Walking through the knee-high grass, construction worker Hua Shankui bent down, pulled up a tuft of grass, and closely looked at the roots.

Having worked on building sites for more than 20 years, Hua, 59, had never imagined he'd become an "expert" on planting grass. But this was exactly what happened at a site he's working on in Wuhan, Central China's Hubei province.

The 18-hectare construction site of the Huashan section of Wuhan metro line 19 is situated near a verdant ecological reserve. Construction workers knew well that efforts had to be made to ensure that the local environment would not be compromised, says Wang Ran, a member of staff at Wuhan Metro Group.

To reduce pollution, using dust nets to cover bare soil is a normal practice on construction sites. However, a decision was made at the Huashan site to plant grass on the soil, a more eco-friendly method.

When Hua was assigned the task of leading a grass-planting team, he knew nothing about horticulture. The first question facing the team was what kind of grass they should plant.

Hua turned to local gardeners, who recommended carpet grass, a species commonly planted in urban landscaping.

However, months after planting the grass, few seeds of carpet grass grew roots as the soil at the site contains too much gravel.

The team thought of improving the soil by picking out the gravel or covering it with straws to preserve moisture. They gave up on both methods as neither proved effective on the soil of 8 hectares.

"Since the soil quality cannot be changed, I tried different varieties of grass. I believe I would eventually find the right one," says Hua.