Comprehensive improvement method for severely hardened saline-alkali soil by combining blind ditch salt elimination with pioneer plant planting and winter irrigation

Abstract

The invention relates to a comprehensive improvement method for severely hardened saline-alkali soil by combining blind ditch salt elimination with pioneer plant planting and winter irrigation, which depends on an original farmland drainage system and comprises the following steps: constructing blind ditches by ditching and filling a filter material, planting pioneer plants, turning, pressing and returning to the field in cooperation with winter irrigation and salt pressing. And a saline-alkaline obstacle reduction technology integrating engineering, agriculture and biology is constructed. The blind ditches form a vertical salt and water drainage channel, so that high-salt irrigation return water of the loose plough layer constructed by planting and turning over pioneer plants directly passes through the alkali drainage channel. According to the method for improving the heavily hardened saline-alkali soil, the consumption of large-water flooding pressure saline water amount is reduced, recarburization and fertility improvement of the barren saline-alkali soil are promoted, saline-alkali obstacle reduction and land productivity improvement can be achieved within 1-2 years, and the method is particularly suitable for rapid curing and continuous utilization of the hardened saline-alkali soil under the matching of irrigation and drainage in western arid regions.

Description

Technical Field

[0001] The present invention belongs to the field of agricultural production, and relates to a method for improving, developing and utilizing obstacle saline-alkali land in arid areas. Background Art

[0002] Sticky and compact saline-alkali land is an important reason for low land productivity and difficult improvement. This type of land accounts for a high proportion in the arid area of the northwest inland. Some irrigation areas downstream of the oasis are distributed on dried-up lake basins, and the soil within 1-2 m is all heavy clay with extremely poor permeability and high salinity. This kind of harsh soil condition is much more serious than other saline-alkali situations, and the effect of irrigation and salt leaching is very poor, directly resulting in difficult utilization after reclamation.

[0003] The technology of subsurface pipe drainage and salt removal is an important technical measure to lower the groundwater level in arid and semi-arid saline-alkali areas. By burying subsurface pipes at a certain depth underground, it can receive the upper irrigation and leaching salt water and control the rise of the lower groundwater. From the effect of implementing subsurface pipe drainage and salt removal in the compact sticky saline-alkali land in recent years, due to the overly fine and sticky upper soil layer, the subsurface pipes are extremely easy to be blocked, and the phenomenon of subsurface pipe system scrapping is serious, causing huge waste.

[0004] For saline-alkali land with deep and compact sticky soil layers, it is extremely difficult to improve the soil structure of the soil profile and rapidly reduce the salt content. On the premise of a perfect irrigation and drainage system, only considering constructing and maintaining a loose, fertile and lightly saline cultivated layer and promoting the rapid discharge of soil water and salt from the cultivated layer farmland will greatly reduce the difficulty of improving and utilizing obstacle saline-alkali land. Summary of the Invention

[0005] The purpose of the present invention is to provide a comprehensive improvement method for severely compact saline-alkali land by combining subsurface ditch salt drainage, pioneer plant planting and winter irrigation. This method relies on the original farmland drainage system, constructs subsurface ditches by trenching and filling filter materials, plants pioneer plants and plows them back into the field in combination with winter irrigation to suppress salt, and constructs a saline-alkali obstacle reduction technology integrating engineering - agronomy - biology. The method described in the present invention reflects the effective combination of engineering, agronomy and biological improvement, and provides a new way for reducing obstacles and improving quality and efficiency of compact saline-alkali land in arid areas.

[0006] The comprehensive improvement method for severely compact saline-alkali land by combining subsurface ditch salt drainage, pioneer plant planting and winter irrigation described in the present invention is carried out according to the following steps: a. Subsurface ditch construction: Select land with a deep compact obstacle layer and heavy soil. With vertical alkali-drainage channels, spaced 10 - 12 m apart, use a chain trencher to dig parallel ditches with a depth of 1.0 - 1.2 m. Fill the ditch bottom with straw or fine sand filter materials between 70 - 90 cm from the ground surface, and backfill the upper part with soil and rake it flat; b. Planting: Drip irrigation and strip sowing are used to plant salt-tolerant pioneer plants. The one-pipe-one-row drip irrigation and strip sowing method is adopted. Shallow trenches with a depth of 10 - 15 cm are dug at intervals of 0.6 - 1.0 m. The drip irrigation tape is laid at the bottom of the trench. The seeds of the pioneer plants are sown on both sides of the drip irrigation tape, and the turning-under depth is ≥ 30 cm. During the maximum growth period of the pioneer plants' biomass, they are turned under and returned to the field to improve the permeability of the plough layer soil. The pioneer plants are Suaeda salsa or Suaeda glauca. c. Winter irrigation for salt leaching: After turning under and returning to the field the pioneer plants Suaeda salsa or Suaeda glauca, winter irrigation is used for salt leaching. d. Irrigation management: Immediately after sowing the pioneer plants Suaeda salsa or Suaeda glauca, irrigation is carried out. Water is replenished once every 2 days, and the irrigation volume is controlled at 10 - 15 m 3 / mu to keep the soil in the sowing area moist. After the seedling stage, irrigation is determined according to the growth trend of the pioneer plants Suaeda salsa or Suaeda glauca and the soil humidity. The irrigation volume for each time is 20 - 30 m 3 / mu; In mid-November, winter irrigation for salt leaching is carried out, and the irrigation volume is 150 - 200 m 3 / mu.

[0007] A comprehensive improvement method for severely compacted saline-alkali land by means of dark ditch salt drainage, combined with pioneer plant planting and winter irrigation according to the present invention. The characteristics of this method are as follows: In view of the characteristics of the soil mass of the compacted saline-alkali land, considering the rapid drainage of soil water and salt in the plough layer soil and the construction and maintenance of a loose, fertile and desalinated plough layer, through the combination of technical measures such as building a field dark ditch system that connects the farmland and the drainage canal system, turning under and returning to the field the pioneer plants Suaeda salsa or Suaeda glauca to increase carbon and improve soil water permeability, and winter irrigation to accelerate the rapid drainage of soil salt in the plough layer from the farmland, the rapid improvement of severely compacted saline-alkali land is achieved. The dark ditch forms a vertical salt drainage channel, enabling the high-salt irrigation return water in the loose plough layer constructed by turning under and planting the pioneer plants Suaeda salsa or Suaeda glauca to directly flow into the alkali drainage canal, thus establishing a new three-dimensional model for the improvement and utilization of compacted saline-alkali land. The improvement method for severely compacted saline-alkali land proposed by the present invention saves the water consumption of flood irrigation for salt leaching, promotes the carbon increase and fertility improvement of barren saline-alkali land, and can achieve the reduction of saline-alkali obstacles and the improvement of land productivity within 1 - 2 years. The method of the present invention is especially suitable for the rapid ripening and sustainable utilization of compacted saline-alkali wasteland with supporting irrigation and drainage in the arid western region. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a drawing of the construction of a mechanical obstacle-breaking ditch for drainage and salt drainage dark ditch according to the present invention; Figure 2 It is a drawing of the treatment of turning under and planting pioneer plants according to the present invention; Figure 3 It is a drawing of the treatment of winter irrigation for soil salt leaching and improvement according to the present invention. DETAILED DESCRIPTION OF THE INVENTION EXAMPLE

[0009] Tajik Abati Town, Taxkorgan County, Kashi Prefecture, 10 mu, with pioneer plant being Suaeda salsa; The test area is located in a low and flat depression with deep, hard and sticky clay soil, heavy salinity. After irrigation, the topsoil of the 0 - 10 cm soil layer remains muddy for a long time, while the soil layer below 20 cm is dry and rigid, making it difficult for crops to grow. Before the experiment, crop planting was basically a complete failure. The specific operation is carried out according to the following steps: a. Construction of blind ditches: Using vertical alkali - drainage channels, with an interval of 10 m, a chain - type ditch - digging machine is used to dig parallel ditches with a depth of 1.0 m. Straw filter materials are filled between 70 cm from the ground at the bottom of the ditch, and the upper part is backfilled with soil and raked flat; b. Planting: In mid - April, drip - irrigation strip seeding of Suaeda salsa is carried out. Adopting the drip - irrigation strip seeding method with one pipe for one row, shallow ditches with a depth of 10 cm are dug at an interval of 0.6 m. The drip - irrigation belt is laid at the bottom of the ditch, and the seeds of Suaeda salsa are sown on both sides of the drip - irrigation belt; In late September, Suaeda salsa is turned over and incorporated into the field to improve the soil permeability of the plough layer, and the turning - over depth is ≥30 cm; c. Winter irrigation for salt leaching: After Suaeda salsa is turned over and incorporated into the field, winter irrigation is used for salt leaching; d. Irrigation management: Irrigation is carried out immediately after sowing Suaeda salsa, and water is replenished once every 2 days. The irrigation volume is controlled at 10 m 3 / mu to keep the soil in the seeding area moist; After the seedling stage, irrigation is judged according to the growth trend of Suaeda salsa and the soil moisture condition. The irrigation volume for each time is 30 m 3 / mu; In mid - November, winter irrigation for salt - leaching water is carried out, and the irrigation volume is 150 m 3 / mu; The method of the present invention was implemented in 2012. After the experiment, the effects of farmland drainage and desalination are very significant; In 2013, the yield of sunflower per mu was 240 kg, approaching the yield level of ordinary farmland. Example

[0010] Karamay Agricultural Development Zone, Karamay Green Agriculture Development Co., Ltd., 30 mu of test land, with pioneer plant being Suaeda glauca; Since 2001, water has been diverted for irrigation in Karamay Agricultural Comprehensive Development Zone. Since the development zone is built on a lacustrine basin, there are many saline - alkali plots with deep, hard and sticky clay barrier layers, and most of them have been in a fallow state for many years. In recent years, some farmers have dug drainage channels to improve the farmland drainage and salt - leaching conditions, but due to the existence of deep, hard and sticky clay soil, the effect is very limited; The specific operation is carried out according to the following steps: a. Construction of blind ditches: Using vertical alkali - drainage channels, with an interval of 12 m, a chain - type ditch - digging machine is used to dig parallel ditches with a depth of 1.0 m. Fine sand filter materials are filled at 80 cm from the ground at the bottom of the ditch, and the upper part is backfilled with soil and raked flat; b. Planting: In the first ten days of May, drip-irrigation and strip-sowing are used to plant Suaeda glauca. The one-pipe-one-row drip-irrigation and strip-sowing method is adopted. Shallow trenches with a depth of 12 cm are dug at intervals of 0.8 m. The drip irrigation tape is laid at the bottom of the trench, and the seeds of Suaeda glauca are sown on both sides of the drip irrigation tape. In late September, Suaeda glauca is plowed and incorporated into the field to improve the permeability of the plow layer soil, and the plowing depth is ≥ 30 cm; c. Winter irrigation for salt leaching: After Suaeda glauca is plowed and incorporated into the field, winter irrigation is used for salt leaching; d. Irrigation management: Irrigation is carried out immediately after sowing Suaeda glauca, and water is replenished once every 2 days. The irrigation volume is controlled at 12 m 3 / mu to keep the soil in the sowing area moist. After the seedling stage, irrigation is determined according to the growth of Suaeda glauca and the soil humidity. The irrigation volume for each time is 20 m 3 / mu; In mid-November, winter irrigation is carried out for salt leaching, and the irrigation volume is 180 m 3 / mu.

[0011] In 2020, the method of the present invention was implemented. Before planting in May 2020, the salt content in the plow layer soil was 19 - 28 g / kg. In May 2021, the salt content in the plow layer soil dropped to 9 - 12 g / kg. In 2021, Suaeda glauca was continuously planted. The above-ground part harvested was mixed with forage corn at a mass ratio of 1:2 to make silage feed, and the yield of silage per mu was 5100 kg / mu. In May 2022, the salt content in the plow layer soil was measured to be 4 - 7 g / kg, and the yield of cottonseed cotton in that year was 350 kg / mu. Example

[0012] In the First Company of Hongqi Farm, the Third Division of Xinjiang Production and Construction Corps, there is a 120-acre experimental plot, and the pioneer plant selected is Suaeda salsa; The First Company of Hongqi Farm, the Third Division of Xinjiang Production and Construction Corps, was established in 1958 and is a national-level farm. The total area of the jurisdiction is 166,100 mu, and most of it is saline-alkali land and gobi desert. The soil of the experimental plot is hard and sticky, with extremely poor water permeability. It is abandoned and idle land, and the previous irrigation and drainage supporting facilities are relatively complete; The specific operation is carried out according to the following steps: a. Construction of blind ditches: Taking the vertical alkali-drainage channels at intervals of 10 m, a chain-type ditcher is used to dig parallel ditches with a depth of 1.2 m. Fine sand filter material is filled at 90 cm from the ground at the bottom of the ditch, and the upper part is backfilled with soil and leveled; b. Planting: In the first ten days of May, drip-irrigation and strip-sowing are used to plant Suaeda salsa. The one-pipe-one-row drip-irrigation and strip-sowing method is adopted. Shallow trenches with a depth of 15 cm are dug at intervals of 1.0 m. The drip irrigation tape is laid at the bottom of the trench, and the seeds of Suaeda salsa are sown on both sides of the drip irrigation tape. In late September, Suaeda salsa is plowed and incorporated into the field to improve the permeability of the plow layer soil, and the plowing depth is ≥ 30 cm; c. Winter irrigation for salt leaching: After Suaeda salsa is plowed and incorporated into the field, winter irrigation is used for salt leaching; d. Irrigation management: Irrigation is carried out immediately after sowing Suaeda salsa, and water is replenished once every 2 days. The irrigation volume is controlled at 15 m 3per mu, keep the soil in the seeding area moist; after the seedling stage, judge the irrigation according to the growth of Suaeda salsa and the soil humidity, and the irrigation amount each time is 30m 3 / mu; in mid-November, irrigate in winter to suppress salt, and the irrigation amount is 200m 3 / mu.

[0013] Implement the method of the present invention in 2024. Before planting in April 2024, the salt content in the plough layer soil is 32-47 g / kg. By March 2025, the salt content in the plough layer soil drops to 8-13 g / kg, and the desalination rate of the plough layer soil in one test cycle exceeds 70%.

Claims

1. A comprehensive improvement method for severely compacted saline-alkali land by planting pioneer plants in combination with subsurface drainage and winter irrigation, characterized in that Proceed as follows: a. Construction of blind ditches: Select land with a deep compacted obstacle layer and heavy clay soil. Construct vertical alkali drainage channels at an interval of 10 - 12 m. Use a chain ditcher to dig parallel ditches with a depth of 1.0 - 1.2 m. Fill the bottom of the ditch, which is 70 - 90 cm from the ground surface, with straw or fine sand filter material, and then backfill the upper part with soil and rake it flat; b. Planting: Plant salt - tolerant pioneer plants by drip - irrigation and strip - sowing. Adopt the drip - irrigation and strip - sowing method with one pipe for one row. Dig shallow ditches with a depth of 10 - 15 cm at an interval of 0.6 - 1.0 m. Lay the drip - irrigation tape at the bottom of the ditch. Sow the pioneer plant seeds on both sides of the drip - irrigation tape and turn them over to a depth of ≥30 cm. During the maximum growth period of the pioneer plant biomass, turn it over and return it to the field to improve the permeability of the plow layer soil. The pioneer plants are Suaeda salsa or Suaeda glauca; c. Winter irrigation for salt leaching: After turning over and returning the pioneer plants (Suaeda salsa or Suaeda glauca) to the field, use winter irrigation for salt leaching; d. Irrigation management: After sowing pioneer plants such as Suaeda salsa or Suaeda glauca, irrigation is carried out immediately, and water is replenished once every 2 days. The irrigation volume is controlled at 10 - 15 m 3 / mu to keep the soil in the sowing area moist; after the seedling stage, irrigation is judged according to the growth of pioneer plants such as Suaeda salsa or Suaeda glauca and the soil moisture condition. The irrigation volume for each time is 20 - 30 m 3 / mu; in mid-November, winter irrigation is carried out to suppress saline water, and the irrigation volume is 150 - 200 m 3 / mu.

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