Straw-overlaying technology is helping to regain the fertile black topsoil of NE China and maximize the natural cycle between straw and soil in farmlands.

Standing at the edge of a large farm in Lishu town, Jilin province, people can see a harvester picking corn cobs and pulling down the golden stalks.

"That straw will rot. The soil will absorb the organic content and provide nutrition for newly planted crops," Wang Yuewu, a farmer at the town said.

Wang has been using the straw overlaying technology, which can both improve nutrient content in the soil and increase crops' capacity to resist natural threats, for three years and his corn has better quality than crops grown without using the technology.

According to Wang, straw-overlaying helps him obtain healthier corps and more corn at lower cost.

The black soil in NE China produces great amounts of rice and grain but the predatory farming of the past dozens of years has decreased the amount of productive land and lowered its quality.

Recovery of topsoil is difficult and takes a long time. Dou Sen, a professor who studies soil science at Jilin Agricultural University, explained that a centimeter of thick black soil needs hundreds of years to form.

"If we continue to pay scant attention to the protection of topsoil, the sustainable development of agriculture may be under threat," Dou added.

Research on straw overlaying technology was started in 2007 by institutes such as the Chinese Academy of Sciences and China Agricultural University.

The technology has been applied on several farms in NE China and topsoil deterioration has been reduced.

In addition, farmers also began to try green and organic agricultural products which have larger output and higher value.

As the soil recovers, farmers have started to plant many other kinds of crops like broom-corn, rye and sweet potatoes.

Protective farming technology is now changing agricultural production in NE China and at the same time promoting sustainable topsoil protection.