Artificial land brings green to urban areas

From the natural and locally available materials, US scientists have just created a soil that can filter rainwater as well as create a better growth environment for greenery, thereby creating shade, cooling and especially limited urban air pollution.

Implementation of the project to reduce the situation of rainwater or puddle on the road, the Urban Forest Research Center of the US Department of Forestry created a soil mixture of 30% mixed clay and 70% porous lava rock from the Sierra Nevada mountain range in California state.

Artificial soil helps plants grow well in ' concrete ' environments in urban areas. (Photo: iStockphoto)

Through many experiments, the experts found that this Davis named soil is capable of removing at least 50% of nitrogen, phosphorus and 75% of heavy metals in wastewater. If used to plant trees in a hole 1.2 square meters deep, Davis soil can absorb and filter 568 liters of water, not including 190 liters of water that a 12-15 m tall tree can absorb and store itself.

In addition to creating shade, trees also attract carbon dioxide (CO ₂ ) and other air pollutants. However, conventional soil and planting methods inadvertently reduce efficiency in this respect. For example, when building a parking lot or footpath, about 60-90 cm of top soil is removed while the rest is paved.

Therefore, when planting shade trees, trees will be difficult to grow well because the roots cannot be spread into the soil layer below. In addition to planting trees, Davis soil can be used to line the pavement, sidewalk or use as a sub-island along the roads to absorb rainwater and filter before water penetrates through the soil layer and added to the water circuit implicit.

N.MINH