Chinese and Canadian scientists are brainstorming ideas to combat desertification in China by adding fly ash and dam reservoir sediments to soil used for agriculture, according to report of China Daily.

Professors from China University of Geosciences and the University of Western Ontario of Canada will test the method next year in the city of Baotou in North China's Inner Mon-golia in the upper reaches of the Yellow River. The area has abundant coal resources, but is surrounded by deserts. They held a discussion recently in Beijing to define research jobs before launching the project.

"Before launching the project, we must consider several issues, such as the number of people affected, the status of local ecosystems, residents' source of incomes, the type of land we are going to work on and methods of regional waste management," said Michael A. Powell, associate professor at the Canadian university.

These issues are related to technology transfer for sustaining local environment, poverty reduction and other objectives to be achieved through the project, he said. It is necessary to reverse desertification through afforestration in the Yellow and Yangtze rivers, he added.

The State Environmental Protection Administration and other relevant ministries have called for the study of fly ash utilization. Presently, only 34 per cent of fly ash is recycled in most provinces.

Baotou produces 1 million tons of fly ash each year, too much for the city's single pit to store. Building a new ash pit requires 10 million yuan (US$1.2 million). The city now has a total of 10 million tons of fly ash, covering 7 million square metres. Only 40,000 tons of the total is utilized each year, according to Sun.

Fly ash, reservoir sediments and mining stone waste can fertilize the tree ground for 10 years because unlike dissolvable chemical fertilizers, they are more difficult for rain to wash away, according to Sun.

Relevant studies showed that reservoir sediments are good fertilizers because they contain large amounts of nitrogen, phosphorus and potassium.

China should quickly make use of the reservoir sediments because the country has many reservoirs.

Some foreign countries have already succeeded in this experiment. For example, the sediments of a reservoir in the south part of Brazil contain nitrogen, phosphorus and potassium as much as five times of the amount in local soil.

China built nearly 19,000 reservoirs by late 1980s, relevant statistics indicated. But serious soil erosion has brought heavy sediments into many reservoirs.

The tremendous floods that hit northeastern and southern China last year, have enhanced governmental and public awareness of the importance of protecting water and soil through afforestration, said Sun.

China has a relatively low rate of green coverage. The country's per capita forest coverage is only 0.11 hectares - one sixth of the world's average.

To counter these developments, afforestration projects are being tried across the country. The State Forestry Administration has announced that over the next 50 years, trees will be planted on all available land.

The nine provinces and regions around the Yellow River will increase green coverage from today's level of 10 per cent to 27 per cent by 2030.

Tree planting requires water and fertilizer. Chemical fertilizer has proven to be expensive and can be washed away by rain. The survival rate for the trees with fertilizer is low. Using low-cost manure to try to increase the survival rate of trees and help them grow faster is very important, said Sun.