BEIJING, June 26 -- In 1978 a group of 18 farmers in Xiaogang Village, Anhui Province, agreed that after they had given a certain percentage of their produce to the government, they would keep the rest of the harvest themselves.

The practice was such a success that it was later rolled out across the country, and became known as the "birth of farmland reform" in China.

To ensure food security, the government has vowed there should be a minimum 1.8 billion mu of productive farmland. However, rapid urbanization has led to land seizures and unregulated change of use across China. Rural Anhui can be seen as a microcosm of this worrying trend.

It is with a heavy heart that Fan Xiangbing, 68, looks upon the farmland he once ploughed: It is now no more than a patch of wasteland, the only plants thriving on the desolate plot are weeds.

It has been four years since he transferred the rights to the 6 mu (0.4 hectare) piece of land. In total, developers have leased 500 mu of land, nearly 50 soccer pitches, in Fan's village in Woyang County, for an industrial zone project that has still not materialized.

Farmland in China is owned collectively, villagers own the rights to use land, but not the rights to sell it. In 2008, farmers were allowed to rent, transfer or merge the land they held the rights to, part of wider measures to bolster modern farming and use abandoned land.

However, many firms and individuals have flouted land management regulations.

A report on national land supervision, issued by the Ministry of Land and Resources, revealed that in 2014 it had uncovered 2,228 cases of illegal land use, involving 122,400 mu of farmland.

In the pursuit of economic growth, arable land has been sacrificed, some local officials admitted.

"Grain is a meager source of tax, on the contrary, it demands continuous investment from the government. However, enterprises can turn in millions of yuan in tax. If you take economic data into account, which one is more appealing?" said a deputy county head in Anhui, who declined to be named.

Besides turning farmland into industrial sites, some investors use the land to grow cash crops purely for profit.

This can be seen in Hebei Province, north China.

Guo Jinxiang, from Neibu No. 2 Village in Neibu Township, Baixiang County, leased his 4 mu plot of land to a vegetable company, which promised to pay him 1,680 yuan (275.41 U.S. dollars) per mu annually for ten years. However, the company suffered losses and it upped sticks and left before the first year was out.

"The land was good for wheat -- it can yield about 500 kilograms of wheat per mu," he said. "But they left it in an awful mess, it is covered with weeds and I cannot get anyone to rent it."

Hu Chenglin, a professor at Anhui Agricultural University, said although rural-land transfers are attracting more interest, many investors might prefer cash crops over crops like grain.

Dang Guoying, with the China Academy of Social Sciences, said farmland is the fundamental guarantee for food security, and agricultural competition should be sharpened through improvements to the quantity and quality of farmland.

To tackle the problem, farmland that is vulnerable should be identified and protected, and agricultural protection zones, which only allow construction of state-level infrastructure, be established, Dang said.

In May, President Xi Jinping suggested that arable land should be protected "the way we protect pandas". The country must ensure food security, and farmland is not allowed to become endangered, he said.