BANGKOK (REUTERS) - Knee-deep in one of three riceberry paddies, Sompot Tubcharoen, 60, ploughs the watery fields of his farm with a handheld machine he calls "the field crusher."

Lined with hundreds of melon trees, the farm planted with the cross-breed rice variety presents a rare green sight in the teeming Thai capital where developers are quick to snap up land if the price is right.

Housing estates, office buildings and traffic-clogged roads are fast encroaching in the area surrounding the farm, located 30km north-east of central Bangkok.

A former university researcher who traded lecture halls for boots and a straw hat to run his family's farm four years ago, Sompot says he regularly turns down developers who want to buy the land.

The farm covers eight hectares, or 50 rai using the common measure in Thailand.

"They offered me 20 million baht per rai last year. Just recently I was asked if I'd sell for 33 million baht (S$1.38 million)," he said.

Many others have succumbed to offers to part with their land in Bangkok, where city central land prices jumped a record 30 per cent in 2017, according to commercial real estate firm CBRE Group, a reflection in part of the growing scarcity of available space.

Earlier this year, Britain's Foreign Office sold its four-hectare embassy compound in the city centre, which it had retained for 96 years, for 420 million pounds (S$747 million), the biggest land sale in Thai history.

Sompot said he believes spaces such as his provide a rare area of greenery in Bangkok.

The 2011 Asian Green City Index, the most recent study to look at environmental factors in urban areas, showed Bangkok had the third-least amount of green space per person among 22 Asian cities.

Sompot plans to open a retreat on the farm where people can escape the city.

"Bangkok life is stressful and people yearn for nature," he said. "They can come for one or two days, rest, and go home refreshed."

Sompot, who has spent 20 million baht to cultivate his land, has yet to break even by selling rice and melons.

But he's in no rush to sell his land.

"The rise in value is higher than any bank interest," he said. "It makes me happy just to wake up and hear the birds chirp. Life is more comfortable this way."