To help nature recover from the impact of the mining industry Svetlana Mesyats and colleagues from the Geological Institute of the Kola Research Centre, Russian Academy of Sciences, Russia, have developed a method that uses a thin polymeric film to stabilise freshly-seeded soil. The material is sprayed directly onto the surface of the soil and protects the new shoots of plant cover from erosion.
Where the Technology is Designed to be Used
On the Kola Peninsula, because of intensive mining, much of the soil around old sites has been eroded and that which is left is often buried under mine spoil. Water, wind erosion and sharp fluctuations in temperature make it impossible for young grass to survive and, with no plants to anchor the soil, dust clouds and storms are a common occurrence. However, around the town of Apatity, using Mesyat’s new variation on a common practice, a thick grass cover has been created on barren spoil heaps, so ending the area’s prevalent dust storms.
Conventional Methods for Growing Grass on Barren Sites
Putting down fertile topsoil and sowing grass seed usually creates lawns. To encourage growth, the surface is the usually covered with coarse cloth sacking or a polymeric material such as lutrosil. For very large areas a layer of soil is put down over the top of the seeds and lightly compacted. The sacking or polymeric material prevents the humus layer and the seeds from being washed away, and at the same time decreases the evaporation of moisture, so helping the grass to germinate and take root.
A New Method for Growing Grass on Barren Sites
However, several hectares of damaged land cannot be covered with cloth. If, on the other hand, a protective covering could be sprayed onto the ground, the size of area requiring covering need not be a problem. This was the approach taken by the researchers at the Geological Institute. They developed a polymeric covering called ‘Biorekulat’ for restoring the vegetation at old mine sites. The covering is a durable plastic film that is formed after applying an aqueous emulsion of polymer to the soil surface. The film effectively stabilises the surface by gluing the small soil particles together, ensuring that the topsoil stays in place. At the same time the polymeric covering is porous, air and water-permeable and consequently does not prevent the earth from breathing. Seeds are comfortable under such a film - it saves heat and moisture and evens out the fluctuations in temperature in the soil. The film also poses no barrier to the young plants as they are easily able to grow through it.
Plastic Film Properties and Behaviour
The film is durable and stays in place for several years before biodegrading. It is also frost and heat resistant, but most importantly lets the seeds germinate and take root in the first year. In the second year, the sod is formed, which knits together the soil and prevents it from eroding, so making the covering unnecessary. Using the sprayed film technique is many times quicker than letting nature take its course and is, according to the researchers, ten times cheaper than using any other form of ground cover, such as cloth or polymeric materials on a roll. In fact, vegetation cover can be restored on bare ground without applying seeds or needing fertile ground, because there are always a number of seeds in the ground which are ready to germinate, just waiting for the right conditions. Consequently vegetation cover will appear without sowing seeds, and perennial grasses can be planted even on infertile ground.
So successful has this invention been, that some UK golf clubs are looking into the possibility of repairing bare spots on golf links via this process.