Biological crusts for reducing erosion of cultivated soils and use thereof

Abstract

The present application relates to the field of agricultural planting technology, and more particularly to a biological crust for reducing soil erosion of cultivated land and application thereof. The biological crust is obtained by artificial propagation and field inoculation and culture of naturally collected algal crust with a thickness of less than or equal to 1 cm and moss crust with a thickness of less than or equal to 2 cm, is suitable for bare cultivated land, and can cover the bare cultivated land in a large area through natural development, thereby effectively preventing water and wind erosion of the cultivated land and improving the soil fertility of the farmland.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural planting technology, and particularly relates to a biological crust for reducing soil erosion of cultivated land and application thereof. BACKGROUND

[0002] Dry farming is the main type of cultivated land in China, accounting for about 50% of the total cultivated land area in China, and mainly distributed in the northern region. Influenced by topography, climate and soil conditions, soil erosion is prone to occur in the northern region of China, among which the northeast black soil area, the northern sandstorm area, the northern soil and rock mountain area and the northwest loess plateau area are the most serious areas of water and soil loss in China, and are the key areas for water and soil conservation work. Under the combined influence of natural environmental conditions and human activities, the soil erosion situation of dry farming in China is very serious. Among them, water erosion and wind erosion are the main types of erosion of dry farming. In the summer and autumn seasons with concentrated rainfall, raindrop splash and runoff erosion are easy to cause water erosion, which can destroy the soil surface structure and block soil pores, causing slope confluence and soil loss; in the dry and windy winter and spring seasons, wind erosion is prone to occur under the action of strong wind, and further lead to floating dust, sandstorm and other sand disasters. Therefore, it is urgent to prevent and control the soil erosion of cultivated land through effective measures, so as to improve soil fertility, improve the quality of cultivated land, protect the ecological environment of farmland, and further promote the sustainable development of economy and society, and promote the harmonious coexistence of man and nature.

[0003] At present, the prevention and control of cultivated land soil erosion mainly includes engineering measures, farming measures and biological measures. Among them, engineering measures are to transform the regional micro-topography through engineering construction to reduce slope, intercept runoff, promote drainage and reduce wind speed, mainly including slope transformation, drainage engineering, mechanical sand barrier, etc.; farming measures are to improve the surface conditions, increase the surface coverage and improve the soil erosion resistance through farming, including high farming, stubble ground cover, increased organic fertilizer, etc.; biological measures are to use the ecological function of vegetation to maintain soil and water and reduce erosion, mainly including contour plant hedge and windbreak forest belt, etc. However, the existing various types of soil and water conservation measures of cultivated land still have some defects, the main performance of which is that it is difficult to build, the cost of management and protection is high, the effect is not sustainable, and it is easy to cause secondary environmental problems. Therefore, a new method of resource saving, ecological friendly and strong sustainability is expected to become a new scheme for preventing and controlling cultivated land erosion.

[0004] Biological soil crust is a kind of active ground cover widely developed in arid, semi-arid and semi-humid regions of northern China. It is a biological enrichment layer formed by the cementation of cryptogams such as mosses, lichens and green algae, and microorganisms such as bacteria and fungi with surface soil particles. As a key layer of soil with multiple ecological environmental functions, biological soil crust can effectively cover bare soil, change the water and soil process on the ground, and reshape the degraded ecosystem. In water and wind erosion areas, biological soil crust coverage can significantly weaken the erosion force and improve the soil erosion resistance, thereby reducing soil erosion. At present, the anti-erosion function of biological soil crust has become a cross frontier and research hotspot of soil science, soil and water conservation science and ecology, and it is expected to provide a new material and method based on nature for preventing and controlling erosion in dryland.

[0005] So far, although the method of using biological soil crust to prevent and control soil erosion has been described, the existing method is mainly aimed at desert or sandy land management, and has not been applied to prevent and control water and wind erosion in dryland. In different ecological systems and land use types, the causes, processes and mechanisms of soil erosion are completely different, so the anti-erosion mechanism and effect of biological soil crust also have essential differences. At the same time, in the preparation of artificial biological soil crust, most of the existing methods only improve and innovate individual links such as seed source collection, indoor propagation, field inoculation and maintenance management, but lack of systematic and overall consideration and design of the whole process from seed source collection to field restoration. Therefore, it is urgent to put forward a new method to provide biological soil crust for covering bare farmland and preventing water and wind erosion.

[0006] Therefore, the present application is proposed. SUMMARY

[0007] To solve the above technical problems, the present application provides a biological soil crust for reducing soil erosion in farmland and its application.

[0008] Specifically, the technical scheme of the present application is as follows:

[0009] In a first aspect, the present application provides a biological soil crust for reducing soil erosion in farmland, which is obtained by artificial propagation and field inoculation of natural collected algal crust with a thickness of ≤1 cm and moss crust with a thickness of ≤2 cm; wherein the artificial propagation of algal crust adopts liquid culture, and the culture is carried out until the dry weight of biomass is ≥0.15 g / L; the artificial propagation of moss crust adopts solid culture, and the culture medium is selected to be soil 2-20 cm below the crust layer, and the culture is carried out until the dry weight of biomass is ≥5 mg / m 2 ; the field inoculation amount of algal crust after artificial propagation is 4-10 L / m 2 ; and the field inoculation amount of moss crust after artificial propagation is 600-3000 g / m 2 .

[0010] The present application takes both algal and moss crusts as culture objects, and uses liquid culture and solid culture methods to propagate algal and moss crusts respectively.

[0011] In one more specific embodiment, the present application is characterized in that:

[0012] Preferably, the artificial propagation of algal crusts uses BG11 culture solution; the environmental conditions for culture include: air temperature of 30±2 / 10±2℃ for day / night; and / or, air humidity of 55%-65%; and / or, CO2 concentration of 350-450ppm; and / or, light intensity of 2800-3200Lux; and / or, light / dark cycle of 15 / 9-17 / 7.

[0013] Preferably, the artificial propagation of moss crusts uses 2-20cm soil under the crust at the collection site as basic culture medium, with soil particle size of 1.0-2.0mm; the surface is sprayed with 80-120g / m 2 of Knop-agar culture medium; the environmental conditions for culture include: air temperature of 30±2 / 10±2℃ for day / night; and / or, air humidity of 55%-65%; and / or, CO2 concentration of 350-450ppm; and / or, light intensity of 2800-3200Lux; and / or, light / dark cycle of 15 / 9-17 / 7; and / or, soil water content of 20%-30%.

[0014] Preferably, the field inoculation amount of algal crusts after artificial propagation is 4-6L / m 2 ; the field inoculation amount of moss crusts after artificial propagation is 600-800g / m 2 .

[0015] In another more specific embodiment, the present application is characterized in that:

[0016] Preferably, the artificial propagation of algal crusts uses BG11 culture solution; the environmental conditions for culture include: air temperature of 25±2℃; and / or, air humidity of 50%-60%; and / or, CO2 concentration of 350-450ppm; light intensity of 1800-2200Lux; and / or, light / dark cycle of 11 / 13-13 / 11.

[0017] Preferably, the artificial propagation of moss crusts uses 2-20cm soil under the crust at the collection site as basic culture medium, with soil particle size of 1.0-2.0mm; the environmental conditions for culture include: air temperature of 15-25℃; and / or, air humidity of 60%-90%; and / or, CO2 concentration of 350-450ppm; and / or, light intensity of 1800-2200Lux; and / or, light / dark cycle of 11 / 13-13 / 11; and / or, soil water content of 20%-30%.

[0018] Preferably, the field inoculation amount of the algal crust after artificial propagation is 6-10L / m 2 ; the field inoculation amount of the moss crust after artificial propagation is 2000-3000g / m 2 .

[0019] The present application uses liquid method and solid method respectively to propagate algal and moss two different types of biological crust, which can realize fine regulation and control of air temperature, humidity, CO2 concentration and light intensity and other key influencing factors of biological crust development.

[0020] In more specific embodiments provided by the present application:

[0021] Preferably, the algal crust and the moss crust are first subjected to resistance training after artificial propagation, and then are inoculated in the field; the resistance training method comprises light training and temperature training; the light training lasts for 5-10 days, and 1000-50000Lux full-spectrum light irradiation is adopted for 13-15h every day; the temperature gradient of the temperature training is 25±2℃, 20±2℃, 30±2℃, 15±2℃, 35±2℃, 10±2℃ and 40±2℃ in sequence, and each temperature gradient lasts for 11-13h.

[0022] More preferably, the algal crust is first subjected to rejuvenation after artificial propagation, and then is inoculated in the field; the rejuvenation method is that 8-12mg / L of a recovery promoting factor is added to the algal suspension after artificial propagation, and the recovery promoting factor is selected from Rpf protein; the Rpf protein is a lysozyme active protein having recovery and growth promoting effects on bacteria such as cyanobacteria; the present application does not particularly limit the source of the Rpf protein, which can be obtained from the market.

[0023] The present application can significantly enhance the adaptability and stress resistance of the artificial crust to the wild environment after inoculation by performing artificial rejuvenation and resistance training before biological crust source inoculation.

[0024] More preferably, after field inoculation, an artificial growth promoter is applied, and the artificial growth promoter is selected from at least two of kaolinite, montmorillonite, TKS7, sodium alginate, chitosan and polyvinyl alcohol.

[0025] In a second aspect, the present application provides application of the biological crust in reducing soil erosion of cultivated land.

[0026] The biological crust provided by the present application can cover bare cultivated land in a large area through natural development, thereby effectively preventing water and wind erosion of cultivated land and improving soil fertility of farmland.

[0027] In a third aspect, the present application provides a method for reducing soil erosion of cultivated land, that is, inoculating the biological crust on the surface of bare cultivated land.

[0028] At present, most of the artificial cultivation techniques of biological crusts are to inoculate the crusts to natural habitats, so the influence of human activities does not need to be considered. Due to the farming, irrigation and other farming activities, the artificial cultivation mode of the biological crusts must be innovated according to the local conditions, and coordinated and combined with the local farming mode. The present application utilizes the artificially cultivated biological crusts to prevent and control the soil erosion of cultivated land, which is an important innovation of the soil and water conservation measures of cultivated land and the application scene of biological crusts.

[0029] Beneficial effects:

[0030] The present application provides a kind of biological crust for reducing soil erosion of cultivated land and its application. The biological crust is obtained by artificially propagating and field inoculating and cultivating the naturally collected algal crust with thickness ≤1cm and moss crust with thickness ≤2cm, is suitable for bare cultivated land, and can cover bare cultivated land in a large area through natural development, thereby effectively preventing water and wind erosion of cultivated land and improving farmland soil fertility. DETAILED DESCRIPTION

[0031] The present application aims to provide a kind of biological crust for reducing soil erosion of cultivated land and its application.

[0032] The biological crust provided by the present application has a seed source of algal and moss crusts naturally developed in the arid, semi-arid and semi-humid regions of northern China, which is artificially propagated and inoculated in bare cultivated land and naturally recovered.

[0033] The process of obtaining the biological crust provided by the present application includes the collection and preparation method of the seed source of the biological crust, the indoor artificial propagation method, the artificial rejuvenation and resistance training method before inoculation, the field inoculation and short-term growth promotion and long-term management method.

[0034] Specifically, the method for covering bare cultivated land with biological crusts and preventing water and wind erosion provided by the present application comprises the following steps:

[0035] 1) selecting naturally developed algal and moss biological crusts, collecting the biological crust layer located at the soil surface layer of 0-2cm which can be peeled off alone;

[0036] 2) collecting the 2-20cm soil underlying the biological crust layer for preparing the moss crust culture medium;

[0037] 3) drying the collected biological crust in the shade, removing impurities and crushing and mixing uniformly, and placing in a cool place as the seed source for indoor propagation;

[0038] 4) carrying out one-, two-, and three-stage propagation of the algal crust seed source in a flask containing sterile BG11 culture solution, a plastic barrel / culture box, and a runway pool, respectively, and artificially controlling the environmental conditions during the propagation;

[0039] 5) After the collected biological crust underlying soil is dried, sieved, and filled into culture boxes as moss crust culture medium at a preset bulk density, the moss seed source is mixed with water and then scattered on the surface of the culture medium, and the environmental factors and soil moisture conditions are artificially controlled for propagation;

[0040] 6) Before field inoculation, the propagated cyanobacteria seed source is artificially rejuvenated by adding a rejuvenation promoting factor; then, the algae and moss seed sources are placed under different light and temperature gradient conditions for resistance training;

[0041] 7) The propagated cyanobacteria suspension is added to irrigation water in equal amounts, and then uniformly sprayed and inoculated on bare farmland; the propagated moss crust is dried, crushed, mixed with fine soil, and then uniformly scattered and inoculated on bare farmland;

[0042] 8) In the early stage of inoculation, a short-term artificial growth is achieved by adding an inoculation aid, and watering and shading measures are used as supplements;

[0043] 9) Before the next year's crop is sown, the farmland crust seed source is collected again, and after a new round of indoor cultivation, it is re-inoculated or appropriately supplemented in the field;

[0044] 10) The unused seed source is temporarily stored under 4℃ shading conditions.

[0045] Among them, the biological crust with high coverage, large thickness and stable development is selected as the seed source. Preferably, the seed source is collected from local farmland, which has natural adaptability to local climate and farmland soil conditions.

[0046] In the present application, the equivalent diameter of the crushed biological crust seed source for indoor propagation is 0.10-0.20mm, preferably 0.15mm.

[0047] In the present application, the primary propagation of the algae crust seed source is carried out in a triangular flask containing 300mL of sterile BG11 culture solution, and lasts for 15 days, during which the environmental conditions are artificially controlled. In one embodiment of the present application, the air temperature is controlled at 30 / 10℃ (day / night), the air humidity is 60%, the CO2 concentration is 400ppm, the light intensity is 3000Lux, and the light / dark cycle is 16 / 8h; in another embodiment, the air temperature is controlled at 25±2℃, the air humidity is 55%, the CO2 concentration is 400ppm, the light intensity is 2000Lux, and the light / dark cycle is 12 / 12h.

[0048] In the present application, the mixed algae liquid after primary propagation is first coated on the BG11 solid culture medium, the single colony with the largest plaque area is selected and separated and purified by streaking method; after continuous separation and purification for 3 times, the dominant algae species are obtained and continue to be cultured in liquid for 15 days, the method is the same as the primary propagation, and then secondary propagation is carried out again.

[0049] In the present application, the secondary propagation of the algal crust seed source is carried out in a 50L plastic barrel or a culture box with a length, width and height of 50cm, 80cm and 60cm respectively, and the culture lasts for 15 days, and the environmental conditions are consistent with those of the primary propagation.

[0050] In the present application, the tertiary propagation (i.e. large-scale propagation) of the algal crust seed source is carried out in a runway pool (5m x 50m) under a plastic greenhouse, and the culture lasts for 7 days, and aeration is continuously carried out during the culture.

[0051] The liquid propagation process of the cyanobacteria is refined and standardized in the present application, and the primary, secondary and tertiary propagations are carried out in a triangular flask, a plastic barrel / culture box and a runway pool respectively, and the dominant algae species are isolated and purified during the process, and various environmental factors are artificially controlled; this multi-stage and step-by-step propagation method is more in line with the breeding habits of cyanobacteria, and can continuously provide new seed sources.

[0052] In the present application, before collecting the moss crust seed source in the wild, the moss plants are first subjected to microscopic identification, and the local dominant moss species are selected for sampling.

[0053] In the present application, the soil particle size used for preparing the moss crust culture medium is 1.0-2.0mm, preferably 1.5mm.

[0054] The culture box has a size of 5cm in length, 15cm in width and 5cm in height, and a layer of 300-mesh nylon gauze is laid at the bottom, and 10 small holes with a diameter of 5mm are reserved for aeration and drainage.

[0055] The bulk density of the culture medium is the average bulk density of the surface soil of the sampling area; in one embodiment of the present application, it is 1.2g / cm 3 , and in another embodiment, it is 1.1g / cm 3 .

[0056] In the present application, the inoculation amount of the moss crust for propagation is 700-2500g / m 2 .

[0057] In one embodiment of the present application, before inoculation for indoor propagation of the moss crust, 100g / m 2 of Knop-agar medium is sprayed on the surface of the culture medium soil to promote the development of the crust.

[0058] In one embodiment of the present application, the moss crust is expanded in a phytotron, and the air temperature, humidity, CO2 concentration and light intensity are set the same as those in the first-stage expansion of the algal crust; in another embodiment, the biological crust is expanded in an artificial greenhouse, which is built with a plastic film and a steel frame, and a spherical ventilator and a water pump with a timing device are installed on the top of the greenhouse; during the expansion, the air temperature in the greenhouse is 15-25℃, and the air humidity is 60%-90%.

[0059] In one embodiment of the present application, the soil volume water content is controlled to be 20%-30%, preferably 25%, by artificial water replenishment during the expansion of the moss crust; the soil water content is monitored in real time by using a portable soil moisture rapid tester. In another embodiment, the water is replenished automatically by using a water pump with a timing device; on the first to fifth day of the expansion, the water is sprayed three times a day, and each time the water is sprayed at a flow rate of 8 L / min for 1 min; before the water is sprayed, the surface of the culture medium is slowly wetted with a small amount of water to prevent the water pump from damaging the crust due to excessive water pressure.

[0060] In the present application, the water is replenished automatically by using a water pump with a timing device, and the soil water content is monitored in real time by using a portable soil moisture rapid tester, so that the soil water content can be accurately controlled.

[0061] In the present application, 10 mg / L of a recovery promoting factor (i.e., Rpf protein) is added to the expanded cyanobacterial suspension before field inoculation to artificially rejuvenate the cyanobacteria, and the essence is a lysozyme active protein that has a recovery and growth promoting effect on cyanobacteria and other bacteria.

[0062] In the present application, the expanded algal and moss sources are subjected to resistance training before inoculation. First, the sources are placed under full-spectrum light with an intensity of 1000-50000 Lux, which is continuously increased, for a single process of 14 h, and the process is performed for 7 days; then, the sources are sequentially placed at 25℃, 20℃, 30℃, 15℃, 35℃, 10℃ and 40℃ to experience temperature fluctuations, and each temperature gradient lasts for 12 h.

[0063] In the present application, the algal crust is inoculated in the field by using a liquid spray seeding method, i.e., the cyanobacterial suspension is added to irrigation water in an equal amount, and is uniformly sprayed and seeded in the bare farmland at an inoculation amount of 5 L / m 2 .

[0064] In the present application, the moss crust is inoculated in the field by using a solid seeding method.

[0065] The moss source for field inoculation has an equivalent diameter of 0.3-1.0 mm, preferably 0.5 mm.

[0066] The fine soil added for the field inoculation of the moss crust has an equivalent diameter of 0.3-1.0 mm, preferably 0.5 mm, which is the same as the type of the farmland soil.

[0067] In this invention, the inter-field planting rate of moss bark is 700–2500 g / m². 2 .

[0068] In this invention, an inoculation adjuvant is added at the initial stage of biological crust inoculation to achieve short-term artificial growth promotion. In one embodiment of this invention, 10 g / m³ of a 1% chitosan aqueous solution is added. 2 As a bioactive substance that promotes the formation of biological crusts, 20 g / m² of polyvinyl alcohol (PVA) is also added. 2 As a water-retaining agent; in another embodiment, 15 g / m³ of kaolinite is added. 2 As a soil stabilizer, 10 g / m³ of Tacki-Spray (TKS7) reagent was added simultaneously. 2 This promotes soil aggregation and provides nutrients for crust microorganisms.

[0069] In one embodiment of the invention, within 15 days after inoculation, the plant is watered twice daily, before sunrise and after sunset, at a rate of 3 L / m² each time. 2 During the day, a shade net with a 70% shading level should be used. No artificial watering or shading should be applied 15 days after inoculation; in another implementation, watering should be done twice daily for 7 days after inoculation, with each application using 3L / m² of water. 2 During the daytime, cover the plants with a shade net that provides 50% shade; after 7 days of inoculation, stop watering and shading.

[0070] In one embodiment of the invention, the farmland in the study area is traditionally tilled; before the next crop is sown after tilling, the soil crust seed source is collected again, and then a new round of indoor cultivation is carried out, followed by re-inoculation in the field; in another embodiment, the farmland in the study area is no-tilled; the biological crust can develop stably for a long time after one inoculation and is not affected by tillage, and only the soil crust seed source needs to be collected again before the next sowing, and after a new round of indoor cultivation, it is appropriately replanted in the field.

[0071] In this invention, unused seed sources are temporarily stored under shading conditions at 4°C.

[0072] This invention collects naturally developed algal and moss crusts, uses them as seed sources, and artificially creates suitable environmental conditions for propagation. After artificial rejuvenation and resistance training, the propagated crust seed sources are inoculated into bare farmland, supplemented by short-term growth promotion and long-term management measures, in order to prevent and control soil erosion by water and wind.

[0073] In this invention, the artificial biological crust seed source used to cover bare farmland is sourced from local farmland. As it is locally sourced, the cryptogamic plants and microbial groups in the seed source are naturally adapted to the local climate and farmland soil conditions, and can quickly colonize, develop naturally, and evolve stably.

[0074] Compared with traditional engineering (slope transformation, drainage engineering, etc.), tillage (contour tillage, stubble mulching, etc.) and biological (contour hedgerow, windbreak, etc.) soil and water conservation measures, the present application has the advantages of low cost, simple operation, extensive management, no maintenance, ecological friendliness and easy popularization.

[0075] The biological crust provided by the present application has significant and multi-aspect erosion reduction effects. For water erosion, the biological crust provided by the present application can reduce raindrop kinetic energy, improve soil resistance to disintegration and water-stable aggregate content, thereby reducing splash erosion, runoff yield, runoff velocity and sediment yield; for wind erosion, the biological crust provided by the present application can reduce near-surface wind speed, wind erosion sediment yield and wind erosion rate. Compared with other measures, the present application applies the biological crust to reducing soil erosion in cultivated land, has higher coverage on the surface and is more closely cemented with the surface soil, thus having more prominent effect on reducing near-surface erosion force and better effect on improving soil resistance to erosion.

[0076] In addition to the erosion reduction effect, the biological crust provided by the present application can further regulate the structure and function of the farmland ecosystem. The biological crust provided by the present application has reasonable internal pore structure and good water and heat conditions, which is beneficial to the reproduction of microorganisms and the improvement of enzyme activity, thereby promoting the nutrient availability and turnover rate of the farmland ecosystem and improving soil fertility; at the same time, the biological crust provided by the present application can regulate ecological hydrological processes such as farmland surface runoff, infiltration and evaporation, thereby improving the farmland water and soil environment.

[0077] By using the biological crust provided by the present application, the coverage of the biological crust reaches 85% after 30 days of expansion and multiplication by artificial regulation of air temperature, humidity, illumination and soil moisture conditions, and the biological crust has reached the condition of field inoculation. After field inoculation, the development state of the biological crust is basically stable after 2-3 months by means of watering and shading measures in the early stage of inoculation, and the coverage can reach 50%-80%; after nearly 1 year of inoculation, the development state of the biological crust is completely stable, and the coverage is maintained at 85%-90%. At this time, the biological crust can effectively cover bare cultivated land, and the raindrop splash erosion, disintegration rate, runoff yield, runoff velocity, sediment yield, wind erosion sediment yield and wind erosion rate are reduced by 52%-90%, and the organic matter, total nitrogen and total phosphorus contents of the surface soil of the farmland are increased by 11%-87%. The method provided by the present application is suitable for dryland cultivation in northern China, and has important value for the prevention and treatment of soil erosion in cultivated land, the improvement of farmland water and soil environment and the green and sustainable development of agriculture.

[0078] Traditional ploughing and no-tillage are two representative tillage methods for dryland cultivation in China.

[0079] The present application provides an artificial cultivation mode of biological crust matched with the two tillage methods of traditional ploughing and no-tillage:

[0080] In the conventional ploughing mode, the seed source of the cultivated soil crust is collected again before the next crop is ploughed and sown, and then a new round of indoor cultivation is carried out, and the field is inoculated again; the seed source that is not used can be stored for a maximum of 5 months under the condition of 4℃ and shading.

[0081] In the no-tillage mode, the biological crust is inoculated once and can develop stably for a long time, is not affected by tillage, and only needs to be supplemented in time; specifically, the cultivated biological crust is collected again before sowing in late April of the next year and is prepared as a new seed source, and after a new round of indoor cultivation, it is appropriately supplemented in the field.

[0082] The present application also proposes that the cyanobacterial suspension is inoculated by being added to the irrigation water in an equal amount, so that the inoculation of the crust is combined with the irrigation activity.

[0083] The present application globally and systematically considers and designs the whole process of artificial cultivation of the biological crust from the seed source collection to the field recovery, covers the seed source collection and preparation method, the indoor artificial propagation method, the artificial rejuvenation and resistance training method before inoculation, the field inoculation and short-term growth promotion and long-term management method, and at the same time, deeply refines and optimizes each link in the implementation process, has obvious advantages in comprehensiveness, systematicness and details.

[0084] The technical solutions provided by the present application will be described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application. If not specifically indicated, the experimental methods used in the examples are conventional methods; the materials, reagents, etc. used can be obtained from commercial channels.

[0085] Example 1 Artificial cultivation technology of biological crust in the northwest loess region and its protection function against cultivated land erosion

[0086] This example was carried out in the Liudaogou watershed in the northern part of the Loess Plateau. The watershed is located in the western part of Shenmu City, Shaanxi Province, and is a transition zone from the Loess Plateau to the Mu Us Desert and from forest steppe to typical arid steppe, which is a typical fragile ecological region of water and wind erosion in the Loess Plateau. The watershed belongs to the semi-arid climate type of the middle temperate zone, with an annual average precipitation of 416mm and an annual average evaporation of 1337mm; most of the rainfall is concentrated in summer and autumn, and is mostly heavy rain, which is easy to cause water erosion; it is dry and windy in winter and spring, which is easy to cause wind erosion.

[0087] The tested biological crusts were algal crust and moss crust developed on loessial soil in Liudaogou watershed, in which the dominant algal species were Lyngbya allorgei, Microcolus vaginatus and Phormidium angustissimum, and the dominant moss species were Barbula fallax Hedw., Didymodon constrictus Mitt. and Bryum dichotomum Hedw.

[0088] In this example, 20 sampling points (2 m x 2 m) were selected in the farmland of the watershed for sampling, and the biological crust layer that could be peeled off separately was collected, in which the thickness of algal crust was ≤1 cm and the thickness of moss crust was ≤2 cm. Before sampling the moss crust, the moss was first identified under a microscope, and among them, Barbula fallax (the dominant moss species in the local area) was selected for sampling. At the same time, the 2-20 cm soil under the crust layer was collected for preparing the culture medium, and the soil type was loessial soil, with sand, powder and clay content of 84.3%, 4.2% and 11.5%, respectively. The collected biological crust was packed into a self-sealing bag for transportation, and after being brought back to the room, it was dried for 3 days in a cool and ventilated place. After air-drying, the gravel, litter and other impurities attached to the crust layer were removed, and the crust layer was placed in a plant crusher at a speed of 28000 r / min for 30 s, then passed through a 0.2 mm sieve and thoroughly mixed, and placed in a cool place as a seed source for standby.

[0089] The seed source of algal crust was expanded by liquid culture method. 10 g of air-dried algal crust seed source was dissolved in a triangular flask containing 300 mL of sterile BG11 culture solution and stirred evenly for 24 h. Then, it was transferred to an artificial climate chamber in Shanxi Shenmu Erosion and Environment National Field Scientific Observation and Research Station for primary expansion, with air temperature of 30 / 10℃ (day / night), air humidity of 60%, CO2 concentration of 400 ppm, light intensity of 3000 Lux, and light / dark cycle of 16 / 8 h. After 15 days of expansion, 100 μL of mixed algal liquid was spread on BG11 solid culture medium, and the single colony with the largest area was picked and separated and purified by streaking method. After continuous separation and purification for 3 times, the dominant algal species Microcolus vaginatus (identified by sequencing) was obtained. After 15 days of liquid culture of the algal species (method same as primary expansion), it was transferred to a 50 L plastic bucket containing BG11 culture solution, and the environmental conditions were kept unchanged, and secondary expansion was continued. After 15 days of expansion, it was transferred to a running track pool (5 m x 50 m) under a plastic greenhouse for tertiary expansion (i.e. large-scale expansion), and 8 t of BG11 culture solution was added to the running track pool, and aeration was continued during the culture process. After 7 days of culture, the biomass dry weight of the cyanobacterial suspension in the culture pool reached 0.30 g / L, which had reached the conditions for inoculation into bare farmland.

[0090] The source of the moss crust was expanded by solid culture. The underlying soil of the collected biological crust was placed in the room for 3 days of indoor drying, then passed through a 2 mm sieve and filled into a culture box with a length, width, and height of 5 cm, 15 cm, and 5 cm, respectively, at a bulk density of 1.2 g / cm 3 The bottom of the culture box was covered with a layer of 300-mesh nylon gauze, and 10 small holes with a diameter of 5 mm were reserved for ventilation and drainage. After filling, 100 g / m 2 of Knop-agar medium was sprayed on the surface of the soil. The crushed source was mixed with water at an inoculation amount of 700 g / m 2 and evenly spread on the surface of the culture medium. The expansion began in the artificial climate chamber. The settings for air temperature, humidity, CO2 concentration, and light intensity were the same as those for the first expansion of the algal crust. During the expansion period, water was replenished at 9:00 every day to control the soil volumetric water content at 20%-30% (determined by a portable soil moisture rapid tester). After 30 days of expansion, the average coverage of the moss crust in the culture box was more than 85%, the thickness was 2.12 cm, the biomass was 10 mg / cm 2 , and it had the conditions for inoculation into bare farmland.

[0091] Before inoculation, 10 mg / L of a recovery promoting factor (Shanghai Tongwei Bio, TW18366) was added to the expanded cyanobacterial suspension to restore its activity. The essence of the recovery promoting factor is Rpf protein, which is a lysozyme active protein that has a recovery and growth promoting effect on bacteria such as cyanobacteria.

[0092] Thereafter, the algae and moss sources were further subjected to indoor resistance training to enhance their adaptability and resistance to the outdoor environment after inoculation. The resistance training method is as follows:

[0093] First, the source was placed under 1000-50000 Lux continuously increasing full-spectrum light (spectrum containing ultraviolet light, visible light, and infrared light) for a single process lasting 14 h, for a total of 7 days; then, the source was placed in turn at 25°C, 20°C, 30°C, 15°C, 35°C, 10°C, and 40°C to experience temperature fluctuations, with each temperature gradient lasting 12 h.

[0094] The main crop in this basin is corn, which is usually sown in late April and harvested in early November. Field inoculation of artificial biological crusts began in early May. Among them, the algal crust inoculation used liquid spray seeding method; that is, the cyanobacterial suspension was added to the irrigation water in equal amounts, and the inoculation amount was 5 L / m 2 . The moss crust inoculation used solid seeding method; the expanded moss crust was taken out of the culture box, dried indoors, crushed, and passed through a 1 mm sieve. The sieved source was mixed with fine soil passing through a 1 mm sieve, and the inoculation amount was 700 g / m 2 .

[0095] After inoculation, inoculation aids are added for short-term artificial promotion. First, 10 g / m 2 of a 1% chitosan aqueous solution is added, which as a natural biological polysaccharide helps to promote the cementation and layering process of the biological crust and improve the microbial activity of the crust layer. After application, it can be gradually degraded by soil microorganisms, has no environmental hazards and no residues. In addition, 20 g / m 2 of polyvinyl alcohol (PVA) is added again as a water-retaining agent. Thereafter, water is continuously sprayed using a small watering can until the ground surface is slightly waterlogged, and a shading net with a shading degree of 70% is laid at the inoculation site. Within 15 days after inoculation, water is sprayed 2 times before sunrise and after sunset every day, 3 L / m 2 , and the shading net is covered during the day. After 15 days, the coverage of the biological crust is about 5%, at which time the rainy season has begun, and artificial watering and shading are no longer performed.

[0096] After 30 days of inoculation, the coverage of the biological crust reaches 10%; when the inoculation is 90 days old and the rainy season is over, the biological crust has covered about 50% of the bare ground surface. After nearly 1 year of development and succession, by April 2022, the artificial biological crust has basically reached a stable state, with a coverage of more than 85% on the bare cultivated land. Specifically, the average thickness of the algal and moss crust layers reaches 0.57 and 1.01 cm, respectively, and the biomass is 1.32 and 5.83 mg / cm 2 , respectively, and the moss density is 20 plants / cm 2 . Before plowing and sowing begin in late April, the developed artificial biological crust of the cultivated land is collected and prepared as a new seed source, after which a new round of indoor cultivation is performed, and the inoculation is performed again in the field. The unused seed source can be stored for a maximum of 5 months under shading conditions at 4°C.

[0097] Compared with the bare cultivated land without treatment, the artificial biological crust developed for nearly 1 year significantly reduces the erosion of the cultivated land. Under the same rainfall conditions, the runoff yield, runoff flow rate and sediment yield of the cultivated land covered by the biological crust are reduced by 65%, 52% and 83%, respectively; under the same wind force, the wind erosion sediment transport and wind erosion rate of the cultivated land covered by the biological crust are reduced by 88% and 90%, respectively. Furthermore, the organic matter, total nitrogen and total phosphorus contents of the cultivated land covered by the biological crust are increased by 87%, 57% and 11%, respectively. The above results show that the artificial biological crust can cover a large area of bare cultivated land through natural development, thereby effectively preventing water and wind erosion of the cultivated land and improving the soil fertility of the farmland.

[0098] Example 2 Artificial cultivation technology of biological crust in the Northeast black soil region and its protection function against erosion of cultivated land

[0099] The present example was carried out in Jilin Pears Experimental Station of China Agricultural University. The experimental station is located in the southeast of Lishu County, Jilin Province, and is situated in a rolling plain that transitions from the Changbai Mountain to the northern plain, belonging to a typical black soil region in Northeast China. The region has a north temperate semi-humid monsoon climate, with an average annual precipitation of 586 mm and an average annual evaporation of 808 mm; about 80% of the total annual rainfall occurs in summer, which can easily cause gully erosion; the winter and spring are dry and cold, and the wind erosion is severe.

[0100] The tested biological crusts were collected from farmlands that were subjected to no-tillage measures. Due to the lack of tillage disturbance, the microenvironment of the farmland under no-tillage conditions was improved year by year, and microorganisms and cryptogams proliferated, creating favorable conditions for the natural development of algal and moss biological crusts. After identification, the dominant algal species were Stigeoclonium, Microcystis and Spirulina; and the dominant moss species were Bryum capillare and Physcomitriumsphaericum.

[0101] In the present example, 20 sample points (2 m x 2 m) were selected in the farmland of the experimental station, and sampling was carried out in the morning on a sunny day after 3 days of rainfall; the biological crust layer that could be peeled off individually was collected, and the thickness of the algal and moss crusts was 0.19 and 0.51 cm on average; among them, the moss crust was sampled after microscopic identification of the moss plants, and Bryum capillare (the dominant moss species in the local area) was selected for sampling. At the same time, 2-20 cm soil under the crust layer was collected for preparing the culture medium, and the soil type was black soil, with sand, silt and clay contents of 13%, 59% and 28%, respectively. The collected biological crusts were packed into self-sealing bags and brought back to the laboratory for 7 days of shade drying, and then the non-crust components such as gravel, litter and plant roots were picked out, placed in a plant crusher at a speed of 28000 r / min for 20 s, then passed through a 0.2 mm sieve and thoroughly mixed and stirred, and stored in a cool place as a seed source for future use.

[0102] The source of the algal crust is propagated by liquid culture. 20 g of air-dried algal crust source is dissolved in a triangular flask containing 300 mL of sterile BG11 culture solution and stirred and soaked for 24 h. Then, it is transferred to the artificial climate chamber of the experimental station for primary propagation, with air temperature of 25±2°C, air humidity of 55%, CO2 concentration of 400 ppm, light intensity of 2000 Lux, and light / dark cycle of 12 / 12 h. After 15 days of propagation, the dominant algal species (Microcystis) is obtained by the same method as in Example 1. After 15 days of liquid culture (the method is the same as the primary propagation), the algal species is transferred to a culture box containing BG11 culture solution (length, width and height are 50 cm, 80 cm and 60 cm, respectively), and the environmental conditions are kept unchanged, and the secondary propagation is continued. After 15 days of propagation, the tertiary propagation (i.e. large-scale propagation) is carried out by transferring the algal species to a raceway pond (5 m x 50 m) under a plastic greenhouse, and 8 t of BG11 culture solution is added to the raceway pond, and aeration is continued during the culture. After 7 days of culture, the biomass dry weight of the cyanobacterial suspension in the culture pond reaches 0.25 g / L, which has reached the conditions for inoculation into bare farmland.

[0103] The source of the moss crust is propagated by solid culture. The underlying soil of the collected biological crust is air-dried in the room for 7 days, and then sieved through a 2 mm sieve and filled into the filling box of Example 1 at a bulk density of 1.1 g / cm 3 After the crushed biological crust source is stirred with water at an inoculation amount of 2500 g / m 2 , it is sown on the surface of the culture medium, and then placed in an artificial greenhouse for artificial propagation. The artificial greenhouse is built with plastic film and steel frame, and a spherical ventilator and a water pump with a timing device are installed on the top of the greenhouse. During the propagation, the air temperature in the greenhouse is 15-25°C, and the air humidity is 60%-90%. During the first 5 days of propagation, water is poured 3 times a day, with a flow rate of 8 L / min for 1 min each time. Before pouring water, the surface of the culture medium is slowly moistened with a little water to prevent the water pump from damaging the crust due to excessive water pressure. After 5 days of propagation, the topsoil begins to turn dark green; after 15 days, the crust coverage reaches more than 60%; and after 30 days, the average crust coverage is 85% and reaches a stable development state, with a biomass dry weight of ≥5 mg / m 2 , which has reached the conditions for inoculation into bare farmland.

[0104] Before inoculation, the cyanobacterial suspension after propagation is added with the recovery promoting factor of Example 1 for rejuvenation. Then, the algal and moss sources are subjected to indoor resistance training by the method of Example 1 to enhance their adaptability and resistance to the outdoor environment after inoculation.

[0105] The main crop type in the study area is corn, which is usually sown in late April and harvested in mid-October. The field inoculation of artificial biological crusts was carried out in early May. Among them, the algal crust inoculation adopts liquid spray method; the cyanobacterial suspension is added to the irrigation water in equal amount, and the inoculation amount is 5 L / m 2 . The moss crust inoculation adopts solid seeding method; the expanded biological crust is taken out from the culture box, dried in the room, crushed and sieved through 1 mm sieve, then the sieved seed source is mixed with fine soil sieved through 1 mm sieve, and the inoculation amount is 2500 g / m 2 .

[0106] After inoculation, inoculation adjuvants need to be added for short-term artificial promotion. First, add 15 g / m 2 of clay mineral kaolinite, which can quickly dehydrate to form a sticky surface layer after application, helping to promote the cementation and layering process of the biological crust. In addition, add 10 g / m 2 of Tacki-Spray (TKS7) reagent, which is essentially a biological polysaccharide, which can further promote soil aggregation and provide nutrients for the microorganisms in the crust layer. Then, water continuously with a small spray bottle until the surface is slightly accumulated, and shade with a shading net with about 50% shading. Water 3 L / m 2 twice a day for 7 days after inoculation, and cover the shading net during the day. Since it is the rainy season at this time, the water and heat conditions are sufficient, and there is no need for artificial watering and shading after 7 days of inoculation.

[0107] After 7 days of inoculation, the coverage of biological crust reaches 10%; after 15 days, the coverage increases to 50%; after 2 months of inoculation, when the rainy season is about to end, the coverage of biological crust in bare farmland reaches more than 80%, and the development state is basically stable. After nearly 1 year of development and succession, by April 2022, the artificial biological crust has reached a stable state, with a coverage of 90% in bare farmland. Specifically, the average thickness of the algal and moss crust layers is 0.15 and 0.48 cm respectively, the biomass is 18.53 and 40.72 mg / g respectively, the height of the moss is 9.83 mm, and the density of the moss is 12 plants / cm 2 . Since the farmland in the study area is no-till, the biological crust can develop stably for a long time after one-time inoculation and is not affected by tillage, and only needs to be supplemented in time. Specifically, before sowing in late April of the next year, the biological crust of the farmland is collected again and prepared as new seed source, which is inoculated in the field after a new round of indoor cultivation. The unused seed source is temporarily stored in a shaded condition at 4°C.

[0108] Compared with the untreated bare farmland, the artificial biological soil crust developed for nearly one year produced a significant erosion reduction effect. Under rainfall conditions, the biological soil crust coverage reduced the raindrop kinetic energy by 0.48 J on average, increased the stability of soil aggregates by 47.1%, and thus reduced the raindrop splash erosion by 80%. At the same time, the disintegration rate of the farmland covered by the biological soil crust was reduced by 55% compared with the bare farmland. In addition, under the same wind force, the wind erosion sediment transport was reduced by 90% under the biological soil crust coverage. In addition to the erosion reduction effect, the organic matter, total nitrogen and total phosphorus contents of the farmland covered by the biological soil crust were increased by 23%, 64% and 21% respectively compared with the farmland without the crust. The above results show that the artificial biological soil crust development can fully cover the bare farmland, effectively prevent water and wind erosion, and significantly improve the soil fertility of farmland.

[0109] The above-described embodiments only express several implementation manners of the present application, facilitate specific and detailed understanding of the technical solutions of the present application, but cannot be understood as a limitation on the patent protection scope of the present application. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application.

Claims

1. A biological crust for reducing erosion of cultivated soil, characterized in that, The algal crusts with thickness ≤1 cm and the moss crusts with thickness ≤2 cm are collected from nature, and are artificially propagated and inoculated in field to obtain; wherein, the artificial propagation of the algal crusts adopts liquid culture, and the culture is carried out until the biomass dry weight ≥0.15 g / L; the artificial propagation of the moss crusts adopts solid culture, and the culture medium is selected to be the soil 2-20 cm below the crust layer, and the culture is carried out until the biomass dry weight ≥5 mg / m 2 ; the inoculation amount of the algal crusts after artificial propagation in field is 4-10 L / m 2 ; the inoculation amount of the moss crusts after artificial propagation in field is 600-3000 g / m 2 ; The artificial propagation of the algal crust is selected from BG11 culture solution; and the environmental conditions for the culture include: air temperature of 30±2 / 10±2 ℃; and / or, air humidity of 55%-65%; and / or, CO2 concentration of 350-450 ppm; and / or, light intensity of 2800-3200 Lux; and / or, light / dark cycle of 15 / 9~17 / 7; The artificial propagation of the moss crust is selected from the group consisting of 2-20 cm soil under the collection site as the basic medium, the soil particle size is 1.0-2.0 mm, the surface is sprayed with 80-120 g / m 2 The Knop-agar medium; the environmental conditions of the culture include: the day / night air temperature is 30±2 / 10±2 DEG C; and / or, the air humidity is 55%-65%; and / or, the CO2 concentration is 350-450 ppm; and / or, the light intensity is 2800-3200 Lux; and / or, the light / dark cycle is 15 / 9~17 / 7; and / or, the soil water content is 20%-30%. After the artificial propagation of the algal crust and the moss crust, resistance training is performed first, and then field inoculation is performed; the method of resistance training includes light training and temperature training; the light training lasts for 5-10 days, and 1000-50000 Lux full-spectrum light is irradiated for 13-15 hours every day; the temperature gradient of the temperature training is 25±2 ℃, 20±2 ℃, 30±2 ℃, 15±2 ℃, 35±2 ℃, 10±2 ℃, and 40±2 ℃, and each temperature gradient lasts for 11-13 hours; After the artificial propagation of the algal crust, rejuvenation is performed first, and then field inoculation is performed; the method of rejuvenation is that 8-12 mg / L of a recovery promoting factor is added to the algal suspension after artificial propagation, and the recovery promoting factor is selected from Rpf proteins; After field inoculation, an artificial growth promoter is applied, and the artificial growth promoter is selected from at least two of kaolinite, montmorillonite, TKS7, sodium alginate, chitosan, and polyvinyl alcohol.

2. The biofilm according to claim 1, characterized in that, The field inoculation amount of algal crust after artificial propagation is 4-6 L / m 2 The field inoculation amount of moss crust after artificial propagation is 600-800 g / m 2 .

3. The biological crust according to claim 1, wherein, The artificial propagation of the algal crust is selected from BG11 culture solution; and the environmental conditions for the culture include: air temperature of 25±2 ℃; and / or, air humidity of 50%-60%; and / or, CO2 concentration of 350-450 ppm; light intensity of 1800-2200 Lux; and / or, light / dark cycle of 11 / 13~13 / 11. The artificial propagation of the moss crust is selected from soil 2-20 cm below the crust layer at the collection site as a basic culture medium, and the soil particle size is 1.0-2.0 mm; and the environmental conditions for the culture include: air temperature of 15-25 ℃; and / or, air humidity of 60%-90%; and / or, CO2 concentration of 350-450 ppm; and / or, light intensity of 1800-2200 Lux; and / or, light / dark cycle of 11 / 13~13 / 11; and / or, soil water content of 20%-30%.

4. The biofilm according to claim 3, characterized in that, The field inoculation amount of algal crust after artificial propagation is 6-10 L / m 2 The field inoculation amount of moss crust after artificial propagation is 2000-3000 g / m 2 .

5. Use of the biological crust according to any one of claims 1-4 in reducing erosion of cultivated land.

6. A method of reducing erosion of arable soil, characterized in that, Inoculating the biological crust according to any one of claims 1-4 on the surface of bare cultivated land.