Saman Kumara, smallholder tea farmer.[Photo provided by Vishwamithra Kadurugamuwa]

"In China we don't have those big plantations that you'll find in India or Sri Lanka. Instead we have vast numbers of small growers, each with land measuring somewhere between 10 mu and 30 mu (between 0.67 hectares and 2 hectares). We reach them through the region's leading tea companies, because they are the buyers of tea leaves and therefore have a big say when it comes to green farming.

"We are also working closely with local government officials responsible for developing the tea industry. Faced with tough competition and land degradation, they have taken part in our training for trainers scheme."

Hu stressed that zero use of chemical pesticides and herbicides is not a prerequisite for a grower to be granted the Rainforest Alliance certificate.

"The reduction of chemicals is bound to a step-by-step process, a process we try to trigger with an encouraging attitude. So we give the certificate to any grower who can prove that efforts have been made and that the use of chemicals has been reduced several years in a row. On rare occasions the use of chemicals may increase in a certain year. We will not withdraw our certificate if the grower can demonstrate that there is a very special reason for doing so - extreme weather or a plague for example."

But then there is the issue of labor costs. To do without chemicals means that many things, such as removing noxious weeds, must be done by hand or at least by people operating portable mechanical grass removers.

Dulshanka Jayathilaka, manager of Bearwell Estate, says labor costs have rocketed in the past few years. His estate was certified by Rainforest Alliance before the UN project started.

"More than 3,300 people live on the estate, which covers 307 hectares, but only 17 percent of them work for us. The rest are the workers' families."

However, he acknowledges that the Sri Lankan Government subsidizes the land, which means the private company has paid less for it than it otherwise would have. In turn, it is expected to take a degree of social responsibility by providing land on which even those who do not work for the estate can live.

Improving tea garden employees' working conditions and lives in general is among the UN project's goals.

"Reducing the use of chemicals obviously benefits the tea garden workers, but we need to do more, and we need to have a whole different mechanism, a whole different mindset and even consumer habits for any change to be sustainable," Hu says.

"We have a long way to go."