阅读说明：本技术 一种增强脱硫石膏改良盐碱旱地的方法 (Method for improving saline-alkali dry land by enhancing desulfurized gypsum ) 是由 赵永敢 王淑娟 李彦 禚玉群 徐立珍 于 2021-09-02 设计创作，主要内容包括：本发明公开了一种增强脱硫石膏改良盐碱旱地的方法。本发明增强脱硫石膏改良盐碱旱地的方法包括如下步骤：S1、在待改良的盐碱旱地中待种植的作物的根系附近施用脱硫石膏；S2、在经步骤S1处理的土地上铺设滴灌带；滴灌带的滴头位于脱硫石膏的正上方；S3、在经过步骤S2处理的土地上播种；播种结束后,在作物生长过程中通过滴灌对脱硫石膏置换出的盐分离子进行淋洗,实现盐碱旱地的高效改良。本发明在滴灌时,可将脱硫石膏中的钙离子逐渐溶解出来,并随土壤水分的迁移而逐渐扩撒,在水平和垂直方向形成钙离子通道,增加土壤渗透性,促进土壤降碱和脱盐；结合土壤墒情确定滴灌用水量,分阶段将黄腐酸和柠檬酸随水滴入土壤中,提高土壤降碱和脱盐效果。(The invention discloses a method for improving saline-alkali dry land by enhancing desulfurized gypsum. The method for enhancing the desulfurized gypsum to improve the saline-alkali dry land comprises the following steps: s1, applying desulfurized gypsum near the root system of the crop to be planted in the saline-alkali dry land to be improved; s2, paving a drip irrigation tape on the land treated in the step S1; the dripper of the drip irrigation belt is positioned right above the desulfurized gypsum; s3, sowing seeds on the land processed by the step S2; after sowing, the salt segregants displaced by the desulfurized gypsum are leached by drip irrigation in the crop growth process, and the high-efficiency improvement of the saline-alkali dry land is realized. When the drip irrigation is carried out, calcium ions in the desulfurized gypsum can be gradually dissolved out and gradually spread along with the migration of soil moisture, calcium ion channels are formed in the horizontal direction and the vertical direction, the permeability of the soil is increased, and the alkali reduction and the desalination of the soil are promoted; the water consumption for drip irrigation is determined by combining the soil moisture content, and the fulvic acid and the citric acid are dripped into the soil along with water in stages, so that the alkali reduction and desalination effects of the soil are improved.)

1. A method for enhancing desulfurized gypsum to improve saline-alkali dry land comprises the following steps:

s1, applying desulfurized gypsum near the root system of the crop to be planted in the saline-alkali dry land to be improved;

s2, paving a drip irrigation tape on the land treated in the step S1; the dripper of the drip irrigation belt is positioned right above the desulfurized gypsum;

s3, sowing seeds on the land processed by the step S2; after sowing, leaching the salt segregant displaced by the desulfurized gypsum by drip irrigation in the crop growth process, and realizing the high-efficiency improvement of the saline-alkali dry land.

2. The method of claim 1, wherein: in step S1, determining the application position of the desulfurized gypsum according to the planting mode of the crops;

the planting mode is wide-narrow row planting, the narrow rows are used as planting belts, and each planting belt is provided with two rows of planting strips;

the positions of the application of the desulfurized gypsum are as follows: and (3) forming a V-shaped groove in the middle of the two rows of planting strips along the row, and uniformly applying desulfurized gypsum in the V-shaped groove.

3. The method of claim 2, wherein: the wide row spacing of the wide-narrow row planting is 70-90 cm, and the narrow row spacing is 50-60 cm;

the depth of the V-shaped groove is 3-5 cm;

the distance between the center position of the bottom of the V-shaped groove and the planting strips on the two sides is 25-30 cm.

4. The method according to any one of claims 1-3, wherein: in step S1, the required amount of desulfurized gypsum is calculated according to the following formula:

GR＝[86.07×CEC×(ESP–5％)+86.04×TA–28.22]×H×D/R×η (1)；

in the formula (1), GR is the required amount of desulfurized gypsum and the unit is kg/hectare; CEC is soil cation exchange capacity, unit cmol/kg; ESP is the soil alkalization degree, and the unit is; TA is total alkalinity of soil, and the unit is cmol/kg; h is the soil improvement depth, and the unit is cm; d is the volume weight of soil and the unit is g/cm³(ii) a R is the effective utilization rate of the desulfurized gypsum and has the unit of percent; eta is the mass fraction of the calcium sulfate dihydrate in the desulfurized gypsum, and the unit is;

determining the application amount of the desulfurized gypsum according to the saline-alkali degree of 0-20 cm of soil:

when the saline-alkali soil is slightly alkalized: when the pH value of the soil is more than or equal to 8.5 and less than or equal to 9, applying 10-15 wt% of GR desulfurized gypsum;

when the saline-alkali soil is moderately alkalized: when the pH value of the soil is more than 9 and less than or equal to 9.5, applying 15-20 wt% of GR desulfurized gypsum;

when the saline-alkali soil is heavily alkalized: the pH value of the soil is more than 9.5, and desulfurized gypsum with 20-30 wt% GR is applied.

5. The method according to any one of claims 1-4, wherein: the following steps are also included between step S2 and step S3: burying a negative pressure meter near a dripper of the drip irrigation tape;

the horizontal distance between the negative pressure gauge and a dripper of the drip irrigation belt is 1-3 cm;

the embedding depth of the negative pressure gauge is 20-25 cm;

the embedding quantity of the negative pressure meters is determined according to the area size of the saline-alkali dry land to be improved, 1 drip irrigation unit is the saline-alkali dry land with the area smaller than 30 mu, and 3-5 negative pressure meters are embedded in each drip irrigation unit;

in step S3, the drip irrigation timing is determined based on the reading of the negative pressure gauge.

6. The method of claim 5, wherein: the drip irrigation time, the drip irrigation quantity and the flow of the drippers are as follows:

immediately carrying out drip irrigation after the crop is sown, wherein the drip irrigation amount is 20-30 m³Controlling the flow rate of the drippers to be 0.5-1L/h per mu;

in the seedling stage of the crops, when the reading mean value of any 3 negative pressure meters exceeds-10 kPa, drip irrigation is carried out, the drip irrigation is stopped until the reading mean value of the negative pressure meters returns to-10 kPa, and the flow rate of a dripper is controlled to be 1-2L/h;

after the plant height of the crops reaches 30-50 cm, carrying out drip irrigation when the reading mean value of any 3 negative pressure meters exceeds-20 kPa until the reading mean value of the negative pressure meters returns to-20 kPa, and stopping drip irrigation, wherein the flow rate of a dripper is controlled at 2-4L/h;

stopping the drip irrigation when the crop enters the mature period.

7. The method according to any one of claims 1-6, wherein: in step S3, applying a water-soluble modifier to the drip irrigation at the same time; the application timing, application mode and application amount of the water-soluble modifier are as follows:

when the drip irrigation is carried out in the seedling stage of the crops, the water-soluble modifying agent is dissolved in water and applied to soil along with the drip irrigation, and the application amount is 1-3 kg/mu each time; the water-soluble modifier is an organic acid modifier, preferably fulvic acid;

when the plant height of the crops reaches 30-50 cm and then drop irrigation is carried out, dissolving the water-soluble modifying agent in water and applying the water-soluble modifying agent into soil along with the drop irrigation, wherein the application amount of each time is 1-3 kg/mu; the water-soluble modifier is an organic acid modifier, preferably citric acid.

8. The method according to any one of claims 1-7, wherein: in step S3, applying water-soluble quick-acting fertilizer at the same time of drip irrigation; the application time, the application mode and the application amount of the water-soluble quick-acting fertilizer are as follows:

when the drip irrigation is carried out in the seedling stage of the crops, the water-soluble quick-acting fertilizer is dissolved in water and applied to soil along with the drip irrigation, and the application amount is 4-10 kg/mu each time;

when the plant height of the crops reaches 30-50 cm and then drop irrigation is carried out, dissolving the water-soluble quick-acting fertilizer in water and applying the water-soluble quick-acting fertilizer into soil along with the drop irrigation, wherein the application amount is 4-10 kg/mu each time;

the water-soluble quick-acting fertilizer is a nitrogen fertilizer, preferably urea.

9. The method according to claim 7 or 8, characterized in that: the time for applying the water-soluble quick-acting fertilizer and the time for applying the water-soluble modifying agent are staggered;

drip irrigation for 2 times in the seedling stage of the crops, the water-soluble modifying agent is applied in the 1 st drip irrigation, and the water-soluble quick-acting fertilizer is applied in the 2 nd drip irrigation;

and (3) carrying out drip irrigation for 2 times when the plant height of the crop reaches 30-50 cm, applying the water-soluble modifying agent in the 1 st drip irrigation, and applying the water-soluble quick-acting fertilizer in the 2 nd drip irrigation.

10. The method according to any one of claims 1-9, wherein: after step S3, the method further includes the following steps: carrying out rotary tillage on the land after the crops are harvested so as to fully mix the residual desulfurized gypsum with the surface soil;

the rotary tillage mode is cross;

the rotary tillage depth is 15-18 cm.

Technical Field

The invention belongs to the technical field of saline-alkali dry land improvement, and particularly relates to a method for improving saline-alkali dry land by using desulfurization gypsum.

Background

The area of the saline-alkali soil in China is large, and the total area of various saline-alkali soil is about 3600 kilohm²Is in China4.88% of the soil area is mainly distributed in 19 provinces (cities and districts) such as inner Mongolia, Liaoning, Jilin, Heilongjiang and the like. The key of saline-alkali soil improvement is to reduce the content of exchangeable sodium ions on soil colloid, and the supplement of calcium ions is a world-recognized effective method. A large number of researches and practices prove that the desulfurized gypsum can be used as an economical and efficient calcium-based soil conditioner and is widely applied to saline-alkali soil improvement. The systematic study of the appropriate amount, time and depth of application of the desulfurized gypsum has been conducted by the former people, and a great progress has been made. However, the current application mode of the desulfurized gypsum is mainly ground surface application, the uniformity of the desulfurized gypsum is greatly influenced by the application equipment, the application amount is often large, the improvement effect is influenced, and the application cost is increased to a certain extent. Therefore, it has become a subject of intensive research by technologists to find a method for reducing the desulfurization gypsum without reducing the effect and with simple and convenient operation.

The technical mechanism of the desulfurized gypsum for improving the saline-alkali soil is that the dissolved calcium ions and the soil undergo ion replacement and salt conversion reaction, thereby realizing the purpose of reducing the saline-alkali harm of the soil. However, the ions displaced by the desulfurized gypsum, and the salts generated by the reaction with the desulfurized gypsum, are required to be leached into deep soil by irrigation measures, or to be dissolved out of soil, which requires a large amount of water consumption. In arid and semiarid regions, fresh water resources are deficient, and the effect of the desulfurized gypsum on improving the saline-alkali soil is influenced to a certain extent.

Disclosure of Invention

The invention aims to provide a method for improving saline-alkali dry land by enhancing desulfurized gypsum, which effectively solves the problems of large water demand and water resource shortage in arid regions in the saline-alkali land improved by desulfurized gypsum, reduces the problems of large application amount of desulfurized gypsum in the traditional ground surface broadcasting application and the like, and improves the utilization efficiency and improvement effect of desulfurized gypsum.

The invention provides a method for improving saline-alkali dry land by enhancing desulfurized gypsum, which comprises the following steps:

s1, applying desulfurized gypsum near the root system of the crop to be planted in the saline-alkali dry land to be improved;

s2, paving a drip irrigation tape on the land treated in the step S1; the dripper of the drip irrigation belt is positioned right above the desulfurized gypsum;

s3, sowing seeds on the land processed by the step S2; after sowing, leaching the salt segregant displaced by the desulfurized gypsum by drip irrigation in the crop growth process, and realizing the high-efficiency improvement of the saline-alkali dry land.

In the invention, the desulfurization gypsum is applied around the root system of the crop, so that the effective components can be concentrated to improve the rhizosphere soil, the application amount of the desulfurization gypsum can be reduced, and the utilization efficiency and the improvement effect of the desulfurization gypsum can be improved; in addition, the desulfurized gypsum is applied to the position right below the drippers of the drip irrigation tape, and the dissolved calcium ions can gradually migrate to the horizontal direction and the vertical direction along with the movement of the wetting front to form calcium ion channels, so that the aims of soil alkali reduction and desalting are fulfilled.

The method as described above, step S1, the crop to be planted includes, but is not limited to, the crop conventionally planted in saline-alkali dry land such as corn, sunflower, sorghum, etc.

In the method, in step S1, a suitable planting method may be selected according to the type of the crop, and the application position of the desulfurized gypsum is determined according to the planting method of the crop;

as an example, the planting mode is wide-narrow row planting, narrow rows are taken as planting belts, and each planting belt is provided with two rows of planting strips;

the positions of the application of the desulfurized gypsum are as follows: and (3) forming a V-shaped groove in the middle of the two rows of planting strips along the row, and uniformly applying desulfurized gypsum in the V-shaped groove.

Furthermore, the wide row spacing of the wide-narrow row planting is 70-90 cm (such as 75-80 cm, 75cm or 80cm), and the narrow row spacing is 50-60 cm (such as 60 cm);

the depth of the V-shaped groove is 3-5 cm, such as 3 cm;

the distance between the center position of the bottom of the V-shaped groove and the planting strips on the two sides is 25-30 cm, such as 25 cm.

The method further includes, before step S1, the following steps: applying base fertilizer along the row strips on two sides of the planting strip to form a fertilizing strip; the distance between the fertilization strip and the planting strip can be 5-10 cm, such as 5-6 cm, 5cm or 6 cm.

In the above method, in step S1, the required amount of the desulfurized gypsum is calculated according to the following formula:

GR＝[86.07×CEC×(ESP–5％)+86.04×TA–28.22]×H×D/R×η (1)；

in the formula (1), GR is the required amount of desulfurized gypsum and the unit is kg/hectare; CEC is soil cation exchange capacity, unit cmol/kg; ESP is the soil alkalization degree, and the unit is; TA is total alkalinity of soil, and the unit is cmol/kg; h is the soil improvement depth, and the unit is cm; d is the volume weight of soil and the unit is g/cm³(ii) a R is the effective utilization rate of the desulfurized gypsum and has the unit of percent; eta is the mass fraction of the calcium sulfate dihydrate in the desulfurized gypsum, and the unit is;

determining the application amount of the desulfurized gypsum according to the salinization degree of 0-20 cm of soil:

when the saline-alkali soil is slightly alkalized: when the pH value of the soil is more than or equal to 8.5 and less than or equal to 9, applying 10-15 wt% of GR desulfurized gypsum;

when the saline-alkali soil is moderately alkalized: when the pH value of the soil is more than 9 and less than or equal to 9.5, applying 15-20 wt% of GR desulfurized gypsum;

when the saline-alkali soil is heavily alkalized: the pH value of the soil is more than 9.5, and desulfurized gypsum with 20-30 wt% GR is applied.

The method, in step S2, the drip irrigation tape may be a capillary drip irrigation tape; the drip irrigation belt is connected with a main pipeline of the drip irrigation system. The distance between the drippers of the drip irrigation zone and the desulfurized gypsum can ensure that the water dripped by the drippers can be used for wetting the desulfurized gypsum, such as 0-2 cm, such as 1 cm.

The method may further include the following steps between the step S2 and the step S3: laminating the planting belt in the land treated by the step S1; the plastic film may have a thickness of 0.01 to 0.02mm, for example, 0.01mm, and a width of 70 cm.

The method described above, between step S2 and step S3 (specifically, after the coating), may further include the following steps: burying a negative pressure meter near a dripper of the drip irrigation tape;

the horizontal distance between the negative pressure gauge and a dripper of the drip irrigation belt is 1-3 cm, such as 1 cm;

the embedding depth of the negative pressure gauge is 20-25 cm, and specifically can be 20cm or 25 cm;

the embedding number of the negative pressure meters is determined according to the area size of the saline-alkali dry land to be improved, 1 drip irrigation unit is the saline-alkali dry land with the area smaller than 30 acres (such as 8-10 acres, 8 acres or 10 acres), and 3-5 (such as 5) negative pressure meters are embedded in each drip irrigation unit;

in step S3, the drip irrigation timing is determined based on the reading of the negative pressure gauge.

The drip irrigation adopts water and fertilizer integrated drip irrigation equipment; determining the water consumption and drip irrigation time according to the water demand characteristics and the growth period of crops; the drip irrigation timing, drip irrigation volume and the flow rate of the drippers may be as follows:

immediately carrying out drip irrigation after the crop is sown, wherein the drip irrigation amount is 20-30 m³Per mu (e.g. 20-25, 20 or 25 m)³Per mu), the flow rate of the drippers is controlled to be 0.5-1L/h (such as 0.5L/h or 1L/h);

in the seedling stage of the crops, when the reading mean value of any 3 negative pressure meters exceeds-10 kPa, drip irrigation is carried out, until the reading mean value of the negative pressure meters returns to-10 kPa, drip irrigation is stopped, and the flow rate of a dripper is controlled to be 1-2L/h (such as 1.5-2L/h, 1.5L/h or 2L/h);

after the plant height of the crops reaches 30-50 cm (for example, more than 50cm), carrying out drip irrigation when the reading mean value of any 3 negative pressure meters exceeds-20 kPa until the reading mean value of the negative pressure meters returns to-20 kPa, and stopping drip irrigation, wherein the flow rate of a dripper is controlled at 2-4L/h (for example, 3-4L/h, 3L/h or 4L/h);

stopping the drip irrigation when the crop enters the mature period.

The method, step S3, wherein the drip irrigation is simultaneously applied with a water-soluble modifier; the application timing, application mode and application amount of the water-soluble modifier are as follows:

when the drip irrigation is carried out in the seedling stage of the crops, the water-soluble modifying agent is dissolved in water and applied to soil along with the drip irrigation, and the application amount of the water-soluble modifying agent is 1-3 kg/mu (such as 1-2 kg/mu, 1 kg/mu or 2 kg/mu) each time; the water-soluble modifier is an organic acid modifier, such as fulvic acid;

when the plant height of the crops reaches 30-50 cm and then drip irrigation is carried out, dissolving the water-soluble modifying agent in water and applying the water-soluble modifying agent into soil along with the drip irrigation, wherein the application amount is 1-3 kg/mu (such as 1-1.5 kg/mu, 1 kg/mu or 1.5 kg/mu) each time; the water-soluble modifier is an organic acid modifier, such as citric acid.

In the invention, the water-soluble modifier of organic acids such as fulvic acid, citric acid and the like is applied in a staged matching manner while drip irrigation is carried out, so that the effect of the desulfurized gypsum on improving the saline-alkali soil can be further enhanced through the synergistic effect with the desulfurized gypsum.

In the method, in step S3, the drip irrigation is performed while applying a water-soluble quick-acting fertilizer; the application time, the application mode and the application amount of the water-soluble quick-acting fertilizer are as follows:

when the drip irrigation is carried out in the seedling stage of the crops, the water-soluble quick-acting fertilizer is dissolved in water and applied to soil along with the drip irrigation, and the application amount is 4-10 kg/mu (such as 6-8 kg/mu, 6 kg/mu or 8 kg/mu);

when the plant height of the crops reaches 30-50 cm and then drip irrigation is carried out, the water-soluble quick-acting fertilizer is dissolved in water and applied to soil along with the drip irrigation, and the application amount of the fertilizer is 4-10 kg/mu (such as 6-8 kg/mu, 6 kg/mu or 8 kg/mu) each time;

the water-soluble quick-acting fertilizer is a nitrogen fertilizer, such as urea.

In the invention, the water-soluble quick-acting fertilizer and the water-soluble modifier are applied at different time, and cannot be applied at the same time. For example, the drip irrigation is carried out 2 times in the seedling stage of the crop, the water-soluble modifying agent is applied in the 1 st drip irrigation, and the water-soluble quick-acting fertilizer is applied in the 2 nd drip irrigation; and (3) carrying out drip irrigation for 2 times when the plant height of the crop reaches 30-50 cm, applying the water-soluble modifying agent in the 1 st drip irrigation, and applying the water-soluble quick-acting fertilizer in the 2 nd drip irrigation.

The method may further include the following steps after step S3: carrying out rotary tillage on the land after the crops are harvested so as to fully mix the residual desulfurized gypsum with the surface soil;

the rotary tillage mode can be cross;

the rotary tillage depth can be 15-18 cm.

The invention has the following beneficial effects:

the invention provides a method for improving saline-alkali dry land by enhancing desulfurized gypsum. During drip irrigation, calcium ions in the desulfurized gypsum can be gradually dissolved out and gradually spread along with the migration of soil moisture, calcium ion channels are formed in the horizontal direction and the vertical direction, the permeability of the soil is increased, and the alkali reduction and desalination of the soil are promoted. Drip irrigation is carried out timely according to the growth and development process of crops, the water consumption of drip irrigation is determined by combining the soil moisture content, fulvic acid and citric acid are dripped into soil along with water in stages, the alkali reduction and desalination effects of the soil are improved, and the improvement effect of the next year can be improved after the residual desulfurized gypsum is rotary-tilled with surface soil.

Drawings

FIG. 1 is a side view of the field layout in the method for enhancing desulfurized gypsum to improve saline-alkali dry land.

The respective symbols in the figure are as follows:

101-base fertilizer; 102-a crop; 103-desulfurized gypsum; 104-drip irrigation tape drippers; 105-a plastic film; 106-negative pressure gauge.

Detailed Description

The invention provides a method for improving saline-alkali dry land by enhancing desulfurized gypsum, which comprises the following steps:

s1, applying desulfurized gypsum near the root system of the crop to be planted in the saline-alkali dry land to be improved;

s2, paving a drip irrigation tape on the land treated in the step S1; the dripper of the drip irrigation belt is positioned right above the desulfurized gypsum;

s3, sowing seeds on the land processed by the step S2; after sowing, the salt segregant displaced by the desulfurized gypsum is leached by drip irrigation in the crop growth process, and the high-efficiency improvement of the saline-alkali dry land can be realized.

In the invention, the desulfurization gypsum is applied around the root system of the crop, so that the effective components can be concentrated to improve the rhizosphere soil, the application amount of the desulfurization gypsum can be reduced, and the utilization efficiency and the improvement effect of the desulfurization gypsum can be improved; in addition, the desulfurized gypsum is applied to the position right below the drippers of the drip irrigation tape, calcium ions dissolved during drip irrigation can gradually migrate to the horizontal direction and the vertical direction along with the movement of the wetting front to form calcium ion channels and increase the permeability of soil, thereby realizing the purposes of alkali reduction and desalination of the soil.

The invention is further illustrated by the following specific embodiment by taking sunflower as a planting crop and planting in wide and narrow rows as a moderate and severe saline-alkali land of the town of Longxingchang, Wuyuan county, Bayankee city of inner Mongolia as the accompanying drawing of the specification. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

Example 1 desulfurization of Gypsum for improving saline-alkali Dry land

The test is carried out on severe saline-alkali soil in Rongchang Zhengyucun in Wuyuan county of Mongolia Bayan Du City of 2017, and is a typical representative of soil salinization and development in arid regions of China. The total area of the test field is 16 mu, the test field is divided into a test group and a control group, the test group and the control group are repeated for 3 times respectively, and the results are averaged. Before the test is started, the detection result of a foundation soil sample shows that the soil with the surface layer of 0-20 cm is silt loam, the average total salt content is 7.3g/kg, the pH value is 9.6, and the alkalization degree is 48.2%.

The test group carries out layout improvement on the saline-alkali dry land according to the side view of the field layout shown in figure 1, and the specific operation is as follows:

(1) land leveling: firstly, roughly leveling a project area by using a disc harrow, then finely leveling by using a laser land leveler, and controlling the height drop of the land surface of the leveled land within 5 cm.

(2) Applying a base fertilizer: and (3) applying base fertilizer by using a fertilizer applicator in a strip mode, wherein diammonium phosphate is adopted as the base fertilizer (101), and the fertilizing amount is 25 kg/mu. A wide-narrow row planting mode is adopted, wherein the wide row spacing is 75cm, the narrow row spacing is 60cm, and the wide row spacing and the narrow row spacing are alternated. And (3) applying fertilizer strips, covering soil on the fertilizer strips by 3cm, and keeping the distance between the fertilizer strips and the crop planting strips to be 6 cm.

(3) Applying desulfurized gypsum: and a V-shaped groove is formed in the middle position of the small row spacing, namely the middle position of two rows of crops (102), the depth of the groove is 3cm, and the distance between the center position of the groove bottom and the crop planting strips at two sides is 25 cm. And applying the desulfurized gypsum (103) into the V-shaped ditch, wherein the application amount of the desulfurized gypsum is 252 kg/mu.

The desulfurization gypsum application amount is determined by the following steps:

calculating the required amount GR of the desulfurized gypsum according to the following formula:

GR＝[86.07×CEC×(ESP–5％)+86.04×TA–28.22]×H×D/R×η(1)；

in the formula (1), GR is the required amount of desulfurized gypsum and the unit is kg/hectare; CEC is soil cation exchange capacity, unit cmol/kg; ESP is the soil alkalization degree, and the unit is; TA is total alkalinity of soil, and the unit is cmol/kg; h is the soil improvement depth, and the unit is cm; d is the volume weight of soil and the unit is g/cm³(ii) a R is the effective utilization rate of the desulfurized gypsum and has the unit of percent; eta is the mass fraction of the calcium sulfate dihydrate in the desulfurized gypsum, and the unit is percent.

In this example, CEC was 7.3 cmol/kg; ESP is 48.2%; TA 3.8 cmol/kg; h is 20 cm; d is 1.45g/cm³(ii) a R is 70 percent; eta is 80%. The GR was calculated to be 1260 kg/.

The saline-alkali soil of the embodiment is heavily alkalized: the pH value of the soil is more than 9.5, and 252 kg/mu is obtained by applying desulfurized gypsum with 20 wt% GR.

(4) Laying a drip irrigation tape: the required desulfurized gypsum is uniformly applied in a strip shape in a V-shaped ditch, then a drip irrigation tape (104) is laid right above the desulfurized gypsum strip (the vertical distance between the desulfurized gypsum and drippers of the drip irrigation tape is 1cm), and the drip irrigation tape is connected with a main pipeline of a drip irrigation system.

(5) Film covering: after the above operation, the plastic film (105) was laminated to a thickness of 0.01mm and a width of 70 cm.

(6) Burying a negative pressure meter: after the film coating is finished, a negative pressure gauge (106) is embedded at a depth of 25cm below a dripper of the drip irrigation tape, the horizontal distance between the negative pressure gauge and the drip irrigation tape is 1cm, and the negative pressure gauge is embedded at 5 representative points respectively.

(7) Sowing: and 6, sowing edible sunflower in 2017 in 5-month and 28-day, wherein the variety is SH 361. And (3) carrying out manual dibbling in the film, wherein the sowing depth is 3cm, two rows are sowed on one film, the row spacing is 60cm, the plant spacing is 45cm, and the planting density is 2600 plants/mu. After sowing, the damaged part of the mulching film is completely covered by sandy soil.

(8) Drip irrigation: after the sunflower is sown, drip irrigation is carried out immediately, and the irrigation quantity is 25m³The flow rate of the drippers is controlled to be 0.5L/h per mu; in the seedling stage, when the average value of the readings of any 3 negative pressure meters exceeds-10 kPa, the irrigation is carried out for 2 times, and the irrigation quantity is 10m each time³The flow rate of the drippers is controlled to be 1.5L/h per mu; after bud period (plant height over 50cm), irrigating for 2 times with 10m of irrigation amount each time when the average reading value of any 3 negative pressure meters exceeds-20 kPa³The flow rate of the drippers is controlled to be 3L/h per mu.

(9) Application of Water-soluble modifier: when the 1 st drip irrigation is carried out in the seedling stage of the sunflower, the fulvic acid is dissolved in water and then applied to soil along with the drip irrigation, wherein the application amount is 2 kg/mu; during the 1 st drip irrigation in the bud period, citric acid is dissolved in water and then applied to soil along with the drip irrigation, and the application amount is 1.5 kg/mu.

(10) Applying water-soluble quick-acting fertilizer: and respectively applying 6 kg/mu of urea during the 2 nd drip irrigation in the seedling stage and the bud stage of the sunflower, dissolving the urea in water, and applying the urea to soil along with the drip irrigation.

(11) Rotary tillage: and (3) harvesting the sunflower in 2017, 9 and 18 months, then smashing the stalks on the overground part and returning the stalks to the field, after the residual films on the earth surface are recovered, carrying out rotary tillage on the surface soil for 2 times by using a rotary cultivator, carrying out rotary tillage in a cross mode, wherein the rotary tillage depth is 15-18 cm, and fully mixing the residual desulfurized gypsum with the surface soil.

The control group was operated in a manner consistent with the test group except that desulfurized gypsum, fulvic acid, and citric acid were not applied.

Table 1 shows the soil improvement index for severe saline and alkaline land and the agronomic trait control for sunflower. Compared with a control group, the rhizosphere soil salinity of the test group adopting the method disclosed by the invention is reduced by 32.1%, the pH value is reduced by 1.2 units, and the alkalization degree is reduced by 25.4 percentage points; the average salt content of the non-rhizosphere soil is reduced by 23.9 percent, the pH value is reduced by 0.9 unit, and the alkalization degree is reduced by 18.7 percentage points. The emergence rate of the sunflower is improved by 26.4 percent, the seedling protection rate is improved by 34.3 percent, and the yield of seeds is improved by 175.8 percent.

As can be seen from Table 1, the technical scheme of the invention can obviously improve saline-alkali dry land, has obvious improvement effect on rhizosphere soil, can also improve the emergence rate and the seedling protection rate of sunflower, increases the yield of sunflower seeds, and has soil improvement and yield increase effects obviously superior to those of the conventional scheme.

TABLE 1 comparison of soil index and sunflower agronomic traits in severe saline and alkaline land

Example 2 desulfurization of Gypsum for improving saline-alkali Dry land

The test is carried out on moderate saline-alkali soil in Rongyun village in Wuyuan county of the Mongolia Bayan Du Er City of 2018, and is a typical representative of soil salinization and development in arid regions of China. The total area of the test field is 20 mu, the test field is divided into a test group and a control group, the test group and the control group are repeated for 3 times respectively, and the results are averaged. Before the test is started, the detection result of a foundation soil sample shows that the soil with the surface layer of 0-20 cm is silt loam, the average salt content is 5.8g/kg, the pH value is 9.1, and the alkalization degree is 37.2%.

The experimental group improves the saline-alkali dry land according to the side view of the field layout shown in figure 1, and the concrete operations are as follows:

(1) land leveling: firstly, roughly leveling a project area by using a disc harrow, then finely leveling by using a laser land leveler, and controlling the height drop of the land surface of the leveled land within 5 cm.

(2) Applying a base fertilizer: and (3) applying base fertilizer by using a fertilizer applicator in a strip mode, wherein diammonium phosphate is adopted as the base fertilizer (101), and the fertilizing amount is 25 kg/mu. A wide-narrow row planting mode is adopted, wherein the wide row spacing is 80cm, the narrow row spacing is 60cm, and the wide row spacing and the narrow row spacing are alternated. And (3) applying fertilizer strips, covering soil on the fertilizer strips by 3cm, and keeping the distance between the fertilizer strips and the crop planting strips by 5 cm.

(3) Applying desulfurized gypsum: and a V-shaped groove is formed in the middle position of the small row spacing, namely the middle position of two rows of crops (102), the depth of the groove is 3cm, and the distance between the center position of the groove bottom and the crop planting strips at two sides is 25 cm. And applying the desulfurized gypsum (103) into the V-shaped ditch, wherein the application amount of the desulfurized gypsum is 154 kg/mu.

The desulfurization gypsum application amount is determined by the following steps:

calculating the required amount GR of the desulfurized gypsum according to the following formula:

GR＝[86.07×CEC×(ESP–5％)+86.04×TA–28.22]×H×D/R×η (1)；

in the formula (1), GR is the required amount of desulfurized gypsum and the unit is kg/hectare; CEC is soil cation exchange capacity, unit cmol/kg; ESP is the soil alkalization degree, and the unit is; TA is total alkalinity of soil, and the unit is cmol/kg; h is the soil improvement depth, and the unit is cm; d is the volume weight of soil and the unit is g/cm³(ii) a R is the effective utilization rate of the desulfurized gypsum and has the unit of percent; eta is the mass fraction of the calcium sulfate dihydrate in the desulfurized gypsum, and the unit is percent.

In this example, CEC was 7.9 cmol/kg; ESP 37.2%; TA 3.2 cmol/kg; h is 20 cm; d is 1.45g/cm³(ii) a R is 70 percent; eta is 80%. The GR is 1030 kg/mu by calculation.

The saline-alkali soil of the embodiment is moderately alkalized: the pH value of the soil is more than or equal to 9 and less than or equal to 9.5, and 154 kg/mu of desulfurized gypsum is obtained by applying 15 wt% GR.

(4) Laying a drip irrigation tape: the required desulfurization gypsum is uniformly applied in a strip shape in a V-shaped ditch, then a drip irrigation tape (104) is laid right above the desulfurization gypsum strip, and the drip irrigation tape is connected with a main pipeline of a drip irrigation system.

(5) Film covering: after the above operation, the plastic film (105) was laminated to a thickness of 0.01mm and a width of 70 cm.

(6) Burying a negative pressure meter: after the film coating is finished, a negative pressure gauge (106) is embedded at a depth of 20cm below a dripper of the drip irrigation tape, the horizontal distance between the negative pressure gauge and the drip irrigation tape is 1cm, and the negative pressure gauge is embedded at 5 representative points respectively.

(7) Sowing: and 6, month and 5 days in 2018, and sowing edible sunflowers, wherein the variety is Sanrui No. 10. And (3) carrying out manual dibbling in the film, wherein the sowing depth is 3cm, two rows are sowed on one film, the row spacing is 60cm, the plant spacing is 50cm, and the planting density is 2200 plants/mu. After sowing, the damaged part of the mulching film is completely covered by sandy soil.

(8) Drip irrigation: after the sunflower is sown, drip irrigation is carried out immediately, and the irrigation quantity is 20m³The flow rate of the drippers is controlled to be 1L/h per mu; in the seedling stage, when the average value of the readings of any 3 negative pressure meters exceeds-10 kPa, the irrigation is carried out for 2 times, and the irrigation quantity is 10m each time³The flow rate of the drippers is controlled to be 2L/h per mu; after bud period (plant height over 50cm), irrigating for 2 times with 10m of irrigation amount each time when the average reading value of any 3 negative pressure meters exceeds-20 kPa³The flow rate of the drippers is controlled to be 4L/h per mu.

(9) Application of Water-soluble modifier: when drip irrigation is carried out for the 1 st time in the seedling stage, fulvic acid is dissolved in water and then applied to soil along with drip irrigation, wherein the application amount is 2 kg/mu; during the 1 st drip irrigation in the bud period, citric acid is dissolved in water and then applied to soil along with the drip irrigation, and the application amount is 1.5 kg/mu.

(10) Applying water-soluble quick-acting fertilizer: and (3) respectively applying 6 kg/mu of urea during the 2 nd drip irrigation in the seedling stage and the bud stage, dissolving the urea in water, and applying the urea to soil along with the drip irrigation.

(11) Rotary tillage: and (3) harvesting the sunflower in 2018, 9 and 25 days, then smashing the stalks on the overground part and returning the stalks to the field, after the residual film on the earth surface is recovered, carrying out rotary tillage on the surface soil for 2 times by using a rotary cultivator, carrying out rotary tillage in a cross mode, wherein the rotary tillage depth is 15-18 cm, and fully mixing the residual desulfurized gypsum with the surface soil.

The control group was operated in a manner consistent with the test group except that desulfurized gypsum, fulvic acid, and citric acid were not applied.

Table 2 shows the medium saline-alkali soil improvement index and the sunflower agronomic trait control. Compared with a control group, the average salt content of rhizosphere soil of a test group adopting the method is reduced by 34.7 percent, the pH value is reduced by 0.9 unit, and the alkalization degree is reduced by 18.7 percentage points; the average salt content of the non-rhizosphere soil is reduced by 21.2 percent, the pH value is reduced by 0.6 unit, and the alkalization degree is reduced by 16.4 percentage points. The emergence rate of the sunflower is improved by 21.3 percent, the seedling protection rate is improved by 26.9 percent, and the yield of seeds is improved by 86.5 percent.

As can be seen from Table 2, the technical scheme of the invention can obviously improve saline-alkali dry land, has obvious improvement effect on rhizosphere soil, can also improve the emergence rate and the seedling protection rate of sunflower, increases the yield of sunflower seeds, and has soil improvement and yield increase effects obviously superior to those of the conventional scheme.

TABLE 2 comparison of soil indexes and sunflower agronomic traits after moderate saline-alkali soil improvement

The present invention has been described in detail above. It will be apparent to those skilled in the art that the invention can be practiced in a wide range of equivalent parameters, concentrations, and conditions without departing from the spirit and scope of the invention and without undue experimentation. While the invention has been described with reference to specific embodiments, it will be appreciated that the invention can be further modified. In general, this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. The use of some of the essential features is possible within the scope of the claims attached below.