A method for preparing an acidic soil conditioner that can replace lime

Abstract

This invention relates to the field of soil improvement technology and provides a method for preparing an acidic soil conditioner that can replace lime. The method includes the following steps: washing clam shells, scallop shells, oyster shells, and mussel shells, drying them at 50°C, and then pulverizing them. The clam shell, scallop shell, oyster shell, and mussel shell powders are mixed evenly in a weight ratio of 1:1:1:1. The mixture is then heated to 800°C under anaerobic conditions at a pyrolysis rate of 20°C per minute and maintained for 2 hours. After cooling to room temperature, the mixture is ground and passed through a 1mm sieve to obtain the acidic soil conditioner. This invention utilizes the secondary development of various seafood shell wastes to obtain a conditioner with acid neutralization capacity equal to or even stronger than lime, strong buffering capacity, abundant and inexpensive resources, and no secondary pollution, thereby significantly reducing the cost of acidic soil improvement.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, and in particular relates to a method for preparing an acidic soil conditioner that can replace lime. Background Technology

[0002] Soil acidification is one of the main types of land degradation. Soil acidification inhibits the growth of soil microorganisms and plants, thus limiting crop yield increases and the sustainable development of agricultural production, ultimately leading to the overall deterioration of the ecological environment. my country has a vast area of ​​acidic soils, and due to the impact of human activities, the acidification situation is showing a further aggravating trend. Therefore, there is an urgent need for effective improvement of acidic soils in my country.

[0003] Lime, due to its very high alkali content, has been widely used as a traditional soil conditioner for acidic soils. However, limestone, the raw material for lime production, is a non-renewable resource. Furthermore, lime is widely used in industrial production such as cement, metallurgy, papermaking, rubber, paint, coatings, pharmaceuticals, cosmetics, animal feed, sealing, bonding, and polishing, making it a scarce and expensive resource. The economic cost and resource and environmental sacrifices of using lime on a large scale in farmland are enormous, and excessive use of lime can lead to seedling burn and re-acidification stress.

[0004] Currently, most acidic soil conditioners on the market have certain drawbacks, such as high price, scarcity of social resources, insufficient acid neutralization capacity, significant risk of re-acidification, or the potential to cause secondary soil pollution. Therefore, there is an urgent need to develop new acidic soil conditioners that can replace or surpass lime, possess strong acid neutralization and buffering capabilities, are abundant and inexpensive, and do not cause secondary pollution, in order to overcome the shortcomings in current practical applications. Summary of the Invention

[0005] The purpose of this invention is to conduct secondary development of various seafood shell wastes and provide a method for preparing an acid soil conditioner that can replace lime, with acid neutralization capacity equal to or even stronger than lime, strong buffering capacity, abundant and inexpensive resources, and no secondary pollution, thereby greatly reducing the cost of acid soil improvement.

[0006] The present invention is implemented as follows: a method for preparing an acidic soil conditioner that can replace lime includes the following steps:

[0007] Step 1: After cleaning the clam shells, scallop shells, oyster shells and mussel shells, dry them at 50℃ and then crush them. Mix the clam shell powder, scallop shell powder, oyster shell powder and mussel shell powder evenly in a weight ratio of 1:1:1:1.

[0008] Step 2: Under anaerobic conditions, the temperature is increased to 800°C at a pyrolysis rate of 20°C per minute and maintained for 2 hours;

[0009] Step 3: Cool to room temperature, grind and pass through a 1mm sieve to obtain the acidic soil conditioner.

[0010] This invention provides a method for preparing an acidic soil conditioner that can replace lime. The raw material for the conditioner is seafood shell waste, which is rich in alkaline substances such as CaO, CaCO3, NaO, and MgO. It is abundant, inexpensive, and has a fast regeneration rate. Its acid neutralization capacity is the same as or even stronger than that of lime. At the same time, it retains some hydroxyl groups and other functional groups. Under the action of organic matter, its stability is much higher than that of lime. It releases slowly, has a strong acid buffering capacity, and will not burn seedlings.

[0011] This soil conditioner has wide applicability and can significantly reduce the acidity and toxic aluminum content of soil solutions in various types of acidic soils in southern my country. Furthermore, it is environmentally friendly and an ideal alternative to traditional lime, effectively alleviating lime resource pressure and significantly reducing the cost of acidic soil improvement. Attached Figure Description

[0012] Figure 1 Acid-base titration curve of an acidic soil conditioner that can replace lime, provided in an embodiment of the present invention.

[0013] Figure 2 The diagram shows the improvement effect of an acidic soil conditioner that can replace lime, provided in an embodiment of the present invention, on different acidic soils in southern my country. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0015] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0016] like Figure 1 As shown, a method for preparing an acidic soil conditioner that can replace lime, according to an embodiment of the present invention, includes the following steps:

[0017] Step 1: After cleaning the clam shells, scallop shells, oyster shells and mussel shells, dry them at 50℃ and then crush them. Mix the clam shell powder, scallop shell powder, oyster shell powder and mussel shell powder evenly in a weight ratio of 1:1:1:1.

[0018] Step 2: Under anaerobic conditions, the temperature is increased to 800°C at a pyrolysis rate of 20°C per minute and maintained for 2 hours;

[0019] Step 3: Cool to room temperature, grind and pass through a 1mm sieve to obtain the acidic soil conditioner.

[0020] Clam shells contain calcium, iron, phosphorus, and some protein; scallop shells are rich in nutrients such as calcium, phosphorus, and zinc; oyster shells are rich in various metallic elements such as calcium, magnesium, zinc, and iron; and mussel shells are rich in nutrients such as calcium and phosphorus. These components can help maintain soil aeration and provide nutrients. Furthermore, clam shells, scallop shells, oyster shells, and mussel shells can improve soil structure and properties. The organic matter in these shells decomposes in the soil, producing abundant humus and increasing soil fertility. They also increase soil aeration and water retention, improving soil quality. In addition, clam shells, scallop shells, oyster shells, and mussel shells can neutralize acidic soil, mitigating the adverse effects of excessive soil acidity on plant growth.

[0021] It is important to note that when using clam shells, scallop shells, oyster shells, and mussel shells, they should be properly treated to ensure their effectiveness in the soil. Treatment methods may include grinding the clam shells, scallop shells, oyster shells, and mussel shells, or drying them, crushing them into powder, and then mixing them into the soil.

[0022] In summary, clam shells, scallop shells, oyster shells, and mussel shells have great potential for application in soil. They can serve as valuable fertilizers and soil conditioners, playing a positive role in improving soil quality and promoting plant growth.

[0023] Verification of the acid neutralization ability of the modifier: The modifier of this invention and lime were added to an acidic solution (pH=4) and allowed to stabilize for 24 hours before the pH value of the solution was measured. The results are shown in Table 1. This indicates that the acid neutralization ability of the modifier of this invention has reached a level equal to or even surpasses that of lime.

[0024] Table 1. pH values ​​of the solution after adding the modifier and lime to the acidic solution (volume ratio of modifier to acidic solution is 1:5).

[0025] Improver Quicklime (for comparison) Improver of the present invention solution pH value 12.60 12.65

[0026] Verification of the acid buffering capacity of the modifier: Using an automatic titrator, titration was performed with nitric acid at a rate of 0.2 mL / min until pH = 2.0. The results are as follows: Figure 1 As shown, lime's buffering capacity against acid is mainly concentrated in the initial stage of addition, and its buffering capacity against acidic soils is inherently weak. This is because the alkali in lime is completely and rapidly released and consumed in a short period after its addition to acidic soils. Therefore, the large-scale use of lime in farmland can lead to seedling burn and rapid re-acidification. The soil conditioner of this invention has a strong acid buffering capacity at pH < 5.0, and is effective against H+.+ Its consumption is more "mild" and "long-lasting," making it a better acid soil conditioner than lime in this respect.

[0027] Determination of the composition of the soil amendment: The inorganic components in the soil amendment were analyzed using X-ray fluorescence spectrometry, and the results are shown in Table 2. This indicates that the composition of the soil amendment of this invention is similar to that of lime, but it contains more alkaline substances such as CaO and Na2O than lime. The CaO content in the soil amendment of this invention is much higher than that in lime. This is attributed to the rapid water absorption and transformation of CaO in lime into Ca(OH)2, indicating that the CaO in the soil amendment of this invention is more stable, allowing it to slowly exert its effects in farmland and effectively avoiding seedling burn caused by lime. Meanwhile, lime contains a relatively large amount of Al2O3 and SO3, both of which produce a large amount of H2O upon hydrolysis. + This leads to soil re-acidification, but the soil conditioner of this invention contains extremely low levels of Al2O3 and SO3, minimizing the risk of rapid soil re-acidification. Furthermore, the conditioner of this invention contains almost no heavy metals, and is even "purer" than lime, posing no risk of secondary soil pollution.

[0028] Table 2 Comparison of the modifier and lime components of this invention

[0029]

[0030] The soil conditioner of this invention is made from seafood shell waste, rich in alkaline substances such as CaO, CaCO3, NaO, and MgO. It is abundant, inexpensive, and regenerates quickly. Its acid neutralization capacity is similar to or even stronger than lime, while retaining some hydroxyl groups and other functional groups. Under the influence of organic matter, its stability is far superior to lime, with slow release and strong acid buffering capacity, preventing fry burn. Simultaneously, it provides a new approach to the resource utilization of fishery waste and solves a series of environmental problems caused by improper disposal of current fishery waste. This soil conditioner does not contain toxic or harmful substances and has many advantages compared to currently available acidic soil conditioners, making it an ideal alternative to lime as an acidic soil conditioner.

[0031] Example 1 - Effect of the amendment of the present invention on the acidity of different types of acidic soils in southern my country

[0032] Three typical acidic soils—red clay from Langxi, Anhui; red sandy soil from Yingtan, Jiangxi; and lateritic red soil from Xuwen, Guangzhou—were used as test soils. Acidic soil samples were collected from these regions, air-dried, ground, and sieved. 300g samples were weighed and mixed with 0.0% (blank control), 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% of the soil conditioner of this invention, and quicklime (for effect comparison), respectively. The mixtures were then placed in plastic cups. The soil moisture content was adjusted to 70% of field capacity using deionized water. The plastic cups were sealed with plastic wrap, leaving small holes in the center to allow gas exchange and prevent excessive moisture loss. The plastic cups were placed in a 25°C constant-temperature incubator for incubation. The soil was weighed and water was added every three days to maintain a constant soil moisture content. After 60 days of incubation, the soil samples were air-dried, ground, sieved, and the soil pH was measured. The results are as follows: Figure 2 As shown in the figure, it can be seen that only a very small amount of the amendment of this invention is needed to significantly reduce the acidity of different types of acidic soils in my country. The improvement effect is almost the same as that of lime, and the effect is particularly good. The amendment of this invention has the characteristics of good effect and small dosage.

[0033] Example 2 - Effect of the amendment of the present invention on improving the cation exchange capacity and acid buffering capacity of acidic soils

[0034] Jiangxi red sandy soil with 0.4% of the amendment of this invention and lime was used as the research object to analyze its effect on the cation exchange capacity (CEC) and acid buffer capacity (pHBC) of acidic soil. The results are shown in Table 3. It can be seen that adding 0.4% of the amendment of this invention can significantly (P<0.05) increase the soil CEC and pHBC in acidic soil. The increase in soil CEC can better retain nutrients and adsorb and fix more Al. 3+ Pb 2+ The presence of toxic metal ions has multiple benefits in alleviating aluminum and heavy metal toxicity and nutrient deficiency in acidic soils, effectively improving crop yield, quality, and nutrient utilization efficiency while reducing the application of chemical fertilizers. The soil conditioner of this invention contains numerous inorganic and organic functional groups such as SiO2, Al2O3, P2O5 (Table 2), and -OH, forming a complex acid buffer system that increases soil pHBC. This increase in soil pHBC effectively inhibits re-acidification after soil amendment. The soil conditioner of this invention is more effective than lime in improving soil CEC and pHBC because it possesses the dual characteristics of both inorganic and organic conditioners, making it a superior acidic soil conditioner compared to lime.

[0035] Table 3. Effects of the amendment of this invention on cation exchange capacity and acid buffering capacity of acidic soil.

[0036]

[0037] Example 3 - The mitigating effect of the amendment of the present invention on aluminum toxicity in acidic soil

[0038] Aluminum (Al) toxicity caused by soil acidification is a major factor inhibiting plant growth. Jiangxi red sandy soil with 0.2% of the amendment of this invention and lime was selected as the research object, and the results are shown in Table 4. After adding 0.2% of the amendment of this invention and lime, the Al concentration in the acidic soil solution decreased by 76% and 83% respectively compared with the control, and the content of exchangeable Al in the soil decreased by 84% and 86% respectively compared with the control. It can be seen that the amendment of this invention can very effectively reduce Al toxicity in acidic soil, and its effect is not significantly different from that of lime (P>0.05), showing excellent results. After adding 0.2% of the amendment of this invention and lime, the content of adsorbed hydroxyl Al in the soil increased by 38% and 34% respectively compared with the control, and the total active Al content decreased by 18% and 28% respectively compared with the control. This indicates that the addition of the amendment of this invention causes some active Al to become more stable solid-phase Al (such as crystalline Al(OH)3).

[0039] Table 4. Effects of adding the amendment of this invention on aluminum speciation in acidic soils.

[0040]

[0041] The above embodiments of the present invention provide a method for preparing an acidic soil conditioner that can replace lime. The raw material of the conditioner is seafood shell waste, which is rich in alkaline substances such as CaO, CaCO3, NaO, and MgO. It is abundant, inexpensive, and has a fast regeneration speed. Its acid neutralization capacity is the same as or even stronger than that of lime. At the same time, it retains some hydroxyl groups and other functional groups. Its stability under the action of organic matter is much higher than that of lime. It releases slowly, has a strong acid buffering capacity, and will not burn seedlings.

[0042] This soil conditioner has wide applicability and can significantly reduce the acidity and toxic aluminum content of soil solutions in various types of acidic soils in southern my country. Furthermore, it is environmentally friendly and an ideal alternative to traditional lime, effectively alleviating lime resource pressure and significantly reducing the cost of acidic soil improvement.

[0043] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present 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 this patent should be determined by the appended claims.

Claims

1. A method for preparing an acidic soil conditioner that can replace lime, characterized in that, Includes the following steps: Step 1: After cleaning the clam shells, scallop shells, oyster shells and mussel shells, dry them at 50℃ and then crush them. Mix the clam shell powder, scallop shell powder, oyster shell powder and mussel shell powder evenly in a weight ratio of 1:1:1:

1. Step 2: Under anaerobic conditions, the temperature is increased to 800°C at a pyrolysis rate of 20°C per minute and maintained for 2 hours; Step 3: Cool to room temperature, grind and pass through a 1mm sieve to obtain the acidic soil conditioner; The raw material for the improver is seafood shell waste, which is rich in alkaline substances such as CaO, CaCO3, NaO, and MgO. It is abundant, inexpensive, and has a fast regeneration speed. Its acid neutralization capacity is the same as or even stronger than that of lime. At the same time, it retains some hydroxyl groups and other functional groups. Under the action of organic matter, its stability is much higher than that of lime. It is released slowly, has a strong acid buffering capacity, and will not burn seedlings. The amendment of this invention has a composition similar to lime, but contains more alkaline substances such as CaO and Na2O. The CaO content in the amendment is significantly higher than in lime. This is attributed to the rapid water absorption and transformation of CaO in lime into Ca(OH)2, indicating that the CaO in the amendment is more stable. This allows it to work slowly in farmland, effectively avoiding seedling burn caused by lime. Meanwhile, lime contains a relatively large amount of Al2O3 and SO3, both of which produce a large amount of H2O upon hydrolysis. + This leads to soil re-acidification, but the soil conditioner of this invention has extremely low Al2O3 and SO3 content, so the risk of rapid soil re-acidification is small; in addition, the soil conditioner of this invention contains almost no heavy metals. Aluminum (Al) toxicity caused by soil acidification is a major factor inhibiting plant growth; the amendment of this invention can very effectively reduce Al toxicity in acidic soils, and the addition of the amendment of this invention causes some active Al to become more stable solid phase Al; The soil conditioner of this invention contains numerous inorganic and organic functional groups such as SiO2, Al2O3, P2O5 and -OH, which form a complex acid buffer system, thereby increasing the soil pHBC. The increase in soil pHBC can effectively inhibit the re-acidification of the soil after improvement.

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