Method for improving soil performance of severe mud flat saline-alkali soil

Abstract

The invention belongs to the technical field of mudflat saline-alkali soil improvement, and particularly relates to a method for improving the soil performance of heavy mudflat saline-alkali soil, which comprises the following steps of: constructing a complete paddy-upland rotation system by synergistically implementing three technologies of engineering salt reduction, dry farming water-adaptive soil improvement and rice season quality and efficiency improvement; the purposes of soil salt reduction, fertility improvement and crop yield increase are achieved through cooperation of technologies of various links such as water retaining plate insertion for water retention and nereis throwing in the rice season, soil organic matter improvement and soil improvement, the soil performance of the mud flat saline-alkali soil is remarkably improved, especially for improvement of heavy mud flat saline-alkali soil, the organic matter content of the soil is increased, and the salinity is reduced; the soil layer structure is optimized, and the purposes of increasing grain and improving economic benefits are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil improvement for tidal flat saline-alkali land, and particularly relates to a method for improving the soil properties of severely tidal flat saline-alkali land. Background Art

[0002] Coastal tidal flat saline-alkali land is an important reserve cultivated land resource. However, affected by multiple factors such as tidal bore, seawater-type groundwater infiltration, and seasonal distribution of rainfall, the tidal flat saline-alkali land shows obvious characteristics of water-salt dynamic imbalance. The salt content of severely saline-alkali land generally exceeds 4‰, and even 6‰. Especially in spring and autumn, the salt frequently accumulates on the soil surface, leading to repeated imbalance of soil salinity and alkalinity, destroying the soil structure and causing continuous loss of soil nutrients, resulting in a reduction in grain yield. At present, the main methods for improving the soil of tidal flat saline-alkali land include leaching and washing salts through irrigation and drainage engineering measures to achieve the purpose of soil salt control; or improving the soil nutrient storage capacity by applying organic fertilizers, green manures, etc.; or planting rice in tidal flat areas with relatively rich water resources to achieve the purpose of controlling salt with rice. However, the above-mentioned methods for improving soil mainly target moderately saline-alkali land, and have little effect on improving the soil of severely saline-alkali land.

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

[0004] Aiming at the problems of the existing technology, the present invention provides a method for improving the soil properties of severely tidal flat saline-alkali land, which is particularly suitable for improving the soil properties of severely tidal flat saline-alkali land with a salinity above 4‰. It breaks through the single soil improvement technologies such as only using salt washing and control or controlling salt with rice, combines the engineering salt reduction measures, dry farming water-adapted soil improvement, and improvement methods of improving quality and increasing efficiency in the rice season, constructs a complete water-flood rotation system for tidal flat saline-alkali land, improves the soil properties of severely tidal flat saline-alkali land, and increases grain yield.

[0005] To solve the above technical problems, the present invention provides a method for improving the soil properties of severely tidal flat saline-alkali land, characterized in that the salinity of the severely tidal flat saline-alkali land is greater than 4‰. An underground pipe component is buried in the severely tidal flat saline-alkali land, the pipe burial depth is 1.0 - 1.3m, the pipe spacing is 15 - 20m, and the depth of the underground pipe drainage ditch is 1.2 - 1.5m. The method for improving the soil properties of the severely tidal flat saline-alkali land includes the following steps: Step (1), engineering salt reduction: washing the salt of the severely tidal flat saline-alkali land 1 - 2 times through the underground pipe component; Step (2), dry farming with water and soil improvement: Plow and level the severely saline-alkali tidal flat land after desalination by the project. The plowing depth is ≤ 30 cm. Then evenly spread acidic volcanic rock debris and fermented lignocellulose particles, and plow again. The plowing depth is 5 - 20 cm. After uniform plowing, shallowly plow and evenly apply humic acid bio-organic fertilizer, slow-release compound fertilizer, and superphosphate into the soil; then plant dry farming crops, and top-dress urea during the jointing stage of the crops, with a dosage of 9 - 12 kg / mu; Step (3), improving quality and efficiency in the rice season: After harvesting the dry farming crops in step (2), return the straw to the field, plow and level the land. The plowing depth is 15 - 20 cm. After 2 - 3 days of plowing, shallowly plow and apply humic acid bio-organic fertilizer into the soil, and then apply slow-release compound fertilizer and superphosphate; plant rice, with a plant spacing of 12 - 15 cm and a row spacing of 20 - 25 cm; top-dress urea during the tillering stage of rice, with a dosage of 9 - 12 kg / mu. During the late tillering stage, put Perinereis aibuhitensis with a body length of 8 - 10 cm into the paddy field; top-dress urea and nitrogen, phosphorus, and potassium compound fertilizer during the booting stage of rice, with dosages of 9 - 12 kg / mu and 13 - 16 kg / mu respectively; insert water retaining boards around the paddy field, with an insertion depth of 15 - 20 cm.

[0006] In the technical solution of the present invention, after the annual soil property improvement of the severely saline-alkali tidal flat land, before performing step (2) in the next year, first return the straw to the field, and then plow and level the land.

[0007] In the technical solution of the present invention, in case of extreme drought weather, such as a weather condition of no rain for 20 - 30 consecutive days, during the process of planting and cultivating dry farming crops, the field needs to be irrigated 1 - 2 times; in terms of the variety selection of dry farming crops, for the saline-alkali tidal flat land with a salinity of 4 - 8‰, it is preferred to plant salt-tolerant crops such as barley and rapeseed; for the saline-alkali tidal flat land with a salinity greater than 8‰, it is preferred to plant pioneer plants such as Sesbania cannabina and Suaeda glauca; in terms of the variety selection of rice, it is preferred to select salt-tolerant varieties such as Nanjing 518 and Yandao 12, so as to improve the crop yield, increase the economic benefit, and achieve a better soil improvement effect.

[0008] In the technical solution of the present invention, when planting rice, by controlling the plant spacing and row spacing of rice, a high-yield population structure of rice can be achieved; during the entire cultivation cycle of rice, by inserting water retaining boards around the paddy field to replace the soil ridge, not only can the water loss caused by the collapse of the silty clay soil in the field be reduced, but also a water layer of 1 - 2 cm can be continuously maintained during the whole growth period of rice, so as to continuously reduce the salt content and control the salt in the field, stabilize the soil structure, improve the soil, and enhance the soil fertility.

[0009] Preferably, in step (2) of the method, the application interval period of acidic volcanic rock debris and fermented lignocellulose particles is 5 - 6 years.

[0010] Preferably, the pH value of the acidic volcanic rock debris is 5.5 - 6.5, the diameter is 6 - 9 mm, and the application rate is 6 - 10 m³ / mu; the pH value of the fermented lignocellulose particles is 6 - 8, the average particle size is 3 - 6 mm, and the application rate is 85 - 150 kg / mu.

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

[0012] Preferably, in the humic acid bio-organic fertilizer, the humic acid content is greater than 25%, the organic matter content is greater than 40%, and the effective viable bacteria count is greater than 0.2×10⁸ / g.

[0013] Preferably, in the slow and 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 release amount of Perinereis aibuhitensis is 5000 - 7000 pieces / mu.

[0015] In the technical solution of the present invention, by putting Perinereis aibuhitensis into the paddy field, the soil can be loosened. Especially for the silty clay soil, it can reduce the soil viscosity and saturated hydraulic conductivity, improve the porosity, enhance the soil water and fertilizer retention capacity and organic matter content, and improve the soil.

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

[0017] Preferably, in step (1), the mixing ratio of the woody materials and the livestock and poultry manure is 3:1 - 5:1, and the livestock and poultry manure is low-salt manure such as cow dung.

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

[0019] The technical solution of the present invention combines the construction of a complete paddy-upland rotation mode with engineering salt reduction and plough layer optimization measures, and realizes the reduction and control of soil salinity in tidal flat saline-alkali land by methods such as applying humic acid organic fertilizer, slow-release and controlled-release compound fertilizer, and releasing Perinereis aibuhitensis, etc., improves soil organic matter, water retention and fertilizer retention capacity, stabilizes soil structure, and improves soil performance.

[0020] Beneficial effects of the present invention Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The technical solution of the present invention combines engineering salt reduction and washing, dry farming with appropriate water for soil improvement, and quality improvement and efficiency increase in the rice season to build a complete paddy-upland rotation system model, achieving the reduction and control of soil salinity in tidal flat saline-alkali land, and improving soil fertility, water retention and fertilizer retention capacity; especially for severely saline-alkali tidal flat land, it can effectively solve the problems of repeated soil salinization and imbalance of water-salt dynamics caused by the frequent aggregation of soil salt to the soil surface layer; the problems of hidden salt accumulation in winter and heavy salt accumulation in spring existing in tidal flat saline-alkali land can be effectively solved, and long-term salt reduction and control effects on the soil layer can be achieved, improving soil performance; (2) In the technical solution of the present invention, by applying acidic volcanic rock debris and fermented wood fiber particles, the organic matter in the plough layer is increased, the plough layer structure is stabilized, and the optimization of the plough layer is realized; after straw returning to the field, humic acid organic fertilizer is applied to improve soil fertility; when planting crops, special slow-release and controlled-release compound fertilizer and superphosphate are applied, and urea and potassium phosphate compound fertilizer are added at different growth stages of the crops to increase crop yield and economic benefits; (3) After the tillering stage of rice in the technical solution of the present invention, by releasing Perinereis aibuhitensis in the paddy field, it has the effect of loosening the soil and stabilizing the plough layer of the soil; especially for the tidal flat saline-alkali land in northern Jiangsu, it can effectively reduce the viscosity of silt soil, reduce the saturated hydraulic conductivity of the soil surface layer, improve the water retention and fertilizer retention capacity of the soil plough layer, and stabilize the soil water-salt dynamic balance; (4) Compared with the dry-dry rotation system or the traditional paddy-upland rotation system in the prior art, the complete paddy-upland rotation system constructed by the technical solution of the present invention optimizes and improves the soil plough layer in the dry season, realizes salt pressing with water by inserting water retaining plates in the field cycle in the rice season, and improves soil fertility by releasing Perinereis aibuhitensis. Each link works together to improve 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 effects. Description of the drawings

[0021] Figure 1 Growth situation of rice without any improvement measures before the comparative test 2; Figure 2 Growth situation of rice planted by the technical solution of Mode 6 in Comparative Experiment 2; Figure 3 Growth situation of rice planted by the technical solution of Mode 4 in Comparative Experiment 2. Specific implementation mode

[0022] The following further describes the technical solution of the present invention in combination with specific embodiments.

[0023] Example 1 This example was carried out in the Tiaozini Experimental Area, Dongtai, Jiangsu Yancheng from November 2023 to October 2024. The soil salinity of this experimental area is greater than 4‰, belonging to severely saline-alkali tidal flats.

[0024] Buried pipe components were installed in the severely saline-alkali tidal flats of this experimental area. The pipe burial depth was 1.0 m, the pipe spacing was 15 m, and the depth of the buried pipe drainage ditch was 1.2 m. The specific improvement methods included the following steps: Step (1), engineering salt reduction: The experimental area was washed with salt once by burying pipe components. Step (2), dry farming and water-adapted soil improvement: Plow and level the land, with the plowing depth ≤ 30 cm. Then evenly spread acidic volcanic rock debris with a pH value of 5.5 and a diameter of 6 mm, with an application rate of 6 m³ per mu; spread fermented lignocellulose particles with a pH value of 8 and an average particle size of 3 mm, with an application rate of 150 kg per mu. After plowing evenly, humic acid biological organic fertilizer, slow-release compound fertilizer, and superphosphate were shallowly plowed and evenly applied to the soil, with application rates of 300 kg per mu, 35 kg per mu, and 30 kg per mu respectively. Then dry farming crops barley were planted, with a seeding rate of 15 kg per mu for barley seeds. Urea was topdressed during the jointing stage of barley, with an application 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, plow and level the land, with a plowing depth of 15 cm. Two days after plowing, humic acid biological organic fertilizer was shallowly plowed and applied to the soil, with an application rate of 400 kg per mu. Then slow-release compound fertilizer and superphosphate were applied, with application rates of 45 kg per mu and 40 kg per mu respectively; then rice was planted, with a plant spacing of 12 cm and a row spacing of 20 cm; Urea was topdressed during the tillering stage of rice, with an application rate of 12 kg per mu. During the late tillering stage, Perinereis aibuhitensis with a body length of 8 cm was put into the paddy field, with a stocking rate of 5000 per mu; Urea and nitrogen-phosphorus-potassium compound fertilizer were topdressed during the booting stage of rice, with application rates of 9 kg per mu and 13 kg per mu respectively; Water retaining boards were inserted around the paddy field, with an insertion depth of 15 cm.

[0025] In steps (2) and (3) of this embodiment, the humic acid content of the humic acid bio-organic fertilizer is greater than 25%, the organic matter content is greater than 40%, and the effective viable bacteria count is greater than 0.2×10⁸ / g; in the slow-release and 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 the technical solution of the present invention, by applying acidic volcanic rock debris and fermented wood fiber particles, the plough layer structure can be optimized and the soil fertility can be improved, and it can be applied once every 5 years; the fermented wood fiber particles are prepared by the following method: Step (201), preparation of fermentation raw materials: Add livestock and poultry manure to the woody materials, and the mixing ratio of the woody materials to the livestock and poultry manure is 3:1. Stir evenly and adjust the carbon-nitrogen ratio to 20 : 1; then add amino acid hydrolysis solution and adjust the pH value to 6 to obtain the fermentation raw materials. Step (202), add water and ventilate and stir in the fermentation raw materials described in step (201), adjust the moisture content to 40%, add Bacillus subtilis, and the addition amount is 0.2% of the fermentation raw materials. Stir evenly to obtain the fermentation product. Step (203), fill the fermentation product described in step (202) into the fermentation container, and the filling volume is less than 70% of the fermentation container. Ferment for 15 days at a fermentation temperature of 60°C to obtain fermented wood fiber particles.

[0027] Based on the engineering desalination and salt control, the technical solution of the present invention constructs a complete paddy-upland rotation system. By the method of circularly planting upland crops and rice, and combined with the application of humic acid organic fertilizer, special slow-release and controlled-release compound fertilizer, and superphosphate, the soil salinity of the tidal flat saline-alkali land is effectively improved, the soil structure is stabilized, and the organic matter in the plough layer is increased. And urea and nitrogen, phosphorus and potassium compound fertilizers are added during different growth periods of the crops to increase the crop yield.

[0028] Example 2 This example was carried out in the experimental area of Tiaozini in Dongtai, Jiangsu Yancheng from November 2023 to October 2024. The soil salinity of this experimental area is greater than 4‰, belonging to severely saline-alkali tidal flat land.

[0029] Bury the subsurface pipe assembly in the severely saline-alkali tidal flat land of this experimental area. The pipe burial depth is 1.3 m, the pipe spacing is 20 m, and the depth of the subsurface pipe drainage ditch is 1.5 m. The specific improvement method includes the following steps: Step (1), engineering desalination: Wash the salt of the severely saline-alkali tidal flat land 2 times through the buried subsurface pipe assembly. Step (2), dry farming with water and soil improvement: Plow and prepare the land, with the plowing depth ≤ 30 cm. Then evenly spread acidic volcanic rock debris with a pH value of 6.5 and a diameter of 9 mm, with an application rate of 10 cubic meters per mu. Spread fermented wood fiber particles with a pH value of 6 and an average particle size of 3 mm, with an application rate of 85 kg per mu. Then return straw to the field and plow again, with a plowing depth of 20 cm. After uniform plowing, shallowly and evenly apply humic acid bio-organic fertilizer, slow-release compound fertilizer, and superphosphate into the soil, with application rates of 400 kg per mu, 45 kg per mu, and 40 kg per mu respectively. Plant barley, with a seeding rate of 15 kg per mu, and top-dress urea during the jointing stage of barley, with an application rate of 12 kg per mu. Step (3), improving quality and efficiency in the rice season: In early June, after returning straw to the field, plow and prepare the land, with a plowing depth of 20 cm. Three days after plowing, shallowly apply humic acid bio-organic fertilizer into the soil, with an application rate of 300 kg per mu. Then apply slow-release compound fertilizer and superphosphate, with application rates of 35 kg per mu and 30 kg per mu respectively. Plant rice, with a plant spacing of 15 cm and a row spacing of 25 cm. Top-dress urea during the tillering stage of rice, with an application rate of 9 kg per mu. During the late tillering stage, put Perinereis aibuhitensis with a body length of 10 cm into the paddy field, with an input amount of 7000 per mu. Top-dress urea and nitrogen, phosphorus, and potassium compound fertilizer during the booting stage of rice, with application rates of 12 kg per mu and 16 kg per mu respectively. Insert water retaining boards around the paddy field, with an insertion depth of 20 cm.

[0030] In step (2) and step (3) of this embodiment, the humic acid content of the humic acid bio-organic fertilizer is greater than 25%, the organic matter content is greater than 40%, and the effective viable bacteria count is greater than 0.2 billion per gram; in the slow-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 period of the acidic volcanic rock debris and the fermented wood fiber particles described in this embodiment is 6 years. Among them, the preparation method of the fermented wood fiber particles includes the following steps: Step (201), preparation of fermentation raw materials: Add livestock and poultry manure to the wood material, with the mixing ratio of the wood material to the livestock and poultry manure being 5:1, stir evenly, and adjust the carbon-nitrogen ratio to 40:1; then add slaked lime and adjust the pH value to 7 to obtain the fermentation raw materials. Step (202), add water and ventilate and stir in the fermentation raw materials described in step (201), adjust the moisture content to 65%, add Bacillus licheniformis, with an addition amount of 0.5% of the fermentation raw materials, stir evenly to obtain the fermentation product. Step (203): Fill the fermented matter described in step (202) into a fermentation container. The filling volume is less than 70% of the fermentation container, and ferment for 30 days at a fermentation temperature of 55°C to obtain fermented lignocellulose particles.

[0032] Example 3 This example was carried out from November 2023 to October 2024 in the Dongtai Tiaozini Experimental Area in Jianggang, Yancheng, Jiangsu. The soil salinity in this experimental area is greater than 4‰, belonging to severely saline-alkali tidal flats.

[0033] Install a buried pipe assembly in the severely saline-alkali tidal flats of this experimental area. The buried pipe depth is 1.2 m, the pipe spacing is 18 m, and the depth of the buried pipe drainage ditch is 1.3 m. The specific improvement method includes the following steps: Step (1): Engineering salt reduction. Conduct one-time salt washing on the severely saline-alkali tidal flats through the installed buried pipe assembly. Step (2): Dry farming and water-adaptive soil improvement. Plow and level the land, with the plowing depth ≤ 30 cm. Then evenly spread acidic volcanic rock debris with a pH value of 6.0 and a diameter of 8 mm, with an application rate of 8 m³ per mu. Spread fermented lignocellulose particles with a pH value of 7 and an average particle size of 4 mm, with an application rate of 120 kg per mu. After straw returning to the field, plow again, with a plowing depth of 12 cm. After uniform plowing, shallowly and evenly apply humic acid bio-organic fertilizer, slow-release compound fertilizer, and superphosphate into the soil, with application rates of 350 kg per mu, 42 kg per mu, and 36 kg per mu respectively. Plant barley, with a barley seed application rate of 15 kg per mu. Top-dress urea during the jointing stage of barley, with a dosage of 15 kg per mu. Step (3): Improving quality and increasing efficiency during the rice season. In early June, return straw to the field, plow and level the land, with a plowing depth of 18 cm. Three days after plowing, shallowly apply humic acid bio-organic fertilizer into the soil, with an application rate of 380 kg per mu. Then apply slow-release compound fertilizer and superphosphate, with application rates of 37 kg per mu and 32 kg per mu respectively. Then plant rice, with a plant spacing of 13 cm and a row spacing of 22 cm. Top-dress urea during the tillering stage of rice, with a dosage of 10 kg per mu. Put Perinereis aibuhitensis with a body length of 9 cm into the paddy field during the late tillering stage, with a stocking rate of 6000 per mu. Top-dress urea and nitrogen-phosphorus-potassium compound fertilizer during the booting stage of rice, with dosages of 11 kg per mu and 15 kg per mu respectively. Insert water retaining boards around the paddy field, with an insertion depth of 17 cm.

[0034] In step (2) and step (3) of this example, the humic acid content of the humic acid bio-organic fertilizer is greater than 25%, the organic matter content is greater than 40%, and the effective viable bacteria count is greater than 0.2×10⁸ / g. In the slow-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 the present invention, applying acidic volcanic rock debris and fermented wood fiber particles can effectively improve the soil structure of tidal flat saline-alkali land, stabilize the plough layer, prevent the repeated salinization of the soil layer, and only need to be applied once every 5 years. Among them, the preparation method of the fermented wood fiber particles includes the following steps: Step (201), preparation of fermentation raw materials: Add livestock and poultry manure to the wood material, and the mixing ratio of the wood material to the livestock and poultry manure is 4:1. Stir evenly and adjust the carbon-nitrogen ratio to 30:1; then add plant ash and adjust the pH value to 7 to obtain the fermentation raw materials; Step (202), add water and ventilate and stir in the fermentation raw materials described in step (201), adjust the moisture content to 55%, add Bacillus subtilis, and the addition amount is 0.35% of the fermentation raw materials. Stir evenly to obtain the fermentation product; Step (203), fill the fermentation product described in step (202) into the fermentation container, and the filling volume is less than 70% of the fermentation container. Ferment for 25 days, and the fermentation temperature is 58°C to obtain the fermented wood fiber particles.

[0036] Comparative experiment Comparative experiment 1 From November 2023 to October 2024, comparative verification was carried out in the experimental area of Tiaozini in Dongtai, Jiangsu Yancheng. The soil performance improvement planting modes for severely saline-alkali tidal flat land are as follows: Mode 1: Carry out the experiment using the technical solution of Example 1 of the present invention; Mode 2: Set a comparative example under Example 1; Carry out the experiment in an experimental area of the same size and similar salinity as Example 1 for comparison.

[0037] In this comparative example, the open ditch drainage method is used to reduce and control the salinity of the soil in the experimental area; the barley + corn dry-dry rotation system mode is used to plant crops; the land management method, fertilization, topdressing and other technical solutions of the barley or corn in the comparative example experimental area adopt the local conventional planting mode management; the application amounts of barley seeds and corn seeds are the same as those of the barley seeds described in Example 1.

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

[0039] Table 1 Various indicators of Comparative Experiment 1 As can be seen from the data in Table 1, through the crop planting system of Mode 1, that is, by using the paddy-upland rotation system of the technical solution of the present invention to plant and manage crops and improve the soil properties of saline-alkali land, after one-year experiment, the salinity of the soil decreased significantly, and the organic carbon content increased significantly; compared with Mode 1, under the technical solution of Mode 2, after one-year soil improvement, the decline range of soil salinity was lower, because the soil salinity in this experimental area was greatly affected by seasonality, the soil salinization was repeated and the salt patches were uneven. Compared with Mode 1, the local conventional crop planting technology adopted in Mode 2 could not solve this problem and could not reduce the soil salinity and stabilize the plough layer structure.

[0040] By comparing the experimental results of Mode 1 and Mode 2, it can be seen that by adopting the technical solution of the present invention, the decline of soil salinity is greater, effectively solving the problem of repeated soil salinization in this area, increasing the soil organic carbon content, realizing grain yield increase, and achieving better economic benefits. That is, the beneficial effects of the technical solution of the present invention in improving the soil properties of tidal flat saline-alkali land, increasing grain yield and enhancing economic benefits are more significant.

[0041] Comparative Experiment 2 From November 2023 to October 2024, a comparative experiment on the paddy-upland rotation system mode of severely saline-alkali land was carried out in the Tiaozini Experimental Area, Dongtai, Jiangsu Yancheng. Before the experiment, soil samples were collected and tested, and the indexes and data of the test items are shown in Table 2.

[0042] Table 2 Indexes of soil samples before Comparative Experiment 2 Comparative experiment settings: Mode 3: Carry out the experiment by adopting the technical solution of Example 2 of the present invention; Mode 4: Carry out the experiment by adopting the technical solution of Example 3 of the present invention; Under Example 2 and Example 3, 2 groups of comparative examples are set, namely Mode 5 and Mode 6.

[0043] For the 2 groups of comparative examples, test areas of the same size and similar salinity as those in Examples 2 and 3 are selected to carry out the experiment; both Mode 5 and Mode 6 adopt the paddy-upland rotation system of barley + rice. Among them, the planting management mode of barley and rice and the soil fertilization management mode are all carried out by using local conventional methods, and the application rate of barley seeds is the same as that described in Examples 2 and 3; the difference between Mode 6 and Mode 5 is that Mode 6 also adopts the technology of inserting water retaining boards around the fields during the rice season.

[0044] After one-year experiment, soil samples in the experimental area are collected for testing, and the indexes and data results of each item are shown in Table 3: Table 3 Indexes of soil samples after Comparative Experiment 2 By comparing the data of each index in Table 2 and Table 3, it can be seen that before the experiment, the average soil salinity in the experimental area was greater than 4‰, and the highest could reach 6.84‰, which was a severely saline-alkali tidal flat. The soil had a high pH value, and the contents of organic carbon, total nitrogen, total phosphorus, and available nitrogen were all low, resulting in poor soil fertility. After improvement by Mode 3 or 4, that is, after improving with the technical solutions of Example 2 or Example 3 of the present 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 the present invention can reduce the soil salinity of severely saline-alkali tidal flats, increase the soil organic matter content, and improve soil fertility. In contrast, after improvement by Mode 5 or 6, that is, after improving the soil by using the local conventional planting method, although the indexes such as soil pH, organic carbon, total nitrogen, total phosphorus, available nitrogen, and porosity were improved, the effect was weak.

[0045] By comparing the test results of Mode 3, Mode 4, and Mode 6, it can be seen that although Mode 6 also adopted the technology of inserting water retaining boards around the paddy field during the rice season, the improvement effect on soil properties was weak. In contrast, by adopting the soil property improvement technical solutions of Mode 3 and Mode 4, that is, in the technical solution of the present invention, inserting water retaining boards around the field during the rice season can not only delay water loss, but also achieve the purpose of pressing salt with water and reducing the repeated salinization of the soil layer, so as to optimize the plough layer and increase grain yield.

[0046] During the test period of Comparative Test 2, the growth situation of rice in the test area is shown in the attached drawings, where Figure 1 is the growth situation of rice in the saline-alkali tidal flat before the experiment without any improvement measures; Figure 2 is the growth situation of rice planted by adopting the technical solution of Mode 6; Figure 3 is the growth situation of rice planted by adopting the technical solution of Mode 4. By comparing the growth situations of rice in each figure, it can be seen that under the technical solution of the present invention, the growth and development of rice are significantly better. Thus, it can be seen that after the severely saline-alkali tidal flat is improved by the technical solution of the present invention, the soil fertility is significantly improved, which is more conducive to the growth of crops.

[0047] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modification, change, and equivalent change made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for improving soil properties in heavy tidal flat saline-alkali land, characterized in that: The salinity of the severe tidal flat saline-alkali land is greater than 4‰. A concealed pipe assembly is buried in the severe tidal flat saline-alkali land. The buried pipe depth is 1.0-1.3m, the pipe spacing is 15-20m, and the concealed pipe drainage ditch depth is 1.2-1.5m. The method for improving the soil performance of the severe tidal flat saline-alkali land comprises the following steps: Step (1), engineering salt reduction: using the blind pipe assembly to wash the salt on the heavy tidal flat saline-alkali land 1-2 times; Step (2), dryland water-adapted soil improvement: the heavy tidal flat saline-alkali land after the salt reduction project is plowed and prepared, the plowing depth is ≤30 cm, then acidic volcanic rock debris and fermented wood fiber particles are evenly sprinkled, and plowed again, the plowing depth is 5-20 cm, after the plowing is uniform, humic acid bio-organic fertilizer, slow-release compound fertilizer and superphosphate are shallowly plowed and evenly applied to the soil; then dryland crops are planted and cultivated, and urea is applied at the jointing stage of the crops, with an application amount of 9-12 kg / mu; Step (3), improving the quality and efficiency of rice: after the dryland crops described in step (2) are harvested, the straw is returned to the field, the land is plowed to a depth of 15-20 cm, and after 2-3 days of plowing, humic acid bio-organic fertilizer is shallowly turned into the soil, and then slow-release compound fertilizer and superphosphate are applied; rice is planted with a rice plant spacing of 12-15 cm and a row spacing of 20-25 cm; urea is applied at a rate of 9-12 kg / mu during the rice tillering stage, and double-toothed sandworms with a body length of 8-10 cm are placed in the rice field at the late tillering stage; urea and nitrogen, phosphorus and potassium compound fertilizers are applied at a rate of 9-12 kg / mu and 13-16 kg / mu respectively during the rice heading stage; water retaining boards are inserted around the rice field at a depth of 15-20 cm.

2. The method for improving soil properties in heavy tidal flat saline-alkali land according to claim 1, characterized in that: In the step (2), the application interval of the acidic volcanic rock debris and the fermented wood fiber particles is 5 to 6 years, and the application time is before planting dryland crops.

3. The method for improving soil properties in heavy tidal flat saline-alkali land according to claim 2, characterized in that: The pH value of the acidic volcanic rock fragments is 5.5-6.5, the diameter is 6-9 mm, and the application amount is 6-10 cubic meters per mu; the pH value of the fermented wood fiber particles is 6-8, the average particle size is 3-6 mm, and the application amount is 85-150 kg per mu.

4. The method for improving soil properties in heavy tidal flat saline-alkali land according to claim 1, characterized in that: In the steps (2) and (3), the application amounts 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.

5. The method for improving soil properties in heavy tidal flat saline-alkali land according to claim 4, characterized in that: In the humic acid biological organic fertilizer, the humic acid content is greater than 25%, the organic matter content is greater than 40%, and the number of effective live bacteria is greater than 20 million / g.

6. The method for improving soil properties in heavy tidal flat saline-alkali land according to claim 4, characterized in that: In the slow-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.

7. The method for improving soil properties in heavy tidal flat saline-alkali land according to claim 1, characterized in that: In the step (3), the amount of double-toothed sandworms released is 5000-7000 per mu.

8. The method for improving soil properties in heavy tidal flat saline-alkali land according to claim 3, characterized in that: The method for preparing fermented wood fiber particles comprises the following steps: Step (1), preparation of fermentation raw materials: adding poultry and livestock manure to wood materials, stirring evenly, adjusting the carbon-nitrogen ratio to 20:1-40:1; then adding amino acid acid hydrolyzate, slaked lime or wood ash, adjusting the pH value to 6-7, and obtaining fermentation raw materials; Step (2), adding water to the fermentation raw material described in step (1), stirring under ventilation, adjusting the moisture content to 40-65%, adding fermentation bacteria agent, the addition amount of which is 0.2-0.5% of the fermentation raw material, stirring evenly, and obtaining a fermentation product; Step (3), filling the fermented product of step (2) into a fermentation container, with the filling volume being less than 70% of the fermentation container, and fermenting for 15 to 30 days at a fermentation temperature of 55 to 60° C. to obtain fermented wood fiber particles.

9. The method for improving soil properties in heavy tidal flat saline-alkali land according to claim 8, characterized in that: In the step (1), the mixing ratio of the wood material and livestock manure is 3-5:

1.

10. The method for improving soil properties in heavy tidal flat saline-alkali land according to claim 8, characterized in that: The fermentation agent in step (2) is Bacillus subtilis or Bacillus licheniformis.

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