BEIJING, April 17 -- Under the smoggy sky, another environment hazard is brought into the spotlight in China as an official report confirmed Thursday about 16.1 percent of its soil is polluted.

Alarmingly, about 19.4 percent of the farming land is polluted, said the report issued jointly by the Ministry of Environmental Protection and the Ministry of Land and Resources. ( The general condition of the land is "not optimistic" as the quality of farming land is worrying and deserted industrial and mining land suffers serious pollution, according to the report.

It was based on a survey conducted from April, 2005, to December last year on about 630 square km of land across the country, except Hong Kong, Macao and Taiwan.

The pollution has been caused by complicated factors over a long period of time. "The main pollution source is human industrial and agricultural activities," the report said.

Industrial waste contaminates land around factories and mines while automobile exhaust pollutes air along the country's main highways.

Irrigation by polluted water, the improper use of fertilizers and pesticides and the development of livestock breeding cause pollution to farming land.

Chen Tongbin, research fellow with the Institute of Geographic Sciences and Natural Resources Research with the Chinese Academy of Sciences, told Xinhua that the report set off "a loud alarm" for the country's economic development pattern and environmental protection system.

"Compared with air and water pollution, soil pollution is more difficult to control and remedy, taking a much longer time and needing more resources," Chen said.

In addition to reduced quality and quantity of crops that threaten people's health upon consumption, such pollution might also result in health hazards for people living in areas where there is polluted soil after breathing in or having skin contact with pollutants.

While affecting the normal growth of plants and microbes and damaging the soils' function to preserve nutrients, these pollutants are likely to permeate into underground layers and contaminate drinking water sources.

In breakdown, 11.2 percent of the country's surveyed land suffers slight pollution, while 1.1 percent is severely polluted.

About 2.3 percent of the land is lightly polluted and 1.5 percent suffers medium pollution.

Some 10 percent of woodland and 10.4 percent of grassland is polluted, the report added.

About 82.8 percent of the polluted land is contaminated by inorganic materials and the top three pollutants are cadmium, nickel and arsenic.

Compared with survey results between 1986 and 1990, inorganic pollutants increased notably. For instance, the level of cadmium pollution rose by 50 percent in southwestern and coastal regions and 10 to 40 percent in other parts.

Geographically speaking, the southern part of China suffers heavier soil pollution than the north. Pollution is severe in three major industrial zones, the Yangtze River Delta in east China, the Pearl River Delta in south China and the northeast corner that used to be a heavy industrial hub.

Southwest and central Chinese provinces report a higher level of heavy metal pollution in the soil.