A method for improving the performance of a heavy beach saline-alkali soil

Abstract

The present application belongs to the technical field of soil improvement of tidal salt-alkali land, and particularly relates to a method for improving the performance of heavy tidal salt-alkali land soil, which is achieved by the synergistic implementation of three technologies of engineering salt reduction, dry farming and water improvement, and construction of a complete water and dry rotation system; the soil organic matter is improved by means of water retention by inserting a water baffle and putting sandworms in the rice season, and the soil improvement technologies are synergistically implemented to achieve the purposes of soil salt reduction, soil fertility improvement and crop yield increase, thereby significantly improving the performance of the tidal salt-alkali land soil, especially for the improvement of heavy tidal salt-alkali land, the soil organic matter content is improved, the salinity is reduced, the soil layer structure is optimized, and the purposes of grain growth and economic benefit increase are achieved.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology for saline-alkali tidal flats, specifically relating to a method for improving the properties of severely saline-alkali tidal flat soil. Background Technology

[0002] Coastal saline-alkali tidal flats are important reserve arable land resources. However, influenced by multiple factors such as tidal backwater, infiltration by seawater-type groundwater, and seasonal rainfall distribution, these tidal flats exhibit a significant dynamic imbalance of water and salt. Severely saline-alkali lands generally have a salt content greater than 4‰, even reaching 6‰. Especially in spring and autumn, frequent salt accumulation on the soil surface leads to repeated imbalances in soil salinity, damaging soil structure and causing continuous nutrient loss, resulting in reduced grain yields. Current methods for improving saline-alkali tidal flat soils mainly include salt leaching through irrigation and drainage projects to control soil salinity; increasing soil nutrient capacity through the application of organic fertilizers and green manure; or planting rice in water-rich tidal flat areas to control salinity through rice cultivation. However, these methods primarily target moderately saline-alkali lands, with minimal effect on severely saline-alkali lands.

[0003] There are many existing soil improvement technologies for saline-alkali tidal flats, but they are basically applicable to moderately saline-alkali tidal flats with a salinity of less than 4‰. There is less research on soil improvement technologies for severely saline-alkali tidal flats with a salinity of more than 4‰, especially for soil improvement technologies for saline-alkali tidal flats. This is because the soil properties are mostly silty clay soils with highly dispersed viscosity, high surface saturated hydraulic conductivity, and poor water and fertilizer retention capacity. In addition, there are problems such as hidden salt accumulation in winter and more significant salt accumulation in spring, which makes soil improvement in this area more difficult. Summary of the Invention

[0004] To address the problems of existing technologies, this invention provides a method for improving the soil properties of severely saline-alkali tidal flats, particularly suitable for improving the soil properties of severely saline-alkali tidal flats with a salinity of 4‰ or higher. It breaks through the limitations of relying solely on single soil improvement techniques such as salt leaching or rice cultivation, by combining engineering measures for salt reduction, dryland irrigation for soil improvement, and rice-season quality and efficiency enhancement. This constructs a complete water-dryland rotation system for saline-alkali tidal flats, thereby improving the soil properties of severely saline-alkali tidal flats and increasing grain yield.

[0005] To solve the above-mentioned technical problems, the present invention provides a method for improving the soil properties of severely saline-alkali tidal flats, characterized in that the salinity of the severely saline-alkali tidal flats is greater than 4‰, and a buried pipe assembly is installed in the severely saline-alkali tidal flats, with a burial depth of 1.0~1.3m, a pipe spacing of 15~20m, and a buried pipe drainage ditch depth of 1.2~1.5m. The method for improving the soil properties of severely saline-alkali tidal flats includes the following steps: Step (1), engineering desalination: the heavily saline-alkali tidal flats are washed with salt 1 to 2 times through the underground pipe assembly; Step (2), dryland irrigation and soil improvement: the severely saline-alkali tidal flats after the salinization of the project are plowed and prepared, with a plowing depth of ≤30 cm. Then, acidic volcanic rock fragments and fermented wood fiber particles are evenly spread, and plowed again with a plowing depth of 5~20 cm. After plowing evenly, humic acid bio-organic fertilizer, slow-release compound fertilizer and superphosphate are shallowly and evenly applied into the soil. Then, dryland crops are planted and cultivated. Urea is applied as a top dressing during the jointing stage of the crops, with a dosage of 9~12 kg / mu. Step (3), improving quality and efficiency during the rice season: After the dryland crops described in step (2) are harvested, the straw is returned to the field, the land is plowed and prepared, the plowing depth is 15-20cm, and after 2-3 days of plowing, humic acid bio-organic fertilizer is shallowly applied into the soil, followed by slow-release compound fertilizer and superphosphate; rice is planted, with a plant spacing of 12-15cm and a row spacing of 20-25cm; urea is applied during the rice tillering stage, with a dosage of 9-12kg / mu, and double-toothed sandworms with a body length of 8-10cm are introduced into the paddy field during the later tillering stage; urea and nitrogen-phosphorus-potassium compound fertilizer are applied during the rice booting stage, with dosages of 9-12kg / mu and 13-16kg / mu respectively; water-blocking boards are inserted around the paddy field, with an insertion depth of 15-20cm.

[0006] In the technical solution of the present invention, after the soil properties of the severely saline-alkali tidal flats have been improved over the years, before the next year's step (2), the straw is returned to the field and then the land is plowed and prepared.

[0007] In the technical aspect of this invention, if extreme drought occurs, such as 20-30 consecutive days without rain, the fields need to be irrigated 1-2 times during the planting and cultivation of dryland crops. Regarding the selection of dryland crop varieties, for saline-alkali tidal flats with a salinity of 4-8‰, salt-tolerant crops such as barley and rapeseed are preferred; for saline-alkali tidal flats with a salinity greater than 8‰, pioneer plants such as sesbania and Suaeda salsa are preferred. In terms of rice variety selection, salt-tolerant varieties such as Nanjing 518 and Salt Rice 12 are preferred to improve crop yield, increase economic benefits, and achieve better soil improvement.

[0008] In the technical solution of this invention, by controlling the plant spacing and row spacing when planting rice, a high-yield rice population structure can be achieved. Throughout the entire rice cultivation cycle, by inserting water-retaining boards around the paddy field instead of soil ridges, not only can water loss caused by the collapse of the silty clay soil be reduced, but also a water layer of 1-2 cm can be maintained throughout the entire growth period of rice. This achieves continuous salt reduction and control in the field, stabilizes the soil structure, improves the soil, and enhances soil fertility.

[0009] Preferably, in step (2) of the method, the application interval between acidic volcanic rock fragments and fermented lignocellulosic particles is 5 to 6 years.

[0010] Preferably, the acidic volcanic rock fragments have a pH of 5.5-6.5, a diameter of 6-9 mm, and an application rate of 6-10 cubic meters per mu; the fermented wood fiber particles have a pH of 6-8, an average particle size of 3-6 mm, and an application rate of 85-150 kg per mu.

[0011] Preferably, in steps (2) and (3) of the method, the application rates of humic acid bio-organic fertilizer, slow-release compound fertilizer and superphosphate are 300~400 kg / mu, 35~45 kg / mu and 30~40 kg / mu, respectively.

[0012] Preferably, the humic acid bio-organic fertilizer contains more than 25% humic acid, more than 40% organic matter, and more than 0.2 billion live bacteria per gram.

[0013] Preferably, in the controlled-release compound fertilizer, the mass ratio of N:P2O5:K2O is 23~26:10~13:7~12, the controlled-release nitrogen content is 8~11%, and the release period is ≥90 days.

[0014] Preferably, in step (3) of the method, the amount of *Pteris vittata* released is 5,000 to 7,000 per mu.

[0015] In the technical solution of this invention, by introducing two-toothed sandworms into paddy fields, the soil can be loosened, especially for silty clay soils, which can reduce soil viscosity, saturated hydraulic conductivity, improve porosity, increase soil water and fertilizer retention capacity and organic matter content, and improve the soil.

[0016] Preferably, the method for preparing the fermented lignocellulose particles includes the following steps: Step (1), preparation of fermentation raw materials: add poultry and livestock manure to the woody material, stir evenly, and adjust the carbon-nitrogen ratio to 20:1~40:1; then add amino acid hydrolysate, quicklime or wood ash, and adjust the pH value to 6~7 to obtain fermentation raw materials; Step (2): Add water to the fermentation raw materials described in step (1), ventilate and stir to adjust the moisture content to 40-65%, add fermentation agent, the amount of which is 0.2-0.5% of the fermentation raw materials, stir evenly to obtain fermentation product; Step (3): Fill the fermentation material described in step (2) into the fermentation container, filling the volume to less than 70% of the fermentation container, ferment for 15 to 30 days at a fermentation temperature of 55 to 60°C, and obtain fermented wood fiber particles.

[0017] Preferably, in step (1), the mixing ratio of wood material and poultry manure is 3:1 to 5:1, wherein the poultry manure is low-salt manure such as cow manure.

[0018] Preferably, the fermentation agent in step (2) is Bacillus subtilis or Bacillus licheniformis.

[0019] The technical solution of this invention combines a complete crop rotation model with engineering measures for salt reduction and topsoil optimization. It also achieves salt reduction and control in saline-alkali land by applying humic acid organic fertilizer, slow-release compound fertilizer, and introducing two-toothed sandworms, thereby improving soil organic matter, water and fertilizer retention capacity, stabilizing soil structure, and improving soil properties.

[0020] Beneficial effects of the invention Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The technical solution of this invention constructs a complete water-dry rotation system by synergistic operation of engineering salt reduction and leaching, dryland water-suitable soil improvement and rice season quality improvement and efficiency enhancement. It achieves the effect of reducing and controlling salt in tidal flat saline-alkali land, and improving soil fertility and water and fertilizer retention capacity. In particular, for severely saline-alkali tidal flat land, it can effectively solve the problem of frequent accumulation of soil salt to the soil surface, which leads to repeated soil salinity and water-salt dynamic imbalance. It can effectively solve the problems of hidden salt accumulation in winter and heavy salt accumulation in spring in tidal flat saline-alkali land, and achieve long-term salt reduction and salt control effect on the soil layer, and improve soil properties. (2) In the technical solution of the present invention, the organic matter in the topsoil is increased and the topsoil structure is stabilized by applying acidic volcanic rock fragments and fermented wood fiber particles, thereby optimizing the topsoil; humic acid organic fertilizer is applied after straw is returned to the field to improve soil fertility; special slow-release compound fertilizer and superphosphate are applied when planting crops, and urea and potassium phosphate compound fertilizer are added at different stages of crop growth to increase crop yield and improve economic benefits. (3) The technical solution of the present invention, after the tillering stage of rice, introduces double-toothed sandworms into the paddy field, which has the effect of loosening the soil and stabilizing the soil topsoil; especially for the saline-alkali land of the tidal flats in northern Jiangsu, it can effectively reduce the viscosity of silty soil, reduce the saturated water conductivity of the soil surface, improve the fertilizer and water retention capacity of the soil topsoil, and stabilize the dynamic balance of soil water and salt. (4) Compared with the existing dry-dry rotation system or the traditional water-dry rotation system, the complete water-dry rotation system constructed by the technical solution of the present invention improves the soil topsoil by optimizing the dry season, inserts water-blocking boards in the field during the rice season to suppress salt with water, and improves soil fertility by releasing double-toothed sandworms. The synergistic effect of each link improves the performance of tidal flat saline-alkali land; especially for severely saline-alkali tidal flat land with a salinity greater than 4‰, it has excellent improvement effect. Attached Figure Description

[0021] Figure 1 Comparative Experiment 2: Rice growth before any improvement measures were taken; Figure 2 The growth of rice planted using the technical scheme of Mode 6 in Comparative Experiment 2; Figure 3 The growth of rice planted using the technical scheme of Mode 4 in Comparative Experiment 2. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0023] Example 1 This experiment was conducted from November 2023 to October 2024 in the Tiaozini Experimental Area of ​​Dongtaijiang Port, Yancheng, Jiangsu Province. The soil salinity of this experimental area is greater than 4‰, which is classified as severely saline-alkali tidal flat.

[0024] In this experimental area, underground pipe assemblies were installed in the severely saline-alkali tidal flats. The pipes were buried at a depth of 1.0m and spaced 15m apart. The drainage ditch for the underground pipes was 1.2m deep. The specific improvement methods included the following steps: Step (1), Engineering salt reduction: The test area is washed once by burying underground pipe components; Step (2), soil improvement for dryland farming: plow and prepare the land to a depth of ≤30cm, then evenly spread acidic volcanic rock fragments with a pH of 5.5 and a diameter of 6mm, at a rate of 6 cubic meters per mu; spread fermented wood fiber particles with a pH of 8 and an average particle size of 3mm, at a rate of 150 kg per mu. After plowing evenly, shallowly plow and evenly apply humic acid bio-organic fertilizer, slow-release compound fertilizer and superphosphate into the soil, at rates of 300 kg per mu, 35 kg per mu and 30 kg per mu respectively. Then plant dryland crop barley, at a rate of 15 kg per mu for barley seeds. Top-dress with urea at the barley jointing stage, at a rate of 9 kg per mu. Step (3), improving quality and efficiency during the rice season: In early June, after returning straw to the field, the land is plowed and prepared to a depth of 15cm. Two days after plowing, humic acid bio-organic fertilizer is shallowly applied to the soil at a rate of 400 kg / mu. Then, slow-release compound fertilizer and superphosphate are applied at rates of 45 kg / mu and 40 kg / mu, respectively. Rice is then planted with a plant spacing of 12 cm and a row spacing of 20 cm. Urea is applied during the rice tillering stage at a rate of 12 kg / mu. During the later tillering stage, 5000 double-toothed sandworms with a body length of 8cm are introduced into the paddy field. Urea and nitrogen-phosphorus-potassium compound fertilizer are applied during the rice booting stage at a rate of 9 kg / mu and 13 kg / mu, respectively. Water barriers are inserted around the paddy field to a depth of 15cm.

[0025] In steps (2) and (3) of this embodiment, the humic acid bio-organic fertilizer has a humic acid content greater than 25%, an organic matter content greater than 40%, and an effective live bacteria count greater than 0.2 billion / g; in the controlled-release compound fertilizer, the mass ratio of N:P2O5:K2O is 23:10:7, the controlled-release nitrogen content is greater than 8%, and the controlled-release period is 90 days.

[0026] In this invention, the application of acidic volcanic rock fragments and fermented wood fiber particles can optimize the topsoil structure and improve soil fertility, and only needs to be applied once every 5 years; wherein the fermented wood fiber particles are prepared by the following method: Step (201), preparation of fermentation raw materials: add poultry and livestock manure to the wood material, the mixing ratio of wood material and poultry and livestock manure is 3:1, stir evenly, and adjust the carbon-nitrogen ratio to 20:1; then add amino acid hydrolysate, adjust the pH value to 6, and obtain fermentation raw materials; Step (202): Add water to the fermentation raw materials described in step (201), aerate and stir, adjust the moisture content to 40%, add Bacillus subtilis at a rate of 0.2% of the fermentation raw materials, stir evenly, and obtain the fermentation product; Step (203): Fill the fermentation material described in step (202) into a fermentation container, filling the container with a volume less than 70% of its capacity. Ferment for 15 days at a temperature of 60°C to obtain fermented wood fiber particles.

[0027] Based on engineering-based salt reduction and control, the technical solution of this invention constructs a complete water-dryland rotation system. By cyclically planting dryland crops and rice, and combining the application of humic acid organic fertilizer, special slow-release compound fertilizer, and superphosphate, it effectively improves the soil salinity of tidal flats and saline-alkali land, stabilizes soil structure, and increases the organic matter in the topsoil. Furthermore, by adding urea and nitrogen-phosphorus-potassium compound fertilizer at different growth stages of crops, it increases crop yield.

[0028] Example 2 This experiment was conducted from November 2023 to October 2024 in the Tiaozini Experimental Area of ​​Dongtaijiang Port, Yancheng, Jiangsu Province. The soil salinity of this experimental area is greater than 4‰, which is classified as severely saline-alkali tidal flat.

[0029] In this experimental area, underground pipe assemblies were installed in the severely saline-alkali tidal flats. The pipes were buried at a depth of 1.3m and spaced 20m apart. The drainage ditch for the underground pipes was 1.5m deep. The specific improvement methods included the following steps: Step (1), engineering desalination: the severely saline-alkali tidal flats are washed twice with salt through buried underground pipe components; Step (2), dryland irrigation and soil improvement: plow and prepare the land to a depth of ≤30cm, then evenly spread acidic volcanic rock fragments with a pH of 6.5 and a diameter of 9mm at an application rate of 10 cubic meters per mu, and spread fermented wood fiber particles with a pH of 6 and an average particle size of 3mm at an application rate of 85 kg per mu; then return the straw to the field, and then plow again to a depth of 20cm. After plowing evenly, shallowly and evenly apply humic acid bio-organic fertilizer, slow-release compound fertilizer and superphosphate into the soil at application rates of 400 kg per mu, 45 kg per mu and 40 kg per mu respectively; plant barley, with barley seeds applied at an application rate of 15 kg per mu, and top-dress with urea at the barley jointing stage at an application rate of 12 kg per mu; Step (3), improving quality and efficiency during the rice season: In early June, after returning straw to the field, the land is plowed and prepared to a depth of 20cm. Three days after plowing, humic acid bio-organic fertilizer is shallowly applied to the soil at a rate of 300 kg / mu. Then, slow-release compound fertilizer and superphosphate are applied at rates of 35 kg / mu and 30 kg / mu, respectively. Rice is planted with a plant spacing of 15 cm and a row spacing of 25 cm. Urea is applied during the rice tillering stage at a rate of 9 kg / mu. During the later tillering stage, 7,000 double-toothed sandworms with a body length of 10cm are introduced into the paddy field. Urea and nitrogen-phosphorus-potassium compound fertilizer are applied during the rice booting stage at a rate of 12 kg / mu and 16 kg / mu, respectively. Water barriers are inserted around the paddy field to a depth of 20cm.

[0030] In steps (2) and (3) of this embodiment, the humic acid bio-organic fertilizer has a humic acid content greater than 25%, an organic matter content greater than 40%, and an effective live bacteria count greater than 0.2 billion / g; in the controlled-release compound fertilizer, the mass ratio of N: P2O5: K2O is 26: 13: 12, the controlled-release nitrogen content is greater than 11%, and the controlled-release period is greater than 90 days.

[0031] The application interval for the acidic volcanic rock fragments and fermented wood fiber particles described in this embodiment is 6 years. The preparation method of the fermented wood fiber particles includes the following steps: Step (201), preparation of fermentation raw materials: add poultry and livestock manure to the wood material, the mixing ratio of wood material and poultry and livestock manure is 5:1, stir evenly, adjust the carbon-nitrogen ratio to 40:1; then add slaked lime, adjust the pH value to 7, and obtain the fermentation raw materials; Step (202): Add water to the fermentation raw materials described in step (201), aerate and stir, adjust the moisture content to 65%, add Bacillus licheniformis, the amount added is 0.5% of the fermentation raw materials, stir evenly, and obtain the fermentation product; Step (203): Fill the fermentation material described in step (202) into a fermentation container, filling the container with a volume less than 70% of its capacity. Ferment for 30 days at a temperature of 55°C to obtain fermented wood fiber particles.

[0032] Example 3 This experiment was conducted from November 2023 to October 2024 in the Tiaozini Experimental Area of ​​Dongtaijiang Port, Yancheng, Jiangsu Province. The soil salinity of this experimental area is greater than 4‰, which is classified as severely saline-alkali tidal flat.

[0033] In the severely saline-alkali tidal flats of the test area, underground pipe assemblies were installed at a depth of 1.2m and a spacing of 18m. The underground pipe drainage ditch was 1.3m deep. The specific improvement methods include the following steps: Step (1), engineering desalination: the salt of the severely saline-alkali tidal flats is washed once through the buried underground pipe assembly; Step (2), dryland irrigation and soil improvement: plow and prepare the land to a depth of ≤30cm, then evenly spread acidic volcanic rock fragments with a pH of 6.0 and a diameter of 8mm at an application rate of 8 cubic meters per mu, and spread fermented wood fiber particles with a pH of 7 and an average particle size of 4mm at an application rate of 120 kg per mu. After returning the straw to the field, plow again to a depth of 12cm. After even plowing, shallowly and evenly apply humic acid bio-organic fertilizer, slow-release compound fertilizer and superphosphate into the soil at application rates of 350 kg per mu, 42 kg per mu and 36 kg per mu respectively; plant barley, with barley seed application rate of 15 kg per mu, and apply urea at the barley jointing stage at an application rate of 15 kg per mu. Step (3), improving quality and efficiency during the rice season: In early June, straw is returned to the field, and the land is plowed and prepared to a depth of 18cm. Three days after plowing, humic acid bio-organic fertilizer is shallowly applied to the soil at a rate of 380 kg / mu. Then, slow-release compound fertilizer and superphosphate are applied at rates of 37 kg / mu and 32 kg / mu, respectively. Rice is then planted with a plant spacing of 13 cm and a row spacing of 22 cm. Urea is applied during the rice tillering stage at a rate of 10 kg / mu. During the later tillering stage, 6,000 two-toothed sandworms with a body length of 9cm are introduced into the paddy field. Urea and nitrogen-phosphorus-potassium compound fertilizer are applied during the rice booting stage at a rate of 11 kg / mu and 15 kg / mu, respectively. Water barriers are inserted around the paddy field to a depth of 17cm.

[0034] In steps (2) and (3) of this embodiment, the humic acid bio-organic fertilizer has a humic acid content greater than 25%, an organic matter content greater than 40%, and an effective live bacteria count greater than 0.2 billion / g; in the controlled-release compound fertilizer, the mass ratio of N:P2O5:K2O is 25:12:10, the controlled-release nitrogen content is greater than 10%, and the controlled-release period is 90 days.

[0035] In the technical solution of this invention, the application of acidic volcanic rock fragments and fermented wood fiber particles can effectively improve the soil structure of saline-alkali tidal flats, stabilize the topsoil, prevent repeated salinization and alkali formation, and only needs to be applied once every 5 years. The preparation method of fermented wood fiber particles includes the following steps: Step (201), preparation of fermentation raw materials: add poultry and livestock manure to the wood material, the mixing ratio of wood material and poultry and livestock manure is 4:1, stir evenly, and adjust the carbon-nitrogen ratio to 30:1; then add wood ash and adjust the pH value to 7 to obtain fermentation raw materials; Step (202): Add water to the fermentation raw materials described in step (201), aerate and stir, adjust the moisture content to 55%, add Bacillus subtilis, the amount added is 0.35% of the fermentation raw materials, stir evenly, and obtain the fermentation product; Step (203): Fill the fermentation material described in step (202) into a fermentation container, filling the container with a volume less than 70% of its capacity. Ferment for 25 days at a temperature of 58°C to obtain fermented wood fiber particles.

[0036] Comparative test Comparative Experiment 1 From November 2023 to October 2024, comparative verification was conducted in the Tiaozini experimental area of ​​Dongtaijiang Port, Yancheng, Jiangsu Province. The planting models for improving the soil properties of severely saline-alkali tidal flats were as follows: Mode 1: Conducting experiments using the technical solution of Embodiment 1 of the present invention; Mode 2: Set up a comparative example under Example 1; conduct the experiment using test areas of the same size and similar salinity as in Example 1 for comparison.

[0037] This comparative example uses open ditch drainage to reduce and control soil salinity in the experimental area; it adopts a barley + corn dry-land rotation system for crop cultivation; the land management methods, fertilization and topdressing techniques for barley or corn in the comparative experimental area adopt the local conventional planting methods; the application rates of barley and corn seeds are the same as those of barley seeds described in Example 1.

[0038] The experiment began at the end of October 2023. After one year, the salinity and organic carbon of the soil in the experimental area were tested, and the annual grain yield and economic benefits of the two planting models were statistically compared. The specific results are shown in Table 1.

[0039] Table 1 Comparison of various indicators in Experiment 1 As shown in Table 1, after one year of trials, the soil salinity of the crops in the Model 1 crop planting system (i.e., the water-dryland rotation system using the technical solution of this invention) was significantly reduced and the organic carbon content was significantly increased. In contrast, under the Model 2 technical solution, the soil salinity decreased less after one year of soil improvement. This is because the soil salinity in this experimental area is greatly affected by seasonality, and the soil salinity is repeatedly affected and the salt patches are uneven. Compared with Model 1, the local conventional crop planting technology used in Model 2 cannot solve this problem and cannot reduce soil salinity and stabilize the topsoil structure.

[0040] Comparing the experimental results of Mode 1 and Mode 2, it can be seen that the technical solution of the present invention has a greater reduction in soil salinity, effectively solving the problem of repeated soil salinization in this area, increasing soil organic carbon content, achieving increased grain production, and realizing better economic benefits. That is, the technical solution of the present invention has more significant beneficial effects on improving the soil properties of tidal flat saline-alkali land, increasing grain production, and improving economic benefits.

[0041] Comparative Experiment 2 From November 2023 to October 2024, a comparative experiment on the water-dry rotation system model was carried out in the Tiaozini Experimental Area of ​​Dongtai Jianggang, Yancheng, Jiangsu Province. Soil samples were collected and tested before the experiment. The test items and their data are shown in Table 2.

[0042] Table 2 Comparative Experiment 2 Soil Sample Indicators Before Experiment Comparative test setup: Mode 3: Conduct experiments using the technical solution of Embodiment 2 of the present invention; Mode 4: Conduct experiments using the technical solution of Embodiment 3 of the present invention; Two comparative examples were set up in Examples 2 and 3, namely Mode 5 and Mode 6.

[0043] Both comparative groups were conducted in experimental plots of the same size and similar salinity as Examples 2 and 3. Both Mode 5 and Mode 6 adopted a barley + rice crop rotation system. The planting and management of barley and rice, as well as the soil fertilization management, were carried out using local conventional methods. The amount of barley seeds applied was the same as that described in Examples 2 and 3. The difference from Mode 5 is that Mode 6 also adopted the technique of inserting water-retaining boards around the field during the rice season.

[0044] One year after the experiment, soil samples were collected from the experimental area for testing. The test results and data for each item are shown in Table 3. Table 3. Soil sample indicators after comparative experiment 2. Comparing the data of various indicators in Tables 2 and 3, it can be seen that before the experiment, the average soil salinity of the experimental area was greater than 4‰, reaching a maximum of 6.84‰, which is a severely saline-alkali land in the tidal flats. The soil pH was high, and the contents of organic carbon, total nitrogen, total phosphorus, and available nitrogen were all low, indicating poor soil fertility. After improvement through Mode 3 or 4, that is, after improvement using the technical solutions of Example 2 or Example 3 of this invention, the soil salinity was significantly reduced, the pH value and total porosity were improved, and the contents of soil organic carbon, total nitrogen, available nitrogen, and total phosphorus were significantly increased. Thus, it can be seen that the technical solution of this invention can reduce the soil salinity of severely saline-alkali land in the tidal flats, increase the soil organic matter content, and improve soil fertility. In contrast, after improvement through Mode 5 or 6, that is, after improvement of the soil using local conventional planting methods, although the soil pH, organic carbon, total nitrogen, total phosphorus, available nitrogen, and porosity were improved, the effect was weaker.

[0045] Comparing the experimental results of Modes 3, 4, and 6, it can be seen that although Mode 6 also uses the technique of inserting water-retaining boards around the paddy field during the rice season, its effect on improving soil properties is relatively weak. In contrast, the soil property improvement technology schemes of Modes 3 and 4, namely the technical scheme of this invention, can not only delay water loss during the rice season, but also achieve the goal of suppressing salt with water and reducing the repeated occurrence of soil salinity, thereby optimizing the topsoil and increasing grain yield.

[0046] During comparative experiment 2, the rice growth in the experimental area was shown in the attached figure. Figure 1 The rice growth in the saline-alkali tidal flats before the experiment, without any improvement measures; Figure 2 The growth status of rice planted using the technical solution of Mode 6; Figure 3 The figures show the growth of rice planted using the technical solution of Mode 4. By comparing the growth of rice in each figure, it can be seen that the growth and development of rice is significantly better under the technical solution of this invention. This indicates that after the technical solution of this invention is used to improve the soil fertility of severely saline-alkali tidal flats, it is more conducive to crop growth.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for improving the properties of severely saline-alkali tidal flat soil, characterized in that, The salinity of the severely saline-alkali tidal flats is greater than 4‰. The method for improving the soil properties of severely saline-alkali tidal flats includes the following steps: Step (1), engineering desalination: buried pipe components are installed in the severely saline-alkali tidal flats. The buried pipe depth is 1.0~1.3 m, the pipe spacing is 15~20 m, and the depth of the buried pipe drainage ditch is 1.2~1.5 m. The severely saline-alkali tidal flats are washed with salt 1~2 times through the buried pipe components. Step (2), soil improvement for dryland farming: The severely saline-alkali tidal flats after the salinization of the project are plowed and prepared to a depth of ≤30 cm. Then, acidic volcanic rock fragments and fermented wood fiber particles are evenly spread and plowed again to a depth of 5-20 cm. After even plowing, humic acid bio-organic fertilizer, slow-release compound fertilizer and superphosphate are shallowly and evenly applied to the soil. Dryland crops are then planted. Urea is applied as a top dressing during the jointing stage of the crops at a rate of 9-12 kg / mu. The application interval of acidic volcanic rock fragments and fermented wood fiber particles is 5-6 years, and the application time is before planting dryland crops. Step (3), improving quality and efficiency during the rice season: After the dryland crops described in step (2) are harvested, the straw is returned to the field, the land is plowed and prepared, the plowing depth is 15-20 cm, and after 2-3 days of plowing, humic acid bio-organic fertilizer is shallowly applied into the soil, followed by slow-release compound fertilizer and superphosphate; rice is planted, with a plant spacing of 12-15 cm and a row spacing of 20-25 cm; urea is applied during the rice tillering stage, with a dosage of 9-12 kg / mu; during the later tillering stage, 8-10 cm long double-toothed sandworms are introduced into the paddy field, with a dosage of 5000-7000 per mu; urea and nitrogen-phosphorus-potassium compound fertilizer are applied during the rice booting stage, with dosages of 9-12 kg / mu and 13-16 kg / mu respectively; water-blocking boards are inserted around the paddy field, with an insertion depth of 15-20 cm.

2. The method for improving the soil properties of severely saline-alkali tidal flats according to claim 1, characterized in that: The acidic volcanic rock fragments have a pH of 5.5-6.5, a diameter of 6-9 mm, and are applied at a rate of 6-10 cubic meters per mu; the fermented wood fiber particles have a pH of 6-8, an average particle size of 3-6 mm, and are applied at a rate of 85-150 kg per mu.

3. The method for improving the soil properties of severely saline-alkali tidal flats according to claim 1, characterized in that: In steps (2) and (3), the application rates of humic acid bio-organic fertilizer, slow-release compound fertilizer and superphosphate are 300~400 kg / mu, 35~45 kg / mu and 30~40 kg / mu, respectively.

4. The method for improving the soil properties of severely saline-alkali tidal flats according to claim 3, characterized in that: The humic acid bio-organic fertilizer contains more than 25% humic acid, more than 40% organic matter, and more than 0.2 billion live bacteria per gram.

5. The method for improving the soil properties of severely saline-alkali tidal flats according to claim 3, characterized in that: In the controlled-release compound fertilizer, the mass ratio of N:P2O5:K2O is 23~26:10~13:7~12, the controlled-release nitrogen content is 8~11%, and the release period is ≥90 days.

6. The method for improving the soil properties of severely saline-alkali tidal flats according to claim 2, characterized in that: The method for preparing the fermented lignocellulose particles includes the following steps: Step (1), preparation of fermentation raw materials: add poultry and livestock manure to the woody material, stir evenly, and adjust the carbon-nitrogen ratio to 20:1 ~ 40:1; then add amino acid hydrolysate, quicklime or wood ash, and adjust the pH value to 6~7 to obtain fermentation raw materials; Step (2): Add water to the fermentation raw materials described in step (1), ventilate and stir to adjust the moisture content to 40-65%, add fermentation agent, the amount of which is 0.2-0.5% of the fermentation raw materials, stir evenly to obtain fermentation product; Step (3): Fill the fermentation material described in step (2) into the fermentation container, filling the volume to less than 70% of the fermentation container, ferment for 15 to 30 days at a fermentation temperature of 55 to 60°C, and obtain fermented wood fiber particles.

7. The method for improving the soil properties of severely saline-alkali tidal flats according to claim 6, characterized in that: In step (1), the mixing ratio of wood materials and poultry manure is 3:1 to 5:

1.

8. The method for improving the soil properties of severely saline-alkali tidal flats according to claim 6, characterized in that: The fermentation agent in step (2) is Bacillus subtilis or Bacillus licheniformis.

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