Effectively controlling desertification has always been a global problem. Given the fluidity of sand, dealing with wind damage is difficult. Among the current main sand fixation technologies, engineering sand fixation uses artificial sand barriers and other engineering means, such as grass grids and stone grids to prevent sand movement; chemical sand fixation uses chemical sand fixation agents such as emulsified asphalt, polymer resin, etc.; plants Sand fixation is to achieve the purpose of sand fixation by stabilizing and blocking the sand body by planting psomatrophic plants. Let’s take a look at the hottest new technologies among these three sand fixation technologies: three-dimensional sand fixation vehicles, algae sand control and sand fixation technology, and plant-based fiber adhesives. The first two of these three technologies have been proven to be effective, and the third This method is still controversial and its effect needs to be verified.
Three-dimensional sand fixing vehicle - the speed is about 180 times that of manual sand barrier
Grass sand barrier is made of wheat straw, straw, reed and other materials tied into square grids in the desert. A sand control method that prevents wind, fixes sand, and conserves water. Because it is located in Shapotou, Ningxia, it is also known as the "Shapotou Desert Control Model." Shapotou has been rated as one of the "Global Environmental Protection Top 500" by the world's desert control peers because of its outstanding achievements in desert control and rich experience.
How to improve the efficiency of desertification control and achieve the effect of desertification prevention and control is a difficult problem in global desertification control. At present, the world's first "multifunctional three-dimensional sand fixing vehicle" and "tracted single sand fixing machine" independently developed and manufactured by my country have filled the "gap" in this field. This is one of the achievements of scientific and technological innovation in Gansu Province and an important step in desert control. A "revolution".
This "multifunctional three-dimensional sand fixing truck" has 11 utility model technologies and invention patents. Use mechanized laying of grass squares, with a grass insertion depth of 15 cm and a grass and sand barrier height of about 30 cm. Compared with manual work, the speed of three-dimensional sand fixing vehicles is about 180 times that of manual work, which can fundamentally solve the problem of desertification speed being faster than manual sand control speed. It not only reduces costs, but also makes the operation more standardized, greatly increasing the roughness of the desert surface, reducing wind force, preventing quicksand from moving and intercepting rainwater. It has higher quality and better sand fixation effect than artificial sand fixation. It turns out that all kinds of wild plants have grown in the barren desert, which is incredible in the eyes of the local people. "A busy day in Zhuangzi is worse than just driving around in this car," commented a local villager.
In 2015, the mechanized desert control team planted more than 80,000 psammophytes such as Haloxylon ammodendron, flower stick, and caragana. Through planting and cultivation, sandy plants are growing well. At the same time, as the sand in the grass-sand barrier is fixed, some wild plants also grow out. The sand dunes that were treated a year or two ago have changed drastically. In 2016, the desertification control team used mechanical and biological desertification control to successfully plant more than ten acres of experimental fields in the desert. After the vegetables and fruits were sent to a well-known testing agency in Shanghai for testing, they concluded that all types of fruits and vegetables are naturally pollution-free. There is zero pesticide residue, and the fruits grown therein have higher sugar content than similar fruits.
Algae sand control and sand fixation technology - rapid formation of soil crust to curb further desertification of the soil
Researchers from the Ye Xili Biological Desert Control Institute began a systematic study of the soil of the Taklimakan Desert in 2009 Biological research has found that desert green algae cells with rich biological diversity still exist in desert soil. So far, the company's R&D personnel have successfully isolated and purified more than 1,000 algae strains from sand samples in the Taklimakan Desert, and have successfully completed the collection and GPS positioning of sand samples at 7 of the 9 sampling points. 2 laps of the Taklimakan Desert.
Studies on the biology and nutrition of desert green algae cells have found that this type of cells not only has unique nutritional properties, but also its biological evolutionary status is at a very ancient stage of development, which fully illustrates the importance of the Taklamakan Desert Once a vast ocean, the seaweed at that time gradually evolved into today's desert algae as the ocean disappeared.
The vitality of desert green algae is much stronger than that of ordinary freshwater green algae or seaweed. This is because the extremely harsh desert living environment makes desert green algae cells have very specific components and functions.
①The desert environment is naturally short of water, and desert green algae cells must accumulate highly active CGF to survive;
②The sunlight in the desert is very strong, and desert green algae cells must accumulate a large amount of CGF. Unsaturated fatty acids can avoid being oxidized by radiation;
③The precipitation in the desert is very low, and desert green algae cells need to accumulate a large amount of extracellular polysaccharides (rich in alkaline polysaccharides) to absorb them when water is available. As much water as possible to continue its growth and reproduction;
④The temperature in the desert is high, and the cell wall (cellulose component) of desert green algae must be thick to effectively prevent excessive water loss and a harsh living environment. Created magical desert green algae.
This technology provides a method to quickly fix quicksand using desert algae. It has fast, efficient and long-lasting sand fixation, soil formation and fertilization effects, and is suitable for mobile and semi-mobile sand dunes in arid and semi-arid areas around the world. The process of fixation and soil formation.
One or more layers of algae soil crusts are artificially formed on the surface of the desert soil, thereby changing the nutrient composition, microbial community and microecological cycle system of the desert soil, and ultimately improving the desert soil, fixing the desert soil, and greening the soil. A new type of pollution-free, pollution-free, environmentally friendly technology.
Scientific research has proven that algae, as a biological group with special significance in the history of biological evolution, plays a special role in comprehensive control of desertification. As colonizing organisms, algae can not only grow and reproduce in harsh environments where most life forms cannot survive, but also affect and improve the natural environment with their unique life and metabolism. Algal biocrusts play an important role in preventing wind and sand fixation, preventing soil erosion and changing water distribution. As desertification becomes increasingly serious, using desert algae to improve soil and prevent wind and sand fixation is of positive significance.
Generally speaking, the role of algae biological sand control in desertification control is mainly reflected in: ① Rapid formation of soil crust (Soil Crust), thus curbing further desertification of the soil ② Desert algae cells metabolize sugar secretions It can increase the organic matter content of the soil, and the desert nitrogen-fixing algae can cause the nitrogen element in the desert soil to rise sharply. The desert soil that has been treated by algae biological desertification will have the nutritional conditions for the growth of higher plants.
Plant-based fiber adhesive---technically flawed
According to media reports, Yi Zhijian, a professor of mechanics at Chongqing Jiaotong University, developed a technology that can Turn the desert into a soil binder. Just put this binder into the sand and add an appropriate amount of water. The sand can turn into soil with ecological-mechanical properties and "universal binding constraints". Capable of storing water, nutrients and air, and capable of breeding microorganisms. To put it simply, it is like a kind of "glue" of sand, which "points sand into soil" from the long yellow sand. This discovery has been applied to the "desert soilification" ecological restoration technology and has been successful. 4,000 acres of experimental desert have been successfully transformed into fertile farmland. The scientific research results have been published in relevant authoritative publications.
The fundamental difference between desert and soil is the difference in mechanics: soil particles have forces acting on each other and can form a whole, while sand is loose and has no such force. What Yi Zhijian and the others have to do is to use a binder to give the sand particles this force, so that they can turn desert into soil.
As long as this plant-based fiber binder is added and water is added, the sand can obtain the same mechanical properties as natural soil. This specific constraint that exists between soil particles is the universal binding constraint, or ODI constraint for short. It allows the soil to self-repair and self-regulate.
Self-healing means that the soil can freely switch between wet and dry states when exposed to water. Self-regulation means that the soil can provide space for plants to take root and sprout, and "hold" the plant roots to provide space for plant growth. possibility. Sand is also a kind of soil, but it is just damaged soil. If you can return it to what it was before it was damaged, you can build an oasis on the sand.
Just mix the sand with the binder and add an appropriate amount of water. In just two minutes, the golden sand will turn into dark brown soil. It will not fall apart when you pick it up with your hands. Just pour the water. No water was lost in the enclosed pit.
According to reports, the Chinese scientific research team has used the "desert soilization" ecological restoration technology in a 25-acre experimental plot in the Ulan Buh Desert of Alxa League, Inner Mongolia, and achieved success.
After construction and transformation, the sand body was immediately fixed and showed long-lasting resistance to wind erosion.
More than 70 kinds of plants are planted in the experimental plot, and they are growing vigorously. In order to test the results of the treatment, the research team planted more than 70 kinds of plants in the transformed desert, and they all grew very well. In order to check the safety, the team also invited a third-party organization to test the adhesive and "sand soil" soil. Yi Zhijian took out the adhesive test report from Xi'an Guolian Quality Inspection Technology Co., Ltd. Many of the above indicators were far lower than the national standards.
For this scientific research result, Yang Wenbin, a researcher at the Institute of Desertification of the Chinese Academy of Forestry Sciences and secretary-general of the Chinese Desert Control and Sand Industry Society, who is on the expert review team of the result, believes that its research is still in a very preliminary stage. For a research, it needs laboratory results, basic results, and field experimental results, that is, large-scale regional experiments. Promotion can only begin after the regional experiments are completed, even if the regional experiments have preliminary results. As a result, it cannot be said that this is a technology that can be promoted. The 4,000-acre experiment conducted by Professor Yi's team may seem vast to ordinary people, but for desertification research, 4,000-acre is too small and is nothing. This so-called achievement cannot reach the stage of large-scale promotion.
Moreover, if there is water in the desert, it will become farmland without any treatment at all. Yang Wenbin said: "The desert is the best soil, but it lacks water. As long as there is water, it is good soil. If the desert has water, you don't need to do any work and you can plant directly. Install irrigation equipment on the desert and keep the vegetation at a certain level. Density growth is a problem that scientists are now trying to solve. "
Some of the current deserts in our country are caused by natural conditions, and some are caused by human factors. Especially in some desert areas near the Hetao area, it is indeed caused by human destruction of vegetation. , so dunes and sandy lands can be transformed by category, and desertification areas caused by human over-exploitation can be restored with priority. These areas once had a basis for the growth of green plants. Therefore, the key to transforming the desert is that it should be classified and partitioned without violating the laws of nature.
The native desert was formed during the geological period. It is a desert ecosystem and a kind of ecosystem. It is an important part of the ecosystem like the wetland ecosystem and the forest. Desertification control is not about eradicating all sandy land, nor is it possible to turn all deserts into oases. Otherwise, if the underlying surface is uniform, there will be no air pressure difference, which is not conducive to the formation of air flow, thereby affecting the movement of water. On the other hand, the regional climate may be worsened, and the pros and cons need to be weighed.