Saline-alkali land salt reduction method with superficial water circulation driven by temperature difference heat

Abstract

The invention discloses a temperature difference thermal driving superficial water circulation saline-alkali land salt reducing method, which comprises the following steps: firstly, preparing the land, turning over and leveling the target land, discarding non-agricultural soil substances in the soil, then ridging and furrowing until the ridge height is 10cm, adjusting the moisture content, and then covering the ridge surface with a transparent plastic film to form a coverage area of the ridge surface and exposed furrows to make A / Bgt; (E-D) / D, A is the width of the coverage area, B is the width of the furrows, D is the precipitation amount, and E is the evaporation amount. According to the technical scheme, discharged high-salinity water is not generated, and pollution to surrounding water and soil is avoided; no extra chemical substance is added, the soil ecological system is prevented from being polluted and damaged, the soil ecological environment is practically protected, and the sustainable agricultural development concept is met. And the implementation process is relatively simple, a large amount of capital investment is not needed, the cost is low, and good popularization and application prospects are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of saline-alkali land improvement, and more particularly to a method for reducing salt in salinized land by utilizing temperature difference heat to drive shallow surface water circulation. Background Art

[0002] In the field of saline-alkali land improvement technology, the current main goal is to reduce soil salinity and alkalinity, improve soil structure, and enhance soil fertility, creating a favorable environment for crop growth. The basic principles include draining and removing salt, regulating soil pH, improving soil structure, and increasing soil organic matter. Currently, there are various saline-alkali land improvement technologies, but all have certain drawbacks.

[0003] Water conservancy improvements involve establishing a comprehensive irrigation and drainage system to remove excess salt and water from the soil and prevent salt from rising to the surface with the water. This can include installing drainage ditches, water pipes, and irrigation equipment, ensuring proper irrigation and drainage, and regularly flushing the soil. However, in salinized areas where precipitation exceeds evaporation, access to freshwater resources presents challenges. On the one hand, freshwater resources in these areas may not be abundant, making it difficult to meet the large-scale freshwater needs for soil flushing. On the other hand, there is a lack of effective means to discharge the highly saline water produced by soil flushing. If discharged indiscriminately, this highly saline water will seep into surrounding soil or water bodies, exacerbating soil salinization in the surrounding area, causing secondary pollution, disrupting the surrounding ecological balance, and affecting agricultural production and ecosystem stability.

[0004] Agricultural technology improvements include leveling the land to ensure even water infiltration, increasing the effectiveness of rainfall leaching and irrigation to remove salt; deep plowing to loosen the soil, cut soil capillaries, reduce evaporation, control soil salinity, and improve soil structure; timely harrowing to loosen the topsoil and cut off the transport of salt from capillary water to the surface; and appropriate fertilization to increase soil organic matter, improve soil structure, and enhance soil fertility. However, these measures only adjust the soil surface and tillage methods and cannot fundamentally reduce soil salt content. For example, while deep plowing can temporarily move surface salt to the lower tillage layer, over time and with water movement, the salt will gradually return to the surface. This fails to completely resolve the soil salinity problem, making it difficult to achieve long-term and effective improvement of saline-alkali land, and thus hindering the sustainable and stable growth of crops.

[0005] Biological improvement mainly improves the soil by planting salt-alkali tolerant plants and using microorganisms. Planting salt-alkali tolerant plants such as Suaeda salsa, Phragmites australis, and Tamarix chinensis, which can adapt to saline-alkali environments and grow well, can improve the soil ecological environment and increase soil fertility to a certain extent; using microbial improvers such as bacterial fertilizers and bio-organic fertilizers, the beneficial microorganisms in them can decompose organic matter and inorganic salts in the soil, promote the formation of soil aggregate structure and the release of nutrients. However, both salt-alkali tolerant plants and microorganisms only adapt to the saline-alkali soil environment and do not directly reduce the total amount of salt in the soil. For example, salt-alkali tolerant plants only absorb some salt during their growth process, but cannot reduce the salt content in the soil to a level suitable for the growth of most crops. They cannot fundamentally solve the problem of soil salinity and cannot meet the needs of deep improvement of saline-alkali land to adapt to the cultivation of a variety of crops.

[0006] Chemical amendments involve applying amendments such as gypsum, black alum, and ferrous sulfate, which react with salt and alkaline substances in the soil to produce insoluble salts or precipitates, thereby reducing soil salinity and alkalinity. Soil conditioners are also used to adjust soil pH, improve soil structure, and increase soil organic matter. However, the addition of these chemicals can increase pollutants in the soil. Long-term use of chemical amendments can lead to excessive residues of certain chemicals in the soil, disrupting the soil's ecological balance, affecting the normal activity of soil microorganisms and the recovery of the soil's natural fertility. These chemicals can also enter the human body through the food chain, posing potential risks to human health and hindering the sustainable use of saline-alkali land and the protection of the ecological environment.

[0007] Therefore, how to overcome the defects of existing saline-alkali land improvement technology and provide a new salinization land salt reduction technology is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the present invention provides a method for reducing salt in salinized land by using temperature difference heat to drive shallow water circulation. By taking advantage of the natural phenomenon in the northwest region where the high temperature during the day causes evaporation of shallow surface soil water and the low temperature at night causes condensation of evaporated water vapor, light transmission heat transfer and water interception measures are implemented on the surface of saline-alkali land to cause shallow soil water to evaporate and condense in a self-circulation manner, bringing the salt in the soil near the surface to the deep soil, reducing the salt content in the upper soil layer and achieving the purpose of growing agricultural products.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A method for reducing salinity in salinized land by using temperature difference heat to drive shallow water circulation, comprising the following steps:

[0011] Step 1: Land preparation

[0012] The target land is plowed and leveled, and non-agricultural soil materials are discarded;

[0013] Step 2: Ridge and furrow

[0014] Ridge the land after treatment in step 1 to a height of 10 cm, adjust the moisture content, and then cover the ridge surface with a transparent plastic film to form a covered area of the ridge surface and an exposed ridge ditch, so that:

[0015] A / B>(ED) / D

[0016] Among them, A is the width of the coverage area, B is the width of the furrow, D is the precipitation, and E is the evaporation.

[0017] Based on local precipitation and evaporation data, accurately calculating the film covering width and spacing ratio, and rationally planning the ridge and furrow layout and the time for film removal and crop planting are the key to regulating the water circulation path under the film and the direction of salt migration, which directly determines the quality of the salt reduction effect.

[0018] Preferably, the moisture content in step 2 is ≥30%. Strictly controlling the moisture content of the soil before film covering to ensure sufficient water under the film for evaporation and condensation cycles is the core driving force for driving salt to migrate deep into the soil along with water, and plays a decisive role in reducing the salinity of the upper soil layer.

[0019] Preferably, the transparent plastic film in step 2 is 8s thick and made of polyethylene. The film can be reused many times, and the film has two functions: one is to intercept the water vapor evaporated from the soil and allow the water vapor to condense at night; the other is to allow sunlight to penetrate into the soil under the film during the day, so that the soil and water shallower than 20 cm are heated and sufficient water vapor is generated.

[0020] Preferably, in step 2, monitoring equipment is buried in the soil before covering the film.

[0021] Furthermore, the monitoring equipment includes a thermometer, a hygrometer, a pH meter and a conductivity tester.

[0022] Furthermore, the monitoring equipment is buried at a depth of 0-40 cm.

[0023] Real-time and comprehensive monitoring of multiple indicators such as temperature, humidity, pH value and salinity at different soil depths is carried out. By obtaining rich and accurate data, it provides strong support for in-depth understanding of the laws of soil environmental changes, scientific evaluation of improvement effects, and timely optimization of improvement strategies.

[0024] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a method for reducing salinization in salinized land by using temperature difference heat to drive shallow surface water circulation, which has the following beneficial effects:

[0025] Practical application has proven that this technology can significantly reduce the salinity of the upper soil layer (0-20cm), with an average reduction of up to 60%. Multiple test plots have proved that after the implementation of this technology, the soil salt content has dropped significantly, effectively improving the high-salt environment of the soil and creating suitable conditions for crop growth.

[0026] During the improvement process, this technology does not produce high-salinity water for discharge, thus avoiding pollution of surrounding water bodies and soil; at the same time, no additional chemical substances are added, thus preventing the soil ecosystem from being polluted and damaged, effectively protecting the soil ecological environment, and complying with the concept of sustainable agricultural development.

[0027] This technology has a relatively simple implementation process, with each step easy to understand and master, requiring no complex expertise from farmers. It also eliminates the need for large investments in expensive equipment or materials, with the primary costs concentrated in plastic film and monitoring equipment. Compared to other saline-alkali land improvement technologies, this technology offers significantly lower costs and holds great promise for widespread adoption. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0029] Figure 1 This is a schematic diagram of the salinity reduction technology project for saline-alkali soil;

[0030] Figure 2 This is a schematic diagram of the saline-alkali soil salt reduction technology monitoring system. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] The method for reducing salinity in salinized land by using temperature difference heat to drive shallow water circulation provided by the present invention comprises the following steps:

[0033] Step 1: Land preparation

[0034] The target land should be plowed and leveled, non-agricultural soil materials in the soil should be discarded, and the soil should be homogenized to achieve the goal of water movement in the soil mainly through pore flow. If the soil is not homogenized or pore flow is not allowed, condensation and infiltration may take the form of fissure channels and fail to achieve the effect of washing and reducing salt.

[0035] Step 2: Ridge and furrow

[0036] The land treated in step 1 was ridged into strips with a height of 10 cm, and then the moisture content was adjusted to ≥ 30%. Then, a polyethylene transparent plastic film 8s thick was covered on the ridge surface to form a covered area on the ridge surface and a bare ridge ditch (such as Figure 1 As shown), so that:

[0037] A / B>(ED) / D

[0038] Among them, A is the width of the covered area, B is the width of the furrow, D is the precipitation, and E is the evaporation;

[0039] Specifically, let: precipitation - D; evaporation - E; coverage area width - A; ridge width - B.

[0040] Then, within the length L, the total amount of rainfall water is D×L×(A+B), and the total amount of evaporated water is E×L×B (at this time, no evaporation occurs due to the presence of the film);

[0041] During the project implementation, if there is precipitation, the water will flow to the ridge ditch;

[0042] Obviously, when D×L×(A+B)>E×L×B, that is, D×(A+B)>E×B, infiltration water will occur in the ridge;

[0043] D×A+D×B>E×B, D×A>E×BD×B, D×A>(ED)×B;

[0044] The ratio of coverage area width to ridge width is obtained: A / B>(ED) / D;

[0045] Obviously, the greater the evaporation, the wider the membrane and the narrower the trench. The greater the rainfall, the narrower the membrane and the wider the trench. If there is no rainfall during construction, the trench will need to be replenished with fresh water based on local evaporation data. This replenishment should be greater than the evaporation between the membranes, causing water infiltration.

[0046] Before implementing the water vapor interception project, select a location to bury monitoring equipment. The monitoring equipment includes thermometers, hygrometers, pH meters and conductivity testers. The burial depth of the monitoring equipment is 0-40cm. More specifically, it is optional (such as Figure 2 (as shown): 0cm (surface), 5cm, 10cm, 15cm, 20cm, 30cm, and 40cm. Due to regional variations in climate, soil moisture content, and daily temperature fluctuations, the evaporation and condensation cycles in shallow saline-alkali soils vary, leading to varying rates of salinity reduction. Therefore, representative monitoring points for indicators such as salinity are essential in practical operations.

[0047] Example 1

[0048] The specific example is located in Zhaojun Town, Dalate Banner, Ordos City, Inner Mongolia Autonomous Region.

[0049] The saline-alkali land involved is 6 mu in area. The soil in the saline-alkali land is sub-sandy with an average salinity of 12.26 g / kg.

[0050] Implementation period: August 22 to September 12, 2024.

[0051] The parameters of the plastic film used for water vapor interception were: polyethylene (PE), 0.08 mm thick, transparent. Based on local evaporation of approximately 1200 mm and precipitation of approximately 300 mm, the film was covered with a width of 100 cm, a furrow width of 25 cm, and a furrow height of 10 cm. The film was applied for salinity reduction for 20 days. Soil samples were collected at different depths on days 9 and 20, and their salinity was analyzed (Tables 1 and 2).

[0052] Table 1 Effect after 9 days of implementation

[0053]

[0054]

[0055] Table 2 Effect after 20 days of implementation

[0056]

[0057] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. 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 apparent 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 method for reducing salinity in salinized land by using temperature difference heat to drive shallow water circulation, characterized in that: The following steps are involved: Step 1: Land preparation The target land is plowed and leveled, and non-agricultural soil materials are discarded; Step 2: Ridge and furrow Ridge the land after treatment in step 1 to a height of 10 cm, adjust the moisture content, and then cover the ridge surface with a transparent plastic film to form a covered area of the ridge surface and an exposed ridge ditch, so that: A / B>(ED) / D Among them, A is the width of the coverage area, B is the width of the furrow, D is the precipitation, and E is the evaporation.

2. The method for reducing salinity in salinized land by using temperature difference heat to drive shallow water circulation according to claim 1, characterized in that: The moisture content in step 2 is ≥30%.

3. The method for reducing salinity in salinized land by using temperature difference heat to drive shallow water circulation according to claim 1, characterized in that: The transparent plastic film in step 2 has a thickness of 8s and is made of polyethylene.

4. The method for reducing salinity in salinized land by using temperature difference heat to drive shallow water circulation according to claim 1, characterized in that: In step 2, monitoring equipment is buried in the soil before covering with film.

5. The method for reducing salinity in salinized land by using temperature difference heat to drive shallow water circulation according to claim 4, characterized in that: The monitoring equipment includes a thermometer, a hygrometer, a pH meter and a conductivity tester.

6. The method for reducing salinity in salinized land by using temperature difference heat to drive shallow water circulation according to claim 4 or 5, characterized in that: The monitoring equipment is buried at a depth of 0-40 cm.

Images