Method for improving acidified soil by using carbon-based material

Abstract

The invention discloses a method for improving acidified soil by using a carbon-based material, which comprises the following steps: 1) adding a compound fertilizer into the acidified soil, and uniformly mixing; (2) adding a carbon-based material into the acidified soil treated in the step (1), and uniformly mixing; and (3) watering and culturing the acidified soil treated in the step (2). According to the method, the compound fertilizer is added into the acidified soil and uniformly mixed, then the carbon-based material is added and uniformly mixed, and watering culture is performed, so that the physicochemical properties of the acidified soil can be improved, the acid-base buffering capacity and the nutrient supply capacity of the acidified soil are improved, the microbial activity in the acidified soil is increased, and the microbial community structure is improved; the raw materials of the method are from agricultural wastes, so that the method is low in treatment cost, convenient to operate, capable of being applied on a large scale, very high in economical efficiency and very suitable for being popularized and used in the industry.

Description

Technical Field

[0001] The present invention generally relates to the field of ecological restoration of acidified soil, and in particular, to a method for improving acidified soil using carbon-based materials. Background Art

[0002] The total area of ​​acidic soil (pH < 6.5) in my country is about 3.111 million km2, accounting for about 32.4% of the country's land area, of which the total area of ​​strongly acidic soil (pH < 5.5) is about 448,000 km2. 2 , accounting for about 4.7% of the country's land area. Soil acidification has become one of the most prominent problems that plague the improvement of cultivated land quality and agricultural production safety, and it is showing a trend of further aggravation with the development of agriculture. In addition, soil microbial communities are also regulated by a variety of environmental factors such as soil nutrient content, moisture content and pH value. However, soil acidification has greatly affected the changes in microbial communities and reduced the ability to resist the invasion of soil-borne pathogens. The traditional treatment of acidified soils with improvers such as lime and fly ash is prone to soil compaction and heavy metal pollution risks, and it still cannot effectively solve a series of problems caused by acidified soils, such as acid release of aluminum, nutrient deficiency and restricted microbial activity.

[0003] Therefore, the industry is in urgent need of a method to improve acidified soil with higher remediation degree, lower cost and more environmentally friendly process. Summary of the invention

[0004] A main purpose of the present invention is to overcome at least one of the defects of the above-mentioned prior art and provide a method for improving acidified soil with carbon-based materials having a higher degree of restoration, lower cost and more environmentally friendly process.

[0005] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0006] According to one aspect of the present invention, there is provided a method for improving acidified soil using a carbon-based material, comprising the following steps:

[0007] 1) Add compound fertilizer to the acidified soil and mix well;

[0008] 2) adding the carbon-based material to the acidified soil treated in step 1) and mixing evenly;

[0009] 3) watering the acidified soil treated in step 2).

[0010] According to one embodiment of the present invention, the mass thousandth ratio of compound fertilizer to acidified soil is (2‰):(999.8‰).

[0011] According to one embodiment of the present invention, the carbon-based material is corn straw and / or corn straw biochar.

[0012] According to one embodiment of the present invention, step 2) further comprises: drying, crushing and sieving the corn stalks, and the mass percentage of the corn stalks to the acidified soil is (3%):(97%).

[0013] According to one embodiment of the present invention, the number of meshes of the sieving process is 10.

[0014] According to one embodiment of the present invention, step 2) further comprises: drying, crushing, screening and pyrolyzing the corn straw biochar, and the mass percentage of the corn straw biochar to the acidified soil is (2-4%): (96-98%).

[0015] According to one embodiment of the present invention, the mesh number of the sieving treatment is 10, and the heating temperature of the pyrolysis treatment is 500°C.

[0016] According to one embodiment of the present invention, step 3) further comprises: maintaining the moisture content of the treated acidified soil at 70% of its maximum water holding capacity.

[0017] According to one embodiment of the present invention, it also includes:

[0018] 4) Cash crops can be planted on the acidified soil treated in step 3), and the soil health status can be judged based on the growth of cash crops, soil physical and chemical properties and microbial ecological functions.

[0019] According to one embodiment of the present invention, step 4) further comprises: performing conventional management on the acidified soil for one hundred and eighty days, and watering regularly to maintain a moisture content of 60%.

[0020] It can be seen from the above technical scheme that the advantages and positive effects of the method of improving acidified soil with carbon-based materials of the present invention are:

[0021] In the present invention, compound fertilizer is added to the acidified soil and mixed evenly, and then carbon-based materials are added and mixed evenly, and watering and cultivation are performed, which can improve the physical and chemical properties of the acidified soil, enhance its acid-base buffering capacity and nutrient supply capacity, increase the microbial activity in the acidified soil and improve the microbial community structure, so as to ensure the long-term healthy development of the soil ecological environment. In addition, the raw materials of the method come from agricultural waste, the processing cost is low, the operation is convenient, and it can be applied on a large scale, with high economy. In addition, the natural organisms used are more environmentally friendly and will not cause secondary pollution, so the method is extremely suitable for promotion and use in the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a graph showing the changes in soil pH content during acidified soil treatment.

[0023] Figure 2This is a graph showing the changes in soil organic matter content during acidified soil treatment.

[0024] Figure 3 This is a graph showing changes in soil ammonium nitrogen content during acidified soil treatment.

[0025] Figure 4 This is a graph showing the changes in soil nitrate nitrogen content during acidified soil treatment.

[0026] Figure 5 This is a diagram of the growth of lettuce in acidified soil treatment.

[0027] Figure 6 Influence diagram of α diversity of soil bacteria (a, b) and fungi (c, d).

[0028] Figure 7 Principal component analysis (PCA) of soil bacterial (a) and fungal (b) community structures.

[0029] Figure 8 Figure 2 shows the composition of soil bacteria (a) and fungi (b) communities under different treatments at the phylum level.

[0030] Fig. 9 In the figure, a and b are ecological network diagrams of bacterial (a) and fungal (b) communities.

[0031] Fig. 9 Figures c and d are schematic diagrams showing the ratios of bacterial (c) and fungal (d) ASVs.

[0032] Fig.10 This figure shows the effect of adding carbon-based materials on soil metabolic function.

[0033] Fig.11 Graph showing the effect of adding carbon-based materials on soil fungal functional groups.

[0034] Fig.12 Graph showing the effect of adding carbon-based materials on soil multifunctionality.

[0035] Fig.13 This is a correlation analysis chart of lettuce growth indicators and soil physical and chemical properties, microbial community diversity and functionality. DETAILED DESCRIPTION

[0036] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present invention will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their detailed description will be omitted.

[0037] In the following description of different examples of the present invention, reference is made to the accompanying drawings, which form a part of the present invention and in which different exemplary structures, systems and steps that can implement multiple aspects of the present invention are shown by way of example. It should be understood that other specific schemes of components, structures, exemplary devices, systems and steps can be used, and structural and functional modifications can be made without departing from the scope of the present invention. Moreover, although the terms "top", "bottom", "front", "rear", "side", etc. may be used in this specification to describe different exemplary features and elements of the present invention, these terms are used herein only for convenience, such as the direction of the examples described in the accompanying drawings. Nothing in this specification should be construed as requiring a specific three-dimensional orientation of the structure to fall within the scope of the present invention.

[0038] The method of improving acidified soil with carbon-based materials of this embodiment comprises the following steps: 1) adding compound fertilizer to the acidified soil and mixing it evenly; 2) adding carbon-based materials to the acidified soil treated in step 1) and mixing it evenly; 3) watering and cultivating the acidified soil treated in step 2).

[0039] In this embodiment, soil acidification is a soil degradation problem in which excessive application of nitrogen fertilizers leads to a significant decrease in soil pH. Acidified soil contains too much acidic substances, which leads to a decrease in the number of beneficial microorganisms and soil animals in the soil, affecting plant growth and crop yields, and thus threatening agricultural production safety. Traditional soil acidification improvement usually involves the addition of modifiers such as lime and fly ash. This traditional method can only slightly improve the physical and chemical properties of acidified soil in the short term, but the acidified soil after long-term treatment still shows low soil pH and nutrient retention capacity and microbial activity, and this traditional improvement method is prone to soil compaction and heavy metal pollution risks, making it difficult to apply for a long time.

[0040] In this embodiment, in step 1), the mass ratio of compound fertilizer to acidified soil is (2‰): (999.8‰), the compound fertilizer is prepared by mixing N, P and K in a certain ratio, and the acidified soil and the compound fertilizer can be evenly mixed by ploughing; the compound fertilizer can supplement the nutrient elements lacking in the acidified soil, improve the fertility of the acidified soil, and provide comprehensive nutrition to promote plant growth; after adding the compound fertilizer to the acidified soil, water can be poured and left to stand at room temperature for two days, and the specific number of days of cultivation can be appropriately adjusted according to the actual changes of the acidified soil, and the soil is gently turned over to further mix it, and the moisture content of the acidified soil is maintained at 70% of its maximum water holding capacity during the cultivation process.

[0041] In this embodiment, the carbon-based material in step 2) is corn straw and corn straw biochar; the corn straw can be first dried by a dryer, and then the dried corn straw is crushed, and then the crushed corn straw is sieved, and the sieve mesh number of the sieve is 10 mesh; the sieved corn straw is added to the acidified soil treated by step 1), and the mass percentage of the corn straw to the acidified soil is (3%): (97%), and the sieved corn straw and the acidified soil treated by step 1) can be mixed evenly by plowing; at the same time, the sieved corn straw is pyrolyzed to obtain corn straw biochar, and the heating temperature of the pyrolysis treatment is 500°C; the sieved corn straw biochar is added to the acidified soil treated by step 1), and the mass percentage of the corn straw biochar to the acidified soil is (2-4%): (96-98%), and the sieved corn straw biochar and the acidified soil treated by plowing can be mixed evenly.

[0042] In this embodiment, in step 3), the acidified soil to which compound fertilizer and carbon-based materials are added is watered and cultured at room temperature for thirty days. The specific number of culture days can be appropriately adjusted depending on the actual changes in the acidified soil. During the culture process, the moisture content of the acidified soil is maintained at 70% of its maximum water holding capacity. The carbon-based material can neutralize the acidity of the soil, increase the pH value of the soil, and improve the acid-base balance of the soil.

[0043] In addition, carbon-based materials are rich in organic matter, which can provide nutrients and enhance microbial activity; at the same time, the application of carbon-based materials can improve the structure of acidified soil and increase the stability of soil aggregates; carbon-based materials have rich porous structures, which can increase the porosity and specific surface area of ​​acidified soil, so that the water retention and nutrient adsorption capacity of acidified soil are significantly improved; the high carbon-nitrogen ratio of carbon-based materials makes their decomposition rate slower, which can delay the release rate of nutrients and provide a long-lasting nutrient supply; the combined action of compound fertilizers and carbon-based materials can significantly increase the pH value of acidified soil, improve the aeration, water retention and fertilizer retention of acidified soil, promote the reproduction and activity of beneficial microorganisms, and adsorb pollutants such as heavy metals in acidified soil to reduce their toxicity, so that the acidified soil can be improved in a short time and provide environmental conditions for the growth of economic crops. When acidified soil is cultivated in potted plants, the methods for maintaining the moisture content of the acidified soil may be the weighing method, the pot bottom watering method or the golden water level cultivation method; when acidified soil is cultivated in the field, the moisture content of the acidified soil can be maintained by regularly measuring the moisture content and regularly irrigating the soil, and it can also be supplemented by covering the acidified soil with anti-evaporation materials such as films.

[0044] This embodiment also includes step 4): planting cash crops on the acidified soil treated in step 3). The secretions of the cash crop roots contain organic matter that can provide nutrients for the acidified soil, thereby improving the structure and quality of the acidified soil. In addition, the crop root secretions affect the composition of the rhizosphere microbiome of adjacent crops, thereby improving the adaptability of the plants. After planting cash crops on the acidified soil, the acidified soil is routinely managed. Routine treatment may include regular watering, as well as water-retaining management measures such as covering with film or straw mats. The duration of routine management may be forty days, and the specific duration may be appropriately adjusted depending on the changes in the acidified soil.

[0045] The following is a specific experimental process and results to illustrate the technical effects that the present invention can have. However, it should be noted that the experimental data is only for explaining the present invention, and the specific content details of the experiment are not limitations of the claims of the present invention:

[0046] Experimental materials: acidified soil was sampled and placed in a cool place to dry naturally, then sieved through a 2 mm sieve for later use; compound fertilizer; corn straw, which needed to be dried, crushed, and sieved through a 10-mesh sieve; corn straw biochar, which was pyrolyzed at 500 °C using sieved corn straw.

[0047] As shown in Table 1, five treatments were set up, and each treatment had three replicates. Compound fertilizer was added and mixed at a ratio of 0.2‰ of the weight of acidified soil; corn straw was added at a ratio of 3% of the weight of acidified soil; and corn straw biochar was added at a ratio of 2% and 4% of the weight of acidified soil, respectively. Compound fertilizer, corn straw, corn straw biochar and acidified soil were fully mixed and placed in a flower pot with a size of 22cm×21.5cm (inner diameter×pot height) and a hole at the bottom, and the upper layer was about 4cm away from the pot mouth. After adjusting and maintaining its moisture content to 70% of its maximum water holding capacity, it was placed in a room temperature (25℃±5℃) environment for 180 days. BC1 used 2% biochar; BC2 used 4% biochar; MS used 3% corn straw; MSBC1 used 3% corn straw + 2% biochar; CK was soil without adding amendments.

[0048]

[0049] Table 1 Treatment design

[0050] Furthermore, after the incubation period, samples were taken for physical and chemical property analysis, and the physical and chemical properties of the acidified soils treated with different treatments were obtained. Figure 1-4As shown, it can be seen that corn straw biochar can effectively neutralize the acidity of acidified soil and increase its pH value; the addition of corn straw and corn straw biochar increases the content of soil organic matter in acidified soil, and at the same time increases its total porosity, thereby improving the water retention and aeration of acidified soil, which is beneficial to plant colonization; the addition of 4% corn straw biochar significantly inhibits soil nitrification, and in the long run not only maintains the ammonium nitrogen content in acidified soil, but also effectively reduces the growth rate of nitrate nitrogen content in acidified soil; 2% corn straw biochar The addition of corn straw in the acidified soil significantly increased the nitrate-nitrogen content in the later stage of cultivation; moreover, the single treatment of corn straw or corn straw biochar and the combined treatment of corn straw and corn straw biochar had better comprehensive effects on the improvement of acidified soil. The combined treatment of the two not only raised the pH value of the acidified soil to 6.01, but also effectively improved the organic matter content of the acidified soil, which had a high content of available nitrogen and was beneficial to plant growth. It also effectively improved the physical structure of the acidified soil and reduced the release of pollutants such as heavy metals.

[0051] The following is the process and results of another specific experiment:

[0052] The acidified soil was air-dried and sieved, and compound fertilizer was added and mixed at a ratio of 0.2‰ of the weight of the acidified soil, that is, 0.35g of compound fertilizer was fully mixed with 1500g of acidified soil, and then placed in a flower pot with a specification of 22cm×21.5cm (inner diameter×pot height) and a hole at the bottom, and the upper layer was about 4cm away from the pot mouth, watered and adjusted to maintain its moisture content to 70% of its maximum water holding capacity, and then placed in a normal temperature (25℃±5℃) environment for two days, and the soil was gently turned over to further mix it to obtain acidified soil (a). The pH value of the acidified soil used was 5.39.

[0053] Further, the carbon-based materials selected were corn stalks and corn stalk biochar. After the corn stalks were dried, crushed and sieved, they were added and mixed at a ratio of 3% of the weight of the acidified soil (a), that is, 45 g of corn stalks were fully mixed with the acidified soil (a). At the same time, after the sieved corn stalks were pyrolyzed at 500°C, they were added and mixed at a ratio of 2% and 4% of the weight of the acidified soil (a), that is, 30 g and 60 g of corn stalk biochar were fully mixed with the acidified soil (a), and then put into the aforementioned flower pots, and after adjusting and maintaining the moisture content to 70% of its maximum water holding capacity, the flower pots were placed in a room temperature (25°C ± 5°C) environment for 30 days to obtain acidified soil (b). The specific experimental treatments are shown in Table 1.

[0054] Furthermore, lettuce, an economic crop, was planted on the aforementioned acidified soil (b), and then watered regularly and cultivated under conventional management for 40 days.

[0055] Furthermore, after forty days of routine management, the physical and chemical properties of the acidified soil are shown in Table 2. The soil pH value increased to 5.63-6.48, and the soil organic matter increased by 33-120% compared with the control treatment. The N and P nutrient elements in the acidified soil treated with the combined treatment of corn straw and corn straw biochar were significantly improved, which can provide the soil nutrients required for plant growth, and the acidified soil environment has been greatly improved.

[0056]

[0057]

[0058] Table 2 Physical and chemical properties of acidified soils under different treatments

[0059] Furthermore, after 40 days of routine management, the growth of lettuce is as follows Figure 5 As shown in Table 3, the addition of carbon-based materials significantly promoted the growth of lettuce. The branching of its root system and the growth of lateral roots increased the ability of lettuce to absorb and utilize nutrients and water in the soil, thereby increasing its plant height and number of leaves. At the same time, the addition of corn straw biochar significantly increased the nitrogen utilization efficiency of lettuce plants. In addition, the acidified soil treated with corn straw and corn straw biochar provided a more suitable soil environment for the growth of lettuce, promoting the growth and health of lettuce. Routine management requires watering to keep the soil at 60% moisture.

[0060]

[0061] Table 3 Determination of different treatments of lettuce plants

[0062] In the present invention, compound fertilizer is added to the acidified soil and mixed evenly, and then carbon-based materials are added and mixed evenly, and watering and cultivation are performed, which can improve the physical and chemical properties of the acidified soil, enhance its acid-base buffering capacity and nutrient supply capacity, increase the microbial activity in the acidified soil and improve the microbial community structure, so as to ensure the long-term healthy development of the soil ecological environment. In addition, the raw materials of the method come from agricultural waste, the processing cost is low, the operation is convenient, it can be applied on a large scale, it has high economy, and is extremely suitable for promotion and use in the industry.

[0063] The technical effects of the present invention are described in detail below based on actual data:

[0064] Soil physical and chemical properties

[0065] As shown in Table 4, the soil pH values ​​of the BC1, BC2, MS, and MSBC1 treatments were 5.63, 6.38, 6.00, and 6.48, respectively, which were significantly higher than those of the CK treatment. The changes in soil cation exchange capacity (CEC) were consistent with the pH values. Similarly, soil organic matter (SOM) also increased significantly in each treatment with the addition of straw and biochar, but the highest value appeared in the MSBC1 treatment. The MSBC1 treatment also greatly increased soil total nitrogen (TN) and total phosphorus (TP). As for soil available phosphorus (AP), it was 62.19, 71.83, and 61.35 mg kg-1 in the three soils with the addition of biochar (BC1, BC2, and MSBC1), respectively, and these values ​​were also significantly higher than those of the MS treatment. However, the available nitrogen in the soil (including NO3--N and NH4+-N) showed an opposite trend with the addition of straw and biochar, and was significantly lower than that of the control soil.

[0066] Five treatments were established for the pot experiment: (1) CK: soil without amendments; (2) BC1: soil + 2% (w / w) biochar; (3) BC2: soil + 4% (w / w) biochar; (4) MS: soil + 3% (w / w) straw; (5) MSBC1: soil + 2% (w / w) biochar + 3% (w / w) straw. Before the pot experiment, corn stover was ground to pass through a 2 mm sieve. Biochar was produced by pyrolysis of corn stover at 500 °C. Each treatment had three replicates, and a total of 15 seedling pots (17.7 cm in diameter and 12 cm in height) were filled with 1.5 kg of a mixture of air-dried soil and individual amendments and then moistened to 60% of their maximum water holding capacity (WHC). After 30 days of equilibration, six lettuce seeds were planted in each pot. After germination, three uniformly growing seedlings were left in each pot. The pots were randomly placed and planted outdoors and watered regularly to maintain a WHC of 60%.

[0067] BC1 BC2 MS MSBC1 CK <![CDATA[pH(H 2 O)]]> 5.63±0.24c 6.38±0.02a 6.00±0.04b 6.48±0.02a 5.13±0.03d <![CDATA[NO 3 - -N(mg kg -1 )]]> 5.47±0.12d 6.31±0.17b 6.04±0.10c 2.86±0.08e 12.79±0.17a <![CDATA[NH 4 + -N(mg kg -1 )]]> 25.13±1.14c 19.87±1.19d 41.33±1.39b 26.38±0.84c 56.55±1.19a <![CDATA[AP(mg kg -1 )]]> 62.19±0.37b 71.83±1.60a 55.24±2.31c 61.35±1.28b 50.63±0.18d <![CDATA[TN(g kg -1 )]]> 0.38±0.02d 0.52±0.02c 0.72±0.02b 0.92±0.03a 0.34±0.02e <![CDATA[TP(g kg -1 )]]> 0.49±0.03b 0.57±0.03a 0.50±0.01b 0.59±0.01a 0.48±0.01b <![CDATA[SOM(g kg -1 )]]> 10.79±0.51c 15.27±0.37b 15.04±0.07b 17.80±0.60a 8.10±0.07d <![CDATA[CEC(cmol kg -1 )]]> 11.11±0.48a 10.15±0.64b 12.01±0.57a 9.62±0.10b 7.41±0.53c C:N 12.39±0.89a 12.83±0.35a 9.17±0.27c 8.46±0.57c 10.55±0.52b

[0068] Table 4 Effects of carbon-based material addition on the physical and chemical properties of lettuce pot soil

[0069] Note: BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn straw; MSBC1, 3% corn straw + 2% biochar; CK, control. NO3--N, soil nitrate nitrogen; NH4+-N, soil ammonium nitrogen; AP, available phosphorus; TN, total nitrogen; TP, total phosphorus; SOM, soil organic matter; CEC, cation exchange capacity; C:N, ratio of soil organic carbon to total nitrogen. All values ​​are reported as mean ± SD, n = 3. Different lowercase letters indicate significant differences among the five treatments at the p < 0.05 level.

[0070] Soil microbial community

[0071] Microbial diversity

[0072] The addition of straw and biochar significantly increased soil bacterial diversity, but had no significant effect on fungal diversity ( Figure 6 The addition of straw significantly increased the richness of soil bacteria and fungi ( Figure 6 Among them, the richness of microorganisms was the highest in the MSBC1 treatment.

[0073] Figure 6 Effects of soil bacterial (a, b) and fungal (c, d) α diversity. BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn stover; MSBC1, 3% corn stover + 2% biochar; CK, control.

[0074] Microbial community structure

[0075] The PCA analysis results showed that there were significant differences in soil bacterial and fungal communities among the treatments with biochar (BC1 and BC2), straw (MS and MSBC1) and control (CK). Figure 7 ).

[0076] Figure 7 Principal component analysis (PCA) of soil bacterial (a) and fungal (b) community structures. BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn stover; MSBC1, 3% corn stover + 2% biochar; CK, control.

[0077] The soil bacterial community was mainly composed of Proteobacteria (38-47%), Actinobacteria (9-13%), Acidobacteria (8-11%), and Planctomycetes (4-12%). Figure 3 a). The relative abundance of Proteobacteria decreased by 19%, 17%, and 12% in the biochar-added (BC1, BC2, and MSBC1) treatments compared to the control treatment.

[0078] The dominant fungal phyla were Ascomycota (11-60%), Basidiomycota (38-47%) and Zygomycota (38-47%), accounting for 74-99% of all identified sequences. Among them, the addition of straw significantly increased the relative abundance of Basidiomycota.

[0079] Figure 8 Figure 2 Soil bacterial (a) and fungal (b) community compositions of different treatments based on phylum level. BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn stover; MSBC1, 3% corn stover + 2% biochar; CK, control.

[0080] In different treatments, soil bacteria and fungal communities showed different symbiotic patterns ( Fig. 9 ), the number of points and edges of the bacterial community are much larger than those of the fungal community. The ecological network diagrams of bacteria and fungi are divided into 5 and 6 modules respectively ( Fig. 9 (a and b), the bacterial and fungal species in these modules mainly come from different treatments. In the co-occurrence ecological network of bacterial communities, the bacterial species from the CK treatment in M0 were significantly higher than those in other treatments. Most of the bacterial species in M1 came from MS and MSBC1. The bacterial species in M2 were mainly composed of the treatments with straw and biochar addition. The proportion of bacterial species in BC1 and BC2 in M3 was relatively high ( Fig. 9 In addition, in the ecological network diagram of fungi, M0 (36.0%), M1 (18.4%), and M2 (16.0%) contained the largest proportion of ASVs. For example, in M0, most fungal species came from MS and MSBC1, while in M1, most came from CK treatment ( Fig. 9 In addition, the distribution of fungal species in BC1 was relatively even across modules, whereas the proportion of fungal species in BC2 was highest in M2 ( Fig. 9 (shown in d).

[0081] Fig. 9 In the figure, a and b are ecological network diagrams of bacterial (a) and fungal (b) communities. Fig. 9 Figures c and d are schematic diagrams showing the ratio of bacterial (c) and fungal (d) ASVs. The ratio of bacterial (c) and fungal (d) ASVs in different treatments under each module. M: module; ASVs: amplicon sequence variants. BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn straw; MSBC1, 3% corn straw + 2% biochar; CK, control.

[0082] Microbial function prediction

[0083] The addition of straw and biochar significantly increased the microbial nucleotide metabolism and the ability of exogenous material biodegradation and metabolism ( Fig.10 ), which may promote the growth and development of bacterial communities under the adverse environment of acid stress. Fig.10 Effects of adding carbon-based materials on soil metabolic function. BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn straw; MSBC1, 3% corn straw + 2% biochar; CK, control.

[0084] FUNGuild analysis showed that the application of straw and biochar could increase the relative abundance of symbiotic and saprophytic fungi ( Fig.11). For example, the major functional groups of undefined saprophytic fungi and root endophytic fungi were more enriched in BC1, BC2, MS, and MSBC1 than in CK. In addition, the relative abundance of arbuscular mycorrhizal fungi in the rhizosphere soil of the biochar alone treatment was significantly higher than that of the other treatments. It should also be noted that the relative abundance of plant pathogens and fungal parasites was the highest in the CK treatment. Fig.11 Effects of adding carbon-based materials on soil fungal functional groups. BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn straw; MSBC1, 3% corn straw + 2% biochar; CK, control.

[0085] Soil Multifunctionality

[0086] The activities of β-glucosidase, β-xylosidase, cellobiohydrolase, β-N-acetylglucosaminidase, leucine aminopeptidase and acid phosphatase increased significantly in the treatments with straw and biochar addition (Table 2). Soil multifunctionality was used to evaluate the comprehensive performance of carbon-based material application. The results showed that the soil multifunctionality of the mixed application of straw and biochar was much higher than that of the control. Fig.12 shown. Fig.12 Effects of adding carbon-based materials on soil multifunctionality. BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn stover; MSBC1, 3% corn stover + 2% biochar; CK, control.

[0087]

[0088] Table 5 Effects of carbon-based material addition on soil enzyme activities in lettuce pots

[0089] Note: BG, β-glucosidase; XYL, β-xylosidase; CBH, cellobiohydrolase; NAG, β-N-acetylglucosaminidase; LAP, leucine aminopeptidase; ACP, acid phosphatase. BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn stover; MSBC1, 3% corn stover + 2% biochar; CK, control. All values ​​are mean ± SD, n = 3. Different lowercase letters indicate significant differences among the five treatments at the p < 0.05 level.

[0090] Fig.12 Effects of adding carbon-based materials on soil multifunctionality. BC1, 2% biochar; BC2, 4% biochar; MS, 3% corn stover; MSBC1, 3% corn stover + 2% biochar; CK, control.

[0091] Factors Affecting the Growth of Lettuce Plants

[0092] Lettuce growth indicators (including plant height, dry weight, total chlorophyll concentration and nitrogen absorption) were significantly correlated with most soil physical and chemical properties at the level of p<0.05, except for total phosphorus and carbon-nitrogen ratio. Similarly, these plant growth parameters representing healthy plant growth were positively correlated with bacterial diversity, symbiotic, saprophytic fungi and soil multifunctionality (p<0.05). It may be because the addition of straw and biochar, especially the mixed application of straw and biochar, increased soil pH and soil nutrient content, provided favorable living conditions for the growth and development of soil microorganisms, improved the ecological functionality of soil microorganisms, and the favorable interaction between plants and soil microorganisms promoted the growth of lettuce.

[0093] Fig.13 Correlation analysis between lettuce growth indicators and soil physical and chemical properties, microbial community diversity and functionality. 3 - -N: soil nitrate nitrogen; NH 3 -N: soil ammonium nitrogen; AP: available phosphorus; TN: total nitrogen; TP: total phosphorus; SOM: soil organic matter; CEC: cation exchange capacity; C:N: ratio of soil organic carbon to total nitrogen; B_Chao1: bacterial richness; B_Shannon: bacterial uniformity; F_Chao1: bacterial richness; F_Shannon: bacterial uniformity; Symbiotroph: symbiotic bacteria; Saprotroph: saprophytic bacteria; SMF: soil multifunctionality. Mantel's r.sign: positive and negative correlations between lettuce growth indicators and soil physical and chemical properties, microbial community diversity and functionality. Mantel's p: p<0.05, there is a significant difference; p≥0.05, there is no significant difference. Mantel's r.abs: absolute value of correlation coefficient. Pearson's r: Pearson correlation coefficient.

[0094] Those skilled in the art should understand that the specific structures and processes shown in the above specific embodiments are only exemplary and not restrictive. Moreover, those skilled in the art can combine the various technical features shown above in various possible ways to form new technical solutions, or make other changes, which are all within the scope of the present invention.

Claims

1. A method for improving acidified soil using carbon-based materials, characterized in that: The following steps are involved: 1) Add compound fertilizer to the acidified soil and mix well; 2) adding the carbon-based material to the acidified soil treated in step 1) and mixing evenly; 3) watering the acidified soil treated in step 2).

2. The method for improving acidified soil using carbon-based materials according to claim 1, characterized in that: The mass thousandth ratio of compound fertilizer to acidified soil is (2‰):(999.8‰).

3. The method for improving acidified soil using carbon-based materials according to claim 1, characterized in that: The carbon-based material is corn straw and / or corn straw biochar.

4. The method for improving acidified soil using carbon-based materials according to claim 3, characterized in that: Step 2) also includes: drying, crushing and sieving the corn stalks, and the mass percentage of the corn stalks to the acidified soil is (3%): (97%).

5. The method for improving acidified soil using carbon-based materials according to claim 4, characterized in that: The mesh number of the sieving process is 10.

6. The method for improving acidified soil using carbon-based materials according to claim 3, characterized in that: Step 2) also includes: drying, crushing, screening and pyrolysis of the corn straw biochar, and the mass percentage of the corn straw biochar to the acidified soil is (2-4%): (96-98%).

7. The method for improving acidified soil using carbon-based materials according to claim 6, characterized in that: The mesh number of the sieving treatment is 10, and the heating temperature of the pyrolysis treatment is 500°C.

8. The method for improving acidified soil using carbon-based materials according to claim 1, characterized in that: Step 3) also includes: maintaining the moisture content of the treated acidified soil at 70% of its maximum water holding capacity.

9. The method for improving acidified soil using carbon-based materials according to claim 1, characterized in that: Also includes: 4) Cash crops can be planted on the acidified soil treated in step 3), and the soil health status can be judged based on the growth of cash crops, soil physical and chemical properties and microbial ecological functions.

10. The method for improving acidified soil using carbon-based materials according to claim 9, characterized in that: Step 4) also includes: performing routine management on the acidified soil for one hundred and eighty days, watering regularly to maintain a moisture content of 60%.

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