A compound type saline-alkali soil modifier and a preparation method thereof

Abstract

This invention relates to the field of soil remediation technology and discloses a compound saline-alkali soil conditioner and its preparation method. The conditioner is composed of biochar, microbial inoculants, humic acid, and desulfurized gypsum; it comprises the following components in parts by weight: 1300-9000 parts biochar, 0.5-2.5 parts microbial inoculants, 3-20 parts humic acid, and 600-4000 parts desulfurized gypsum. In this invention, the formulation of biochar, desulfurized gypsum, humic acid, and the compound microbial inoculants is optimized and synergistically designed, which can simultaneously reduce salinity and alkalinity while also improving soil structure, activating nutrients, and restoring the microecological environment, achieving comprehensive, end-to-end management of saline-alkali soils.

Description

Technical Field

[0001] This invention relates to the field of soil remediation technology, and in particular to a compound saline-alkali soil conditioner and its preparation method. Background Technology

[0002] Saline-alkali soils, due to the long-term accumulation of soluble salts and alkalis, generally exhibit abnormally high soil pH and electrical conductivity, excessively high exchangeable sodium content, damaged soil aggregate structure, insufficient porosity, poor aeration, and weak water and fertilizer retention capacity. This not only severely inhibits crop seed germination and root growth but also triggers secondary problems such as soil microbial community degradation and a significant reduction in nutrient availability, leading to hindered seed germination, restricted root growth, and decreased nutrient absorption efficiency. Furthermore, saline-alkali stress easily causes secondary problems such as soil microbial community degradation and reduced nutrient availability, thereby restricting agricultural production and ecological restoration in saline-alkali areas.

[0003] Defects and shortcomings of existing technology: 1. Physical improvement involves a high degree of engineering, high cost and workload, and the salt content is prone to rebound: it is highly dependent on water resources and salt discharge conditions, making it difficult to promote stable long-term application in large-scale saline-alkali areas.

[0004] 2. Single chemical amendments have a "single dimension of action" and are difficult to achieve comprehensive management: they tend to focus more on the goal of "salt reduction / alkali reduction", and have insufficient linkage effect on soil structure improvement, nutrient activation and micro-ecological restoration; long-term or improper application of some materials may also bring environmental risks or soil micro-ecological imbalance.

[0005] 3. Biological improvement is slow to take effect and is greatly affected by environmental stress: In areas with strong salinity stress or significant water and salt fluctuations, the effect of relying solely on biological improvement is not stable enough, and its ability to improve moderate to severe salinity in the short term is limited.

[0006] 4. Existing compound formulations are mostly "simple superposition" of functional components, lacking ratio optimization and synergistic mechanism design: the advantages of each component are difficult to complement and amplify, and may even have asynchronous effects, resulting in an unsatisfactory overall improvement effect.

[0007] 5. Most products focus only on the single goal of "salt and alkali reduction", making it difficult to achieve simultaneous improvement across the entire chain of structure, nutrients, micro-ecology, and crop growth promotion. This often manifests as "significant improvement in one indicator but limited improvement in other indicators," lacking sustainability and failing to meet the long-term remediation needs of saline-alkali soils.

[0008] Therefore, there is an urgent need for a compound saline-alkali soil improvement technology that can achieve complementary advantages and synergistic effects of multiple components through scientific compounding and ratio optimization, and can simultaneously improve soil structure, activate nutrients, restore micro-ecology and promote crop growth while reducing salinity and alkalinity. Summary of the Invention

[0009] The purpose of this invention is to solve the problems of high pH and electrical conductivity, high exchangeable sodium content, poor aggregate structure, and weak aeration and water and fertilizer retention capacity in saline-alkali soils in the prior art, and to propose a compound saline-alkali soil conditioner and its preparation method.

[0010] To achieve the above objectives, the present invention provides a compound saline-alkali soil conditioner and its preparation method: it is made by combining biochar, microbial inoculants, humic acid and desulfurized gypsum.

[0011] As a further description of the above technical solution: It includes the following components by weight: 1300-9000 parts biochar, 0.5-2.5 parts microbial inoculant, 3-20 parts humic acid, and 600-4000 parts desulfurized gypsum.

[0012] As a further description of the above technical solution: It includes the following components in parts by weight: 2500-4500 parts biochar, 1-2 parts microbial inoculant, 8-15 parts humic acid, and 700-2000 parts desulfurized gypsum.

[0013] As a further description of the above technical solution: Biochar 3000-4000 parts, microbial agent 1-1.5 parts, humic acid 10-15 parts, desulfurized gypsum 800-1200 parts.

[0014] As a further description of the above technical solution: The components include the following parts by weight: 3750 parts biochar, 1 part microbial agent, 12.5 parts humic acid, and 833 parts desulfurized gypsum.

[0015] As a further description of the above technical solution: The microbial agent is a salt-alkali tolerant compound microbial agent with an effective viable count ≥10 billion CFU / g.

[0016] This invention also provides a compound saline-alkali soil conditioner and a preparation method thereof, comprising the following steps: S1: Screen the biochar to remove large particles and dust agglomerates, crush and sieve the desulfurized gypsum, and dry the humic acid for later use; prepare the microbial inoculant in powder or granule form for later use. S2: Weigh out biochar, desulfurized gypsum and humic acid, put them into the mixing equipment and mix them evenly to obtain the basic mixture; S3: Add the microbial agent to the above basic mixture and continue mixing until the agent is evenly dispersed; if necessary, low-temperature mixing can be used to ensure the activity of the agent; S4: The mixture can be used directly as a powder product, or it can be granulated, dried at low temperature and packaged to obtain a finished product improver.

[0017] The present invention has the following beneficial effects: 0. In this invention, biochar, desulfurized gypsum, humic acid and compound microbial agents are formulated and synergistically designed to reduce salinity and alkalinity while simultaneously improving soil structure, activating nutrients and restoring the micro-ecology, thus achieving comprehensive management of saline-alkali soil across the entire chain.

[0018] 1. In this invention, desulfurized gypsum provides Ca²⁺, which can effectively replace Na⁺ adsorbed by soil colloids and reduce the risk of soil alkalization; humic acid helps regulate the soil chemical environment and promotes ion balance; the synergistic effect of multiple components can reduce salt and alkali stress and improve soil salinity composition, thereby improving soil suitability and crop root growth environment.

[0019] 2. In this invention, biochar has a well-developed pore structure, which can improve soil porosity and aggregate structure stability, improve aeration and infiltration, and enhance soil water and fertilizer retention capacity; in synergy with desulfurized gypsum and humic acid, it can alleviate soil compaction and structural damage problems, making the improvement effect more stable.

[0020] 3. In this invention, humic acid can promote nutrient complexation and slow release, and improve nutrient availability; microbial agents promote the transformation of nutrients such as nitrogen and phosphorus in the soil and rhizosphere activity, and improve the crop's nutrient absorption efficiency; under the combined effect, it can significantly improve the crop's growth status and enhance yield and quality stability.

[0021] 4. In this invention, the microbial agent can promote the establishment and restoration of beneficial microbial communities, enhance soil enzyme activity and nutrient cycling capacity; combined with the carrier effect of biochar, it is conducive to the survival and colonization of microbial communities, improves stability under saline-alkali stress environment, and makes the improvement effect more sustainable. Attached Figure Description

[0022] Figure 1 This is a bar chart showing the comprehensive score ranking of the compound saline-alkali soil conditioner and its preparation method proposed in this invention; Figure 2 This is a standardized index heatmap of a compound saline-alkali soil conditioner and its preparation method proposed in this invention. Figure 3 This is a three-dimensional sub-score radar diagram of a compound saline-alkali soil conditioner and its preparation method proposed in this invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all 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.

[0024] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used in the following examples are all purchased from commercial channels.

[0025] To address the issue of the inability to achieve complementary advantages and synergistic effects among the components, this application presents a compound saline-alkali soil conditioner and its preparation method, comprising the following components: Biochar: Prepared from corn stalks by oxygen-limited pyrolysis at 550℃, with a fixed carbon content of 62% and a specific surface area of ​​18.6 m² / g; Microbial agent: Salt-alkali tolerant compound microbial agent, with an effective live bacteria count of 20 billion CFU / g, is composed of Bacillus subtilis, Bacillus laterosporus, and Pseudomonas fluorescens in a mass ratio of 2:1:1; Humic acid: Mineral-derived humic acid extracted from weathered coal, with a water-soluble humic acid content of 55%; Desulfurized gypsum: a byproduct of flue gas desulfurization in thermal power plants, with a calcium sulfate dihydrate content of 88%.

[0026] And it is prepared using the following steps: S1: Weigh out biochar, humic acid, and desulfurized gypsum according to the proportion, and feed them into a twin-screw mixer. Mix them at room temperature at a speed of 40 r / min for 20 min to obtain a uniform basic mixture. S2: Weigh the microbial agent according to the ratio, and feed it into the two-dimensional motion mixer with the basic mixture obtained in step S1 for secondary mixing. The mixing speed is 25 r / min and the mixing time is 15 min. After the mixing is completed, the compound saline-alkali soil conditioner and its preparation method are obtained.

[0027] The desulfurized gypsum provides Ca²⁺ to replace Na⁺ adsorbed by soil colloids, reducing the risk of alkalization; humic acid improves the soil chemical environment and promotes nutrient activation; biochar increases porosity and aggregate structure and enhances water and fertilizer retention capacity; and compound microbial agents promote rhizosphere microecological restoration and nutrient transformation. The synergistic effect of these multiple components achieves comprehensive improvement of saline-alkali soils.

[0028] Results analysis: An orthogonal design was adopted, selecting four factors: biochar, microbial inoculants, humic acid, and desulfurized gypsum, with three levels for each factor, using an L9 (32) design. 4The orthogonal array (Tables 1 and 2) was used to arrange 9 experimental groups, 1 blank group, and a control group treated with lemon YS with only water, for a total of 11 treatments.

[0029] Table 1, L9 (3) 4 Orthogonal Experiment Factor Level Table Table 2. Orthogonal Experimental Design Table The experimental area is located at Puhui Farm, Korla City, Bayingolin Mongol Autonomous Prefecture, Xinjiang Uygur Autonomous Region (41°22′51.6″N, 85°53′52.9″E), at an altitude of 901 meters. Situated on the northern edge of the Tarim Basin, in the alluvial plain region of the Peacock River and Kaidu River, it has a typical temperate continental arid climate. In the experimental year, the average annual temperature was 11.7℃ and the annual precipitation was approximately 40 mm. The soil at this site is sandy loam with the following physicochemical properties: pH value of 8.47 and electrical conductivity (EC) of 1429 µS / cm. −1 The salt content is 4.34 g / kg. −1 The organic matter content is 8.33 g / kg. −1 Total nitrogen (TN) was 1.07 g / kg. -1 Total phosphorus (TP) was 0.51 g / kg. −1 Total potassium (TK) was 1.10 g / kg. −1 The effective phosphorus (AP) content was 23.83 mg / kg. −1 The effective potassium (AK) content was 343.97 mg / kg. −1 .

[0030] Application method: An orthogonal experimental design was adopted, selecting four factors: biochar, microbial inoculant, humic acid, and desulfurized gypsum. Each factor was set with three levels (Table 1). Nine soil conditioner combinations were designed using an L9(34) orthogonal array, namely A1B1C1D1 (experimental group 1), A1B2C2D2 (experimental group 2), A1B3C3D3 (experimental group 3), A2B1C2D3 (experimental group 4), A2B2C3D1 (experimental group 5), A2B3C1D2 (experimental group 6), A3B1C3D2 (experimental group 7), A3B2C1D3 (experimental group 8), A3B3C2D1 (experimental group 9), and A0B0C0D0 (blank group), and single application of lemon (187.5 kg / hm2) (YS), for a total of 11 treatments. The field experiment adopted a completely randomized block design, with each treatment replicated 4 times, for a total of 44 plots. The plots were 4.0m × 5.0m in size, with a spacing of 1.0m between plots. On May 1, 2025, the soil conditioner was mixed according to its composition ratio and dosage, evenly spread into the plots, and then the soil was tilled to a depth of 40cm. After leveling and compacting the plots appropriately, Xinmu No. 4 alfalfa was sown on May 5, 2025, at a rate of 1.5 kg / hm2, in rows with a row spacing of 20cm. During the experiment, all treatments maintained the same irrigation and other field management practices throughout the entire growth period, and no other fertilizers were applied.

[0031] The following key indicators were measured three months after planting: Soil physicochemical indicators: pH value was tested by potentiometry, electrical conductivity (EC) was tested by electrical conductivity method, available phosphorus content was tested by sodium bicarbonate extraction-molybdenum antimony colorimetric method, and available potassium content was tested by ammonium acetate extraction-flame photometry method. Crop agronomic traits: alfalfa plant height and dry matter yield; Soil microbial indicators: Shannon diversity index of soil bacterial communities.

[0032] The comprehensive scores and standardized index heatmaps for the 11 processes were obtained through PCA weight calculation and standardized heatmaps. The test results are shown below. Figures 1-3 .

[0033] As shown in the attached figure, the comprehensive scores of the 11 treatments were calculated based on standardization and PCA weighting, and ranked from highest to lowest score. The results show that there are significant differences in the comprehensive scores of different treatments, indicating that there are significant differences in the synergistic effects of different combinations of soil conditioners on saline-alkali soil improvement and alfalfa production. The comprehensive ranking results are as follows: Experimental group 5 (0.7074) > Experimental group 9 (0.6537) > Experimental group 6 (0.6035) > Experimental group 2 (0.5769) > Experimental group 8 (0.5332) > Experimental group 7 (0.5021) > Experimental group 3 (0.4795) > Experimental group 1 (0.4429) > YS (0.4144) > Experimental group 4 (0.3669) > Control group (0.1316).

[0034] Among them, experimental group 5 scored the highest and was determined to be the treatment with the best comprehensive improvement effect under the conditions of this study; experimental groups 9 and 6 followed closely behind and can be used as advantageous alternative combinations; the blank group scored the lowest, indicating that the absence of soil conditioner under saline-alkali stress will significantly limit alfalfa production and soil quality improvement.

[0035] The high-scoring treatments (experimental groups 5, 9, 6, and 2) showed a synchronous improvement in most indicators, demonstrating the synergistic effect of the compound soil conditioner: on the one hand, they were generally better in terms of yield and growth indicators (such as yield, plant height, and stem diameter); on the other hand, in terms of soil improvement, they showed a decrease in salt and alkali stress indicators (such as EC, salt content, and Na⁺) and an increase in fertility indicators (such as available phosphorus, available potassium, total nutrients, and organic matter), showing a dual improvement of "salt control and alkali reduction - fertility enhancement and efficiency enhancement". Quality indicators (such as NDF and ADF) also made an important contribution to the overall difference, which can explain why some treatments increased yield but did not have a superior overall score.

[0036] In contrast, the low- and medium-scoring treatments mostly exhibited "single-item improvement but overall deficiency," meaning that while one indicator was outstanding, there were shortcomings in dimensions such as yield, quality, or soil fertility improvement, resulting in weak overall synergy. Overall, experimental group 5 showed a more balanced performance across the three dimensions of yield improvement, quality improvement, and soil improvement, representing the optimal treatment with multi-dimensional synergy.

[0037] The treatments showed significant differences in their three-dimensional performance. Experimental group 5 demonstrated the best overall performance, excelling in yield increase, quality improvement, and optimization of soil physicochemical properties, exhibiting a strong synergistic effect. Some treatments only showed advantages in a single dimension (such as yield increase or quality improvement), and their overall coordination was not as good as experimental group 5. The control treatment had the lowest overall performance. This indicates that the preferred formulation of this invention (experimental group 5) can achieve multi-dimensional synergistic improvement of saline-alkali soil through "yield increase, quality improvement, and soil enhancement," resulting in a superior overall effect.

[0038] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A complex salt-affected soil conditioner and its method of preparation, characterized by, It is made from a combination of biochar, microbial inoculants, humic acid, and desulfurized gypsum.

2. The compound saline-alkali soil conditioner and its preparation method according to claim 1, characterized in that, It includes the following components by weight: 1300-9000 parts biochar, 0.5-2.5 parts microbial inoculant, 3-20 parts humic acid, and 600-4000 parts desulfurized gypsum.

3. The compound saline-alkali soil conditioner and its preparation method according to claim 2, characterized in that, It includes the following components in parts by weight: 2500-4500 parts biochar, 1-2 parts microbial inoculant, 8-15 parts humic acid, and 700-2000 parts desulfurized gypsum.

4. The compound saline-alkali soil conditioner and its preparation method according to claim 3, characterized in that, It includes the following components by weight: 3000-4000 parts biochar, 1-1.5 parts microbial inoculant, 10-15 parts humic acid, and 800-1200 parts desulfurized gypsum.

5. A compounded saline soil ameliorant according to claim 4, and a method of preparing the same, characterized in that, The components include the following parts by weight: 3750 parts biochar, 1 part microbial agent, 12.5 parts humic acid, and 833 parts desulfurized gypsum.

6. The compound saline-alkali soil conditioner and its preparation method according to claim 5, characterized in that, The microbial agent is a salt-alkali tolerant compound microbial agent with an effective viable count ≥10 billion CFU / g.

7. A compounded saline soil ameliorant according to claim 6, and a method of preparing the same, characterized in that, The microbial agents include Bacillus subtilis, Bacillus laterosporus, and Pseudomonas fluorescens.

8. A complex salt-affected soil conditioner and a process for its preparation, characterized by, Includes the following steps: S1: Screen the biochar to remove large particles and dust agglomerates, crush and sieve the desulfurized gypsum, and dry the humic acid for later use; prepare the microbial inoculant in powder or granule form for later use. S2: Weigh out biochar, desulfurized gypsum and humic acid, put them into the mixing equipment and mix them evenly to obtain the basic mixture; S3: Add the microbial agent to the above basic mixture and continue mixing until the agent is evenly dispersed; if necessary, low-temperature mixing can be used to ensure the activity of the agent; S4: The mixture can be used directly as a powder product, or it can be granulated, dried at low temperature and packaged to obtain a finished product improver.

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