An oil shale source acid soil amendment, and a preparation method and application thereof

Abstract

This invention relates to the field of soil improvement technology, specifically disclosing an acidic soil conditioner derived from oil shale, its preparation method, and its application. The acidic soil conditioner is composed of oil shale, decomposed straw, wood ash, magnesium sulfate, fulvic acid, and amino acids. The acidic soil conditioner provided by this invention can rapidly neutralize soil acidity, increase soil pH, reduce the total amount of exchangeable acids, increase the total amount of exchangeable base ions and cation exchange capacity, improve organic matter content, improve soil structure, promote crop growth, and increase yield, showing promising prospects for widespread application.

Description

Technical Field

[0001] This invention relates to the field of soil improvement technology, specifically to an acidic soil conditioner derived from oil shale, its preparation method, and its application. Background Technology

[0002] Soil acidification is exacerbated by acid deposition, excessive nitrogen fertilizer, and improper tillage, leading to base leaching, structural damage, and a continuous decline in pH in black soil regions. Acidification reduces nutrient availability, enhances heavy metal activity, and disrupts microbial communities, threatening crop growth and food security. To improve acidic soils, soil conditioners have evolved from neutralizing materials (lime, gypsum, etc.) to a combination of mineral and synthetic materials, and further towards composite and functional formulations. Existing types include: inorganic types (calcareous, alkaline minerals), which neutralize acidity, replenish bases, and reduce aluminum toxicity; organic types (livestock manure, biochar), which improve organic matter, structure, adsorb aluminum ions, and regulate acidity through microbial metabolism, providing long-lasting effects; and composite types (inorganic-organic composites), which synergistically achieve neutralization, fertilization, and structural improvement.

[0003] However, all types of soil amendments have their shortcomings: Among inorganic amendments, long-term single application of lime-based amendments can easily lead to soil compaction, thereby reducing soil microbial activity and destroying soil aggregate structure; improper dosage control can easily cause soil nutrient imbalance, and it is prohibited to apply them simultaneously with nitrogen-containing fertilizers, resulting in strong limitations in their use. Alkaline mineral amendments are weaker in neutralizing soil acidity than lime-based amendments and take effect more slowly; the raw material processing, such as activation treatment, is more expensive, making the overall cost higher than lime-based amendments. Among organic amendments, livestock and poultry manure fermentation amendments take effect slowly and need to be applied 15-20 days before crop sowing; the fermentation process requires high temperature and humidity control, and if the fermentation is not thorough, it can easily produce odors and carry pathogens, affecting soil and crop health. Biochar amendments require energy consumption in their preparation process, and processes such as pyrolysis and activation lead to high preparation costs; when applied alone, their ability to neutralize soil acidity is weak, and they must be used in combination with inorganic amendments to achieve the ideal acidity control effect.

[0004] Inorganic-organic composite soil conditioners also have certain limitations in their effectiveness, and it is difficult to balance their acid-adjusting efficiency with fertilizer compatibility: products that focus on rapid acid adjustment are prone to causing local soil alkalization, exacerbating the loss of ammonium nitrogen volatilization, and cannot be applied simultaneously with nitrogen fertilizer, thus having strong limitations in use; products that focus on organic fertilization have a slow acid-adjusting effect, and their effect on reducing soil exchangeable acid in the early stage of crop growth is insufficient. Moreover, the synergistic compatibility between the organic and inorganic components of most products is poor, and the overall improvement effect on soil cation exchange capacity, base saturation and other indicators is not stable enough, making it difficult to achieve multi-dimensional and continuous soil improvement. Summary of the Invention

[0005] To develop a novel soil conditioner, this invention provides an acidic soil conditioner derived from oil shale, its preparation method, and its application.

[0006] The present invention adopts the following technical solution: This invention provides an acidic soil conditioner derived from oil shale, comprising the following raw materials: oil shale, decomposed straw, wood ash, magnesium sulfate, fulvic acid, and amino acids; The mass ratio of oil shale, decomposed straw, wood ash and magnesium sulfate is 1~8:1~8:1:1; The amounts of fulvic acid and amino acids added are 1% to 5% of the total mass of oil shale, decomposed straw, wood ash and magnesium sulfate.

[0007] The acidic soil conditioner of this invention uses oil shale, decomposed straw, wood ash, and magnesium sulfate as main raw materials, supplemented with fulvic acid and amino acids as synergists. Through the synergistic effect of alkaline minerals in the oil shale and wood ash, soil acidity is rapidly neutralized. Decomposed straw improves soil structure, provides organic matter, and maintains microbial activity. Simultaneously, fulvic acid and amino acids can adsorb and slowly release nitrogen, reducing the impact of alkaline materials on the volatilization of ammonium nitrogen. This allows for synergistic application with nitrogen fertilizer, achieving multi-dimensional and efficient comprehensive improvement of acidic soils.

[0008] Furthermore, the mass ratio of the oil shale, decomposed straw, wood ash, and magnesium sulfate is 2~6:2~6:1:1.

[0009] Furthermore, the amount of fulvic acid and amino acids added is 2% to 3% of the total mass of oil shale, decomposed straw, wood ash and magnesium sulfate.

[0010] The present invention also provides a method for preparing the aforementioned acidic soil conditioner, comprising the following steps: The oil shale is crushed into particles with a diameter of <5 mm for later use; After crushing the straw, mix it with the composting agent at a mass ratio of 900~1100:2 and ferment for 7~10 days. During this period, turn the pile over every 2~3 days and add water to maintain a volume moisture content of 50%~60%. Then cool it down to 30℃~40℃ and continue to compost. After the straw is fully decomposed, dry it until the moisture content is ≤15% and then crush it into small pieces <2 cm to obtain decomposed straw. Oil shale, decomposed straw, wood ash and magnesium sulfate are mixed evenly according to the specified ratio to obtain a mixture. Add fulvic acid and amino acids to the mixture and continue stirring until the raw materials are mixed evenly without clumping or stratification, thus obtaining the acidic soil conditioner.

[0011] Furthermore, the straw is pulverized into small pieces of 1 cm to 5 cm.

[0012] Furthermore, the fermentation temperature is 55℃~60℃; the composting time is 15~20 days.

[0013] Furthermore, the stirring speed is 100~120 r / min, and the stirring time is 15~20 min.

[0014] The present invention also provides the application of the aforementioned acidic soil conditioner in the improvement of acidic soil.

[0015] Furthermore, the acidic soil conditioner is used to increase soil pH, reduce the total amount of exchangeable acids, and increase the total amount of exchangeable bases, cation exchange capacity, and base saturation.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The acidic soil conditioner provided by this invention is a compound made from oil shale, decomposed straw, wood ash, and magnesium sulfate. Decomposed straw is rich in organic matter, which improves soil aggregate structure and enhances permeability, avoiding soil compaction caused by the simple application of alkaline inorganic materials. Simultaneously, organic matter provides a carbon source for soil microorganisms, which is beneficial for maintaining and restoring microbial community activity. Wood ash is a strongly alkaline substance that can quickly neutralize soil acidity. Oil shale itself contains a certain amount of alkaline minerals (such as carbonates and silicates), which, in synergy with wood ash, can significantly increase soil pH and rapidly reduce the total amount of exchangeable acid in the soil, thus overcoming the slow-acting defect of single alkaline minerals. In terms of preparation process, this invention directly uses pulverized oil shale raw materials, without the need for high-temperature calcination or chemical activation. Straw undergoes high-temperature fermentation (55-60℃) and composting (30-40℃) to achieve complete decomposition, effectively killing pathogens and insect eggs and eliminating odors. Decomposed straw rapidly releases organic matter, eliminating the need for pre-application; it can be mixed immediately upon use, significantly shortening the improvement cycle. Wood ash and magnesium sulfate are both common and inexpensive raw materials. The entire preparation process involves only simple operations such as crushing, mixing, and stirring, requiring no high-temperature, high-pressure, or special equipment, significantly reducing production costs and energy consumption.

[0017] The organic matter and humic acid substances (fulvic acid, amino acids) contained in this invention can adsorb and slowly release nitrogen, reducing nitrogen fertilizer loss. Although wood ash is alkaline, when combined with decomposed straw, fulvic acid, etc., it can reduce the impact of local alkalinity on the volatilization of ammonium nitrogen, allowing it to be applied in conjunction with nitrogen fertilizer and improving fertilizer utilization.

[0018] Compared with existing single or compound soil conditioners, this invention achieves multi-dimensional soil improvement through the synergistic effect of oil shale (providing mineral bases), decomposed straw (replenishing organic matter and increasing cation exchange capacity), wood ash (providing potassium, calcium, and other base ions), magnesium sulfate (replenishing magnesium), and fulvic acid and amino acids (synergists): increasing soil pH, reducing the total amount of exchangeable acids, increasing the total amount of exchangeable base ions, improving cation exchange capacity and base saturation, increasing soil organic matter content, enhancing crop growth, and increasing corn dry weight and yield. Therefore, this invention has good prospects for widespread application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The effect of acidic soil conditioner on soil pH under incubation conditions is shown in the figure. In the figure, A is the soil pH after 20 days of incubation, B is the soil pH after 40 days of incubation, C is the soil pH after 60 days of incubation, D is the soil pH after 80 days of incubation, E is the soil pH after 100 days of incubation, and F is the soil pH after 120 days of incubation.

[0021] Figure 2 The effect of acidic soil conditioner on the total exchangeable acid in the soil under cultivation conditions is shown in the figure. In the figure, A represents the total exchangeable acid in the soil after 20 days of cultivation, B represents the total exchangeable acid in the soil after 40 days of cultivation, C represents the total exchangeable acid in the soil after 60 days of cultivation, D represents the total exchangeable acid in the soil after 80 days of cultivation, E represents the total exchangeable acid in the soil after 100 days of cultivation, and F represents the total exchangeable acid in the soil after 120 days of cultivation.

[0022] Figure 3 The effect of acidic soil conditioner on the total amount of exchangeable basic ions in the soil under incubation conditions is shown in the figure. In the figure, A represents the total amount of exchangeable basic ions in the soil after 20 days of incubation, B represents the total amount of exchangeable basic ions in the soil after 40 days of incubation, C represents the total amount of exchangeable basic ions in the soil after 60 days of incubation, D represents the total amount of exchangeable basic ions in the soil after 80 days of incubation, E represents the total amount of exchangeable basic ions in the soil after 100 days of incubation, and F represents the total amount of exchangeable basic ions in the soil after 120 days of incubation.

[0023] Figure 4 The effect of different dosages of acidic soil conditioner on soil pH at different growth stages of maize.

[0024] Figure 5The effects of different dosages of acidic soil conditioner on the total amount of exchangeable acid in the soil at different growth stages of maize.

[0025] Figure 6 The effects of different dosages of acidic soil conditioner on the total amount of exchangeable basic ions in the soil at different growth stages of maize.

[0026] Figure 7 The effects of different dosages of acidic soil conditioner on soil cation exchange capacity at different growth stages of maize.

[0027] Figure 8 The effects of different dosages of acidic soil conditioner on soil base saturation at different growth stages of maize.

[0028] Figure 9 The effects of different dosages of acidic soil conditioner on soil organic matter content at different growth stages of maize.

[0029] Figure 10 The effect of different dosages of acidic soil conditioner on the dry weight of maize at different growth stages was investigated. Detailed Implementation

[0030] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0031] Example 1: A method for preparing an acidic soil conditioner derived from oil shale.

[0032] The oil shale (taken from the Engineering Technology Research Center of Fushun Mining Group Co., Ltd.) was crushed into particles with a diameter of less than 5 mm and set aside for later use.

[0033] Crush corn stalks to a size less than 5 cm, mix with a composting agent at a ratio of 1000:2, and ferment at 60℃ for 10 days. During this period, turn the pile regularly, once every 2 days, and add moisture to maintain a volumetric moisture content of 55%. After high-temperature fermentation, cool to 35℃ and continue composting for 20 days to ensure complete decomposition of the stalks. Dry the decomposed stalks until the moisture content is ≤15%, and crush them into small pieces less than 2 cm.

[0034] Two parts of oil shale, six parts of decomposed straw, one part of wood ash (purchased from Jilin Mengqi Agricultural Development Co., Ltd.), and one part of magnesium sulfate (purchased from Shanghai Minhang Shenlong Light Chemical Co., Ltd.) were sequentially placed into a mixer and mixed at 120 r / min for 10 min to obtain a mixture. At 2% of the total mass of the mixture, 85% mineral-derived fulvic acid (purchased from Beijing Bowei Shennong Technology Co., Ltd.) and compound free amino acids (purchased from Beijing Bowei Shennong Technology Co., Ltd.) were added respectively, and the mixture was stirred at 120 r / min for 15 min to ensure that the raw materials were mixed evenly without lumps or stratification, thus obtaining an acidic soil conditioner, denoted as ORH1.

[0035] Example 2: A method for preparing an acidic soil conditioner derived from oil shale.

[0036] Four parts of oil shale, four parts of decomposed straw, one part of wood ash, and one part of magnesium sulfate were sequentially placed into a mixer and mixed. The mixture was stirred at 120 r / min for 10 min to obtain a mixture. At 2% of the total mass of the mixture, 85% mineral-derived fulvic acid and compound free amino acids were added respectively. The mixture was stirred at 120 r / min for 15 min to ensure that the raw materials were mixed evenly without clumping or stratification. The resulting acidic soil conditioner was designated as ORH2.

[0037] Example 3: A method for preparing an acidic soil conditioner derived from oil shale.

[0038] Six parts of oil shale, two parts of decomposed straw, one part of wood ash, and one part of magnesium sulfate were sequentially placed into a mixer and mixed. The mixture was stirred at 120 r / min for 10 min to obtain a mixture. At 2% of the total mass of the mixture, 85% mineral-derived fulvic acid and compound free amino acids were added as synergists. The mixture was stirred at 120 r / min for 15 min to ensure that the raw materials were mixed evenly without clumping or stratification. The resulting acidic soil conditioner was designated ORH3.

[0039] Comparative Example 1: Take 4 portions of oil shale, add 2% of the total mass of oil shale to the synergist fulvic acid and amino acids respectively, stir at 120 r / min for 15 min to ensure that the raw materials are mixed evenly without clumping or stratification, and obtain an acidic soil conditioner, denoted as O.

[0040] Comparative Example 2: Take 4 portions of decomposed straw, add 2% of the total mass of decomposed straw to the synergist fulvic acid and amino acids respectively, stir at 120 r / min for 15 min to ensure that the raw materials are mixed evenly without clumping or stratification, and obtain an acidic soil conditioner, denoted as R.

[0041] Comparative Example 3: Take 4 parts of wood ash, add 2% of the total mass of wood ash to the synergist fulvic acid and amino acids respectively, stir at 120 r / min for 15 min to ensure that the raw materials are mixed evenly without lumps or stratification, and obtain the acidic soil conditioner, denoted as H.

[0042] Comparative Example 4: One part of oil shale and three parts of decomposed straw were placed in a mixer and mixed at 120 r / min for 10 min to obtain a mixture. At 2% of the total mass of the mixture, humic acid and amino acids were added respectively, and the mixture was stirred at 120 r / min for 15 min to ensure that the raw materials were mixed evenly without clumping or stratification. The resulting acid soil conditioner was denoted as OR1.

[0043] Comparative Example 5: Two parts of oil shale and two parts of decomposed straw were placed in a mixer and mixed at 120 r / min for 10 min to obtain a mixture. At 2% of the total mass of the mixture, humic acid and amino acids were added respectively, and the mixture was stirred at 120 r / min for 15 min to ensure that the raw materials were mixed evenly without clumping or stratification. The resulting acidic soil conditioner was denoted as OR2.

[0044] Comparative Example 6: Three parts of oil shale and one part of decomposed straw were placed in a mixer and mixed at 120 r / min for 10 min to obtain a mixture. At 2% of the total mass of the mixture, humic acid and amino acids were added respectively, and the mixture was stirred at 120 r / min for 15 min to ensure that the raw materials were mixed evenly without clumping or stratification. The resulting acidic soil conditioner was denoted as OR3.

[0045] Soil incubation experiments were conducted to compare the effects of O, R, H, OR1, OR2, OR3, ORH1, ORH2, and ORH3 on soil pH, total exchangeable acidity, and total exchangeable basic ions; CK served as the control.

[0046] Soil incubation experiment: The test soil was taken from Yongfeng Village, Panshi County, Jilin City, Jilin Province. The soil pH was 4.56, total nitrogen content was 2.20 g / kg, organic matter content was 24.89 g / kg, available nitrogen content was 146 mg / kg, available phosphorus content was 65.7 mg / kg, and available potassium content was 149 mg / kg. The soil was air-dried and sieved for later use. At a mass ratio of 1:25, each group of acidic soil conditioner was mixed with 900 g of air-dried soil and placed into plastic containers 15 cm high and 10 cm in diameter. Deionized water was added to adjust the soil moisture content to 60% of field capacity. The container openings were sealed with sealing film, with vent holes provided. A control group was included, containing only soil without acidic soil conditioner. The culture tanks were placed in the outdoor environment of the Shenyang Agricultural University Back Mountain Research Base. During the experiment, the outdoor environment of the Shenyang Agricultural University Back Mountain Research Base transitioned from the warming of late spring to the high temperature and rainfall of midsummer, with a temperature range of 5℃ to 34℃ and a diurnal temperature range decreasing from 12℃ to 15℃ to 8℃ to 10℃. The relative humidity was 35% to 65% on sunny days and could rise to 80% to 98% during precipitation. The culture experiment began on April 25, 2025. Soil was weighed every 10 days to ensure that soil moisture was maintained at 60% of field capacity. Soil samples were collected on days 20, 40, 60, 80, 100, and 120 of culture to determine soil pH, total exchangeable acid, and total exchangeable basic ions. Soil pH was measured using a pH meter, total exchangeable acid was determined using potassium chloride extraction-neutralization titration, and total exchangeable basic ions were determined using ammonium acetate extraction-NaOH titration.

[0047] Figure 1 The results showed that, with prolonged incubation time, soil pH in all treatments except R showed a fluctuating upward trend compared to CK. The pH in treatment R initially increased and then decreased, gradually declining after day 40 and eventually stabilizing at around 4.5, indicating that straw addition only increased soil pH within the first 40 days, and subsequently decreased. Treatment H showed a slight increase in pH compared to CK, but the increase was small. Treatment O significantly and continuously increased soil pH, maintaining an upward trend even after 120 days, which is related to the relatively high pH of the oil shale itself. Among different ratios of oil shale to straw, OR1 and OR2 showed similar trends, with OR2 having a slightly higher pH than OR1; OR3 showed the largest increase, significantly higher than OR1 and OR2, and continued to rise, but its pH was lower than that of treatment O in the early stages of incubation, with the largest increase occurring on day 100. The conditioner treatment with added wood ash and magnesium sulfate (ORH) significantly increased soil pH compared to CK, but its pH was also lower than that of treatment O due to the lower amount of oil shale used. On day 20, the pH values ​​of ORH2 and ORH3 were significantly higher than those of ORH1. Thereafter, there were no significant differences among the three, but ORH3 had the highest pH value. Overall, the O treatment showed the best short-term effect, OR3 showed the best long-term effect, and ORH3 exhibited more stable performance throughout the entire culture cycle.

[0048] Figure 2 The results showed that during the incubation period, the total exchangeable acidity in the R and H treatments initially decreased and then increased; the CK and O treatments initially increased rapidly, then decreased and then increased again; the OR and ORH treatments showed similar trends, exhibiting a slow increase followed by a rapid decrease, then a rebound and a decrease again; the OR3 treatment showed a continuous rapid decrease, rebounding after day 100. All treatments reduced the total exchangeable acidity compared to the CK treatment, with the H treatment showing the lowest reduction. Among the OR treatments, OR1 was lower than OR2 and OR3; among the ORH treatments, ORH1 was lower than ORH2 and ORH3. Overall, the H, R, OR1, and ORH1 treatments had lower total exchangeable acidity, indicating that the acidic soil conditioner effectively reduced exchangeable acidity, with the H treatment showing the best effect.

[0049] Figure 3 The changes in total exchangeable bases in the soil during the cultivation period are shown. The R and H treatments showed an initial increase, followed by a decrease and then an increase, peaking at 100 days before decreasing again. The O and OR2 treatments generally showed an initial decrease followed by an increase. The CK, OR1, OR3, and ORH3 treatments all showed an initial decrease, followed by an increase and then a decrease, with OR3 and ORH1 experiencing two troughs. ORH2 showed an initial decrease, followed by an increase, then a decrease before leveling off. The total exchangeable bases in all ORH treatments were generally higher than in the other treatments, with the H treatment also showing a relatively higher total. It is evident that soil conditioners increased the total exchangeable bases, with ORH2 showing the best short-term effect and ORH1 showing the best long-term effect. Overall, ORH1 treatment showed the best effect throughout the entire cultivation period.

[0050] The field experiment was conducted in Guomu Village, Hailang Township, Fushun County, Fushun City, Liaoning Province (41°39'N, 123°50'E), located in a gently hilly area (slope 3°). The climate is temperate monsoon, with an average annual temperature of 6°C to 8°C and annual precipitation of 700 mm to 900 mm. The soil is silty loam. Before the experiment, the topsoil layer (0 cm to 20 cm) had a pH of 5.28, total nitrogen of 0.59 g / kg, organic carbon of 5.12 g / kg, ammonium nitrogen of 4.28 mg / kg, and nitrate nitrogen of 8.98 mg / kg. Four treatments were included: no acidic soil conditioner (CK), 1% of Example 3 acidic soil conditioner (G1), 2% of Example 3 acidic soil conditioner (G2), and 3% of Example 3 acidic soil conditioner (G3). The plot area was 10 m × 5 m, with 3 replicates per treatment; the crop planted was maize, sown on May 10, 2025 and harvested on October 9, 2025. The fertilizer was a nitrogen-phosphorus-potassium compound fertilizer (N:P2O3:K2O=27:10:13, w:w:w), applied as a base fertilizer in one application; the tillage method was rotary tillage, to a depth of 10 cm to 15 cm.

[0051] Field trials showed that applying different dosages (1%, 2%, 3%) of the acidic soil conditioner from Example 3 (G1, G2, G3) could increase soil pH. Figure 4), organic matter content ( Figure 9 ), reduce the total amount of exchangeable acids ( Figure 5 ), increase the total amount of exchangeable bases ( Figure 6 ), cation exchange capacity ( Figure 7 ) and base saturation ( Figure 8 ), and increase plant biomass ( Figure 10 The production capacity increased by 3.27% to 8.11% (Table 1) and corn production.

[0052] Table 1. Corn yield indicators after applying different amounts of acidic soil conditioner Although preferred embodiments of the invention have been described, those skilled in the art, once they have learned the basic inventive concept, can make other changes and modifications to these embodiments.

[0053] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An acidic soil conditioner derived from oil shale, characterized in that, It contains the following raw materials: oil shale, decomposed straw, wood ash, magnesium sulfate, fulvic acid, and amino acids; The mass ratio of oil shale, decomposed straw, wood ash and magnesium sulfate is 1~8:1~8:1:1; The amounts of fulvic acid and amino acids added are 1% to 5% of the total mass of oil shale, decomposed straw, wood ash and magnesium sulfate.

2. The acidic soil conditioner according to claim 1, characterized in that, The mass ratio of the oil shale, decomposed straw, wood ash, and magnesium sulfate is 2~6:2~6:1:

1.

3. The acidic soil conditioner according to claim 1, characterized in that, The amounts of fulvic acid and amino acids added are 2% to 3% of the total mass of oil shale, decomposed straw, wood ash and magnesium sulfate.

4. A method for preparing the acidic soil conditioner according to any one of claims 1 to 3, characterized in that, Includes the following steps: The oil shale is crushed into particles with a diameter of <5 mm for later use; After crushing the straw, mix it with the composting agent at a mass ratio of 900~1100:2 and ferment for 7~10 days. During this period, turn the pile over every 2~3 days and add water to maintain a volume moisture content of 50%~60%. Then cool it down to 30℃~40℃ and continue to compost. After the straw is fully decomposed, dry it until the moisture content is ≤15% and then crush it into small pieces <2 cm to obtain decomposed straw. Oil shale, decomposed straw, wood ash and magnesium sulfate are mixed evenly according to the specified ratio to obtain a mixture. Add fulvic acid and amino acids to the mixture and continue stirring until the raw materials are mixed evenly without clumping or stratification, thus obtaining the acidic soil conditioner.

5. The preparation method according to claim 4, characterized in that, The straw is shredded into small pieces of 1 cm to 5 cm.

6. The preparation method according to claim 4, characterized in that, The fermentation temperature is 55℃~60℃; the composting time is 15~20 days.

7. The preparation method according to claim 4, characterized in that, The stirring speed is 100~120 r / min, and the stirring time is 15~20 min.

8. The application of the acidic soil conditioner according to any one of claims 1 to 3 in the improvement of acidic soil.

9. The application according to claim 8, characterized in that, The acidic soil conditioner is used to increase soil pH, reduce the total amount of exchangeable acids, and increase the total amount of exchangeable bases, cation exchange capacity, and base saturation.

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