invention will be described in detail below through specific embodiments. In this embodiment, the average concentration of arsenic in the farmland soil is 30.5±1.2 mg / kg, and the arsenic content in the rice of the previous year is 0.42 mg / kg, which exceeds the limit requirements for agricultural products in the "National Food Safety Standard Limits for Contaminants in Food" (GB2762-2017). The cotton planted is preferably Xiangza Cotton No. 9.

[0063] Example 1

[0064] To make organic fertilizer, mix 8 parts humic acid, 35 parts rice straw, 30 parts pig manure, 10 parts diammonium hydrogen phosphate, 30 parts waste food, and rotten vegetables and fruits evenly, control the moisture content to 30%, and ferment at 64℃. Then ferment and pile up to decompose to obtain organic fertilizer.

[0065] In the leveled farmland, apply 300 kg / mu of organic fertilizer and 20 kg / mu of compound fertilizer, and till evenly with a tiller. After transplanting the cotton seedlings, water them promptly to help them establish roots and promote seedling growth. Dissolve sodium silicate in water at a ratio of 0.05 g / kg (soil mass) to obtain a sodium silicate solution, and irrigate the cotton seedlings with the sodium silicate solution. Apply topdressing fertilizer and phytic acid activator. The weight ratio of urea, compound fertilizer and activator is 3:5:5. Monitor the growth of cotton and carry out cotton disease and pest control and plant management. After the cotton matures, harvest the cotton and straw. Subsequently, test the cotton yield and the content of heavy metal arsenic in the straw and soil.

[0066] Example 2

[0067] To produce organic fertilizer, mix 8 parts humic acid, 35 parts rice straw, 10 parts diammonium hydrogen phosphate, 30 parts waste food, and rotten vegetables and fruits evenly, control the moisture content to 30%, and ferment at 60℃. Then ferment and pile the mixture to decompose to obtain organic fertilizer.

[0068] In the leveled farmland, apply 300 kg / mu of organic fertilizer and 20 kg / mu of compound fertilizer, and till evenly with a tiller. After transplanting the cotton seedlings, water them promptly to help them establish roots and promote seedling growth. Dissolve sodium silicate in water at a ratio of 0.05 g / kg (soil mass) to obtain a sodium silicate solution, and irrigate the cotton seedlings with the sodium silicate solution. Apply topdressing fertilizer and phytic acid activator. The weight ratio of urea, compound fertilizer and activator is 3:5:5. Monitor the growth of cotton and carry out cotton disease and pest control and plant management. After the cotton matures, harvest the cotton and straw. Subsequently, test the cotton yield and the content of heavy metal arsenic in the straw and soil.

[0069] Example 3

[0070] To make organic fertilizer, mix 8 parts humic acid, 35 parts rice straw, 30 parts pig manure, 30 parts waste food, and rotten vegetables and fruits evenly, control the moisture content to 20%, and ferment at 60℃. Then ferment and pile up to decompose to obtain organic fertilizer.

[0071] In the leveled farmland, apply 300 kg / mu of organic fertilizer and 20 kg / mu of compound fertilizer, and till evenly with a tiller. After transplanting the cotton seedlings, water them promptly to help them establish roots and promote seedling growth. Dissolve sodium silicate in water at a ratio of 0.05 g / kg (soil mass) to obtain a sodium silicate solution, and irrigate the cotton seedlings with the sodium silicate solution. Apply topdressing fertilizer and phytic acid activator. The weight ratio of urea, compound fertilizer and activator is 3:5:5. Monitor the growth of cotton and carry out cotton disease and pest control and plant management. After the cotton matures, harvest the cotton and straw. Subsequently, test the cotton yield and the content of heavy metal arsenic in the straw and soil.

[0072] Example 4

[0073] To make organic fertilizer, mix 8 parts humic acid, 35 parts rice straw, 30 parts pig manure, 10 parts diammonium hydrogen phosphate, 30 parts waste food, and rotten vegetables and fruits evenly, control the moisture content to 25%, and the fermentation temperature to 60℃. Then ferment and pile up to decompose to obtain organic fertilizer.

[0074] In the leveled farmland, apply 300 kg / mu of organic fertilizer and 20 kg / mu of compound fertilizer, and till evenly with a tiller. After transplanting the cotton seedlings, water them promptly to help them establish roots and promote seedling growth. Dissolve sodium silicate in water at a ratio of 0.1 g / kg (soil mass) to obtain a sodium silicate solution, and irrigate the cotton seedlings with the sodium silicate solution. Apply topdressing fertilizer and phytic acid activator. The weight ratio of urea, compound fertilizer and activator is 3:5:5. Monitor the growth of cotton and carry out cotton disease and pest control and plant management. After the cotton matures, harvest the cotton and straw. Subsequently, test the cotton yield and the content of heavy metal arsenic in the straw and soil.

[0075] Example 5

[0076] To make organic fertilizer, mix 8 parts humic acid, 35 parts rice straw, 30 parts pig manure, 10 parts diammonium hydrogen phosphate, 30 parts waste food, and rotten vegetables and fruits evenly, control the moisture content to 25%, and the fermentation temperature to 62℃. Then ferment and pile up to decompose to obtain organic fertilizer.

[0077] In the leveled farmland, apply 300 kg / mu of organic fertilizer and 20 kg / mu of compound fertilizer, and till evenly with a tiller. After transplanting the cotton seedlings, water them promptly to help them establish roots and activate the soil. Dissolve sodium silicate in water at a ratio of 0.15 g / kg (soil mass) to obtain a sodium silicate solution, and irrigate the cotton seedlings with the sodium silicate solution. Apply topdressing fertilizer and phytic acid activator. The weight ratio of urea, compound fertilizer and activator is 3:5:5. Monitor the growth of cotton and carry out cotton disease and pest control and plant management. After the cotton matures, harvest the cotton and straw. Subsequently, test the cotton yield and the content of heavy metal arsenic in the straw and soil.

[0078] Example 6

[0079] To make organic fertilizer, mix 8 parts humic acid, 35 parts rice straw, 30 parts pig manure, 10 parts diammonium hydrogen phosphate, 30 parts waste food, and rotten vegetables and fruits evenly, control the moisture content to 30%, and ferment at 62℃. Then ferment and pile up to decompose to obtain organic fertilizer.

[0080] In the leveled farmland, apply 300 kg / mu of organic fertilizer and 20 kg / mu of compound fertilizer, and till evenly with a tiller. After transplanting the cotton seedlings, water them promptly to help them establish roots and activate the soil. Dissolve sodium silicate in water at a ratio of 0.05 g / kg (soil mass) to obtain a sodium silicate solution, and irrigate the cotton seedlings with the sodium silicate solution. Apply topdressing fertilizer and phytic acid. The weight ratio of urea, compound fertilizer and activator is 3:5:5. Monitor the growth of cotton and carry out cotton disease and pest control and plant management. After the cotton matures, harvest the cotton and straw. Subsequently, test the cotton yield and the content of heavy metal arsenic in the straw and soil.

[0081] Comparative Example 1

[0082] No organic fertilizer was applied; instead, compound fertilizer was applied as base fertilizer. The soil was tilled evenly using a tiller. After transplanting the cotton seedlings, timely watering was applied to establish roots and activate the seedlings. Sodium silicate was dissolved in water at a ratio of 0.05 g / kg (soil mass) to obtain a sodium silicate solution. The sodium silicate solution was then used to irrigate the cotton seedlings. Topdressing was applied, along with the application of phytic acid activator. The weight ratio of urea, compound fertilizer, and activator was 3:5:5. The growth of the cotton was monitored, and cotton pests and diseases were controlled, along with plant management. After the cotton matured, the cotton and straw were harvested. Subsequently, the cotton yield and the content of heavy metal arsenic in the straw and soil were tested.

[0083] Comparative Example 2

[0084] To make organic fertilizer, mix 8 parts humic acid, 35 parts rice straw, 30 parts pig manure, 10 parts diammonium hydrogen phosphate, 30 parts waste food, and rotten vegetables and fruits evenly, control the moisture content to 30%, and ferment at 60℃. Then ferment and pile up to decompose to obtain organic fertilizer.

[0085] In the leveled farmland, apply 300 kg / mu of organic fertilizer and 20 kg / mu of compound fertilizer, and till evenly with a tiller. After transplanting cotton seedlings, water them promptly to help them establish roots and promote seed growth. Apply topdressing fertilizer and phytic acid activator. The weight ratio of urea, compound fertilizer and activator should be 3:5:5. Monitor the growth of cotton and carry out cotton disease and pest control and plant management. After the cotton matures, harvest the cotton and straw. Subsequently, test the cotton yield and the content of heavy metal arsenic in the straw and soil.

[0086] The cotton yield, straw and soil heavy metal content of Examples 1-6 and Comparative Examples 1-2 are shown in Table 1 below.

[0087] Table 1. Statistics on cotton yield, straw, and soil heavy metal content.

[0088]

[0089] As can be seen from the results of the above examples and comparative examples, the method provided in this application, by applying organic fertilizer, irrigating with sodium silicate solution, and applying activator, can effectively activate heavy metals in the soil, promote the absorption of heavy metal arsenic by cotton, thereby reducing the content of heavy metal arsenic in farmland soil and ensuring the subsequent planting of rice in the farmland.

[0090] Those skilled in the art will understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the invention. Although embodiments of the invention have been described, it should be understood that the invention is not limited to these embodiments, and those skilled in the art can make changes and modifications within the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for remediating an arsenic-contaminated farmland, characterized by, Includes the following steps: S100: Apply base fertilizer to farmland and till it evenly. The base fertilizer includes organic fertilizer, and the amount of organic fertilizer applied is 200-500 kg / mu. The organic fertilizer includes 7-10 parts of humic acid, 30-40 parts of rice straw, 20-30 parts of pig manure, 5-15 parts of diammonium hydrogen phosphate, and 20-30 parts of kitchen waste. S200: Transplant cotton seedlings to farmland and manage water usage; S300: Irrigate cotton seedlings with a prepared sodium silicate solution; wherein, 0.05-1.5g of sodium silicate is applied per kg of soil, and the sodium silicate is dissolved in water according to the specified ratio to obtain a sodium silicate solution, which is then used to irrigate each cotton seedling; S400: Fertilizer management and planting management are carried out during the cotton growth process, and an activator that promotes the translocation of heavy metals into cotton plants is applied. The activator is applied during the bud stage and includes phytic acid and sodium silicate. The fertilizer management includes topdressing, which uses urea and compound fertilizer. The weight ratio of urea, compound fertilizer and activator is 3:5:2 to 10. S500: Cotton matures, cotton is harvested, and straw is cut; The process of making the organic fertilizer includes: S101: Weigh out humic acid, rice straw, pig manure, diammonium hydrogen phosphate, and kitchen waste according to the specified ratio, adjust the moisture content, and mix thoroughly; the moisture content should be 20-35%. S102: Ferment the mixed materials in a pile at a temperature of 60-65℃. S103: The fermented material is piled up and decomposed to obtain organic fertilizer.

2. The method for remediating arsenic-contaminated farmland as described in claim 1, characterized in that, The base fertilizer also includes compound fertilizer, and the application rate of the compound fertilizer is 20-30 kg / mu.

3. The method for remediating arsenic-contaminated farmland as described in claim 1, characterized in that, In step S500, the obtained straw is recycled in a biomass power plant.

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