A method for reducing lead content in cassava tubers

Abstract

The present application relates to a kind of cultivation methods for reducing cassava root lead content, the method includes the planting and fertilization management of selection;Wherein, the fertilization management includes the application of base fertilizer and topdressing, specifically: (1) before cassava seedling sowing, after soil pretreatment, base fertilizer is applied;(2) after sowing 4-7 months, leaf surface fertilizer A and leaf surface fertilizer B are used to carry out leaf surface spraying to cassava plant until leaf blade just drips water, the application time interval of leaf surface fertilizer A and leaf surface fertilizer B is 5-7 days;Wherein, the calcium content in leaf surface fertilizer A is 150-200mg / L, the magnesium content is 10-30mg / L, interval 15-20d is sprayed once, and is sprayed 2-5 times in total;The selenium content in the leaf surface fertilizer B is 15-60mg / L, interval 20-25d is sprayed once, and is sprayed 3-4 times in total;Through the method, cassava with low lead content can be obtained, the edible safety of cassava is improved, and the yield of cassava under the cultivation method is high.

Description

[Technical Field]

[0001] This invention relates to the field of cassava cultivation technology, and in particular to a cultivation method for reducing the lead content in cassava tubers. [Background Technology]

[0002] Cassava (Manihot esculenta Crantz) is a plant belonging to the genus cassava in the family Euphorbiaceae.

[0003] Lead in food poses numerous health risks, especially to children and pregnant women. Therefore, reducing lead levels and controlling lead content in food are crucial measures to protect public health. The national food safety standard for limits of contaminants in food (GB2762-2022) sets the lead limit for tubers at <0.2 mg / kg for fresh tubers. However, due to variations in growth characteristics and environmental factors such as surrounding soil, air, and water, some cassava varieties tend to accumulate lead in their tubers, resulting in edible cassava products that do not meet the national standard's lead content limits for fresh tubers.

[0004] Reducing the lead content in cassava tubers through cultivation techniques is of great significance for improving the safety of edible cassava and accelerating its food production. Currently, no relevant research reports have been found. Therefore, this application proposes a cultivation method for reducing the lead content of cassava to address the aforementioned problem. [Summary of the Invention]

[0005] In view of the above, it is necessary to provide a cultivation method to reduce the lead content of cassava tubers. This method can produce cassava with low lead content, improve the safety of cassava for consumption, and also result in high cassava yield.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A cultivation method for reducing lead content in cassava, the method comprising site selection for planting and fertilization management;

[0008] The fertilization management includes the application of base fertilizer and topdressing, specifically: (1) applying base fertilizer before sowing cassava seedlings and after soil pretreatment; (2) 4-7 months after sowing, applying foliar fertilizer A and foliar fertilizer B to the seedlings, spraying until the leaves just drip water, with an application interval of 5-7 days between foliar fertilizer A and foliar fertilizer B; wherein, the calcium content in foliar fertilizer A is 150-200 mg / L, the magnesium content is 10-30 mg / L, sprayed once every 15-20 days, for a total of 2-5 times; the selenium content in foliar fertilizer B is 15-60 mg / L, sprayed once every 20-25 days, for a total of 3-4 times.

[0009] Furthermore, the base fertilizer is mainly composed of the following raw materials in parts by weight: 60-80 parts organic compost, 1-3 parts urea, 5-9 parts calcium magnesium phosphate fertilizer, and 3-8 parts potassium chloride; the base fertilizer is applied by mixing it with the soil in the planting hole, and the application rate of the base fertilizer is 700-750 kg / mu.

[0010] Furthermore, the foliar fertilizer A is prepared by adding calcium nitrate and chelated calcium to water and stirring until completely dissolved, then adding magnesium sulfate, chelated magnesium, boric acid, and chelated zinc and stirring until completely dissolved. Next, polyoxyethylene ether, glycerol, and citric acid are added sequentially and stirred until homogeneous. The pH is then adjusted to 6.5 to obtain foliar fertilizer A. The mass ratio of calcium nitrate, chelated calcium, magnesium sulfate, chelated magnesium, boric acid, chelated zinc, polyoxyethylene ether, glycerol, and citric acid is 10-15:8:3-5:1-2:2:3:0.1-0.5:0.5-1:0.2.

[0011] Furthermore, the foliar fertilizer B is prepared by mixing sodium selenite, selenomethionine, urea, zinc sulfate and brassinolide in a mass ratio of 1:2:2-3:1-2:0.1, adding it to deionized water, and stirring thoroughly.

[0012] Furthermore, the site selection and planting specifically includes: selecting plots with low soil background values, no heavy metal pollution, deep soil layers, and convenient irrigation and drainage as planting sites; applying compound soil conditioner to the soil after land preparation, with an application rate of 400-600 kg / mu; then using mature cassava seed tubers as sowing material, planting them from mid-to-late March to early April, using a horizontal or oblique planting method, with a plant spacing of 0.8-1.2m, and covering the ridge surface and furrows with silver and black double-color mulch film.

[0013] Furthermore, the land preparation is completed by machine tillage, with a tillage depth of 30-40cm, ensuring that the soil is deep, loose, fine, broken, level, and free of weeds. Ridges are made according to the planting row spacing, with double rows or single rows per ridge, and the ridge height is 10-15cm. Drainage ditches are dug around the ridges.

[0014] Furthermore, the composite soil conditioner is obtained by mixing ferrous sulfate-humic acid complex, biochar and calcium oxide in a mass ratio of 1:2-3:1-2, granulating and drying.

[0015] Furthermore, the preparation method of the ferrohydrate-humic acid complex includes the following steps: 1) Dissolving ferric chloride in 100-200 times its volume of deionized water to obtain an iron salt solution, adjusting the pH of the iron salt solution to 7-8, and then continuously stirring the reaction until a reddish-brown ferrohydrate precipitate is formed. The precipitate is washed with deionized water and then dried to obtain ferrohydrate powder; 2) Dissolving humic acid in 100-200 times its volume of deionized water to obtain a humic acid solution, mixing the two according to a mass ratio of humic acid solution to ferrohydrate powder of 0.5-1:1, centrifuging the mixture to collect the precipitate, washing the precipitate with deionized water, and then drying it to obtain the ferrohydrate-humic acid complex.

[0016] Furthermore, before sowing, the mature cassava seed stems are cut into 15-20cm long sections, soaked in a 1000-fold dilution of 50% carbendazim wettable powder for 3-5 minutes, then removed, dried, and ready for sowing.

[0017] The present invention has at least the following beneficial effects:

[0018] 1. The cultivation method of this application can effectively reduce the lead content in cassava tubers while ensuring the yield of fresh cassava tubers, thus obtaining a high-quality cassava with low lead content and rich selenium.

[0019] 2. The cultivation method described in this application mainly includes site selection and fertilization management. First, by selecting a suitable planting site and conducting soil improvement pretreatment, experiments have shown that applying the compound soil conditioner described in this application can improve soil structure and effectively reduce the lead content in cassava. This may be because the active ingredients in the soil conditioner can reduce the bioavailability of lead in the soil, thereby reducing the absorption of lead by cassava. Furthermore, this application applies base fertilizer before sowing, which is rich in organic matter and promotes crop growth. It was also unexpectedly discovered that the base fertilizer applied in this application can also reduce the lead content in cassava. Through extensive experimental research, the applicant has concluded... It is possible that the calcium, magnesium, and phosphate fertilizers and potassium chloride in the base fertilizer can compete with lead ions for absorption sites in the plant roots, thereby inhibiting the absorption of lead by cassava plants. After applying the base fertilizer, cassava seed tubers are sown, and then topdressing is carried out at an appropriate time. Specifically, the topdressing in this application is achieved by spraying foliar fertilizers, including foliar fertilizer A and foliar fertilizer B. Foliar fertilizer A contains rich calcium and magnesium components, while foliar fertilizer B is a selenium-rich foliar fertilizer. By spraying the two alternately, the goal of obtaining edible cassava tubers with low lead content can be achieved. Compared with spraying only one type of foliar fertilizer, the lead content of cassava is effectively reduced, which greatly enhances the market competitiveness of cassava and has broad application prospects.

Detailed Implementation Methods

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Example 1:

[0022] This embodiment provides a cultivation method for reducing the lead content in cassava tubers, which includes the following steps:

[0023] (1) Site selection and planting:

[0024] Site selection and land preparation: Select a plot of land with low soil background value, no heavy metal pollution, deep soil layer, and convenient irrigation and drainage as the planting site. After selecting the site, use machine to complete the land preparation. The tillage depth is 40cm, and the land should be deep, loose, fine, broken, flat, and free of weeds. Make ridges according to the planting row spacing. Double rows or single rows can be planted on one ridge. The ridge height is 15cm. Drainage ditches should be dug around the perimeter.

[0025] Soil improvement: After land preparation, a compound soil conditioner is applied to the soil at a rate of 600 kg / mu. The compound soil conditioner is obtained by mixing ferric chloride-humic acid complex, biochar, and calcium oxide in a mass ratio of 1:3:2, granulating, and drying. The preparation method of the ferric chloride-humic acid complex includes the following steps: 1) Dissolve ferric chloride in 200 times the amount of deionized water to obtain an iron salt solution. Adjust the pH of the iron salt solution to 8, and then continuously stir the reaction until a reddish-brown ferric chloride precipitate is formed. Wash the precipitate with deionized water and then dry it to obtain ferric chloride powder. 2) Dissolve humic acid in 200 times the amount of deionized water to obtain a humic acid solution. Mix the humic acid solution and ferric chloride powder in a mass ratio of 1:1. Centrifuge the mixture to collect the precipitate. Wash the precipitate with deionized water and then dry it to obtain the ferric chloride-humic acid complex.

[0026] Sowing: Next, use mature cassava stems as sowing material. Before sowing, cut the stems into 20cm long sections, soak them in a 1000-fold dilution of 50% carbendazim wettable powder for 5 minutes, take them out and dry them before sowing. Then, from mid-March to early April, sow the cassava stems by laying them flat or inserting them at an angle. The planting spacing is 1.2m, and cover the bed surface and furrows with silver and black double-color plastic film.

[0027] (2) Fertilizer management: including the application of base fertilizer and topdressing, specifically: 1) Apply base fertilizer before sowing cassava seedlings and after soil pretreatment; the base fertilizer is mainly composed of the following raw materials in parts by weight: 80 parts organic compost, 3 parts urea, 9 parts calcium magnesium phosphate fertilizer, and 8 parts potassium chloride; the method of applying the base fertilizer is to mix the base fertilizer with the soil in the planting hole, and the application rate of the base fertilizer is 750 kg / mu; 2) Four to seven months after sowing, that is, from early July to mid-October, foliar fertilizer A and foliar fertilizer B are used to spray the seedlings, with an application interval of 7 days between foliar fertilizer A and foliar fertilizer B; among them, the calcium content in foliar fertilizer A is 200 mg / L, the magnesium content is 30 mg / L, and it is sprayed once every 20 days, for a total of 5 sprays; the selenium content in foliar fertilizer B is 6 Foliar fertilizer A is prepared by spraying 0 mg / L of calcium nitrate and chelated calcium in water at 25-day intervals for a total of 4 applications. The solution is obtained by adding calcium nitrate and chelated calcium to water and stirring until completely dissolved, then adding magnesium sulfate, chelated magnesium, boric acid, and chelated zinc and stirring until completely dissolved. Next, polyoxyethylene ether, glycerol, and citric acid are added sequentially and stirred until homogeneous. The pH is then adjusted to 6.5. The mass ratio of calcium nitrate, chelated calcium, magnesium sulfate, chelated magnesium, boric acid, chelated zinc, polyoxyethylene ether, glycerol, and citric acid is 10:8:3:1:2:3:0.1:0.5:0.2. Foliar fertilizer B is prepared by mixing sodium selenite, selenomethionine, urea, zinc sulfate, and brassinolide in a mass ratio of 1:2:2:2:0.1, adding the mixture to deionized water, and stirring thoroughly.

[0028] Example 2:

[0029] This embodiment provides a cultivation method for reducing the lead content in cassava tubers, which includes the following steps:

[0030] (1) Site selection and planting:

[0031] Site selection and land preparation: Select a plot of land with low soil background value, no heavy metal pollution, deep soil layer, and convenient irrigation and drainage as the planting site. After selecting the site, use machine to complete the land preparation. The tillage depth is 35cm, and the land should be deep, loose, fine, broken, flat, and free of weeds. Make ridges according to the planting row spacing. Double rows or single rows can be planted on one ridge. The ridge height is 12cm. Drainage ditches should be dug around the perimeter.

[0032] Soil improvement: After land preparation, a compound soil conditioner is applied to the soil at a rate of 500 kg / mu. The compound soil conditioner is obtained by mixing ferric chloride-humic acid complex, biochar, and calcium oxide in a mass ratio of 1:3:1, granulating, and drying. The preparation method of the ferric chloride-humic acid complex includes the following steps: 1) Dissolve ferric chloride in 150 times the amount of deionized water to obtain an iron salt solution. Adjust the pH of the iron salt solution to 7.5, and then continuously stir the reaction until a reddish-brown ferric chloride precipitate is formed. Wash the precipitate with deionized water and then dry it to obtain ferric chloride powder. 2) Dissolve humic acid in 150 times the amount of deionized water to obtain a humic acid solution. Mix the humic acid solution and ferric chloride powder in a mass ratio of 0.7:1. Centrifuge the mixture to collect the precipitate. Wash the precipitate with deionized water and then dry it to obtain the ferric chloride-humic acid complex.

[0033] Sowing: Next, mature cassava stems are used as sowing material. Before sowing, the stems are cut into 18cm long sections and soaked in a 1000-fold dilution of 50% carbendazim wettable powder for 4 minutes. After soaking and drying, they are ready for sowing. Then, from mid-March to early April, they are sown by laying them flat or inserting them at an angle. The planting spacing is 1.0m, and the bed surface and furrows are covered with silver and black double-color plastic film.

[0034] (2) Fertilizer management: including the application of base fertilizer and topdressing, specifically: 1) Apply base fertilizer before sowing cassava seedlings and after soil pretreatment; the base fertilizer is mainly composed of the following raw materials in parts by weight: 70 parts organic compost, 2 parts urea, 7 parts calcium magnesium phosphate fertilizer, and 6 parts potassium chloride; the method of applying the base fertilizer is to mix the base fertilizer with the soil in the planting hole, and the application rate of the base fertilizer is 720 kg / mu; 2) Four to seven months after sowing, that is, from early July to mid-October, foliar fertilizer A and foliar fertilizer B are used to spray the seedlings, with an application interval of 6 days between foliar fertilizer A and foliar fertilizer B; among them, the calcium content in foliar fertilizer A is 180 mg / L and the magnesium content is 20 mg / L, sprayed once every 18 days, for a total of 4 sprays; the selenium content in foliar fertilizer B is 4 Foliar fertilizer A is prepared by spraying calcium nitrate and chelated calcium in water at 22-day intervals for a total of 3 applications. The solution is obtained by adding magnesium sulfate, chelated magnesium, boric acid, and chelated zinc to water and stirring until completely dissolved. Then, polyoxyethylene ether, glycerol, and citric acid are added sequentially and stirred until homogeneous. The pH is then adjusted to 6.5. The mass ratio of calcium nitrate, chelated calcium, magnesium sulfate, chelated magnesium, boric acid, chelated zinc, polyoxyethylene ether, glycerol, and citric acid is 12:8:4:1:2:3:0.3:0.7:0.2. Foliar fertilizer B is prepared by mixing sodium selenite, selenomethionine, urea, zinc sulfate, and brassinolide in a mass ratio of 1:2:2:1:0.1, adding the mixture to deionized water, and stirring thoroughly.

[0035] Example 3:

[0036] This embodiment provides a cultivation method for reducing the lead content in cassava tubers, which includes the following steps:

[0037] (1) Site selection and planting:

[0038] Site selection and land preparation: Select a plot of land with low soil background value, no heavy metal pollution, deep soil layer, and convenient irrigation and drainage as the planting site. After selecting the site, use machine to complete the land preparation. The tillage depth is 40cm, and the land should be deep, loose, fine, broken, flat, and free of weeds. Make ridges according to the planting row spacing. Double rows or single rows can be planted on one ridge. The ridge height is 15cm. Drainage ditches should be dug around the perimeter.

[0039] Soil improvement: After land preparation, a compound soil conditioner is applied to the soil at a rate of 600 kg / mu. The compound soil conditioner is obtained by mixing ferric chloride-humic acid complex, biochar, and calcium oxide in a mass ratio of 1:3:2, granulating, and drying. The preparation method of the ferric chloride-humic acid complex includes the following steps: 1) Dissolve ferric chloride in 200 times the amount of deionized water to obtain an iron salt solution. Adjust the pH of the iron salt solution to 8, and then continuously stir the reaction until a reddish-brown ferric chloride precipitate is formed. Wash the precipitate with deionized water and then dry it to obtain ferric chloride powder. 2) Dissolve humic acid in 200 times the amount of deionized water to obtain a humic acid solution. Mix the humic acid solution and ferric chloride powder in a mass ratio of 1:1. Centrifuge the mixture to collect the precipitate. Wash the precipitate with deionized water and then dry it to obtain the ferric chloride-humic acid complex.

[0040] Sowing: Next, use mature cassava stems as sowing material. Before sowing, cut the stems into 20cm long sections, soak them in a 1000-fold dilution of 50% carbendazim wettable powder for 5 minutes, take them out and dry them before sowing. Then, from mid-March to early April, sow the cassava stems by laying them flat or inserting them at an angle. The planting spacing is 1.2m, and cover the bed surface and furrows with silver and black double-color plastic film.

[0041] (2) Fertilizer Management: This includes applying base fertilizer and topdressing, specifically: 1) Apply base fertilizer before sowing cassava seedlings and after soil pretreatment; the base fertilizer mainly consists of the following raw materials in parts by weight: 80 parts organic compost, 3 parts urea, 9 parts calcium magnesium phosphate fertilizer, and 8 parts potassium chloride; the base fertilizer is applied by mixing it with the soil in the planting hole, and the application rate is 750 kg / mu; 2) Four to seven months after sowing, i.e., from early July to mid-October, foliar fertilizer A and foliar fertilizer B are applied to the seedlings, with an application interval of 7 days between the two; among them, foliar fertilizer A contains 200 mg / L of calcium and 30 mg / L of magnesium, and is applied once every 20 days for a total of 5 applications; the selenium content of foliar fertilizer B is... Foliar fertilizer A is prepared by spraying 60 mg / L of calcium nitrate and chelated calcium in water at 25-day intervals for a total of 4 applications. The solution is obtained by adding magnesium sulfate, chelated magnesium, boric acid, and chelated zinc to water and stirring until completely dissolved. Then, polyoxyethylene ether, glycerol, and citric acid are added sequentially and stirred until homogeneous. The pH is then adjusted to 6.5. The mass ratio of calcium nitrate, chelated calcium, magnesium sulfate, chelated magnesium, boric acid, chelated zinc, polyoxyethylene ether, glycerol, and citric acid is 15:8:5:2:2:3:0.5:1:0.2. Foliar fertilizer B is prepared by mixing sodium selenite, selenomethionine, urea, zinc sulfate, and brassinolide in a mass ratio of 1:2:3:2:0.1, adding the mixture to deionized water, and stirring thoroughly.

[0042] To illustrate the effectiveness of this application, the applicant conducted the following experiment:

[0043] The applicant compared the cassava yield, lead content, and selenium content in fresh cassava among the following groups, specifically categorizing them as follows:

[0044] Group 1: The cultivation method described in Example 2;

[0045] Group 2: In fertilization management, remove foliar fertilizer B and apply foliar fertilizer A at the original time when foliar fertilizer B was to be applied. Other methods are the same as in Example 2.

[0046] Group 3: In fertilization management, foliar fertilizer A is removed, and foliar fertilizer B is applied at the original time when foliar fertilizer A was originally applied. Other methods are the same as in Example 2.

[0047] Group 4: In fertilization management, the application method of foliar fertilizer A and foliar fertilizer B is changed to root fertilization, and other methods are the same as in Example 2;

[0048] Group 5: Remove calcium magnesium phosphate and potassium chloride from the base fertilizer; otherwise, the process is the same as in Example 2.

[0049] Group 6: Remove the ferrous sulfate-humic acid complex from the composite soil conditioner; otherwise, the process is the same as in Example 2.

[0050] Comparing the cultivation effects of cassava in the above groups, the cassava variety selected in this experiment was SC9, and the data are recorded as shown in Table 1:

[0051] Table 1 Comparison of cassava cultivation effects in different groups

[0052]

[0053]

[0054] According to the results in Table 1, the cassava produced using the cultivation method described in this application not only has a high yield but also low lead and high selenium content in its fresh tubers. This cultivation method can produce a low-lead, selenium-enriched cassava with high food safety and excellent quality. In the second group, removing foliar fertilizer B resulted in a sharp decrease in selenium content, indicating that selenium could not be enriched. Simultaneously, the lead content in the second group was also found to be relatively high, suggesting that selenium-enriched foliar fertilizer can not only increase selenium content but also reduce lead content in cassava. In the third group, removing foliar fertilizer A significantly increased lead content, failing to achieve the goal of cultivating low-lead cassava. In the fourth group, root fertilization resulted in a higher lead content, possibly because the fertilizer described in this application can be directly absorbed through leaf stomata and epidermal cells, resulting in faster absorption and facilitating competition with lead ions for plant roots. The cassava root system has absorption sites, and after root application in the soil, nutrients are released slowly, and the plant may absorb more lead from the soil. In addition, cassava roots are quite sensitive to lead absorption, but the selenium content is high, so the impact is not as great as that of lead. This was an unexpected discovery by the applicant in cultivation experiments, which is considered to have a very outstanding effect. The fifth group, which removed calcium magnesium phosphate and potassium chloride from the base fertilizer, and the sixth group, which removed ferrous sulfate-humic acid complex, both showed higher lead content, indicating that these components are beneficial to reducing the lead content in cassava. In summary, the various steps of this application are coordinated with each other. If a certain component is removed or a certain step is changed, the effect described in this application may not be achieved, indicating that the fertilizer used and the method of fertilization have a great influence on the growth of cassava and the enrichment of elements.

[0055] The examples described above are merely illustrative of several embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A cultivation method for reducing lead content in cassava tubers, characterized in that, The method includes site selection for planting and fertilization management; The fertilization management includes the application of base fertilizer and topdressing, specifically: (1) applying base fertilizer before sowing cassava seedlings and after soil pretreatment; (2) spraying seedlings with foliar fertilizer A and foliar fertilizer B 4-7 months after sowing, with an application interval of 5-7 days between foliar fertilizer A and foliar fertilizer B; wherein, the calcium content in foliar fertilizer A is 150-200 mg / L, the magnesium content is 10-30 mg / L, and it is sprayed once every 15-20 days, for a total of 2-5 times; the selenium content in foliar fertilizer B is 15-60 mg / L, and it is sprayed once every 20-25 days, for a total of 3-4 times; the base fertilizer is mainly composed of the following raw materials in parts by weight: 60-80 parts organic compost, 1-3 parts urea, 5-9 parts calcium magnesium phosphate fertilizer, and 3-8 parts potassium chloride; Foliar fertilizer A is prepared by adding calcium nitrate and chelated calcium to water and stirring until completely dissolved, then adding magnesium sulfate, chelated magnesium, boric acid, and chelated zinc and stirring until completely dissolved. Next, polyoxyethylene ether, glycerol, and citric acid are added sequentially and stirred until homogeneous. The pH is then adjusted to 6.5 to obtain foliar fertilizer A. The mass ratio of calcium nitrate, chelated calcium, magnesium sulfate, chelated magnesium, boric acid, chelated zinc, polyoxyethylene ether, glycerol, and citric acid is 10-15:8:3-5:1-2:2:3:0.1-0.5:0.5-1:0.

2. Foliar fertilizer B is prepared by mixing sodium selenite, selenomethionine, urea, zinc sulfate, and brassinolide in a mass ratio of 1:2:2-3:1-2:0.1, adding the mixture to deionized water, and stirring thoroughly.

2. The method according to claim 1, characterized in that, The method of applying the base fertilizer is as follows: mix the base fertilizer with the soil in the planting hole, and the amount of base fertilizer applied is 700-750 kg / mu.

3. The method according to claim 1, characterized in that, The specific site selection and planting process includes: selecting plots with low soil background values, no heavy metal pollution, deep soil layers, and convenient irrigation and drainage as planting sites; applying a compound soil conditioner to the soil after land preparation at a rate of 400-600 kg / mu; then using mature cassava seed tubers as sowing material, planting them from mid-March to early April using a horizontal or oblique planting method, with a plant spacing of 0.8-1.2 m, and covering the ridges and furrows with silver and black double-colored mulch film.

4. The method according to claim 3, characterized in that, The land preparation is done by machine tillage, with a tillage depth of 30-40 cm, ensuring that the soil is deep, loose, fine, broken, level, and free of weeds. Ridges are made according to the planting row spacing, with two rows planted on one ridge or a single row planted on one ridge. The ridge height is 10-15 cm, and drainage ditches are dug around the perimeter.

5. The method according to claim 3, characterized in that, The composite soil conditioner is obtained by mixing ferrous ore-humic acid complex, biochar and calcium oxide in a mass ratio of 1:2-3:1-2, granulating and drying.

6. The method according to claim 5, characterized in that, The preparation method of the ferrohydrate-humic acid complex includes the following steps: 1) Dissolve ferric chloride in 100-200 times its volume of deionized water to obtain an iron salt solution. Adjust the pH of the iron salt solution to 7-8, and then continuously stir the reaction until a reddish-brown ferrohydrate precipitate is formed. Wash the precipitate with deionized water and then dry it to obtain ferrohydrate powder; 2) Dissolve humic acid in 100-200 times its volume of deionized water to obtain a humic acid solution. Mix the two according to a mass ratio of humic acid solution to ferrohydrate powder of 0.5-1:

1. Centrifuge the mixture to collect the precipitate. Wash the precipitate with deionized water and then dry it to obtain the ferrohydrate-humic acid complex.

7. The method according to claim 3, characterized in that, Before sowing, the mature cassava stems are cut into 15-20 cm long sections, soaked in a 1,000-fold dilution of 50% carbendazim wettable powder for 3-5 minutes, then removed and dried before sowing.

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