Standing atop a sand dune in the "Three-North" Shelter Forest Program zone in the Baitujing area of Minqin County, Gansu Province, Gao Feng-a senior forestry engineer with the Minqin County Forestry and Grassland Bureau-crouched down and patted the bulging "sandbag" at his feet. These cylindrical fabric bags, filled with yellow sand, are arranged in a 1.5-meter-by-1.5-meter grid across the sandy terrain, tightly anchoring the shifting sands.
"In the past, sand control relied on wheat straw; now, we can use a 'sand-to-control-sand' approach," Gao Feng explained, pointing to the sandbags. "These bags will naturally degrade after a few years, providing nutrients to the *Haloxylon* seedlings."
Minqin County is surrounded on the east, west, and north by the Tengger and Badain Jaran deserts; in the last century, desertified land once accounted for over 90% of its territory. Residents began exploring ways to lock down the shifting sands as early as the 1950s. Under the guidance of technical experts, locals learned to create "straw checkerboards." However, Gao Feng noted, "Minqin doesn't produce rice straw locally, so materials had to be brought in from elsewhere. Straw is prone to weathering and breaking down; if the wind picked up before the *Haloxylon* plants-which anchor the sand-had taken firm root, the grids would have to be reinstalled."
In recent years, inspired by research into bio-based biodegradable materials, the Minqin County Forestry and Grassland Bureau collaborated with institutions like the Gansu Desert Control Research Institute to propose a new concept: using biodegradable materials to create cylindrical bags that could be filled directly with shifting sand, thereby using the sand itself to stabilize the dunes.
But what material to choose? Minqin's sandy soil is already barren and fragile, so sand-control materials absolutely could not introduce new pollution. The team started with biomass raw materials such as corn starch and cassava, using microbial fermentation to produce small-molecule lactic acid, followed by polycondensation and melt spinning. These bio-based polylactic acid fiber sandbags offer excellent UV resistance; furthermore, through the action of microorganisms, they undergo gradual hydrolysis and enzymatic degradation, eventually breaking down completely into water and carbon dioxide-achieving natural degradation.
"The principle behind 'using sand to control sand' is actually quite ingenious," Gao Feng said, pointing to the interface between the sandbag and the surrounding sandy ground. When the wind rises, near-surface shifting sands strike the sandbags, dissipating much of their kinetic energy. The sand swirls within the grid compartments and packs increasingly tight, effectively "welding" the sandbags to the sandy surface-a practice rooted in the traditional wisdom of "harnessing the wind to control the sand." The rough texture of the sandbags further reduces near-surface wind speeds, ensuring long-term stability of the sand surface.
Even better, the sandbags are permeable yet moisture-retentive; rainwater or irrigation water seeps through the material into the sand layer but does not easily evaporate. "The operation is relatively simple, offering strong capabilities for sand fixation and wind erosion resistance; once the material degrades, it nourishes the vegetation growing within the barriers," explains Gao Feng, lifting a section of a partially degraded sandbag to reveal vegetation already half a foot tall.
Today, Minqin County boasts over 2.61 million mu of preserved artificial forests and 3.25 million mu of enclosed natural psammophytic (sand-loving) vegetation. A 380-kilometer "green belt" of forest and grass now fully encircles the oasis, resulting in a reduction of both the total area and the severity of desertification and sandy land degradation. Across the Qingtu Lake area, biodegradable sandbag grids dot the landscape alongside traditional straw checkerboard barriers, providing a home for species such as *Calligonum* (sand-fixing shrubs), *Haloxylon ammodendron* (saxaul), and *Nitraria* (nitre bush). Combined with photovoltaic panels-creating a model of "power generation above, sand fixation below, and planting between"-this approach establishes an integrated protection system that combines fixation, obstruction, and transport control, charting a new path of ecological priority and green development for arid desert regions.
**Bio-based Biodegradable Polylactic Acid (PLA) Sand Barrier Technology**
These bio-based, biodegradable sand barrier bags are woven from polylactic acid (PLA) fibers produced via a specialized process. They feature high UV resistance and tear strength, with a service life exceeding ten years. Upon completing their windbreak and sand-fixation mission, the material undergoes complete biodegradation into carbon dioxide and water, leaving no microplastic residues and preventing secondary pollution. The product is permeable to both air and water, enabling a "sand-to-control-sand" approach using locally sourced materials. It offers simple, efficient installation and significant lifecycle cost advantages, making it an ideal alternative to traditional straw checkerboards and non-biodegradable plastic sand barriers.
**Applicability:**
* **Domestic:** Suitable for arid regions in Northwest China (e.g., Kubuqi, Badain Jaran, and Tengger Deserts); applicable to shifting or semi-fixed sand dunes with aeolian sandy soil.
* **International:** Suitable for ecologically sensitive areas in Central Asia, West Asia, North Africa, and Mongolia.
**Technical Highlights:**
* The material is fully biodegradable, breaking down into carbon dioxide and water without leaving microplastic residues, thereby avoiding secondary pollution.
* It features high UV resistance and tear strength, with a wind-blocking and sand-fixing lifespan exceeding ten years, meeting long-term engineering requirements for sand control.
* The bag structure facilitates water infiltration and air circulation, improving the microenvironment and supporting vegetation recovery.
* No specialized technical expertise is required; a two-person team can operate the system after simple training, and it supports both manual and mechanical installation.
* Available in diverse specifications: diameters of 8–9 cm (for standard sand-fixing areas) and 17–18 cm (for severe wind-sand zones such as wind gaps), compatible with 1m×1m or 2m checkerboard sand barrier layouts.
