The illegal selling of black earth in the country must be cracked down on to protect the invaluable nonrenewable agricultural resource.

Black earth, or chernozem, is a kind of black-colored soil containing a high percentage of humus and phosphoric acids, phosphorus and ammonia. It is very fertile soil and can produce high agricultural yields with its high moisture storage capacity. The black earth belt in Northeast China, about 320,000 square kilometers, is the smallest one of the four major black earth belts in the world, after the one that stretches from Ukraine to central Russia, the one in the middle and lower reaches of the Mississippi River in the United States and the Pampas fertile lowlands extending from Argentina to Uruguay.

Statistics show that the thickness of the black earth belt in Northeast China has declined from about 1 meter to about 50 centimeters since it was cultivated on a large scale in the 1950s. Its area is also shrinking because of water and soil erosion, and the grain output per unit of its arable land has contracted 20 percent compared with that of the 1950s, despite the application of large amounts of chemical fertilizers today.

It takes about 400 years to form a layer of black earth 1 centimeter deep. And China's black earth belt loses a depth of about 0.3 centimeters to 1 centimeter each year because of weathering and cultivation.

So the country must take some concrete measures to protect and restore its black earth and treat it as a resource of strategic importance to national security. It is good that the country's top legislature will review a bill banning all forms of transactions of black soil in the country next week.

Before the bill becomes a law, the black earth traders might try their best to speculate on the business for a last gold rush. So local governments must take immediate actions to put an end to the trading of black earth from the perspective of ecological preservation and arable land protection without any delay before the business is officially outlawed.