Method for recycling saline water of alkali drainage channel and improving saline-alkali soil in Xinjiang region

Abstract

The invention provides a Xinjiang region alkali drainage channel salt water reutilization and saline-alkali land improvement method, which comprises the following steps: building strip fields and water storage ridges after autumn harvest, then taking preceding crops out of the field, recovering residual films and turning over; according to the water-soluble salt of the soil and the salinity and sodium adsorption ratio of the salt water in the alkali drainage channel, determining the irrigation height according to a formula; when the daily average temperature in winter is kept for a certain number of days, first-time irrigation is carried out, and after the first-time irrigation is completely frozen, second-time irrigation is carried out to form a stable salt water ice layer; in the temperature rising process in spring, after the salt water ice layer is completely melted, a mulching film is covered within one week; then corn planting is carried out, wherein spring soil preparation, sowing and field management are carried out in sequence. According to the improvement method, unconventional water resources in the alkali drainage channel in the Xinjiang irrigation area are fully utilized, and fresh water resources in the winter irrigation process of the Xinjiang irrigation area are saved; and the investment of other infrastructures such as well digging is reduced by utilizing the surface salty water resource.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of saline-alkali soil improvement, and particularly relates to a method for recycling saline water in an alkali discharge ditch and improving saline-alkali soil in the Xinjiang region. BACKGROUND

[0002] At present, the common practice in the process of saline-alkali soil treatment in Xinjiang is to use underground fresh water resources for large water flooding and salt compression (winter irrigation) in winter. Although this can reduce the salt content of the surface soil to some extent, the cost of winter irrigation with fresh water is relatively high due to the shortage of fresh water resources. How to reduce the amount of fresh water irrigation in winter has become an urgent problem to be solved. The saline water freezing irrigation technology is to carry out field saline water irrigation under low temperature conditions in winter. During the freezing and thawing process of saline water, saline water and fresh water are separated to obtain a certain proportion of fresh water resources for soil surface leaching and salt removal. The open ditch in the irrigation area in Xinjiang has abundant brackish water resources. The open ditch collects winter and spring irrigation and drainage as well as crop growth season drainage, but has not been effectively utilized. Moreover, most areas in Xinjiang have low temperature conditions in winter. Therefore, reasonable utilization of open ditch saline water for winter irrigation and salt leaching can save a large amount of fresh water resources. At present, the saline water freezing irrigation technology has been successfully applied in coastal saline-alkali soil, but a perfect application technology specification has not been formed in Xinjiang. Xinjiang and coastal saline-alkali soil are quite different in soil type, salt type, salt degree and winter and spring climate conditions. Therefore, the key technical parameters of the saline water freezing irrigation technology need to be researched and determined in Xinjiang. SUMMARY

[0003] The technical problem to be solved by the application is to provide a method for recycling saline water in an alkali discharge ditch and improving saline-alkali soil in the Xinjiang region to solve the problems of the prior art. The improvement method fully utilizes unconventional water resources in the alkali discharge ditch in the Xinjiang irrigation area, saves fresh water resources in the winter irrigation process in the Xinjiang irrigation area, utilizes surface saline water resources, and reduces the investment in infrastructure such as well digging.

[0004] To solve the above technical problems, the technical scheme adopted by the application is as follows: a method for recycling saline water in an alkali discharge ditch and improving saline-alkali soil in the Xinjiang region, the method comprising the following steps:

[0005] S1, land leveling: after autumn harvest, a strip field is built, and a water storage dike is built around the strip field; then the previous crop is removed from the field, and residual film is recycled, and then soil plowing is carried out;

[0006] S2, soil salt content investigation: the soil water-soluble salt content is determined to determine the degree of soil salinization. The water-soluble salt content of the moderate salinization soil in the Xinjiang region is 6-12 g·kg -1 , and the water-soluble salt content of the severe salinization soil is 12-20 g·kg -1 ;

[0007] S3, water quality investigation of alkali discharge channel: the salinity and sodium adsorption ratio of the salt water in the alkali discharge channel are detected;

[0008] S4, determination of irrigation height: for the moderately salinized soil in S2, the salinity and sodium adsorption ratio of the salt water detected in S3 are substituted into the regression equation: Formula (1)

[0009] In formula (1), is the desalination rate of 0-20 cm soil layer, %; X1 is the irrigation height, mm; X2 is the salinity, g·L -1 ; X3 is the sodium adsorption ratio, mmol 1 / 2 ·L −1 / 2 ; the irrigation height X1 under the optimal soil desalination rate is calculated;

[0010] For the severely salinized soil in S2, the salinity and sodium adsorption ratio of the salt water detected in S3 are substituted into the regression equation: Formula (2)

[0011] In formula (2), is the desalination rate of 0-20 cm soil layer, %; is the irrigation height, mm; is the salinity, g·L -1 ; is the sodium adsorption ratio, mmol 1 / 2 ·L −1 / 2 ; the irrigation height under the optimal soil desalination rate is calculated;

[0012] S5, freezing irrigation: when the daily average temperature in winter continues for a certain temperature and days, the first irrigation is carried out, and after the first irrigation is completely frozen, the second irrigation is carried out to reach the irrigation height obtained in S4, and under the condition of low temperature, a stable salt water ice layer is formed;

[0013] S6, mulching: during the warming process in spring, the stable salt water ice layer formed in S5 carries out salt leaching of the salinized soil in the order of salt water melting first and fresh water melting later, and after the salt water ice layer is completely melted, the mulching film is covered within one week;

[0014] S7, corn planting: spring soil preparation, sowing and field management are carried out in turn.

[0015] Preferably, the width of the water storage dike in S1 is 50 cm, and the height is 35 cm; the depth of soil ploughing is 35-37 cm.

[0016] Preferably, the daily average temperature in S5 is continuously lower than -7 DEG C and the future duration is not less than 10 days or the daily average temperature is continuously lower than -5 DEG C and the future duration is not less than 25 days, and the first irrigation is carried out, and the height of the first irrigation is 5 cm.

[0017] Preferably, the width of the mulching film in S6 is 70 cm.

[0018] Preferably, the spring tillage in S7 is ploughing when the soil is suitable for entropy, and land leveling is carried out again before sowing; the depth of the ploughing is 28-30 cm, and the depth of the land leveling is 10-12 cm.

[0019] The sowing step is: when the temperature of the ground surface 5 cm is stabilized at 10-12 DEG C or above, mechanical film sowing is adopted, the film width is 70 cm, corn is sowed according to the planting mode of 'one film one tube two rows', the row spacing on the film is 30-35 cm, the row spacing between the films is 65-70 cm, the plant spacing is 18-20 cm, one hole one particle sowing is adopted during sowing, the theoretical hole number per mu is 6667-7410 holes, and side sealing, soil covering and compaction are carried out; 2 times of intertillage are carried out during the corn seedling stage to the jointing stage, the intertillage is carried out between the two films, and the depths of the 2 times of intertillage are 8-10 cm and 30 cm or above respectively, and the subsequent field water and fertilizer management and pest control are consistent with the local management.

[0020] Compared with the prior art, the application has the following advantages:

[0021] 1. The application is mainly suitable for the moderately severe salinized soil in Xinjiang, and the existing saline water freezing irrigation application range is mainly in coastal saline-alkali soil, and the soil type, soil salinization type, soil salinization degree and winter and spring climate conditions are quite different, so the existing saline water freezing irrigation technical parameters cannot be directly copied. Therefore, the application obtains the technical parameters of the saline water freezing irrigation suitable for the different degree salinized soil in the Xinjiang arid irrigation area based on the ternary quadratic general rotary combination design, and the technical parameters of the saline water irrigation can be modified combined with the actual situation of the region to determine the applicable technical parameters in the region, and the practicability is high.

[0022] 2. The application fully utilizes the unconventional water resources in the alkali discharge channel in the Xinjiang irrigation area, saves the fresh water resources in the winter irrigation process in the Xinjiang irrigation area, utilizes the surface saline water resources, and reduces the investment in infrastructure such as well digging.

[0023] 3. The application reduces the soil salinity in the plough layer after the saline water ice melts, guarantees the formation of a low-salinity area in the crop root area, and is helpful for the emergence and later growth of crops.

[0024] 4. Under the guidance of the improved method of the present application, the desalination rate of the 0~20 cm soil layer of the salt water ice irrigation treatment group with a 300 mm irrigation height is greater than 52%, which is better than the salt water ice irrigation treatment group with a 180 mm irrigation height, and the 180 mm irrigation height is the recommended irrigation height of coastal saline-alkali soil; during the corn seedling stage, the emergence rate of the salt water ice irrigation treatment group with a 300 mm irrigation height is higher than that of the fresh water treatment group with the same irrigation height, and the emergence rate is more than 92%, and the seedling growth is good; the salt water ice irrigation parameters obtained by the present application are suitable for leaching desalination of saline-alkali soil in Xinjiang.

[0025] The present application will be further described in detail below in combination with the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is the indoor soil column simulation test flowchart in the present application;

[0027] Figure 2 It is the influence of irrigation height, salt water salinity and SAR on the desalination rate of the 0~20 cm soil layer of moderate saline soil;

[0028] Figure 3 It is the influence of interaction on the desalination rate of the 0~20 cm soil layer of moderate saline soil;

[0029] Figure 4 It is the interaction of irrigation height and SAR, salt water salinity and SAR on the desalination rate of the 0~20 cm soil layer of moderate saline soil;

[0030] Figure 5 It is the influence of irrigation height, salt water salinity and SAR on the desalination rate of the 0~20 cm soil layer of severe saline soil;

[0031] Figure 6 It is the influence of interaction on the desalination rate of the 0~20 cm soil layer of severe saline soil;

[0032] Figure 7 It is the interaction of irrigation height and SAR, salt water salinity and SAR on the desalination rate of the 0~20 cm soil layer of severe saline soil;

[0033] Figure 8 It is the salt water recycling and salt water ice irrigation flowchart of the alkali drainage ditch. DETAILED DESCRIPTION

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] The experimental area in this embodiment is located at Lingfeng Family Farm in Bohu County, Xinjiang Uygur Autonomous Region, my country, which is one of the main planting areas in the Bosten Lake Irrigation District. The area has an average annual temperature of 21.3 ℃, an average annual precipitation of 49.7 mm, an evaporation of 1133.03 mm, an annual sunshine duration of 2793.6~3136.5 h, a frost-free period of 219 days, and soil textures that are mostly loam, sandy loam, and sandy soil, with an average dry bulk density of 1.4 g·cm³. -3 High evaporation rates and low rainfall have resulted in high soil salinity in the region, severely limiting crop growth and agricultural development. In addition, the large-scale extraction of groundwater for agricultural production in the past has led to a drop in the groundwater level, with the groundwater depth during the irrigation season ranging from 1.2 to 1.8 meters. This has exacerbated the water resource conflict and become a "bottleneck" affecting agricultural production and sustainable development in Bohu County.

[0037] The method for reusing saline water from drainage ditches and improving saline-alkali land in Xinjiang, as described in this embodiment, is used to treat this area. The specific steps are as follows:

[0038] S1. Leveling the land: After the autumn harvest, construct strip fields 5 m wide and 30 m long, and build water storage dikes 50 cm wide and 35 cm high around the strip fields; use a combine harvester to remove the previous crop corn stalks from the field and use a rake / spring-toothed residual film recycling machine to collect the residual film. After the removal and treatment, carry out autumn plowing, and the soil plowing depth is 36 cm.

[0039] S2. Soil salinity survey: The water-soluble salt content of the soil was tested and determined to be 16.7 g·kg⁻¹. -1 Between 12 and 20 g·kg -1 Between these areas lies severely saline soil;

[0040] S3. Water quality survey of the drainage canal: The salinity and sodium adsorption ratio of the saline water in the drainage canal were tested, and the salinity of the saline water in the drainage canal around the experimental field was determined to be 13.80 g·L⁻¹. -1 The sodium adsorption ratio was 36.37 mmol. 1 / 2 ·L −1 / 2 ;

[0041] S4. Determine the irrigation height: For severely saline soils, substitute the salinity and sodium adsorption ratio of the saline water obtained in S3 into the regression equation: Equation (2)

[0042] In equation (2), The desalination rate of the 0~20 cm soil layer, % The water level is in mm. Mineralization, g·L -1 ; Sodium adsorption ratio, mmol 1 / 2 ·L −1 / 2 ; Calculate the irrigation height under the optimal soil desalination rate ;

[0043] When the irrigation depth reaches 300 mm, the desalination rate can reach over 52%, and the water-soluble salt content in the soil can be reduced to 8 g·kg⁻¹. -1 When the irrigation height is approximately 400 mm, the desalination rate decreases by only 0.71 g·kg compared to an irrigation height of 300 mm. -1 Soil contains water-soluble salts; therefore, under the condition of ensuring normal crop growth and minimizing the input of saline water, an irrigation height of 300 mm is selected.

[0044] S5. Irrigation under freezing conditions: From December 24th to 26th (when the average daily temperature is below -5℃ and the duration is not less than 25 days), saline water freezing irrigation will be carried out. The saline water in the drainage canal will be pumped out for irrigation. The irrigation will be carried out in two stages. The first irrigation will be 5 cm high to fully freeze the soil surface and reduce the infiltration of water during subsequent irrigation. This will ensure that the thawing rate of fresh water after freezing is high. After the first irrigation is completely frozen, the second irrigation will be carried out to a depth of 300 mm. The two irrigations will form a stable saline water ice layer of the predetermined height on the soil surface.

[0045] S6. Mulching: By collecting stable saline ice layers in winter and melting them in 5 cm layers, the results showed that the saline water underwent obvious stratification during the freezing process, with a saline water layer at the bottom and a fresh water layer at the top. Furthermore, during the warming process in spring, the saline ice layers obtained in S5 leached salt into the saline soil in the order of saline water melting first and fresh water melting later. The rate of infiltration of saline ice melt was significantly higher than that of fresh water ice melt, which improved the physical structure of the soil to a certain extent and accelerated the infiltration of meltwater.

[0046] On March 17, after the saltwater ice layer formed in S5 has completely melted, a 70 cm wide mulch film will be used to cover the area within a week to reduce surface evaporation and salt return.

[0047] S5. Corn Planting:

[0048] S501. Spring land preparation: On April 25, deep plowing should be carried out when the soil is at its optimal entropy, with a depth of 29 cm; after that, the land should be leveled again with a harrow before sowing, with a depth of 11 cm.

[0049] S502. Sowing: Corn is sown on May 5th (when the temperature at 5 cm soil depth is stable above 10-12℃). The corn variety selected is Denghai 605. Mechanized mulching sowing is adopted, with a film width of 70 cm. Sowing is carried out in the "one film, one pipe, two rows" pattern, with a row spacing of 33 cm above the film, a row spacing of 67 cm between films, and a plant spacing of 19 cm. One seed is sown per hole, with a theoretical number of holes per mu (6667-7410 holes per acre). The soil is then covered and compacted. Two cultivations are carried out between the two films during the corn seedling stage and the jointing stage, with cultivation depths of 9 cm and 35 cm respectively. Subsequent field water and fertilizer management and pest and disease control are consistent with local management practices.

[0050] In S1, the soil tillage depth can be 35 cm, 35.5 cm, 36.5 cm, or 37 cm; in S501, the deep tillage depth can be 28 cm, 28.5 cm, 29.5 cm, or 30 cm; the land leveling depth can be 10 cm, 10.5 cm, 11.5 cm, or 12 cm; in S502, the row spacing above the film can be 30 cm, 31 cm, 32 cm, 34 cm, or 35 cm, the row spacing between films can be 65 cm, 66 cm, 68 cm, 69 cm, or 70 cm, the plant spacing can be 18 cm, 18.5 cm, 19.5 cm, or 20 cm, and the depth of the first cultivation can be 8 cm, 8.5 cm, 9 cm, or 10 cm.

[0051] Comparative Example 1

[0052] In this comparative example, the method for reusing saline water from drainage ditches and improving saline-alkali land in Xinjiang region involves a second irrigation in step S5, which irrigates to a depth of 180 cm in one go. All other steps are exactly the same as the improvement method in Example 1.

[0053] Comparative Example 2

[0054] In this comparative example, the method for reusing saline water from drainage ditches and improving saline-alkali land in Xinjiang region involves a second irrigation in step S5, which irrigates to a depth of 240 cm. All other steps are exactly the same as the improvement method in Example 1.

[0055] According to the results of field trials, the seedling emergence rate of maize in the saline water freezing irrigation treatment groups with irrigation heights of 180 mm, 240 mm, and 300 mm was higher than that in the freshwater treatment group with the same irrigation height, with an emergence rate of over 92% and better seedling growth. Among them, the emergence rate of the 300 mm irrigation treatment group was the highest, at 94.10%. In terms of desalination rate in the 0-20 cm soil layer, the saline water freezing irrigation treatment group with an irrigation height of 300 mm was better than the saline water freezing irrigation treatment groups with irrigation heights of 180 mm and 240 mm.

[0056] In summary, the saline-alkali land management method in Example 1 helps to conserve freshwater resources in arid areas, and to a certain extent, it helps to reduce the salinity of saline-alkali land, improve soil structure, and promote the development of agriculture in irrigated areas.

[0057] The water level confirmation test in this invention is as follows:

[0058] Using soil column simulation experiments, a regression equation model was established between the desalination rate of moderately and severely saline soils in Xinjiang and the irrigation height, salinity of saline water, and sodium adsorption ratio during the salt water freezing irrigation process; the steps of the soil column simulation experiment ( Figure 1 (As shown) This includes initial data acquisition, design of a ternary quadratic general rotational combination design experimental scheme, simulation of water and salt movement processes under different parameter combinations, single-factor and interaction effect analysis, and determination of the optimal regression equation model;

[0059] Initial data collection included the total water-soluble salt content of saline soil, the content of the eight major ions, water content, and the quality of irrigation saline water.

[0060] A ternary quadratic universal rotatable design was selected to determine the experimental scheme. The ternary quadratic universal rotatable design has fixed coding values, including -1.682, -1, 0, 1, and 1.682, and the number of trials is 20. First, the experimental factors need to be determined. This experiment selected irrigation height, salinity, and SAR as the three experimental factors, and determined the lower level (corresponding to coding value -1), zero level (corresponding to coding value 0), and upper level (corresponding to coding value 1) for each factor.

[0061] Table 1 Experimental factors and levels

[0062] Secondly, the actual level values ​​under different coding values ​​are calculated based on the existing coding values ​​and formulas (1) and (2).

[0063] in, The actual level value corresponding to the encoded value. This represents the actual level value corresponding to a coded value of 0. For encoded values, Step size, This represents the actual level value corresponding to a code value of 1. This represents the actual level value corresponding to a coded value of -1. The correspondence between coded values ​​and actual level values ​​is shown in Table 2.

[0064] Table 2. Test treatment code values ​​and actual level values

[0065] Finally, based on the experimental table of the ternary quadratic general rotational combination design (20 experiments), the orthogonal experimental scheme was finally determined (as shown in Table 3).

[0066] Table 3 Orthogonal Table of Experimental Treatments

[0067] Based on the experimental results, a regression equation model was established between irrigation height, salinity, SAR and desalination rate. A single-factor analysis of variance and interaction effect analysis of parameter combinations were performed on the model to determine the final regression equation model.

[0068] Figure 2 To investigate the effects of three single factors—irrigation height, salinity, and SAR—on the desalination rate of the 0–20 cm soil layer in moderately saline soil, the following analysis was conducted: Figure 2 It can be seen that the desalination rate of moderately saline soil (0-20 cm) is positively correlated with irrigation volume, negatively correlated with saline water mineralization, and has a downward-opening parabolic relationship with SAR. Moreover, from the perspective of a single factor, the correlation between desalination rate and SAR is relatively small.

[0069] Figure 3 To investigate the effect of interaction on the desalination rate of moderately saline soil in the 0–20 cm soil layer, from... Figure 3 It can be seen that under moderately saline soil conditions, the interaction between saline water salinity and SAR is the most significant, followed by the interaction between irrigation amount and SAR. Moreover, their interaction is positively correlated with the desalination rate. The interaction between irrigation amount and saline water salinity is reflected in the fact that the higher the irrigation amount and the lower the salinity, the higher the desalination rate.

[0070] Figure 4 To investigate the interaction between irrigation height and SAR, salinity and SAR on the desalination rate of moderately saline soil layer 0–20 cm, from Figure 4 It can be seen that, in the interaction between salinity and SAR on desalination rate, the maximum desalination rate is 48.51%, of which salinity is 3 g·L⁻¹. −1The SAR value reached its maximum at 27. Among the interactions between irrigation height and SAR on the desalination rate, the maximum desalination rate was 49.74%, which was reached at an irrigation height of 300 mm and a SAR value of 27.

[0071] Figure 5 To investigate the effects of three single factors—irrigation height, salinity of saline water, and SAR—on the desalination rate of the 0–20 cm soil layer in severely saline soil, the following analysis was conducted: Figure 5 It can be seen that the desalination rate of severely saline soil in the 0-20 cm depth is positively correlated with irrigation height, negatively correlated with saline water mineralization, and has a downward-opening parabolic relationship with SAR. Moreover, from the perspective of a single factor, the correlation between desalination rate and SAR is relatively small.

[0072] Figure 6 To investigate the effect of interaction on the desalination rate of the 0–20 cm soil layer in severely saline soil, from... Figure 6 It can be seen that under the condition of severely saline soil, the interaction between saline water salinity and SAR is the most significant and is positively correlated with the desalination rate. The second most significant interaction is between irrigation height and SAR, which is negatively correlated with the desalination rate. The interaction between irrigation height and saline water salinity is reflected in the fact that the higher the irrigation height and the lower the salinity, the higher the desalination rate.

[0073] Figure 7 To illustrate the interaction between irrigation height and SAR, salinity and SAR on the desalination rate of the 0-20 cm soil layer in severely saline soil, from... Figure 7 It can be seen that, in the interaction between salinity and SAR on desalination rate, the maximum desalination rate is 51.52%, of which salinity is 3 g·L⁻¹. −1 The SAR reaches its maximum at 27. Among the interaction between irrigation height and saline SAR on desalination rate, the maximum desalination rate is 50.52%, with the irrigation height being 300 mm and the SAR reaching its maximum at 27.

[0074] For moderately saline soils, the regression equations for irrigation height, salinity of saline water, sodium adsorption ratio, and soil desalination rate are as follows: Equation (1)

[0075] In equation (1), X1 represents the desalination rate (%) of the 0~20 cm soil layer, X2 represents the irrigation height (mm), and X3 represents the salinity of the saline water (g·L). -1 X3 represents the sodium adsorption ratio (mmol). 1 / 2 ·L −1 / 2 );

[0076] The significance test yielded R. 2= 0.9804, F = 0.3715 (p>0.05) in the failure test, the model fits the data well and there is no obvious failure phenomenon. The regression equation can explain the effect of different water quality on the desalination of moderately saline soil under different irrigation heights, as well as the correlation between irrigation height, mineralization, SAR and the desalination rate of the top 0~20 cm soil.

[0077] For severely saline soils, the regression equations for irrigation height, salinity of saline water, sodium adsorption ratio, and soil desalination rate are as follows: Equation (2)

[0078] In equation (2), The desalination rate (%) of the 0~20 cm soil layer. The water level is in mm. salinity (g·L) -1 ), Sodium adsorption ratio (mmol) 1 / 2 ·L −1 / 2 );

[0079] The significance test yielded R. 2 = 0.9867, F=0.6762 (p>0.05) in the failure test, the model fits the data well and there is no obvious failure phenomenon; the regression equation can explain the effect of different water quality on the desalination of severely saline soil at different irrigation heights, as well as the correlation between irrigation height, mineralization, SAR and the desalination rate of the top 0~20 cm soil.

[0080] Before winter irrigation, a survey of soil salinity and drainage canal water quality in the irrigation area was conducted; the regression equation model to be used was determined based on the soil salinity level, which was 6–12 g·L⁻¹. -1 At that time, a regression equation model was used to analyze the desalination rate of moderately saline soil in relation to irrigation height, salinity of saline water, and sodium adsorption ratio. The soil salinity was 12–20 g·L⁻¹. -1 When selecting a model, a regression equation model is chosen to connect the desalination rate with irrigation height, salinity of saline water, and sodium adsorption ratio under severely saline soil. Then, the known salinity of saline water and sodium adsorption ratio are substituted into the regression equation model to solve for the irrigation height under the optimal desalination rate. After determining the irrigation height, field irrigation with saline water freezing is carried out when the average daily temperature in winter is below a certain temperature and will remain below a certain number of days in the future.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for reusing saline water from drainage ditches and improving saline-alkali land in Xinjiang, characterized in that, The method includes the following steps: S1. Leveling the land: After the autumn harvest, construct strip fields and build water storage dikes around the strip fields; then remove the previous crop from the field, collect the residual plastic film, and then till the soil. S2. Soil salinity survey: The water-soluble salt content of the soil was measured to determine the degree of soil salinization. In Xinjiang, the water-soluble salt content of moderately salinized soils ranged from 6 to 12 g·kg⁻¹. -1 The water-soluble salt content of severely saline soils ranges from 12 to 20 g / kg. -1 ; S3. Water quality survey of drainage canal: The salinity and sodium adsorption ratio of the saline water in the drainage canal were tested. S4. Determine the irrigation height: For the moderately saline soil described in S2, substitute the salinity and sodium adsorption ratio of the saline water obtained in S3 into the regression equation: Equation (1) In equation (1), The desalination rate of the 0-20 cm soil layer is %; X1 is the irrigation height in mm; X2 is the mineralization degree in g·L. -1 X3 represents the sodium adsorption ratio, in mmol. 1 / 2 ·L −1 / 2 ; Calculate the irrigation height X1 under the optimal soil desalination rate; For the severely salinized soil described in S2, the mineralization degree and sodium adsorption ratio of the saline water detected in S3 are substituted into the regression equation: Equation (2) In equation (2), The desalination rate of the 0~20 cm soil layer, % The water level is in mm. Mineralization, g·L -1 ; Sodium adsorption ratio, mmol 1 / 2 ·L −1 / 2 ; Calculate the irrigation height under the optimal soil desalination rate ; S5. Irrigation under freezing conditions: When the average daily temperature in winter is maintained at a certain temperature and for a certain number of days, the first irrigation is carried out. After the first irrigation is completely frozen, the second irrigation is carried out to reach the irrigation height obtained in S4. Under low temperature conditions, a stable saltwater ice layer is formed. S6. Mulching: During the spring warming process, the stable saline ice layer formed in S5 is used to leach salt into the saline soil in the order of saline water melting first and fresh water melting later. After the saline ice layer has completely melted, mulching is carried out within one week. S7. Corn planting: Spring land preparation, sowing, and field management are carried out in sequence.

2. The method for reusing saline water from drainage ditches and improving saline-alkali land in Xinjiang region according to claim 1, characterized in that, The water storage embankment described in S1 is 50 cm wide and 35 cm high; the soil tillage depth is 35-37 cm.

3. The method for reusing saline water from drainage ditches and improving saline-alkali land in Xinjiang region according to claim 1, characterized in that, In S5, if the average daily temperature remains below -7°C for at least 10 days or if the average daily temperature remains below -5°C for at least 25 days, the first irrigation shall be carried out, and the height of the first irrigation shall be 5 cm.

4. A method for reusing saline water from drainage ditches and improving saline-alkali land in Xinjiang region according to claim 1, characterized in that, The width of the mulch film described in S6 is 70 cm.

5. A method for reusing saline water from drainage ditches and improving saline-alkali land in Xinjiang region according to claim 1, characterized in that, The steps for spring land preparation described in S7 are as follows: tilling is carried out when the soil is at an appropriate entropy, and land leveling is carried out again before sowing; the tilling depth is 28-30 cm, and the land leveling depth is 10-12 cm. The sowing steps are as follows: When the temperature at a depth of 5 cm is stable above 10-12 ℃, mechanized film mulching sowing is adopted. The film is 70 cm wide, and corn is sown according to the "one film, one pipe, two rows" planting pattern. The row spacing above the film is 30-35 cm, the row spacing between films is 65-70 cm, and the plant spacing is 18-20 cm. One seed is sown per hole, with a theoretical number of holes per acre of 6667-7410. The soil is then covered and compacted. Two cultivations are carried out between the two films during the corn seedling stage to the jointing stage. The cultivation depths are 8-10 cm and 30 cm or more, respectively. Subsequent field water and fertilizer management and pest and disease control are consistent with local management practices.

Images