Method for regreening gobi desert by utilizing microalgae crust and application

Abstract

The invention discloses a method for regreening gobi deserts by utilizing microalgae crust and application, and belongs to the technical field of ecological restoration. The method mainly adopts a mode of combining microalgae spraying liquid with an engineering remediation method. When the microalgae spraying liquid is prepared, indigenous microalgae and known domesticated desert algae are mixed and co-cultured to prepare a spraying agent, and then soil bacillus is added before spraying. The engineering regulation method mainly comprises the following steps: forming a concave-convex structure by piling up soil mound bags and digging ditches, increasing the specific surface area of the growth of the microalgae spraying liquid by using the uneven land surface layer, and reducing the evaporation speed of the moisture of the microalgae spraying liquid by using the concave land, thereby promoting the growth rate and adaptability of the microalgae and improving the skinning efficiency. In addition, nutritional functional organic fertilizers and / or nano conditioners need to be added into the soil to be remediated in advance. According to the method, the vegetation coverage rate can be increased to about 60% from the initial nearly zero, the gobi desert ecological environment can be obviously improved, the soil salinity and alkalinity can be obviously reduced, and the soil water retention capacity is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of ecological restoration, and in particular relates to a spraying liquid for regreening a Gobi desert by using microalgae crusts, a method for regreening a Gobi desert by using microalgae crusts, and applications of the same in regreening a Gobi desert. Background Art

[0002] At present, the methods of Gobi Desert regreening mainly include vegetation restoration, ecological engineering measures, water-saving irrigation, soil improvement, biological crust technology, etc. A large number of studies have shown that biological crust technology is one of the important technologies to simulate natural ecological restoration and improve desertification.

[0003] Most of the existing biological crusting technologies use artificially screened desert algae for inoculation and restoration. The engineering technology of artificial desert algae restoration mainly follows the process of desert algae collection, desert algae screening, desert algae cultivation and then spraying. In view of the coexistence of various microorganisms including bacteria, fungi, and algae in the locally collected soil, the screening and purification process is complicated and time-consuming, and the cost of cultivating each algae species separately after purification is high. The spraying method is to spray directly on the surface of the Gobi soil. Due to the poor nutrition of the Gobi soil and the high temperature and dry climate environment, the spray liquid evaporates quickly, the activity of microorganisms is reduced, and even death occurs, and the crusting effect is greatly reduced. The entire desert greening project takes about 3-5 years, and the restoration effect is uncertain and the restoration cost is high.

[0004] The naturally formed biological crust in the Gobi Desert is a mixture of various algae. If the desert algae are screened without separation and purification in engineering applications, time and economic costs can be greatly saved. In nature, vegetation often grows in the low-lying depressions and behind the mounds of the Gobi Desert. The difference in microtopography has a significant impact on the growth and distribution of vegetation. Exploring the morphology of depressions or holes on the surface, increasing the specific surface area, and effectively resisting water evaporation to the maximum extent, increasing water retention time, and promoting rapid reproduction of microorganisms are the key engineering technology directions for using microalgae crusts to regreen the Gobi Desert. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method and application of using microalgae crusting to regreen the Gobi Desert. The present invention mainly adopts a combination of microalgae spraying liquid and engineering remediation method. When preparing the microalgae spraying liquid, the indigenous microalgae and the known domesticated desert algae are first mixed and co-cultured to form a spraying agent, and then soil Bacillus is added before spraying. The engineering remediation method mainly forms a concave-convex structure by piling up earth mounds and digging ditches, using the uneven land surface to increase the specific surface area for the growth of the microalgae spraying liquid, and using the concave land to slow down the evaporation rate of the water of the microalgae spraying liquid, thereby promoting the growth rate and adaptability of the microalgae and improving the crusting efficiency. In addition, the soil to be repaired needs to be added with nutrient functional organic fertilizers and / or nano conditioners in advance. The present invention can increase the vegetation coverage rate from the initial almost zero to about 60%, can significantly improve the ecological environment of the Gobi Desert, can significantly reduce the salinity of the soil, and enhance the water retention capacity of the soil.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] One of the purposes of the present invention is to provide a method for regreening the Gobi Desert using microalgae crusts, the method comprising the following steps:

[0008] Step 1: Domestication and cultivation of indigenous microalgae and alien algae species:

[0009] The indigenous microalgae are derived from soil samples in the target area; the foreign algae species include Microcoleus vaginatus and Scytonema javanicum; the domestication and cultivation use a mixture of culture medium and soil juice, and the domestication and cultivation are performed for at least 5 generations until the absorbance of the cultured algae solution at a wavelength of 680 nm reaches between 2.5 and 3.0;

[0010] Step 2: Preparation of microalgae seeds:

[0011] The method comprises mixing the three algae solutions cultured or domesticated in step one with bare sand;

[0012] Step 3: Site preparation and renovation:

[0013] It includes site cleaning, fertilization, building earth mounds and digging ditches; the number of earth mounds built is 5-7 per mu, with a diameter of 4-6 meters and a height of 1-2 meters; the ditches are dug between the earth mounds, with a depth of 18-22 centimeters, a width of 28-32 centimeters, and a total length of 58-62 meters;

[0014] Step 4: Microalgae seed spraying and crust formation:

[0015] First, the microalgae seeds are cultured until the absorbance of the algae liquid at a wavelength of 680 nm reaches between 2.5 and 3.0, and then the algae liquid is mixed with soil Bacillus dry powder in a weight ratio of (4-6):1; finally, the algae liquid is sprayed on the trimmed site until a microalgae crust can be observed;

[0016] Step 5: Subsequent vegetation restoration:

[0017] Next spring, repeat the method in step 4 to spray the microalgae seeds again, and then plant vegetation restoration plants.

[0018] Furthermore, the method for obtaining the indigenous microalgae in step 1 includes: taking soil samples from red willow bags or poplar forests in the Gobi Desert, removing impurities and ensuring the possibility of survival of microorganisms, then air-drying, crushing, and sieving the soil samples, and putting them into liquid culture medium. After culturing for 4-6 weeks or a certain amount of microalgae biomass has accumulated, floating microalgae are picked, microalgae growing on the wall are scraped, and filtering, centrifuging, and collecting to obtain the indigenous microalgae.

[0019] Furthermore, the culture medium in step one is BG11 culture medium; the preparation method of the mixed solution includes: taking soil samples from red willow bags or poplar forests in the Gobi Desert, then mixing them with clean water in a weight ratio of 1: (2-4), boiling them for 2-4 hours every day for 2-4 consecutive days, then sterilizing the upper layer of liquid at 120-125°C for 0.5-1.5 hours, and after cooling, adding soil juice to the culture medium at a ratio of 20-40mL of soil juice to 1L of culture medium to obtain the mixed solution.

[0020] Furthermore, the step 2 specifically includes the following steps:

[0021] 1) Collect bare sand from the Gobi Desert, sieve it, dry it and set it aside;

[0022] 2) Mix the three algae solutions cultured or domesticated in step 1 in a volume ratio of (0.8-1.2): (0.8-1.2): (0.8-1.2), and then mix with bare sand in a weight ratio of (0.8-1.2): (0.8-1.2), and culture in BG11 medium for 5-7 weeks;

[0023] 3) Cultivating a microalgae-sand mixture until a densely attached structure is formed, taking it out, detecting it by absorbance to show that it is evenly mixed, air-drying, crushing and sieving, and thus obtaining the microalgae seeds.

[0024] Furthermore, the fertilization in step three is functional organic fertilizer, which is nano-sized granular organic fertilizer, which is made by mixing livestock and poultry manure and PAL modified materials in a weight ratio of (3.5-4.5):1, and the total amount is 280-350kg / mu.

[0025] Furthermore, the diameter of the soil mound in step three is 5 meters and the height is 1.5 meters.

[0026] Furthermore, the ditch in step three is 20 cm deep and 30 cm wide.

[0027] Furthermore, the spraying amount of the spraying liquid in step 4 is controlled at 3-5 L per square meter, and the spraying is performed 2-3 times in total. Microalgae crusting can be observed after 4-6 weeks.

[0028] Furthermore, the step five specifically includes: in the spring of next year, when the temperature of the Gobi Desert reaches about 20°C, first spray water on the surface of the trimmed site to wet it, then repeat the method in step four to spray microalgae seeds, then sow salt-tolerant grass seeds and cover the ground with film, and after the grass grows out of the film, plant salt-tolerant herbs and / or salt-tolerant shrubs.

[0029] The second object of the present invention is to provide application of the method in regreening the Gobi Desert.

[0030] The innovative point of the invention lies in the preparation process of the homemade microalgae spray liquid and the engineering treatment method for repairing the land. Both are two necessary conditions for regreening and are indispensable. The importance of the engineering treatment method is reflected in that it can use the uneven land surface to increase the specific surface area for the growth of the microalgae spray liquid, and use the concave land to slow down the evaporation rate of the water in the microalgae spray liquid, thereby promoting the growth rate and adaptability of the microalgae and improving the crusting efficiency.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. After using the method of the present invention for 4-6 weeks, obvious microalgae crust formation can be observed, and the crust thickness can reach 0.8-1.2 cm, and the crust coverage rate can reach about 80%.

[0033] 2. After the microalgae are crusted using the method of the present invention, a drone is used to sow salt-tolerant grass seeds, and each soil mound is covered with a degradable mulch film. After 4 weeks, the germination rate of the grass seeds can reach about 80%.

[0034] 3. Using the method of the present invention, the vegetation coverage rate was finally increased from almost zero at the beginning to about 60%, which significantly improved the ecological environment of the Gobi Desert. At the same time, the soil salinity was also reduced, and the soil water retention capacity was greatly enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the concave-convex structure formed by the soil mound and ditch in Example 1 using the engineering treatment method in Example 1;

[0036] Figure 2Comparison pictures before and after restoration using the method in Example 1 of the present invention, wherein: the left picture is before restoration, and the right picture is after restoration. DETAILED DESCRIPTION

[0037] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Without departing from the spirit and essence of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention are within the scope of the present invention. The products, equipment, etc. used in the following examples are commercially available unless otherwise specified, and the methods used are consistent with conventional methods unless otherwise specified.

[0038] The technical solution of the present invention is further described in detail below in conjunction with embodiments.

[0039] Example 1

[0040] Experimental site: Lunnan Town, Luntai County, Bayinguoleng Mongol Autonomous Prefecture, Xinjiang, China, was selected. The area belongs to the warm temperate continental climate, which is characterized by rich light and heat resources, long frost-free period, scarce precipitation, large evaporation, more windy and dusty weather, distinct four seasons, cold winter, hot summer, fast and unstable spring temperature rise, and fast autumn temperature drop; the average temperature for many years is 10.2℃-10.6℃, the average temperature in January is -17℃, and the average temperature in July is 34℃; the average frost-free period is 188 days per year, the longest is 194 days, and the shortest is 179 days; the duration above 0℃ is 247 days, and the average annual precipitation is 52.2 mm. The annual precipitation is less than 200mm, and the salt content of the soil within 3.0 meters is greater than the saline soil standard of 0.3%, which belongs to saline soil. The type is sulfurous acid-medium saline soil, and the vegetation is scarce.

[0041] Experimental time: Starts in spring (March) and lasts until autumn (October) of the following year.

[0042] Step 1: Domestication and cultivation of indigenous microalgae and exotic algae species

[0043] 1. Soil sample collection and processing:

[0044] 1) 2 kg of soil samples were collected from under the red willow bags, and weeds, stones and various impurities were removed. After removing the impurities, half of the soil samples were used for the isolation and culture of indigenous microalgae, and the other half was used for the subsequent culture of indigenous microalgae and the adaptive domestication of foreign algae species after preparing local soil juice mixed culture medium and sterilizing.

[0045] Among them, the method for isolating and culturing indigenous microalgae is as follows: half (1 kg) of the soil sample used for isolating and culturing indigenous microalgae is air-dried, crushed, sieved, and then put into BG11 liquid culture medium. After culturing for 4-6 weeks or when a certain amount of microalgae biomass has accumulated, the floating microalgae are picked, the microalgae growing on the wall are scraped, and the indigenous microalgae are filtered, centrifuged, and collected.

[0046] The preparation method of local soil juice mixed culture medium is as follows: mix the other half of the sandy soil (1kg) with 3L of clean water, boil it for 3 hours every day for 3 consecutive days, then sterilize the upper liquid (soil juice) at 121℃ for 1 hour, cool it for use, and finally add 30mL of soil juice to 1LBG11 culture medium.

[0047] 2) After the indigenous microalgae are cultured, filtered, centrifuged and collected, they are expanded and cultured using the above-mentioned local soil juice mixed culture medium (a liquid mixed with BG11 culture medium and soil juice at a volume ratio of 100:3). After repeated cultivation for 5-6 times from one generation to another, the algae liquid is cultured until the absorbance at a wavelength of 680nm reaches between 2.5 and 3.0, thereby obtaining a high-concentration indigenous microalgae liquid.

[0048] 3) Microcoleus spp. (FACHB-2002 from the Freshwater Algae Species Bank of the Chinese Academy of Sciences) and Pseudocephalum javanicum (FACHB-887 from the Freshwater Algae Species Bank of the Chinese Academy of Sciences) were also adaptively acclimated for at least 5 generations using the above-mentioned local soil juice mixed culture medium (a liquid mixed with BG11 culture medium and soil juice in a volume ratio of 100:3), and the algae liquid was cultured until the absorbance at a wavelength of 680nm reached between 2.5-3.0, thereby obtaining a high-concentration acclimated algae liquid.

[0049] 2. Experimental data record:

[0050] 1) After taking the soil sample, strictly follow the steps. During the process of cultivating indigenous microalgae, record the appearance changes of the liquid culture medium, such as color, turbidity, etc., once a week. At the same time, use a spectrophotometer to measure the absorbance of the algae solution at a wavelength of 680nm, and record the data as shown in Table 1 below.

[0051] Table 1 Details of absorbance changes during the cultivation of indigenous microalgae

[0052] time OD680 Day 1 0.214 Day 7 0.82 Day 14 1.302 Day 21 1.983 Day 28 2.332 Day 35 2.615

[0053] 2) Success rate of domestication of foreign algae: By measuring the change in absorbance: measuring the absorbance of the algae solution at a specific wavelength of 680nm, the increase in absorbance can reflect the increase in algae cell concentration. After a period of cultivation, the absorbance can eventually stabilize in a range close to that of native microalgae (2.5-3.0), which can be considered effective in domestication. The changes in absorbance during the domestication of Microcoleus scaly and Pseudoclase javanica are shown in Table 2.

[0054] Table 2 Details of absorbance changes during the acclimation of Microcoleus spp. and Pseudocloclade javanica

[0055] time Microcoleus Pseudoclaea javanica Day 1 <![CDATA[OD 680 =0.524]]> <![CDATA[OD 680 =0.438]]> Day 5 <![CDATA[OD 680 =1.023]]> <![CDATA[OD 680 =0.879]]> Day 10 <![CDATA[OD 680 =1.477]]> <![CDATA[OD 680 =1.135]]> Day 15 <![CDATA[OD 680 =2.128]]> <![CDATA[OD 680 =2.048]]> Day 20 <![CDATA[OD 680 =2.59]]> <![CDATA[OD 680 =2.503]]>

[0056] Step 2: Preparation of microalgae seeds

[0057] 1. Bare sand treatment and mixed culture:

[0058] 1) Collect 50 kg of bare sand from the Gobi Desert, sieve it, and dry it for later use.

[0059] 2) The three algae solutions (indigenous microalgae, sheathed microalgae, and javanica) cultured or domesticated in the first step were mixed in a volume ratio of 1:1:1, and then mixed with cooled bare sand in a weight ratio of 1:1, and cultured in a 5L Erlenmeyer flask using BG11 culture medium for 6 weeks.

[0060] 3) After the culture was completed, the microalgae-sand mixture with a dense attachment structure weighed about 25 kg, and the absorbance test showed that the mixture was uniform, meeting the requirements for subsequent use.

[0061] 2. Data Recording:

[0062] 1) The formation process of the microalgae-sand mixture is shown in Table 3. The results show that the formation time of the microalgae-sand mixture is 5 weeks.

[0063] Table 3 Specific formation process of microalgae-sand mixture

[0064] time Microalgae combined with bare sand Week 1 Microalgae begin to attach, and the bond is loose Week 2 The combination is gradually becoming closer Week 3 Forming a preliminary dense structure Week 4 More stable structure Week 5 Reached a densely attached state

[0065] 2) The algal cell density in the final product (observed under a microscope and counted using a hemocytometer): about 10^8 cells / mL.

[0066] Step 3: Site preparation and renovation

[0067] 1. Site cleaning and fertilization:

[0068] 1) Use a soil stone cleaner to remove the surface gravel, covering an area of ​​about 1 mu.

[0069] 2) Ploughing and spreading functional organic fertilizer, which is a nano-sized granular organic fertilizer (Sunongfei (2017) No. 0226, Anhui Lenong Environmental Protection Technology Co., Ltd.) processed by mixing livestock and poultry manure and PAL modified materials in a ratio of 4:1, with a total amount of 300 kg. About 6 soil mounds are formed, each with a diameter of 5 meters and a height of 1.5 meters.

[0070] 2. Trench excavation: Dig a 20 cm deep and 30 cm wide ditch with a total length of about 60 meters.

[0071] Step 4: Microalgae seed spraying and crust formation

[0072] 1. Microalgae seed cultivation:

[0073] 1) Use a racetrack expansion system to expand the microalgae seeds until the absorbance of the algae solution at a wavelength of 680nm reaches between 2.5-3.0, and the microalgae and sand are observed to be densely attached under a microscope. This process takes about 5-6 weeks. Finally, about 3 tons of microalgae solution are obtained.

[0074] 2) Mix the microalgae liquid and soil Bacillus dry powder (Shandong Runwo Biological, 2023926) in a weight ratio of 5:1 and load it into a sprinkler truck.

[0075] 2. Spraying and crusting observation:

[0076] 1) Spray the microalgae mixture, the spraying amount is controlled at 3-5L per square meter, and spray three times in total.

[0077] 2) After 6 weeks, obvious microalgae crust formation was observed, with a crust thickness of 0.8-1.2 cm and a crust coverage of about 80%.

[0078] Step 5: Subsequent vegetation restoration

[0079] 1. Rehydrate and re-spray in spring: In the spring of the following year, when the temperature reaches 20°C, first spray water to wet the surface 1cm-2cm, then use the above method to spray the microalgae liquid once to increase the thickness and stability of the crust.

[0080] 2. Drone sowing of grass seeds and mulching: Drones are used to sow salt-tolerant grass seeds, and each mound is covered with a degradable mulch. After 4 weeks, the germination rate of grass seeds is about 80%.

[0081] 3. Final effect evaluation:

[0082] The vegetation coverage rate has increased from almost zero to about 60%, significantly improving the ecological environment of the Gobi Desert. The soil salinity has decreased and the soil's water retention capacity has increased.

[0083] Using the engineering treatment method in this embodiment, the concave-convex structure diagram formed by the soil mound and the ditch in this embodiment is as shown in Figure 1 The comparison diagram before and after the repair using the method in this embodiment is shown in FIG. Figure 2 shown.

[0084] Comparative Example 1

[0085] The other steps were the same as in Example 1, but no restoration engineering measures were performed on the spraying site, only sand and gravel were removed and sprayed directly, and functional organic fertilizer was not applied, and ordinary organic fertilizer (Devodo compound organic fertilizer 6940296801261) was applied instead. Biodiversity was measured by microbial biomass carbon determination, and water retention on the soil surface was observed by naked eye.

[0086] The results showed that the microbial biomass carbon in Example 1 was 1.35 g / kg, while the microbial biomass carbon in the comparative example was 0.87 g / kg; the soil surface in Example 1 was still wet after one week of observation with the naked eye, while it was obviously dry after one week in this comparative example. This shows that the soil biodiversity and water retention in the comparative example are significantly reduced compared with those in Example 1.

[0087] Comparative Example 2

[0088] The other steps are the same as those in Example 1, but Microcoleus javanica, Pseudocephalum javanica, and native algae species are cultured separately until OD680=2.5-3.0, then mixed and sprayed into the same treatment site as in Example 1, and the spraying method is also consistent with the steps in Example 1.

[0089] The results showed that the soil crusting effect in this comparative example was not as good as that in Example 1. Meanwhile, microscopic observation showed that the number of agglomerated microalgae cells in this comparative example was also less than that in Example 1.

[0090] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for regreening the Gobi Desert using microalgae crusts, characterized in that: The following steps are involved: Step 1: Domestication and cultivation of indigenous microalgae and alien algae species: The indigenous microalgae are derived from soil samples in the target area; the foreign algae species include Microcoleus vaginatus and Scytonema javanicum; the domestication and cultivation use a mixture of culture medium and soil juice, and the domestication and cultivation are performed for at least 5 generations until the absorbance of the cultured algae solution at a wavelength of 680 nm reaches between 2.5 and 3.0; Step 2: Preparation of microalgae seeds: The method comprises mixing the three algae solutions cultured or domesticated in step one with bare sand; Step 3: Site preparation and renovation: It includes site cleaning, fertilization, building earth mounds and digging ditches; the number of earth mounds built is 5-7 per mu, with a diameter of 4-6 meters and a height of 1-2 meters; the ditches are dug between the earth mounds, with a depth of 18-22 centimeters, a width of 28-32 centimeters, and a total length of 58-62 meters; Step 4: Microalgae seed spraying and crust formation: First, the microalgae seeds are cultured until the absorbance of the algae liquid at a wavelength of 680 nm reaches between 2.5 and 3.0, and then the algae liquid is mixed with soil Bacillus dry powder in a weight ratio of (4-6):1; finally, the algae liquid is sprayed on the trimmed site until a microalgae crust can be observed; Step 5: Subsequent vegetation restoration: Next spring, repeat the method in step 4 to spray the microalgae seeds again, and then plant vegetation restoration plants.

2. The method according to claim 1, characterized in that The method for obtaining the indigenous microalgae in step 1 comprises: taking soil samples from red willow bags or poplar forests in the Gobi Desert, removing impurities and ensuring the possibility of survival of microorganisms, then air-drying, crushing, sieving the soil samples, and putting them into liquid culture medium. After culturing for 4-6 weeks or until a certain amount of microalgae biomass has accumulated, floating microalgae are picked, microalgae growing on the wall are scraped, and filtering, centrifuging, and collecting to obtain the indigenous microalgae.

3. The method according to claim 2, characterized in that The culture medium in step 1 is BG11 culture medium; the preparation method of the mixed solution comprises: taking soil samples from red willow bags or poplar forests in the Gobi Desert, then mixing the soil samples with clean water in a weight ratio of 1: (2-4), boiling the soil samples for 2-4 hours every day for 2-4 consecutive days, then sterilizing the upper layer of liquid at 120-125° C. for 0.5-1.5 hours, and after cooling, adding soil juice to the culture medium in a ratio of 20-40 mL of soil juice to 1 L of culture medium, thereby obtaining the mixed solution.

4. The method according to claim 3, characterized in that The step 2 specifically includes the following steps: 1) Collect bare sand from the Gobi Desert, sieve it, dry it and set it aside; 2) Mix the three algae solutions cultured or domesticated in step 1 in a volume ratio of (0.8-1.2): (0.8-1.2): (0.8-1.2), and then mix with bare sand in a weight ratio of (0.8-1.2): (0.8-1.2), and culture in BG11 medium for 5-7 weeks; 3) Cultivating a microalgae-sand mixture until a densely attached structure is formed, taking it out, detecting it by absorbance to show that it is evenly mixed, air-drying, crushing and sieving, and thus obtaining the microalgae seeds.

5. The method according to claim 4, characterized in that The fertilization in step three is functional organic fertilizer, which is nano-sized granular organic fertilizer, which is made by mixing livestock and poultry manure and PAL modified materials in a weight ratio of (3.5-4.5):1, and the total amount is 280-350kg / mu.

6. The method according to claim 5, characterized in that The soil mound in step 3 has a diameter of 5 meters and a height of 1.5 meters.

7. The method according to claim 6, characterized in that The ditch in step 3 is 20 cm deep and 30 cm wide.

8. The method according to claim 7, characterized in that The spraying amount of the spraying liquid in step 4 is controlled at 3-5 L per square meter, and the spraying is performed 2-3 times in total. Microalgae crusting can be observed after 4-6 weeks.

9. The method according to claim 8, characterized in that The step five specifically includes: in the spring of next year, when the temperature of the Gobi Desert reaches about 20°C, first spray water on the surface of the trimmed site to wet it, then repeat the method in step four to spray microalgae seeds, then sow salt-tolerant grass seeds and cover with film, and after the grass grows out of the film, plant salt-tolerant herbs and / or salt-tolerant shrubs.

10. Use of the method according to any one of claims 1 to 9 in greening the Gobi Desert.

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