Water-saving alkali-reducing salt-leaching seedling protection method for saline-alkali soil

Abstract

The invention provides a water-saving, alkali-reducing, salt-leaching and seedling-protecting method for saline-alkali soil, which comprises the following steps: step 1, arranging blind ditches for salt and water drainage in the saline-alkali soil, arranging a reservoir for water-saving irrigation, and putting calcium sulfate into the reservoir as irrigation water; 2, spreading a soil conditioner on the earth surface, and uniformly mixing the soil conditioner with the soil of the plough layer; step 3, leaching the saline-alkali soil with irrigation water for 1-3 times; step 4, performing hill-seeding planting on the crops by adopting a dry-seeding and wet-out technology, and applying a combined solution of ammonium polyphosphate and citric acid during drip irrigation of seedling emergence water. According to the invention, gypsum is put into a reservoir to form a calcium sulfate solution; the calcium sulfate solution is used for saline-alkali soil leaching and crop drip irrigation. In the leaching process, since no solid gypsum exists in the soil, the use amount of the gypsum is remarkably reduced.

Description

TECHNICAL FIELD

[0001] The application relates to a saline-alkali soil crop planting technology field, in particular to a saline-alkali soil water-saving alkali-reducing leaching salt seedling protection method. BACKGROUND

[0002] There are large areas of saline-alkali soil in arid and semiarid irrigation areas in China. At present, the saline-alkali soil which is difficult to improve and utilize is mainly distributed in low-lying areas with poor drainage. The soil is both saline and alkaline. At present, the underground pipe is arranged for salt discharge and improvement. However, due to the low-lying terrain, the salt-containing water which is washed out of the soil through flood irrigation still remains in the area, resulting in unstable improvement effect of the regional saline-alkali soil and easy repetition. Therefore, flood irrigation for salt washing is often required. In addition, the excessive sodium ions in the saline-alkali soil can be combined with the soil colloids (such as clay minerals and humus) to form stable "sodium-colloid complex", resulting in soil structure hardening and poor permeability. The commonly used material for chemical improvement is desulfurized gypsum or phosphogypsum. After the gypsum is applied to the soil, it is slowly dissolved under the action of water and releases calcium ions, which have a cation exchange reaction with sodium ions on the surface of the soil colloids. In this process, the binding capacity of calcium ions to the soil colloids is more than 30 times that of sodium ions, so that the sodium ions adsorbed by the colloids can be efficiently replaced and converted from "fixed state" to "free state". The binding force between the calcium ions and the negative charges on the surface of the colloids is strong, which can compress the hydration film of the colloidal particles, make the particles close to each other, and agglomerate into stable granular structure through "electrostatic attraction". The air voids and capillary voids are formed between the granules, which improves the water permeability and air flow capacity. At the same time, the free sodium ions replaced will be combined with the sulfate ions generated by the dissolution of the gypsum to form high-solubility sodium sulfate, which can achieve the purpose of alkali reduction and salt discharge through leaching.

[0003] For general moderate to severe saline-alkali soil, the application amount of gypsum per mu needs to reach 1.5 tons. After the gypsum is fully mixed with the soil in the 0-30 cm soil layer, a large amount of water is used for washing salt through the irrigation canal or underground drainage facilities. In the actual process of saline-alkali soil treatment, due to the poor permeability of the saline-alkali soil and the low solubility of calcium sulfate in water, the calcium ions are difficult to fully contact with the soil colloids. In the process of salt washing, a large amount of water is consumed to dissolve the gypsum. The dissolved gypsum in water is discharged from the underground ditch with the water flow, and the undissolved part of the gypsum is also washed into the underground ditch with the water flow, resulting in the waste of gypsum and irrigation water. For moderate to severe saline-alkali soil, it usually takes more than three years to achieve the effect of loose soil and significant reduction of salinity on the basis of multiple leaching per year. During this period, the seedling emergence rate and seedling survival rate of crops cannot be guaranteed, and the growth of crops in the later period is also significantly limited. SUMMARY

[0004] Therefore, the application provides a saline-alkali soil water-saving, alkali-reducing, salt-leaching and seedling-protecting method, which can reduce the use of gypsum and leaching irrigation water, improve the seedling emergence rate and seedling protection rate of crops planted in saline-alkali soil, and improve the yield of crops.

[0005] A saline-alkali soil water-saving, alkali-reducing, salt-leaching and seedling-protecting method comprises the following steps. Step 1: arranging a salt-draining and water-draining ditch in the saline-alkali soil, and arranging a water storage tank for water-saving irrigation, and putting calcium sulfate into the water storage tank as irrigation water; Step 2: applying a soil conditioner on the ground surface, and mixing the soil conditioner with the soil in the plough layer; Step 3: leaching the saline-alkali soil with the irrigation water for 1-3 times; Step 4: planting the crops by dry sowing and wet emergence, and applying a combined solution of ammonium polyphosphate and citric acid when drip irrigation is performed to make the crops emerge.

[0006] In order to reduce local waterlogging caused by water accumulation in the saline-alkali soil, preferably, in step 1, the saline-alkali soil is first subjected to laser land leveling, and is designed to have a terrain with a middle part being higher and two side parts being lower, so as to form a slope land with a slope of 5°, and long ditches are arranged in low-lying parts of the slope land, and short ditches are arranged in the direction perpendicular to the long ditches.

[0007] In order to better drain salt, preferably, the ditches are sequentially laid with straw, sandy soil and original soil from bottom to top.

[0008] In order to better improve the soil, preferably, the soil conditioner comprises organic fertilizer, furfural residue, straw and microbial complex inoculant.

[0009] In order to promote the emergence of crops, the saline-alkali soil water-saving, alkali-reducing, salt-leaching and seedling-protecting method further comprises step 5: detecting the electrical conductivity of the soil, and planting corresponding crops according to the electrical conductivity of the soil.

[0010] The technical effect of the application lies in that the gypsum is put into the water storage tank to form a calcium sulfate solution, and then the calcium sulfate solution is used for leaching the saline-alkali soil and drip irrigation of crops. In the leaching process, the use amount of gypsum is significantly reduced because there is no solid gypsum in the soil. Meanwhile, the calcium sulfate is fully dissolved, and the content of calcium sulfate in the water is significantly improved compared with the case of mixing gypsum in the soil and leaching, so that the utilization rate of gypsum is improved, and the alkali-reducing and salt-draining effect is better.

[0011] The calcium sulfate solution is used for drip irrigation of crops, which is more targeted, significantly reduces the content of sodium ions near the roots of crops, improves the permeability of the soil, and cooperates with the combined solution of ammonium polyphosphate and citric acid, so that the seedling emergence rate and seedling protection rate of crops can be significantly improved.

[0012] The application uses calcium sulfate solution for drip irrigation of crops, can continuously reduce the alkali of soil during the growth stage of crops, can effectively inhibit the reverse alkali of saline-alkali soil, reduce the improvement time of saline-alkali soil, and improve the yield of crops. DETAILED DESCRIPTION

[0013] The embodiments of the technical scheme of the application are described in detail below. The following embodiments are only used to more clearly illustrate the technical scheme of the application, and therefore only serve as examples, and cannot limit the protection scope of the application.

[0014] A salt-alkali soil water-saving alkali-reducing salt leaching seedling protection method comprises the following steps: Step 1: salt-alkali soil is arranged with a hidden ditch for salt and water drainage, and a water storage tank is arranged for water-saving irrigation, and calcium sulfate is put into the water storage tank as irrigation water; The water in the water storage tank comes from a nearby lake or a canal. If it rains, rainwater can also be collected. In the northwest region, rainfall is relatively concentrated. Many saline-alkali soils are formed due to the repeated effects of rainfall and transpiration, causing more and more salt accumulation in low-lying areas. The water storage tank of the application can effectively collect rainfall and use it as salt drainage irrigation water or crop drip irrigation water according to the needs. When there is more rainfall, the rainfall is guided to the water storage tank to prevent rainwater from gathering in low-lying areas.

[0015] The amount of calcium sulfate put in is determined according to the solubility of calcium sulfate. Since calcium sulfate is slightly soluble in water, it can continuously improve the saline-alkali condition of the soil as drip irrigation water. The prior art generally believes that the solubility of calcium sulfate in water is small, and the sulfur and calcium contained therein are difficult to release, so it is more used as a solid soil conditioner, which slowly releases calcium ions by slowly dissolving, rather than by drip irrigation in the form of a solution. At the same time, calcium sulfate has a high risk of clogging the pipeline and is not suitable for drip irrigation. However, the application has been verified that calcium sulfate is put into the water storage tank for long-term and sufficient dissolution, and then used for daily drip irrigation, which has a significant alkali-reducing effect and is not easy to clog the drip irrigation pipeline.

[0016] The reasons are as follows. The application puts calcium sulfate into the water storage tank for long-term and sufficient dissolution, and a stable and relatively saturated calcium sulfate solution is formed in the water storage tank. Compared with dissolving gypsum in water for drip irrigation, the calcium sulfate concentration of the application is higher and more uniform, and the amount of precipitate produced in the drip irrigation water is less, which is not easy to clog the pipeline.

[0017] The frequency of daily drip irrigation is relatively high, generally once every 5-7 days. The calcium sulfate solution continuously supplements calcium ions to replace sodium ions adsorbed by soil colloids, and gradually leaches soluble sodium sulfate to below the plough layer through water infiltration, and relies on the hidden ditch formed by the corn straw and coarse yellow sand to discharge the sodium sulfate, which can avoid the salt aggregation on the surface caused by rainfall.

[0018] During routine fertilization, use fertilizers that can increase the solubility of calcium sulfate, such as ammonium phosphate, so that more calcium ions can enter the soil and replace sodium ions.

[0019] The rainwater collected in the reservoir is weakly acidic, which can increase the solubility of calcium sulfate.

[0020] The above reasons enable this application to use sodium sulfate in daily drip irrigation and produce a significant alkalinity reduction effect.

[0021] The culvert in this application is connected to the drainage ditch of the saline-alkali land so that the water can be discharged through the culvert in a timely manner after rinsing.

[0022] In order to reduce waterlogging in saline-alkali land, in a preferred embodiment, the saline-alkali land is first leveled by laser and designed as a terrain that is high in the middle and low on both sides to form a slope with a slope of 5°. Long underground ditches are set in the low-lying areas of the slope, and short underground ditches are set at intervals perpendicular to the long underground ditches.

[0023] To facilitate better salt removal, in a preferred embodiment, the underground ditch is laid with straw, sand, and native soil in sequence from bottom to top.

[0024] Specifically, in a preferred embodiment, the implementation process is as follows: For saline-alkali abandoned land, laser leveling is first carried out. During the operation, a micro-topography with a high center and low sides (slope of 5°) is designed. Long underground ditches are laid in the lower parts of the sides. When water is used to wash away salt, the salt is leached to both sides with the water. The underground ditches on both sides further discharge salt, improving the efficiency of salt leaching. When laying underground ditches, in areas with clay obstacles in the field, a chain-type ditching machine is used to dig ditches perpendicular to the nearby farm ditch (or drainage ditch or low-lying area). The ditches are aligned with the long side of the field (hereinafter referred to as long ditches). The spacing between ditches is 5-15m. The depth of the ditches is based on breaking the clay interlayer. The width of the ditches is 40-60cm and the depth is 60-80cm. When backfilling, first fill with a 20cm thick layer of corn stalks (the stalks are about 20cm long), then fill with a 20cm thick layer of coarse yellow sand. The topsoil is backfilled with the original soil. Then, short ditches are dug perpendicular to the long ditches every 25-50m. The width, depth and backfill material of the ditches are the same as those of the long ditches. For fields with thick clay barrier layers and high soil salinity, the spacing between long and short underground ditches should be smaller.

[0025] Step 2: Apply soil conditioner to the surface and mix it thoroughly with the topsoil; In order to better improve the soil, in a preferred embodiment, the soil conditioner includes organic fertilizer, furfural residue, straw, and microbial compound inoculant.

[0026] Specifically, in a preferred embodiment, step 2 is implemented as follows: The organic fertilizer, furfural residue, crushed corn stalk and microbial complex bacteria agent (containing salt-tolerant bacillus, actinomycetes and phosphorus solubilizing bacteria) are applied on the surface of the earth, and the calcium sulfate is completely dissolved in the water storage pool at the head of the drip irrigation system. The organic fertilizer is selected from mature sheep manure or cow dung, the application amount per mu is 1.5 t to 3 t, the application amount per mu of the furfural residue and the crushed corn stalk is 200 to 300 kg, and the microbial complex bacteria agent is added at 0.2% to 0.3% of the total application amount of the organic material, and all the soil improvement materials are mixed with the soil in the 0 to 30 cm soil layer by using the deep scarifier and the rotary cultivator.

[0027] Step 3: The saline-alkali soil is leached 1 to 3 times with irrigation water; The leaching of the saline-alkali soil is determined according to the actual situation, and can be selected in the autumn and winter seasons in addition to the leaching before planting. At this time, the water consumption of the crops is less. The Yellow River water can be introduced into the water storage pool, and then the gypsum is added. After the pool water is clarified, the water in the water storage pool is pumped out to leach the saline-alkali soil. The power for pumping water is preferentially selected to be solar power. There are many saline-alkali wastelands, and it is more convenient to install photovoltaic modules. Similarly, the solar power can also be used for power supply for drip irrigation.

[0028] Step 4: The crops are planted by using the dry sowing and wet emergence technology, and the combined solution of the ammonium polyphosphate and the citric acid is applied when the seedling water is drip irrigated.

[0029] The dry sowing and wet emergence technology is a full name of the film mulching, water dripping, water storage, salinity removal and planting technology, which is a commonly used method for agricultural planting in the arid and semi-arid regions. The core of the technology is that the winter irrigation or spring irrigation is not needed before sowing, but the film mulching and the drip irrigation belt are laid after the land is prepared, and then the sowing is performed. When the suitable seedling temperature is reached, a small amount of water is drip irrigated under the film to make the soil moisture content under the film meet the requirements of the seedling emergence.

[0030] In the present application, the combined solution of the ammonium polyphosphate and the citric acid is formed by using the calcium sulfate solution as the calcium source, and is used as the seedling water when the seedling water is drip irrigated.

[0031] The calcium sulfate in the seedling water is used as the calcium source, and the sodium ions adsorbed on the soil colloid are replaced by the calcium ions to convert the difficultly leached adsorbed sodium ions into the easily leached soluble sodium sulfate, so that the soil electrical conductivity in the plough layer is reduced by cooperating with the irrigation leaching. At the same time, the calcium ions can promote the coagulation of the soil colloid to form the granular structure, improve the permeability and avoid the root system anoxic necrosis.

[0032] The hydrogen ions are dissociated from the citric acid in the emergence water, neutralizing the alkalinity of the soil, and the hydrogen ions can replace part of the sodium ions on the surface of the soil colloid and replace the calcium ions of calcium sulfate to form a "double sodium reduction" effect, accelerating the leaching of salt. At the same time, the carboxyl group of citric acid can form a soluble complex with calcium ions, avoiding the combination of calcium ions with carbonate ions and bicarbonate ions in the soil to form insoluble calcium carbonate, improving the effectiveness of calcium ions in the soil solution and enhancing the replacement efficiency of sodium ions. The small organic carbon produced by the decomposition of citric acid can be used as a carbon source for microorganisms to promote the reproduction of rhizosphere beneficial bacteria, while relieving the damage of high salt and alkali to root cell membranes and enhancing the water and fertilizer absorption capacity of seedlings.

[0033] The ammonium polyphosphate in the emergence water gradually releases orthophosphate ions through hydrolysis, avoiding the rapid fixation of conventional phosphorus fertilizers such as calcium superphosphate into calcium phosphate precipitates in high-pH soil, continuously providing phosphorus for seedlings and promoting root elongation and cell division. The polyphosphate ion has complexing ability and can form soluble complexes with calcium ions, trivalent iron ions, zinc ions, etc., reducing the adsorption and fixation of metal ions on soil colloids, improving the absorption of seedlings of trace elements such as calcium and iron, and enhancing the ability to resist salt and alkali stress. Ammonium nitrogen can regulate the osmotic pressure of seedling cell sap, reduce the passive absorption of sodium ions, reduce intracellular ion toxicity, and cooperate with the pH regulation effect of citric acid to maintain the normal physiological function of root cells.

[0034] At the soil level, calcium sulfate and citric acid can efficiently reduce alkaline and leach salt through pH regulation and chelation, improving soil structure and creating a "low-salt, loose, high-calcium" root zone environment for seedlings. At the nutrient level, the phosphorus and nitrogen fertility provided by ammonium polyphosphate and the effect of activating nutrients by citric acid can avoid nutrient fixation, improve the effectiveness of key elements such as phosphorus and calcium, and meet the nutrient needs of seedlings during the germination period (seed shell breaking-root system establishment). Under the combined action of calcium sulfate, citric acid, and ammonium polyphosphate, the soil EC and pH are reduced to the tolerance threshold of crops, the root system of seedlings develops well, and the stress resistance is enhanced, ultimately achieving a significant increase in the emergence rate and seedling survival rate.

[0035] Through the synergistic mechanism of "calcium salt reduction-salt, organic acid reduction-alkali, and polyphosphate nutrition", the three form a virtuous cycle of "soil environment improvement-nutrient efficient absorption-seedling stress resistance growth", which not only solves the core limitations of high salt and alkali, low nutrients, and poor structure in moderate and severe saline-alkali lands, but also meets the needs of seedlings for low salt, suitable acidity, and available nutrients, thereby achieving the synergistic effect of promoting seedlings and seedling survival.

[0036] In a preferred embodiment, the dosage of ammonium polyphosphate is 3-4 kg / acre, and the dosage of citric acid is 0.5-1 kg / acre. When preparing the solution, ammonium polyphosphate and citric acid are added to the calcium sulfate solution in sequence and stirred.

[0037] In a preferred embodiment, the crops are preferably corn, soybean, sweet sorghum.

[0038] In order to promote the emergence of crops, the saline-alkali soil water-saving and alkali-reducing and seedling protection method of the application further comprises step 5: detecting the electrical conductivity of the soil, and planting corresponding crops according to the soil electrical conductivity.

[0039] Specifically, when sweet sorghum is cultivated by shallow buried drip irrigation or corn is cultivated by film mulching drip irrigation, the electrical conductivity is less than 1.5 mS / cm. If it exceeds 1.5 mS / cm, corn can be sown after drip irrigation once, and the soil salinity in the planting area can be further reduced by drip irrigation measures to ensure that the soil electrical conductivity during the corn seedling stage is at the level of slightly salinized soil. When soybean is cultivated by film mulching drip irrigation, the soil electrical conductivity of the plough layer before sowing is less than 1.0 mS / cm, and the soil salinity in the planting area is further reduced by drip irrigation measures after sowing to ensure that the soil electrical conductivity during the soybean seedling stage is at the level of slightly salinized soil.

[0040] The following are specific embodiments of the application.

[0041] Example 1 The test farmland is located in Haiyan Village, Yanzidun Township, Huinong District, Shizuishan City, and is a saline-alkali wasteland for many years. Before improvement, it has been laser leveled, the average value of soil pH is 8.96 (range 8.76~9.45), the average value of electrical conductivity is 2.04 mS / cm (range 1.25~3.14), and the average value of alkalization degree is 20.76% (range 14.46~27.35). The soil is saline-alkali, the plough layer soil is sandy loam, and locally it is clay loam. The whole area is about 44 meters wide and about 780 meters long. The soil body in the middle part of the area is a dense clay interlayer in the 20~80 cm soil layer, and the emergence rate of cultivated crops under unimproved drip irrigation is less than 20%.

[0042] In October 2023, in the area with serious clay obstacles, about 15 mu of land was vertically ditched with a chain type ditcher near the farmland ditch, the ditching interval was 10 m, two ditches with a width and depth of 60 cm were excavated in the middle, the clay interlayer was removed from the field, and then backfilling was carried out. When backfilling, 20 cm thick corn straw was filled first, and then 20 cm thick coarse yellow sand was filled on top. The plough layer soil was backfilled with original soil. Then, every 25 m, a short ditch was excavated vertically to the long ditch, and the width, depth and filling material of the ditch were consistent with those of the long ditch. At the same time, a water storage tank was set up at the end of the drainage ditch, and 0.15% of the water volume was added with gypsum for salt washing and drip irrigation in saline-alkali soil. At the same time, 2 mu of land in the area with serious clay obstacles was reserved for a control experiment.

[0043] Surface application of composted cow manure, furfural residue, crushed corn stalks, and microbial complexing agent (containing salt-tolerant Bacillus, actinomycetes, and phosphorus solubilizing bacteria), etc. The composted cow manure was applied at a rate of 2 tons per mu, and the furfural residue and crushed corn stalks were applied at a rate of 300 kg per mu. After the soil improvement materials were mixed with the 0-30 cm soil by a rotary cultivator, the soil was flooded and irrigated twice to wash away the salt.

[0044] In the spring of 2024, no spring irrigation was performed. The surface and subsurface soil was collected before sowing in late April, and the pH values were measured to be 8.45 and 8.74, respectively, and the conductivities were measured to be 1.4 mS / cm and 1.6 mS / cm, respectively. The dry sowing and wet emergence technique was used to apply the shallow buried drip irrigation and film mulching sowing integrated machine to sow corn. The drip irrigation was used to water the seedlings within one week after sowing, and a combined solution of 4 kg / mu of ammonium polyphosphate and 1 kg / mu of citric acid was applied. Calcium sulfate solution was used for daily drip irrigation. When applying nitrogen and phosphorus fertilizers, ammonium sulfate, ammonium nitrate, and phosphoric acid were used together with calcium sulfate solution.

[0045] In October 2024, after the crops were harvested, the soil of the corn planting row was detected. The soil pH value was measured to be 8.29-8.32, and the conductivity was 0.86-1.1 mS / cm. The soil salinity was reduced by more than 40%, the corn emergence rate reached 91.4%, the seedling survival rate reached 87.5%, and the fresh biological yield of corn per mu was 4.2 tons, reaching the yield level of local light saline-alkali land.

[0046] Example 2 The test farmland is located in Xinchao Village, Tongfu Township, Shizuishan City, and has been laser leveled. The whole area is about 40 m wide and about 830 m long. Half of the farmland has heavy saline-alkali soil. Before improvement, the collected soil sample showed that the conductivity of the plough layer soil was between 1.0 and 2.7 mS / cm, the pH value was between 8.7 and 9.2, and the alkali degree was between 13.45% and 27.37%. The average values of conductivity, pH value, and alkali degree were 1.8 mS / cm, 8.95, and 21.46%, respectively, indicating that it was a medium to heavy saline-alkali land. The emergence rate of directly planted corn was less than 40%, and the area that did not emerge was replanted twice but still did not emerge. The seedling stage was seriously affected by rain, and the seedlings died. After irrigation to wash away the salt, oil palm was planted instead, and there was basically no yield of oil palm that year. From the soil texture of the soil profile, the plough layer soil is mostly loam, and locally sandy loam. The soil texture below 20 cm is compact, which is clay loam or clay. The clay barrier layer is irregularly distributed in the field, and the depth is not uniform. The area is provided with a water storage tank, and the water source is the Yellow River water. The mineralization is 0.48 g / L, and the pH is 8.12.

[0047] The saline-alkali land water-saving and alkali-reducing leaching salt seedling protection method of the present application was implemented for the half of the farmland with heavy saline-alkali soil, as follows.

[0048] In October 2023, ditching operation was performed perpendicularly to the long side of the field by using a chain ditcher, with a ditching interval of 13 m, and a width and depth of 60 cm. The soil at the clay interlayer was removed out of the field, and then backfilling operation was performed. During backfilling, 20 cm thick corn straw was filled first, and then 20 cm thick coarse yellow sand was filled thereon. The soil at the tillage layer was backfilled by using the original soil, and the loosened soil excavated was also backfilled as backfilling soil. Then, short ditches were excavated perpendicularly to the long ditches every 25 m, and the width, depth and filling materials of the ditches were consistent with those of the long ditches.

[0049] Before the soil was improved, 0.15% of the water storage capacity of the reservoir was added with gypsum, and the surface was applied with decomposed cow dung and furfural residue, with a use amount of 1.5 tons and 300 kg per mu, respectively. After the soil improvement materials and the soil at 0-30 cm were fully mixed by using a rotary tiller, the salt was washed once by using the Yellow River water containing gypsum for large water flooding. At the same time, 2 mu of the half farmland with heavy saline-alkali soil was reserved for a control experiment.

[0050] In spring 2024, no spring irrigation was performed, the electrical conductivity was 1.3-1.5 mS / cm, the dry seeding and wet emergence technology was used, the shallow buried drip irrigation film mulching sowing integrated machine was used to sow corn, the drip irrigation emergence water was used within one week after sowing, and the combined solution of 3 kg / mu of polyphosphoric acid ammonium and 0.5 kg / mu of citric acid was applied. The drip irrigation water source was the Yellow River water in the reservoir and the collected seasonal rainfall. The calcium sulfate solution was used for daily drip irrigation. When the nitrogen fertilizer and phosphorus fertilizer were applied, the ammonium sulfate, ammonium nitrate and phosphoric acid were used together with the calcium sulfate solution.

[0051] In October 2024, after the corn was harvested, the pH value of the soil at the planting row was detected to be 8.32-8.39, and the electrical conductivity was 0.72-1.2 mS / cm. The soil salinity was reduced by more than 30%. At the same time, the emergence rate of the corn at the emergence stage reached 91.6%, the seedling survival rate reached 89.5%, the fresh biological yield per mu of the corn at the growth stage was 4.1 tons, and the yield reached the yield level of the local light saline-alkali land.

[0052] Comparative Example 1 For the 2 mu of the clay obstacle serious saline-alkali land reserved in Example 1, other conditions were the same as those in Example 1, except that gypsum was applied instead of gypsum solution, and the water for daily drip irrigation was not added with calcium sulfate.

[0053] Comparative Example 2 For the 2 mu of the clay obstacle serious saline-alkali land reserved in Example 2, other conditions were the same as those in Example 2, except that when the emergence water was added, the nitrogen and phosphorus fertilizers were replaced by the equivalent phosphorus fertilizer and nitrogen fertilizer. In this comparative example, ammonium phosphate and urea were used instead of polyphosphoric acid ammonium and citric acid.

[0054] The soil conditions, gypsum use amount and survival and growth of corn of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 are shown in Table 1. Table 1 As can be seen from Table 1, after one year of planting, the saline-alkali soil of Example 1, compared with Comparative Example 1, the soil salinity of the planting row decreased from moderate to severe to mild, the soil electrical conductivity increased from 1.25-3.14 to 0.86-1.1, and the corn fresh biomass yield per mu increased from 1.8 t to 4.2 t. At the same time, during the corn emergence period, the corn emergence rate increased from 54.8% to 91.4%, and the corn seedling survival rate increased from 38.9% to 87.5%. At the same time, the amount of gypsum was reduced to one third of the original, and the saline-alkali soil treatment time was changed from more than three years to only one year. Therefore, the saline-alkali soil water-saving and alkali-reducing leaching salt and seedling preservation method of the present application significantly reduces the soil salinity by dissolving calcium sulfate in the water storage tank and using it for daily drip irrigation, while significantly improving the emergence rate, seedling survival rate and fresh biomass yield per mu of corn. At the same time, the saline-alkali soil treatment time is significantly reduced.

[0055] After one year of planting, the saline-alkali soil of Example 2, compared with Comparative Example 2, the emergence rate of the saline-alkali soil increased from 76.2% to 91.6%, the seedling survival rate increased from 63.1% to 89.5%, and the corn fresh biomass yield per mu increased from 3.2 t to 4.1 t. Therefore, the saline-alkali soil water-saving and alkali-reducing leaching salt and seedling preservation method of the present application can significantly improve the emergence rate and seedling survival rate of crops and the yield per mu by applying ammonium polyphosphate, citric acid and calcium sulfate in the emergence water.

[0056] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A water-saving, alkali-reducing, salt-leaching method for protecting seedlings in saline-alkali land, characterized in that: The method comprises the following steps: Step 1: salt and alkali land is laid with a hidden ditch for salt and water drainage, and a water storage tank is arranged for water-saving irrigation, and calcium sulfate is put into the water storage tank as irrigation water; Step 2: soil amendment is applied on the ground, and the soil amendment and the plough layer soil are mixed; Step 3: the salt and alkali land is leached 1-3 times with irrigation water; Step 4: dry sowing and wet emergence technology is used for planting crops, and a combined solution of polyphosphoric acid ammonium and citric acid is applied when drip irrigation is used for seedling emergence.

2. The method of claim 1, wherein the method is characterized by: In step 1, the salt and alkali land is first subjected to laser land leveling, and is designed as a terrain with high middle and low sides, forming a slope land with a slope of 5°, long hidden ditches are arranged in low-lying places of the slope land, and short hidden ditches are arranged in a direction perpendicular to the long hidden ditches.

3. The method of claim 1, wherein the method is characterized by: In step 1, the hidden ditches are sequentially laid with straw, sand, and original soil from bottom to top.

4. The method of claim 1, wherein the method is characterized by: In step 2, the soil amendment comprises organic fertilizer, furfural residue, straw, and microbial compound microbial agent.

5. The method of claim 1, wherein the method is characterized by: Step 5: the soil conductivity is detected, and corresponding crops are planted according to the soil conductivity.

6. The method of claim 1, wherein the method is characterized by: In step 4, the polyphosphoric acid ammonium is used in an amount of 3-4 kg / mu, and the citric acid is used in an amount of 0.5-1 kg / mu; when the solution is prepared, the polyphosphoric acid ammonium, the citric acid, and the gypsum are sequentially added to a stirring tank for dissolution.

7. The method of claim 1, wherein the method is characterized by: In step 4, the crops are selected from one or more of corn, soybean, and sweet sorghum. In step 1, the salt and alkali land is first subjected to laser land leveling, and is designed as a terrain with high middle and low sides, forming a slope land with a slope of 5°, long hidden ditches are arranged in low-lying places of the slope land, and short hidden ditches are arranged in a direction perpendicular to the long hidden ditches. In step 1, the hidden ditches are sequentially laid with straw, sand, and original soil from bottom to top. In step 2, the soil amendment comprises organic fertilizer, furfural residue, straw, and microbial compound microbial agent. Still comprising step 5: detecting the soil conductivity, and planting corresponding crops according to the soil conductivity. In step 4, the polyphosphoric acid ammonium is used in an amount of 3-4 kg / mu, and the citric acid is used in an amount of 0.5-1 kg / mu; when the solution is prepared, the polyphosphoric acid ammonium, the citric acid, and the gypsum are sequentially added to a stirring tank for dissolution. In step 4, the crops are selected from one or more of corn, soybean, and sweet sorghum.

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