Differential comprehensive improvement method for moderate saline-alkali soil

Abstract

The invention relates to the technical field of saline-alkali soil improvement, in particular to a differential comprehensive improvement method for moderate saline-alkali soil. Comprising the following steps: improving salt spots according to specific conditions of the salt spots; while the salt spot soil is improved, the non-salt spot soil is subjected to strip type mechanical improvement; and carrying out a sunflower-sweet potato intercropping planting mode on the strip soil after mechanical improvement. By adopting relatively low improvement cost, the productivity of the moderately salinized farmland is improved, and the yield of crops is increased.

Description

Technical Field

[0001] The invention relates to the technical field of saline-alkali land improvement, in particular to a differentiated comprehensive improvement method for moderate saline-alkali land. Background Art

[0003] At present, the measures commonly used to improve saline-alkali land in my country are chemical improvement and engineering improvement measures. Among them, chemical improvement has the advantages of low cost, quick effect, no dependence on supporting projects, and flexible and adjustable formulas. Adding soil conditioners with different formulas to adjust the physical and chemical properties of salinized soil is considered to be a simple and efficient method for improving saline-alkali land.

[0004] Moderate saline-alkali land has large spatial differences in soil salinity, usually with stubborn salt spots and high soil salt content, poor crop seedlings, and serious lack of seedlings and broken ridges. Generally, soil improvement technologies for mild saline-alkali land, such as increasing the application of organic fertilizers, have limited effects. Large-scale projects are costly and inefficient, and there is a lack of relevant improvement technologies with good economic costs and high feasibility. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and propose a differentiated comprehensive improvement method for moderately saline-alkali land, which uses a lower improvement cost to improve the productivity of moderately saline-alkali farmland and increase the yield of crops.

[0006] The technical solution of the present invention is: a differentiated comprehensive improvement method for moderate saline-alkali land, which comprises the following steps:

[0007] S1. Improve the salt spots according to their specific conditions;

[0008] S2. While improving the salt-spotted soil, perform strip-type mechanical improvement on the non-salt-spotted soil;

[0009] S3. Sunflower-sweet potato intercropping pattern is carried out on the strip soil that has been mechanically improved.

[0010] In the present invention, in step S1, when the salt spot area has obvious surface salt crust and the salt crust coverage reaches more than 80%, the specific salt spot improvement steps are as follows:

[0011] S1A.1. The surface salt crust needs to be mechanically removed along with 1-2 cm of soil;

[0012] S1A.2. Deep plowing should be carried out on the salt spot area, with the depth of deep plowing not less than 60cm;

[0013] S1A.3. Build ridges around the salt spots and irrigate the area to a depth of no less than 10 cm. After three days, drain the accumulated water.

[0014] S1A.4. After the soil surface is dry, deep plowing and deep loosening shall be carried out on the surface soil. The operation depth of deep plowing and deep loosening shall not be less than 60cm. Soil conditioner shall be applied on the soil surface.

[0015] S1A.5. Till the soil several times to break up the soil clods until the soil is loose;

[0016] S1A.6. In mid-May, sow sesbania seeds in the salt spot amendment area at a sowing rate of 3-4 kg / mu. After sowing, harrow the soil and sprinkle the soil until the sesbania seedlings emerge. When the sesbania completes the surface coverage, apply 5 kg / mu of granular urea.

[0017] In early September, when the sesbania pods are formed but not fully mature, use a field return machine to kill the stubble of the sesbania. After returning all the sesbania to the field, the soil is rotary tilled to a depth of more than 25 cm.

[0018] When there is obvious salt crystallization in the salt spot area and the salt crystallization reaches more than 60%, the specific steps for salt spot improvement are as follows:

[0019] S1B.1. Deep plowing should be carried out on the salt spot area, with the depth of deep plowing not less than 60cm;

[0020] S1B.2. Build ridges to surround the salt spots and irrigate the area to a depth of no less than 10 cm. After three days, drain the accumulated water.

[0021] S1B.3. After the soil surface is dry, deep plowing and deep loosening shall be carried out on the surface soil. The operation depth of deep plowing and deep loosening shall not be less than 60cm. Soil conditioner shall be applied on the soil surface.

[0022] S1B.4. Till the soil several times to break up the soil clods until the soil is loose;

[0023] S1B.5. In mid-May, sow sesbania seeds in the salt spot amendment area at a sowing rate of 3-4 kg / mu. After sowing, harrow the soil and sprinkle the soil until the sesbania seedlings emerge. When the sesbania completes the surface coverage, apply 5 kg / mu of granular urea.

[0024] In early September, when the sesbania pods are formed but not fully mature, use a field return machine to kill the stubble of the sesbania. After returning all the sesbania to the field, the soil is rotary tilled to a depth of more than 25 cm.

[0025] The soil conditioner comprises straw, fungus residue and feces of herbivorous animals and is prepared through an aerobic composting and fermentation process.

[0026] The strip machine performs S-shaped operations along the non-salty soil. During the operation, it sequentially carries out trenching, application of organic improvement materials, backfilling, and application of organic improvement materials on the soil surface.

[0027] The organic improvement material comprises a soil improver and coated slow-release urea in a weight ratio of 50:1.

[0028] The organic improvement material also includes biochar, a mixture obtained by mixing the soil conditioner and coated slow-release urea, and the weight ratio of the mixture to the biochar is 200:1;

[0029] A mixture of soil conditioner, coated slow-release urea and biochar is made into organic improvement material through aerobic composting and fermentation.

[0030] In step S3, the sunflower-sweet potato set sowing mode specifically includes the following steps:

[0031] S3.1. In the strip soil improved in step S2, sunflowers are sown in the winter of the current year or the early spring of the next year. The sunflowers are sown in intervals and staggered along the strip soil, and the sunflowers are irrigated and fertilized to ensure the emergence of the sunflowers;

[0032] S3.2. In late May or early June, after sunflowers bud, transplant salt-tolerant sweet potato seedlings in the improved strip soil on the side opposite to the sunflowers. After transplanting, irrigate and fertilize the sweet potato seedlings, and dig trenches between rows to cultivate soil.

[0033] S3.3. After the sunflowers mature normally and before the sweet potatoes have covered the rows, the sunflowers are harvested. After the sunflowers are harvested, irrigation and topdressing are carried out.

[0034] S3.4. After the sweet potatoes mature in autumn, they should be harvested in time.

[0035] In step S2, since the strip machine performs S-shaped operation in the non-salt-spotted soil, when the area of ​​the non-salt-spotted soil is equal to the sum of the areas of the N improved strips of soil, it is necessary to complete the sunflower-sweet potato interplanting on the non-salt-spotted soil in N times and N years;

[0036] Each year, sunflower and sweet potato intercropping is carried out in only one of the improved strips of soil, and the strips of soil that have previously been intercropped with sunflower and sweet potato can be used to grow other crops.

[0037] The sesbania can be replaced by Suaeda salsa, kenaf, Tamarix, Amaranthus chinensis, Sorghum sorghum, and Cassia seed.

[0038] The beneficial effects of the present invention are:

[0039] (1) In moderate saline-alkali land, differentiated improvement operation modes are carried out for salt spots and non-salt spots. Mechanized strip improvement is carried out in non-salt spots. Through strip machinery, the operation process of strip application of organic fertilizer and base fertilizer in saline-alkali land, trenching, mixing, backfilling, and surface covering is completed, so as to realize the hierarchical improvement of saline-alkali land by concentrated material input;

[0040] (2) Salt-spot areas should adopt desalination technologies such as local irrigation and drainage, mechanical deep plowing, organic matter addition, and green manure planting according to different actual conditions to solve the soil restrictions of stubborn salt spots. Through the planting of summer green manure crops and returning all of them to the fields, soil quality can be quickly improved, soil structure can be improved, and the cost of saline-alkali land improvement can be reduced, so as to achieve the improvement and utilization of moderate saline-alkali land;

[0041] (3) Application of the improved high-efficiency oil sunflower-sweet potato planting model, making full use of the width of the improved strips, intercropping oil sunflowers and sweet potatoes, coordinating the growth periods of the two crops, using the shade of sunflower leaves to prevent the sweet potato seedlings from being exposed to direct sunlight, ensuring the survival of the sweet potato seedlings, and maintaining soil moisture. As the sunflowers gradually mature, the leaves gradually wither, freeing up enough light space for the growth of sweet potatoes. At the same time, the sweet potatoes gradually grow, and the sunflower harvest is completed before the sweet potatoes close the ridges and cause inconvenience in farming operations. The sweet potatoes can use the excess fertilizer of the sunflowers, thereby increasing the crop yield.

[0042] To summarize, this application improves the overall soil quality level of moderately saline-alkali land by improving the machinery for applying organic fertilizer in orchards and combining it with organic improved materials formed by waste composting and fermentation technology; at the same time, salt spot areas are targetedly improved through multiple measures such as mechanical deep plowing, incremental organic matter return to the field, and green manure planting, thereby improving the productivity of the soil at the salt spot location, and combining the efficient intercropping pattern of economic crops in moderately saline-alkali land to form a comprehensive improvement and utilization model for moderately saline-alkali land. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the structure for planting sunflowers and sweet potatoes in strip-type improved soil. DETAILED DESCRIPTION

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0045] In the following description, specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0046] Example 1

[0047] The differentiated comprehensive improvement method for moderate saline-alkali land described in this application includes the following specific steps. The characteristic of moderate saline-alkali land is that there are salt spots in the soil. Therefore, moderate saline-alkali land includes salt-spotted soil and non-salt-spotted soil. This application adopts different improvement methods for salt-spotted soil and non-salt-spotted soil respectively. Specifically, it includes the following improvement steps.

[0048] The first step is to accurately improve salt spots.

[0049] The window period for salt spot improvement is spring, when salt accumulation in the soil surface is the most serious during the year.

[0050] First, use aerial photography and on-site investigation to determine the scope of the salt spots and mark their boundaries.

[0051] If the salt spot area has obvious surface salt crust and the salt crust coverage reaches more than 60%, the surface salt crust and 1-2cm thick soil need to be mechanically removed, and the removed soil with surface salt crust is transported outside the improved area. Use machinery to deep plow the salt spot area, with a depth of more than 60cm; build ridges to surround the salt spot, irrigate the area locally, and flood the area to a depth of more than 10cm. After three days, drain the accumulated water outside the improved area. After the soil surface is dry, deep plowing is performed again.

[0052] If there is obvious salt crystallization in the salt spot area, and the salt crystallization reaches more than 60%, a small part of the area will be covered on the surface, and the salt spot area will be deep-plowed by machinery, with a depth of more than 60cm. The salt spot will be surrounded by ridges, and local water will be irrigated to a depth of more than 10cm. After three days, the accumulated water will be drained out of the seed improvement area.

[0053] After completing the above operations, wait for the soil surface to dry, and then use excavators, reversing plows and other machinery to deep-plow and loosen the surface soil. The operating depth of deep-plowing and loosening is more than 60cm. And apply soil conditioners on the soil surface.

[0054] In this embodiment, the soil conditioner is made of agricultural waste such as straw, fungus residue, and herbivorous animal feces, and is added with nutrients such as fast-decomposing bacteria and urea, and is made through aerobic composting and fermentation for 25-30 days. 5 tons of soil conditioner are applied per mu.

[0055] In this embodiment, the soil conditioner is specifically mixed by the following substances: grain straw, with a mass ratio of 1; vegetable waste, with a mass ratio of 0.8-1; mushroom residue, with a mass ratio of 1-1.2; herbivorous animal feces, with a mass ratio of 1-1.2; omnivorous animal feces, with a mass ratio of 0.5-0.6.

[0056] After mixing the above materials using loaders, mixers and other machines, adjust the moisture content to 60%-65%, and pile them into strip piles or put them into fermentation tanks for fermentation. Use normal organic fertilizer production processes for aeration or turning to maintain sufficient oxygen supply inside the pile. After 25-30 days of pile making, the temperature of the pile drops to below 35°C and remains relatively constant, completing the preparation of the soil conditioner.

[0057] Use a rotary tiller to till the soil multiple times to break up soil clods until the soil remains loose.

[0058] In mid-May, sesbania seeds were sown in the salt spot improvement area, with a sowing rate of 3-4 kg per mu. After sowing, the soil was raked flat with a toothed rake and sprinkled with water until the sesbania seedlings emerged. After the sesbania seedlings emerged, the sesbania was allowed to grow naturally. When the sesbania completed the surface coverage, 5 kg / mu of granular urea was applied, and no additional treatment was done afterwards.

[0059] Until autumn, i.e. early September, when the sesbania pods have formed but are not fully mature, the sesbania pods are killed using a field return machine. After all the sesbania pods have been returned to the field, the soil is rotary tilled to a depth of more than 25 cm.

[0060] The second step is to carry out strip mechanical improvement on non-salt-spotted soils while precisely improving the salt-spotted soils.

[0061] The strip machine is used to dig trenches, apply fertilizers, backfill, and cover the surface of the soil with amendments. The strip machine performs S-shaped operations in the non-salty soil. During the operation, trenching is first performed, and organic amendment materials are then applied in the trenches, and the trenches are backfilled. After backfilling, organic amendment materials are applied again on the soil surface.

[0062] In this embodiment, the strip-type machinery includes a tractor and a soil improvement machine mounted on the tractor. The tractor can be a commonly used tractor or the like. The soil conditioner can simultaneously realize the processes of trenching, fertilization, backfilling and fertilization. The existing agricultural machinery can meet its needs, so the existing agricultural machinery can be used. The soil improvement machine includes a rear discharge port and a front discharge port. The front discharge port is used to apply organic improvement materials into the trench after trenching. The fertilization speed of the front discharge port is 120kg / min; the rear discharge port is used to apply organic improvement materials to the soil surface. The fertilization speed of the rear discharge port is 40kg / min. The operating speed of the strip-type machinery is maintained at 30 meters / minute, and an S-shaped operation is adopted. The working row spacing is about 90cm, and the amount of organic improvement materials added per mu is 4 tons. Figure 1 As shown, in this embodiment, the width of the strip soil is 30 cm, and the width of the unimproved saline soil between two adjacent strips is 60 cm.

[0063] In this embodiment, the organic improvement material includes a soil improver and coated slow-release urea. The specific formula of the soil improver is as described above and will not be repeated here. The soil improver and the coated slow-release urea are added to the dry soil improver in a weight ratio of 50:1.

[0064] The organic improvement material may also include biochar. The weight ratio of the mixture obtained by mixing the soil improver and coated slow-release urea to the biochar is 200:1. The biochar in the above ratio is added to the soil improver and coated slow-release urea.

[0065] In addition, mineral improvers can be added to the mixture obtained by mixing the soil conditioner and coated slow-release urea according to the soil chemical cost.

[0066] In the process of preparing organic improved materials, the above materials are mixed, the moisture content is adjusted to 60%-65%, and the materials are piled into strip piles or placed in fermentation tanks for fermentation. Aeration or turning is carried out using normal organic fertilizer production processes to maintain sufficient oxygen supply inside the pile. After 25-30 days of pile making, the temperature of the pile drops to below 35°C and remains relatively constant. During the pile making process, the preparation of organic improved materials is achieved.

[0067] The third step is to carry out sunflower-sweet potato intercropping on the mechanically improved strip soil.

[0068] On the strip soil improved in the second step, sunflowers are sown in winter or early spring, with the sunflowers spaced and staggered along the strip soil.

[0069] In this embodiment, the distance between the sunflower sowing point and the edge of the strip is more than 5 cm. The lateral distance between two adjacent sunflower sowing points, that is, the distance parallel to the strip width direction, is 20 cm. The longitudinal distance between two adjacent sunflower sowing points, that is, the distance parallel to the strip length direction, is 30 cm. Since the adjacent sunflowers are sown in an interlaced manner, in this embodiment, the actual spacing between the two adjacent sunflowers is 36 cm. The planting density of sunflowers is 2500 plants / acre.

[0070] Lay a drip irrigation system or sprinkler irrigation system to ensure the normal emergence of sunflowers in spring. If there are no corresponding irrigation conditions, you need to pay attention to weather changes and complete sowing before effective precipitation. After the emergence of seedlings, flush or strip urea 10kg / mu, refer to the relevant sunflower planting technical regulations to manage fertilizer and water, and control pests and diseases and weeds for sunflower planting.

[0071] Generally, in late May to early June, after the sunflowers bud, the salt-tolerant sweet potato seedlings are transplanted on the improved strip soil and on the side opposite to the sunflower planting. After transplanting, irrigation is performed to ensure the survival rate of the sweet potato seedlings. Urea is applied again by flushing or strip application at 10 kg / mu, and furrows are dug between the rows to cultivate the soil. Thereafter, the field management of sunflower planting is carried out normally. In this embodiment, the salt-tolerant sweet potato seedlings and sunflowers are planted symmetrically in the improved strip soil.

[0072] After the sunflowers mature normally and before the sweet potatoes have covered the rows, the sunflowers are harvested. After the sunflowers are harvested, they are irrigated and fertilized with 15-20 kg / mu of nitrogen, phosphorus and potassium compound fertilizer and 40-50 kg / mu of soybean meal cake fertilizer. After that, the sweet potatoes are managed in the field according to the relevant sweet potato planting technical regulations.

[0073] During the intercropping of sunflowers and sweet potatoes, the sunflower plants are tall and slender and do not cover the ground, while the sweet potatoes spread along the ground to form a covering layer on the surface, which can make full use of the morphological characteristics of the two crops: first, sunflowers grow at high altitudes, while sweet potatoes grow along the ground, making full use of the upper and lower growth spaces; second, in the early stage of transplanting sweet potato seedlings, the lushly growing sunflower leaves provide shade for the sweet potato seedlings, preventing them from being exposed to strong sunlight. At the same time, the sunflower's shade can also maintain soil moisture, which is beneficial to the rooting and survival of the sweet potato seedlings, and provides a slow growth environment for the sweet potato seedlings; third, when the sunflower is in the mature stage, the sunflower leaves gradually fall, and the already alive sweet potatoes just need sufficient light. At this time, the sunflower leaves can no longer continue to shade, and the time that the sunflower shines directly on the sweet potatoes becomes longer, so that the sweet potatoes can effectively utilize the sun's light and increase the overall yield of the sweet potatoes.

[0074] The intercropping model of sunflower and sweet potato can not only increase the yield and income of crops per unit area, but also reduce the use of herbicides during the growth of sweet potatoes covering the ground.

[0075] After the sweet potatoes mature in autumn, they should be harvested in time.

[0076] The fourth step is to improve the saline-alkali soil between the strips.

[0077] In the second step, during the process of strip-type mechanical improvement of the soil, there is a certain distance between the formed strips of soil. In this embodiment, the width of the saline-alkali soil between adjacent strips of soil is 60 cm. Therefore, it is necessary to further improve these saline-alkali soils.

[0078] Due to the limitation of strip-type soil improvement, the saline-alkali soil between two adjacent strips of soil may not be completely improved within one year. In this case, it is necessary to improve the saline-alkali soil between the strips of soil in batches and years according to the width of the strip-type improved soil and the width of the saline-alkali soil between two adjacent strips of soil. In this embodiment, the width of the saline-alkali soil between adjacent strips of soil is 60 cm, and the width of the strip-type improved soil is 30 cm. Therefore, when using soil machinery to mechanically improve these saline-alkali soils, it is impossible to complete the improvement of the saline-alkali soils in sequence, and it usually takes the next two years to complete the improvement of all saline-alkali soils.

[0079] Repeat the specific operations of the second step, use soil machinery to perform strip-type mechanical improvement on the saline-alkali soil between the strip soils, sow sunflowers in the winter of the current year or the early spring of the second year, interplant sunflowers and sweet potatoes in the strip-type improved soil, and repeat the planting steps of the third step.

[0080] In the strip-type improved soil where sunflower-sweet potato intercropping has been completed in the first year, other crops need to be planted to prevent repeated cropping.

[0081] Next, the remaining saline-alkali soil is mechanically improved in strips using soil machinery, and sunflowers are sown in the winter of the second year or the early spring of the third year, and sunflowers and sweet potatoes are interplanted in the improved strip soil. At the same time, other crops are planted in the improved strip soil.

[0082] The method described in this application is further described below based on specific experimental data.

[0083] By using the strip-type machinery described in this application, organic improvement materials can be placed more accurately, more concentratedly, and more evenly in a small area of ​​saline-alkali land, achieving gradient and differentiated improvement of saline-alkali land. In the control experiment, three improvement methods were compared: manual application (treatment 1), application by an organic fertilizer spreader (treatment 2), and application by a strip-type machinery (treatment 3). Under the conditions of the same fertilizer application amount per unit area and crop planting management, the use of the strip-type machinery has significant advantages in indicators such as soil desalination rate, nutrient content, and organic matter content.

[0084] Table 1 Comparison of the effects of different improvement methods

[0085]

[0086] For the stubborn salt spots commonly seen in moderate saline-alkali land, the investment and improvement effects of engineering regional improvement, conditioner improvement and this scheme after one year of implementation were compared. It was found that although the pure engineering improvement method has a good soil improvement effect, the investment is relatively high, and the improved soil has a potential risk of secondary salinization. Only by adding soil conditioners, the improvement effect of stable salt spots in moderate saline-alkali land is of low significance, and there is no obvious improvement in soil physical and chemical properties, nutritional indicators and crop emergence. In contrast, the application is used to accurately treat stubborn salt spots in moderate saline-alkali land, and the soil-related indicators in the salt spot area are significantly improved, and the crop seedlings are effectively improved. The cost is relatively controllable and feasible.

[0087] Table 2 Improvement methods and investment of stubborn salt spots in different moderate saline-alkali lands

[0088]

[0089] The yield of general grain and oil crops planted in moderate saline-alkali land is generally low, and the economic benefits are low. Compared with several common saline-alkali land crop planting patterns, the sunflower-sweet potato intercropping pattern formed by this application on the basis of strip improvement has a higher per-mu input level than the general monocropping pattern, but has good crop yield and income, and has good compatibility with soil improvement operations. At the same time, the crop rotation can be arranged flexibly, and the window period for succession is relatively long, which can effectively improve the per-mu income of saline-alkali land, especially light to moderate saline-alkali land, which is more than 20% higher than the income of general grain and oil crop planting.

[0090] Table 3 Input and effectiveness of different saline-alkali land crop planting patterns

[0091]

[0092] Example 2

[0093] Different from Example 1, in the first step of this example, green manure crops such as Suaeda salsa can be used to replace the sesbania in claim 1. The planting method of Suaeda salsa is the same as the planting method of sesbania in Example 1.

[0094] In addition, it can also be replaced by other green manures such as kenaf, tamarind, amaranth, sorghum, cassia seed, etc.

[0095] The rest is the same as in Example 1.

[0096] The above is a detailed introduction to the differentiated comprehensive improvement method for moderate saline-alkali land provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present invention. Various modifications to these embodiments will be obvious to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A differentiated comprehensive improvement method for moderate saline-alkali land, characterized in that: The following steps are involved: S1. Improve the salt spots according to their specific conditions; S2. While improving the salt-spotted soil, perform strip-type mechanical improvement on the non-salt-spotted soil; S3. Sunflower-sweet potato intercropping pattern is carried out on the strip soil that has been mechanically improved.

2. The differentiated comprehensive improvement method for moderate saline-alkali land according to claim 1, characterized in that: In step S1, when the salt spot area has obvious surface salt crust and the salt crust coverage reaches more than 60%, the specific salt spot improvement steps are as follows: S1A.

1. The surface salt crust needs to be mechanically removed along with 1-2 cm of soil; S1A.

2. Deep plowing should be carried out on the salt spot area, with the depth of deep plowing not less than 60cm; S1A.

3. Build ridges around the salt spots and irrigate the area to a depth of no less than 10 cm. After three days, drain the accumulated water. S1A.

4. After the soil surface is dry, deep plowing and deep loosening shall be carried out on the surface soil. The operation depth of deep plowing and deep loosening shall not be less than 60cm. Soil conditioner shall be applied on the soil surface. S1A.

5. Till the soil several times to break up the soil clods until the soil is loose; S1A.

6. In mid-May, sow green manure crop seeds in the salt spot amendment area at a sowing rate of 3-4 kg / mu. After sowing, harrow the soil and sprinkle the soil until the sesbania seedlings emerge. When the sesbania completes the surface coverage, apply 5 kg / mu of granular urea. In early September, when the sesbania pods are formed but not fully mature, use a field return machine to kill the stubble of the sesbania. After returning all the sesbania to the field, the soil is rotary tilled to a depth of more than 25 cm.

3. The differentiated comprehensive improvement method for moderate saline-alkali land according to claim 1, characterized in that: When there is obvious salt crystallization in the salt spot area and the salt crystallization reaches more than 60%, the specific steps for salt spot improvement are as follows: S1B.

1. Deep plowing should be carried out on the salt spot area, with the depth of deep plowing not less than 60cm; S1B.

2. Build ridges to surround the salt spots and irrigate the area to a depth of no less than 10 cm. After three days, drain the accumulated water. S1B.

3. After the soil surface is dry, deep plowing and deep loosening shall be carried out on the surface soil. The operation depth of deep plowing and deep loosening shall not be less than 60cm. Soil conditioner shall be applied on the soil surface. S1B.

4. Till the soil several times to break up the soil clods until the soil is loose; S1B.

5. In mid-May, sow sesbania seeds in the salt spot amendment area at a sowing rate of 3-4 kg / mu. After sowing, harrow the soil and sprinkle the soil until the sesbania seedlings emerge. When the sesbania completes the surface coverage, apply 5 kg / mu of granular urea. In early September, when the sesbania pods are formed but not fully mature, use a field return machine to kill the stubble of the sesbania. After returning all the sesbania to the field, the soil is rotary tilled to a depth of more than 25 cm.

4. The differentiated comprehensive improvement method for moderate saline-alkali land according to claim 2 or 3, characterized in that: The soil conditioner comprises straw, fungus residue and feces of herbivorous animals and is prepared through an aerobic composting and fermentation process.

5. The differentiated comprehensive improvement method for moderate saline-alkali land according to claim 1, characterized in that: The strip machine performs S-shaped operations along the non-salty soil. During the operation, it sequentially carries out trenching, application of organic improvement materials, backfilling, and application of organic improvement materials on the soil surface.

6. The differentiated comprehensive improvement method for moderate saline-alkali land according to claim 4, characterized in that: The organic improvement material comprises a soil improver and coated slow-release urea in a weight ratio of 50:

1.

7. The differentiated comprehensive improvement method for moderate saline-alkali land according to claim 6, characterized in that: The organic improvement material also includes biochar, a mixture obtained by mixing the soil conditioner and coated slow-release urea, and the weight ratio of the mixture to the biochar is 200:1; A mixture of soil conditioner, coated slow-release urea and biochar is made into organic improvement material through aerobic composting and fermentation.

8. The differentiated comprehensive improvement method for moderate saline-alkali land according to claim 1, characterized in that: In step S3, the sunflower-sweet potato set sowing mode specifically includes the following steps: S3.

1. In the strip soil improved in step S2, sunflowers are sown in the winter of the current year or the early spring of the following year. The sunflowers are sown alternately along the strip soil, and the sunflowers are irrigated and fertilized to ensure the emergence of the sunflowers. S3.

2. In late May or early June, after sunflowers bud, transplant salt-tolerant sweet potato seedlings in the improved strip soil on the side opposite to the sunflowers. After transplanting, irrigate and fertilize the sweet potato seedlings, and dig trenches between rows to cultivate soil. S3.

3. After the sunflowers mature normally and before the sweet potatoes have covered the rows, the sunflowers are harvested. After the sunflowers are harvested, irrigation and topdressing are carried out. S3.

4. After the sweet potatoes mature in autumn, they should be harvested in time.

9. The differentiated comprehensive improvement method for moderate saline-alkali land according to claim 1, characterized in that: In step S2, since the strip machine performs S-shaped operation in the non-salt-spotted soil, when the area of ​​the non-salt-spotted soil is equal to the sum of the areas of the N improved strips of soil, it is necessary to complete the sunflower-sweet potato interplanting on the non-salt-spotted soil in N times and N years; Each year, sunflower and sweet potato intercropping is carried out in only one of the improved strips of soil, and the strips of soil that have previously been intercropped with sunflower and sweet potato can be used to grow other crops.

10. The differentiated comprehensive improvement method for moderate saline-alkali land according to claim 2 or 3, characterized in that: The sesbania can be replaced by Suaeda salsa, kenaf, Tamarix, Amaranthus chinensis, Sorghum sorghum, and Cassia seed.

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