Method for rapidly improving saline-alkali soil by using urea phosphate

Abstract

The application discloses a method for rapidly improving saline-alkali soil by using urea phosphate, and comprises the following steps: S1, preparation of an improving agent; S1-1, preparation of a liquid improving agent; S1-2, preparation of a solid improving agent; S2, excavation of a salt discharge ditch; S3, salt discharge by drip irrigation; and S4, deepening of salt discharge. The method for rapidly improving saline-alkali soil by using urea phosphate can be used in saline-alkali soil in cooperation with the liquid improving agent and the solid improving agent in two different forms, can improve the physical and chemical properties of soil, can improve the organic matter content of soil, can make the obstacle soil suitable for plant growth, can simplify the improvement process, is harmless to the environment, and has wide economic and ecological benefits.

Description

Technical Field

[0001] This invention relates to the field of soil regeneration technology, specifically to a method for rapidly improving saline-alkali soil using urea phosphate. Background Technology

[0002] Saline-alkali land is a special type of soil characterized by high salt content and strong alkalinity. It can be classified as saline-alkali land when the electrical conductivity of the soil solution exceeds 1 mS / cm and the pH value is higher than 8.5. This type of soil hinders plant growth, reduces crop yields, and damages soil structure, thus severely impacting production activities and the ecological environment. With the continuous growth of the global population and the increasing scarcity of land resources, improving saline-alkali soil and enhancing its utilization rate has become a crucial issue that urgently needs to be addressed.

[0003] Currently, there are various methods for improving saline-alkali soils, mainly falling into three categories: physical improvement, chemical improvement, and biological improvement. Physical improvement methods encompass technologies such as drainage, salt leaching, and topsoil replacement, with the core being the use of mechanical means to adjust the salt content or improve soil structure. Chemical improvement focuses on applying chemical amendments to adjust the soil's physicochemical properties, reducing salinity and alkalinity, thereby optimizing soil structure and improving fertility. Biological improvement methods utilize biotechnologies such as planting salt-tolerant plants or applying microbial agents to improve soil characteristics from multiple dimensions, including physical, chemical, and biological aspects. However, these improvement methods generally have some problems, such as high cost, incomplete treatment effects, significant dependence on specific environmental conditions, and even potential adverse environmental impacts.

[0004] The main drawback of chemical soil amendment methods is that their remediation effect is not thorough enough, and they may have other negative environmental impacts. Therefore, developing a soil amendment agent that simplifies the process and is harmless to the environment is gradually becoming a research hotspot.

[0005] For example, patent publication number CN118389156A provides an alkalizing soil conditioner, its preparation method, and its application, including the following steps: P1, mixing humic acid and urea phosphate evenly, adding water, and allowing the mixture to stand to react, obtaining product A; P2, mixing sunflower seed shells and amino acid fermentation tail liquid evenly, and allowing natural fermentation, obtaining product B; P3, mixing gypsum, aluminum sulfate, product A, and product B evenly, and granulating the mixture to obtain the alkalizing soil conditioner. By combining fast-acting and slow-release materials to create a composite conditioner, it can significantly reduce soil pH and total salt content, and increase soil organic matter content, with a particularly significant effect on rhizosphere soil, thereby significantly improving crop emergence rate and yield. However, this method does not provide a specific application method for the conditioner; that is, it is unclear whether the amount of conditioner needed is the same for soils with different salinity levels. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for rapidly improving saline-alkali soil using urea phosphate.

[0007] The technical solution of this invention is:

[0008] A method for rapidly improving saline-alkali soil using urea phosphate includes the following steps:

[0009] S1. Preparation of Modifier:

[0010] S1-1, Preparation of liquid modifier: A liquid modifier is obtained by mixing urea phosphate with water, wherein the mass-volume ratio of urea phosphate to water is 1g:2~10L;

[0011] S1-2, Preparation of solid modifier: Urea phosphate, humic acid and travertine are mixed in a mass ratio of 1-1.5:1-1.5:1.5-2 and granulated by a granulator to obtain a solid modifier;

[0012] S2. Excavation of drainage ditches: Several drainage ditches are excavated inside the saline-alkali soil to be treated. All drainage ditches have the same direction, the depth of the drainage ditches is 30-80cm, the interval between the drainage ditches is 2-5m, and the area between two adjacent drainage ditches is used as a drip irrigation area.

[0013] S3. Drip irrigation for salt removal: Drip irrigation is carried out in the middle of the drip irrigation area, using the liquid conditioner prepared in S1-1. The interval between drip irrigations is 8-10 days, and the drip volume is 3500-5000m³ each time. 3 / hm 2 Drip irrigation 3 to 5 times in total;

[0014] S4. Deepen salt removal: After the last drip irrigation, wait 10 to 15 days and apply the solid amendment prepared in S1-2 to the drip irrigation area at a rate of 50 to 100 kg / mu. Mix the solid amendment with the soil in the drip irrigation area and then drip irrigate with water 3 to 8 times.

[0015] Furthermore, in S1, the particle size of the solid modifier is 2-10 mm.

[0016] Explanation: By optimizing the particle size of solid amendments, they can be fully mixed with the soil, thereby improving desalination efficiency.

[0017] Furthermore, in S2, the top width of the salt drainage ditch is 40-80cm, and the bottom width of the salt drainage ditch is 20-30cm.

[0018] Note: Optimizing the size of the salt drainage ditch can ensure the smooth discharge of high-salinity water.

[0019] Furthermore, in step S3, drip irrigation points are arranged in the middle of the drip irrigation area, with an interval of 20-60cm between the drip irrigation points.

[0020] Explanation: By optimizing the spacing of drip irrigation points, uniform drip irrigation can be achieved, promoting salt removal.

[0021] Furthermore, in step S4, the stirring depth is 10–20 cm.

[0022] Instructions: Mix the solid amendment thoroughly with the soil by turning and stirring.

[0023] Furthermore, in step S4, the time interval for each drip irrigation is 10 to 20 days, and the drip irrigation volume for each irrigation is 2000 to 4000 m³. 3 / hm 2 .

[0024] Explanation: By extending the interval between drip irrigation sessions and optimizing the amount of water used for drip irrigation, a suitable drip irrigation scheme can be selected based on soil salinity and alkalinity.

[0025] Furthermore, in step S4, after drip irrigation with water 1 to 3 times, improved soil is applied to the center of the drip irrigation area. The improved soil is obtained by mixing the solid amendment prepared in step S1-2 with bentonite, wherein the solid amendment accounts for 10 to 15% of the total mass of the improved soil. After the improved soil is applied, a raised part with an arc-shaped cross-section is formed in the center of the drip irrigation area. The height of the raised part is 20 to 40 cm, and the width of the bottom of the raised part is 30 to 60 cm.

[0026] Explanation: The raised sections can further guide the flow of salt, allowing it to accumulate upwards under capillary force. This accumulation of salt in the raised sections, combined with the internal components, achieves the purpose of continuous salt reduction.

[0027] Furthermore, salt-tolerant plants are planted on both sides of the raised portion, such as *Imperata cylindrica*, *Senecio scandens*, *Adenophora stricta*, or *Apocynum venetum*.

[0028] Note: Planting salt-tolerant plants can help reduce salinity, increase biodiversity, and promote soil restoration.

[0029] The beneficial effects of this invention are:

[0030] (1) This invention uses two different forms of amendments, liquid amendment and solid amendment, in combination in saline-alkali soil. This not only improves the physical and chemical properties of the soil, but also increases the organic matter content of the soil, making the soil suitable for plant growth. It simplifies the improvement process and is harmless to the environment, thus having broad economic and ecological benefits.

[0031] (2) In this invention, urea phosphate solution is used as a liquid amendment for leaching. The urea and phosphoric acid released directly neutralize alkaline substances in the soil, such as Na2CO3 and NaHCO3, which are discharged with water. At the same time, it can activate the primary calcium in the soil, reduce soil dispersion, enhance the stability of aggregates, improve water permeability, and promote salt leaching.

[0032] (3) This invention uses travertine as a carrier and its unique hollow nanotube structure to physically adsorb phosphate ions in urea phosphate onto the tube wall or trap them inside the tube lumen, thus delaying their release. At the same time, its tube wall is rich in Al-OH and Si-OH groups, which can adsorb polar molecules, such as NH4, through hydrogen bonding or electrostatic interactions. + H2PO4 - Meanwhile, humic acid encapsulates the travertine nanotubes, forming a physical barrier that inhibits the rapid hydrolysis of urea by soil microorganisms. When applied after leaching with liquid amendments, it further slows down the release of nitrogen sources and promotes the growth of salt-tolerant crops.

[0033] (4) This invention adds raised sections during drip irrigation and optimizes the components of the raised sections. It is based on the fact that salt in the soil accumulates in the raised sections under the action of capillary force. Bentonite is used because its capillary action is stronger and it is easier to accumulate salt than clay. Therefore, it is easier to accumulate, dissolve and discharge insoluble salts. At the same time, bentonite itself is close to neutral and can slightly buffer the pH value of strongly alkaline saline-alkali soil, improve microbial activity and benefit crop growth. Attached Figure Description

[0034] Figure 1 These are the drainage ditches and drip irrigation points in Example 1;

[0035] Figure 2 This is a schematic diagram of the stirring depth in Example 1;

[0036] Figure 3 This is a schematic diagram of the raised portion in Example 1;

[0037] Figure 4 It is the soil column apparatus structure used in Experiment Example 1 for irrigating soil.

[0038] Figure 5 This refers to the pH changes of soil samples at a depth of 10 cm in a soil column apparatus under different irrigation treatments in Experiment Example 1.

[0039] Figure 6 This refers to the pH changes of soil samples at a depth of 50cm in a soil column apparatus under different irrigation treatments in Experiment Example 1.

[0040] Figure 7 The change in electrical conductivity of soil samples at a depth of 10cm in a soil column apparatus under different irrigation treatments in Experiment Example 1;

[0041] Figure 8 The change in electrical conductivity of soil samples at a depth of 50cm in a soil column apparatus under different irrigation treatments in Experiment Example 1;

[0042] Figure 9 This refers to the changes in organic matter in soil samples at a depth of 10cm in a soil column apparatus under different irrigation treatments in Experiment Example 1.

[0043] Figure 10 This refers to the changes in organic matter in soil samples at a depth of 50cm in a soil column apparatus under different irrigation treatments in Experiment Example 1.

[0044] Figure 11 This refers to the pH changes of the soil at different times during the pot experiment in Experiment Example 1;

[0045] Figure 12 This refers to the change in soil electrical conductivity at different times during the pot experiment in Example 1.

[0046] Figure 13 This refers to the changes in soil organic matter at different times during the pot experiment in Experiment Example 1;

[0047] Figure 14 This refers to the change in the fresh weight of ryegrass in the pot experiment in Experiment Example 1;

[0048] Figure 15 This refers to the change in the fresh weight of lettuce in the potted plant experiment in Experiment Example 1. Detailed Implementation

[0049] Example 1: A method for rapidly improving saline-alkali soil using urea phosphate, comprising the following steps:

[0050] S1. Preparation of Modifier:

[0051] S1-1, Preparation of liquid modifier: A liquid modifier is obtained by mixing urea phosphate with water, wherein the mass-volume ratio of urea phosphate to water is 1g:6L;

[0052] S1-2, Preparation of solid modifier: Urea phosphate, humic acid and travertine are mixed in a mass ratio of 1:1:2 and granulated by a granulator to obtain a solid modifier with a particle size of 5 mm.

[0053] S2. Excavation of drainage ditches: Several drainage ditches are excavated inside the saline-alkali soil to be treated, such as... Figure 1 As shown, all the drainage ditches have the same direction, a depth of 50cm, a spacing of 3m, a top width of 60cm, a bottom width of 25cm, and the area between two adjacent drainage ditches is used as a drip irrigation zone.

[0054] S3. Drip Irrigation for Salt Removal: Drip irrigation is carried out in the central part of the irrigation area, with drip points spaced 40cm apart. The liquid conditioner prepared in S1-1 is used for drip irrigation. The interval between drip irrigations is 9 days, and the drip volume is 4000m³ each time. 3 / hm 2 A total of 4 drip irrigations were performed;

[0055] S4. Deepen salt removal: After the last drip irrigation, wait 12 days and apply the solid soil conditioner prepared in S1-2 to the drip irrigation area at a rate of 75 kg / mu. Mix the solid soil conditioner with the soil within the drip irrigation area. Figure 2 As shown, the mixing depth is 15cm, followed by drip irrigation 5 times, with each drip irrigation session spaced 15 days apart. The drip irrigation volume for each session is 3000m³. 3 / hm 2 ;

[0056] After two drip irrigations, improved soil is applied to the center of the drip irrigation area. This improved soil is obtained by mixing the solid conditioner prepared in S1-2 with bentonite, with the solid conditioner accounting for 12% of the total mass of the improved soil. After application, the improved soil forms an arched ridge in the center of the drip irrigation area, such as... Figure 3 As shown, the height of the raised section is 30cm and the width of the bottom of the raised section is 40cm. Salt-tolerant plants are planted on both sides of the raised section. The salt-tolerant plants are alkali grass and alfalfa. Alkali grass (non-leguminous) and alfalfa (leguminous) do not compete for nutrients. Alfalfa fixes nitrogen, which can indirectly promote the growth of alkali grass. Alkali grass has a dense root system and can fix the soil. Alfalfa has a deep root system, which can prevent wind and fix sand, and is suitable for sandy saline-alkali land.

[0057] Example 2: This example differs from Example 1 in that:

[0058] S1-1, Preparation of liquid modifier: A liquid modifier is obtained by mixing urea phosphate with water, wherein the mass-volume ratio of urea phosphate to water is 1g:2L.

[0059] Example 3: This example differs from Example 1 in that:

[0060] S1-1, Preparation of liquid modifier: A liquid modifier is obtained by mixing urea phosphate with water, wherein the mass-volume ratio of urea phosphate to water is 1g:10L.

[0061] Example 4: This example differs from Example 1 in that:

[0062] S1-2, Preparation of solid modifier: Urea phosphate, humic acid and travertine are mixed in a mass ratio of 1:1:1.5 and granulated by a granulator to obtain a solid modifier with a particle size of 2 mm.

[0063] Example 5: This example differs from Example 1 in that:

[0064] S1-2, Preparation of solid modifier: Urea phosphate, humic acid and travertine are mixed in a mass ratio of 1.5:1.5:2 and granulated by a granulator to obtain a solid modifier with a particle size of 10 mm.

[0065] Example 6: This example differs from Example 1 in that:

[0066] S2. Excavation of drainage ditches: Several drainage ditches are excavated inside the saline-alkali soil to be treated. All drainage ditches have the same direction, a depth of 30cm, a spacing of 2m, a top width of 40cm, and a bottom width of 20cm. The area between two adjacent drainage ditches is used as a drip irrigation area.

[0067] Example 7: This example differs from Example 1 in that:

[0068] S2. Excavation of drainage ditches: Several drainage ditches are excavated inside the saline-alkali soil to be treated. All drainage ditches have the same direction, a depth of 30cm, a spacing of 5m, a top width of 80cm, and a bottom width of 30cm. The area between two adjacent drainage ditches is used as a drip irrigation area.

[0069] Example 8: This example differs from Example 1 in that:

[0070] S3. Drip Irrigation for Salt Removal: Drip irrigation is carried out in the central part of the irrigation area, with drip points spaced 20cm apart. The liquid conditioner prepared in S1-1 is drip-irrigated. The interval between drip irrigations is 8 days, and the drip volume is 3500m³ each time. 3 / hm 2 A total of 3 drip irrigations were performed.

[0071] Example 9: This example differs from Example 1 in that:

[0072] S3. Drip Irrigation for Salt Removal: Drip irrigation is carried out in the central part of the irrigation area, with drip points spaced 60cm apart. The liquid conditioner prepared in S1-1 is used for drip irrigation. The interval between drip irrigations is 10 days, and the drip volume is 5000m³ each time. 3 / hm 2 A total of 5 drip irrigations were performed.

[0073] Example 10: This example differs from Example 1 in that:

[0074] S4. Deepen Salt Removal: After the last drip irrigation, wait 10 days and apply the solid soil conditioner prepared in S1-2 to the drip irrigation area at a rate of 50 kg / mu. Mix the solid conditioner with the soil in the drip irrigation area to a depth of 10 cm. Then, perform drip irrigation three times, with each irrigation spaced 10 days apart. Each drip irrigation should have a volume of 2000 m³. 3 / hm 2 ;

[0075] After drip irrigation once, improve soil is applied to the center of the drip irrigation area. The improve soil is prepared by mixing the solid improver prepared in S1-2 with bentonite. The solid improver accounts for 10% of the total mass of the improve soil. After the improve soil is applied, an arch-shaped ridge is formed in the center of the drip irrigation area. The height of the ridge is 20cm and the width of the bottom of the ridge is 30cm. Salt-tolerant plants are planted on both sides of the ridge. The salt-tolerant plants are sesbania and alfalfa. Both are leguminous plants with nitrogen-fixing ability and can complement each other to improve soil fertility. Sesbania has good moisture tolerance and alfalfa has strong drought tolerance, making them suitable for areas with uneven water distribution in saline-alkali land.

[0076] Precautions: Avoid planting too densely to prevent competition for sunlight.

[0077] Example 11: This example differs from Example 1 in that:

[0078] S4. Deepen Salt Removal: After the last drip irrigation, wait 15 days and apply the solid soil conditioner prepared in S1-2 to the drip irrigation area at a rate of 100 kg / mu. Mix the solid conditioner with the soil in the drip irrigation area to a depth of 20 cm. Then, perform drip irrigation 8 times, with each irrigation occurring 20 days apart. Each drip irrigation should have a volume of 4000 m³. 3 / hm 2 ;

[0079] After drip irrigation three times, improved soil is applied to the center of the drip irrigation area. The improved soil is made by mixing the solid amendment prepared in S1-2 with bentonite, wherein the solid amendment accounts for 15% of the total mass of the improved soil. After the improved soil is applied, an arch-shaped raised section is formed in the center of the drip irrigation area, with a height of 40cm and a bottom width of 60cm. Salt-tolerant plants are planted on both sides of the raised section. The salt-tolerant plants are Apocynum venetum and Sesbania spp. Apocynum venetum is a shrub, and it is layered with the herbaceous Sesbania spp. to make use of space and light. Apocynum venetum is highly drought-resistant, and the alkali grass or Sesbania spp. covers the surface to reduce evaporation, which is suitable for arid and saline-alkali areas.

[0080] Experimental Example 1: To verify the feasibility of the method of the present invention, an indoor simulation experiment was first conducted to test the effect of the liquid modifier:

[0081] The soil samples used were collected from the lower soil layer (>20cm) of a former chemical plant site in Nantong City, Jiangsu Province. The site was a chemically contaminated site after the remediation of organically contaminated soil using alkali-activated persulfate. The main problems faced by the remediated site were high salt content in the soil, destruction of organic structure, and imbalance of ecological factors. The basic physicochemical properties are shown in Table 1. Sufficient soil samples were collected, air-dried, and then crushed for later use.

[0082] Table 1. Physicochemical properties of the tested soil samples

[0083]

[0084]

[0085] The soil sample was added evenly in layers to the soil column apparatus (the structure of the soil column apparatus is as follows). Figure 4 (As shown) to 50cm, lightly compact.

[0086] Watering volume is calculated at 3500m³. 3 / hm 2 5000m 3 / hm 2 6500m 3 / hm 2 The soil column was irrigated, and the calculated amounts of water added to the soil column were 27.48L, 39.25L, and 51.03L, respectively, which were recorded as low dosage (water), medium dosage (water), and high dosage (water).

[0087] Dissolve urea phosphate (≥99%) in 5000 ml of water at concentrations of 0.0025%, 0.01%, and 0.0175% (based on the mass fraction of the soil), respectively. 3 / hm 2 When water is used for irrigation, the conversion is that 3.93g, 15.70g, and 27.48g of citric acid are dissolved in 39.25L of water for irrigation, and these are recorded as low dosage (urea phosphate), medium dosage (urea phosphate), and high dosage (urea phosphate), respectively.

[0088] Humic acid (≥50%) was dissolved in 5000 ml of water at concentrations of 0.01%, 0.0175%, and 0.025% (based on the mass fraction of the soil), respectively. 3 / hm 2 When watering, the conversion is that 15.70g, 27.48g, and 39.25g of humic acid are dissolved in 39.25L of water for watering, which are recorded as low dosage (humic acid), medium dosage (humic acid), and high dosage (humic acid), respectively.

[0089] After irrigation, on the 14th day, soil samples were collected from the soil column at depths of 10cm and 50cm. After being dried in the sun, pH, organic matter and electrical conductivity were measured. The remaining soil in the soil column was removed, dried in the sun and used for later use.

[0090] Before the experiment, 20g of air-dried soil samples from 10cm and 50cm depths through a 10-mesh sieve were weighed into 200ml beakers, 100ml of water was added, and the mixture was stirred and allowed to stand for 30min. The pH was measured using a Bante902P. Then, 20g of air-dried soil samples from 10cm and 50cm depths through a 10-mesh sieve were weighed into 200ml beakers, 100ml of water was added, and the mixture was stirred and filtered repeatedly with filter paper until the filtrate was clear. 50ml of the filtrate was collected and measured using a Bante902P. The determination of organic matter was performed according to NY / T 1121.6-2006 Soil Testing Part 6 - Determination of Soil Organic Matter - Titration Method.

[0091] Soil samples treated with urea phosphate solution with better data were used for planting, and plants planted with water were used as a comparison.

[0092] The selected soil sample comes from the remaining part (20-40cm) in the soil column apparatus. After the soil sample is taken out, it is dried in the sun and then passed through a 10-mesh sieve for later use.

[0093] Disinfect ryegrass seeds and lettuce seeds with 3% H2O2 for 5 minutes, then place them in a seedling tray to germinate until they show white sprouts;

[0094] Add soil samples to 20cm up the pots, and add water to the pots until the soil is completely moist.

[0095] Select seeds that have already sprouted white and are of similar plumpness, and distribute them evenly in the pot. Then take a small amount of the corresponding soil sample and cover the seed surface until the seeds are completely covered.

[0096] After the potted plant experiment began, routine watering and observation were carried out.

[0097] Before the start of the pot experiment, on day 15 and day 30, soil samples were taken from the pots to measure pH, organic matter and electrical conductivity. On day 30 of the pot experiment, plant samples were taken to measure plant biomass (fresh weight).

[0098] like Figure 5 As shown, at a soil depth of 10 cm using a soil column apparatus, the pH values ​​for low, medium, and high water application treatments were 8.69, 8.80, and 8.97, respectively. Figure 7 As shown, the electrical conductivities are 0.47, 0.27, and 0.23 mS / cm, respectively. Figure 9 As shown, the organic matter content was 5.51, 6.71, and 6.13 g / kg, respectively; Figure 5As shown, the pH values ​​of irrigation treatments with low, medium, and high dosages of the liquid conditioner urea phosphate solution were 9.03, 8.93, and 8.88, respectively. Figure 7 As shown, the electrical conductivities are 0.27, 0.34, and 0.40 mS / cm, respectively. Figure 9 As shown, the organic matter content was 8.10, 6.14, and 7.21 g / kg, respectively; Figure 5 As shown, the pH values ​​for low, medium, and high humic acid irrigation treatments were 8.99, 9.05, and 9.00, respectively. Figure 7 As shown, the electrical conductivities are 0.36, 0.38, and 0.30, respectively. Figure 9 As shown, the organic matter content was 6.50, 6.66 and 6.46 g / kg, respectively.

[0099] like Figure 6 As shown, at a soil depth of 50cm using a soil column apparatus, the pH values ​​for low, medium, and high water dosage irrigation treatments were 8.60, 8.69, and 9.03, respectively. Figure 8 As shown, the electrical conductivities are 0.53, 0.37, and 0.29 mS / cm, respectively. Figure 10 As shown, the organic matter content was 4.41, 4.99, and 5.34 g / kg, respectively; Figure 6 As shown, the pH values ​​of irrigation treatments with low, medium, and high dosages of the liquid conditioner urea phosphate solution were 8.81, 8.87, and 8.88, respectively. Figure 8 As shown, the electrical conductivities are 0.43, 0.43, and 0.53 mS / cm, respectively. Figure 10 As shown, the organic matter content was 5.36, 4.77, and 5.37 g / kg, respectively; Figure 6 As shown, the pH values ​​for low, medium, and high humic acid irrigation treatments were 8.95, 8.85, and 8.99, respectively. Figure 8 As shown, the electrical conductivities are 0.44, 0.49, and 0.32 mS / cm, respectively. Figure 10 As shown, the organic matter content was 5.10, 4.13 and 5.30 g / kg, respectively.

[0100] Water leaching improves saline-alkali soils by dissolving soil salts through irrigation and draining them through a drainage system, thereby reducing soil salinity, improving structure, and enhancing fertility. Urea phosphate is an acidic soil conditioner, primarily prepared through chemical synthesis. When applied to saline-alkali land, it neutralizes alkalinity, lowers soil pH, and simultaneously provides nutrients and replenishes organic matter, enhancing soil fertility and water retention capacity. Therefore, dissolving urea phosphate in water and using it as a liquid conditioner for irrigation of saline-alkali soils allows for more effective application and rapid improvement.

[0101] like Figures 11-13As shown, the pH value of the soil irrigated with high-dosage urea phosphate solution was significantly lower than that of the original soil and the soil irrigated with medium-dosage water, and met the standard of "Green Planting Soil" (CJT340-2016) (5.0-8.3); its electrical conductivity was lower than that of the original soil, and although slightly higher than that of the soil irrigated with medium-dosage water, it still met the standard (0.15-0.9 mS / cm); its organic matter content was higher than that of the original soil, and although slightly lower than that of the soil irrigated with medium-dosage water, it also met the standard (12-80 g / kg).

[0102] Pot experiments showed that soil irrigated with a high dose of urea phosphate solution exhibited significantly better plant growth than soil irrigated with a medium dose of water. Biomass (fresh weight) measurements taken after 30 days showed:

[0103] like Figure 14 and Figure 15 As shown, the biomass of ryegrass irrigated with a high dose of urea phosphate solution (35.945 g) increased by approximately 208.7% compared to irrigated with a medium dose of water (11.645 g); the biomass of lettuce irrigated with a high dose of urea phosphate solution (4.092 g) increased by approximately 269.3% compared to irrigated with a medium dose of water (1.108 g).

[0104] This significant improvement may be related to the fact that urea phosphate provides the soil with a richer supply of available nutrients.

[0105] Experimental Example 2: Following Experimental Example 1, we verified the good improvement effect of the liquid soil conditioner of this invention on saline-alkali soil. Therefore, we tested the effect of the solid soil conditioner and subsequent drip irrigation, including the setting of raised sections, using an indoor method that replicates the field conditions on a proportional scale. The test chamber used was 1m long and wide, and 0.5m high. The test soil was the same as in Experimental Example 1. The test was conducted according to the proportional replication method in Example 1. The pH and conductivity of the raised sections were monitored in real time. During the first drip irrigation cycle after setting the raised sections, the pH value was 7.1, and the conductivity... The initial concentration was 0.12 mS / cm. Before the next drip irrigation cycle began, the pH was 7.8 and the conductivity was 0.21 mS / cm, indicating that soil salts were beginning to accumulate in the raised areas. After the entire drip irrigation cycle ended, the pH was 7.4 and the conductivity was 0.18 mS / cm, indicating that drip irrigation with improved soil in the raised areas could further accumulate and reduce soil salinity. We also monitored the pH and conductivity of the raised areas for the following month. At this time, the pH was 7.5 and the conductivity was 0.20 mS / cm, indicating no significant salt accumulation. This is likely because the solid amendment in the improved soil continuously degraded the accumulated salts in the raised areas through slow-release action, thus preventing excessively high salt content in the raised areas. Furthermore, it reduced the salt content in the soil of the plants planted on both sides of the raised areas and increased organic matter, which is beneficial to plant growth.

Claims

1. A method for rapidly improving saline-alkali soil using urea phosphate, characterized in that, Includes the following steps: S1. Preparation of Modifier: S1-1, Preparation of liquid modifier: A liquid modifier is obtained by mixing urea phosphate with water, wherein the mass-volume ratio of urea phosphate to water is 1g:2~10L; S1-2, Preparation of solid modifier: Urea phosphate, humic acid and travertine are mixed in a mass ratio of 1~1.5:1~1.5:1.5~2 and granulated by a granulator to obtain a solid modifier; S2. Excavation of drainage ditches: Several drainage ditches are excavated inside the saline-alkali soil to be treated. All drainage ditches have the same direction, the depth of the drainage ditches is 30-80cm, the interval between the drainage ditches is 2-5m, and the area between two adjacent drainage ditches is used as a drip irrigation area. S3. Drip irrigation for salt removal: Drip irrigation is carried out in the middle of the drip irrigation area, using the liquid conditioner prepared in S1-1. The interval between drip irrigations is 8-10 days, and the drip volume is 3500-5000m³ each time. 3 / hm 2 Drip irrigation 3-5 times in total; S4. Deepen salt removal: After the last drip irrigation, wait 10 to 15 days and apply the solid amendment prepared in S1-2 to the drip irrigation area at a rate of 50 to 100 kg / mu. Mix the solid amendment with the soil inside the drip irrigation area and then drip irrigate with water 3 to 8 times. After drip irrigation 1-3 times, improved soil is applied to the center of the drip irrigation area. The improved soil is obtained by mixing the solid amendment prepared in S1-2 with bentonite. The solid amendment accounts for 10-15% of the total mass of the improved soil. After the improved soil is applied, a raised part with an arc-shaped cross-section is formed in the center of the drip irrigation area. The height of the raised part is 20-40cm and the width of the bottom of the raised part is 30-60cm.

2. The method for rapidly improving saline-alkali soil using urea phosphate according to claim 1, characterized in that, In S1, the particle size of the solid modifier is 2~10mm.

3. The method for rapidly improving saline-alkali soil using urea phosphate according to claim 1, characterized in that, In S2, the top width of the salt drainage ditch is 40-80cm, and the bottom width of the salt drainage ditch is 20-30cm.

4. The method for rapidly improving saline-alkali soil using urea phosphate according to claim 1, characterized in that, In step S3, drip irrigation points are set up in the middle of the drip irrigation area, with an interval of 20~60cm between drip irrigation points.

5. The method for rapidly improving saline-alkali soil using urea phosphate according to claim 1, characterized in that, In step S4, the mixing depth is 10~20cm.

6. The method for rapidly improving saline-alkali soil using urea phosphate according to claim 1, characterized in that, In step S4, the time interval for each drip irrigation is 10-20 days, and the drip irrigation volume for each irrigation is 2000-4000m³. 3 / hm 2 .

7. The method for rapidly improving saline-alkali soil using urea phosphate according to claim 1, characterized in that, Salt-tolerant plants are planted on both sides of the raised portion. The salt-tolerant plants are alkali grass, sesbania, alfalfa, or apocynum.

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