By Jan Rocha
BBC News, Brazil
Soya bean farmers in Brazil are demanding that a 600-mile-long stretch of highway, which runs due north through the Amazon region, should be paved so it can be used in all weathers. But environmentalists are alarmed at the plans to cut through the country's natural assets.
Jan travelled with scientists to assess the impact of development
We began the week-long journey in Cuiaba, which is the capital of Brazil's major soybean state, Mato Grosso.
There were five of us, squeezed into a 4x4. For the first 300 miles, the road ran through vast fields, which stretched away to the horizon, with not a tree in sight.
Once this was all rainforest, but now it is all farming land, mostly soybeans.
It is the soy farmers who want the road paved, so they can export more cheaply, going straight up the road to the River Amazon, and then over the Atlantic to Europe and beyond.
The second day, we were driving through hills. The tarmac and the huge fields had ended. Now it was a dirt road, which became a sea of mud when it rained.
The forest here had been cleared more recently. Humped white cattle were grazing among charred stumps of trees.
The night we arrived, a man was stabbed in a brawl
At night we came to a frontier town, just a wide dirt street, lined with bars and billiard saloons.
This was Castelo dos Sonhos, or the Castle of Dreams, a product of the 1980s goldrush.
We passed the Cawboy Bar, and the Everything for the Gold Prospector General Store. There was also Salome's Unisex Hairdressers, which seemed a bit out of place in this tough environment.
The night we arrived, a man was stabbed in a brawl in one of the bars.
When gold fever was at its height in the Amazon, 40,000 gold prospectors poured into this area.
The bridges were precarious: logs lashed together on top of the remains of earlier bridges that had been swept away by the rains
We met one of them at a disused airstrip. Like the ancient mariner, he seized upon us to tell us his tale of woe.
For 20 years he had travelled from gold camp to gold camp, making money, spending it, too busy to visit his family back in the north-east.
When he finally went home to see his mother, he was too late. She had just died.
So now he was back, still searching for gold. Most of the former gold prospectors have gone to work in the sawmills.
In Castelo alone there are more than fifty sawmills. Logs have to be brought in from a wider and wider area. Much of this logging is illegal.
Leaving Castelo the road got much worse. We passed lorries leaning at crazy angles, stranded in the mud. One had fallen into a river bed.
The bridges were precarious: logs lashed together on top of the remains of earlier bridges that had been swept away by the rains.
At the height of the rainy season, lorries and buses can get trapped in the mud for 10 or even 20 days. People cook over fires, waiting for rescue.
Overturned vehicles are a common sight along this dangerous road
We stop to eat at the odd scruffy roadside bar. Some of them have faded photographs of giant snakes killed when the road was being built, eight or 10 men holding a monster five or six metres long.
Then it began to rain and the road got treacherous, slippery as glass.
The 4x4 began to slide about. Mauricio, who was driving, wrestled to keep it on the road, but he never stopped the heated literary discussion he was engaged in with one of the others about a great Brazilian writer, Guimaraes Rosa.
As Brazilians cannot talk without using their hands, there was a constant chorus from the rest of us: "Mauricio! Cuidado! Look out!"
We came to the shore of the Tapajos river. On the other side, a ferry ride away, the lights of Itaituba twinkled. After days of bumping and skidding, of mud and flies, it was like arriving in a big city.
In reality, Itaituba is another former goldrush town, which now aspires to better things, with banks and supermarkets and cyber cafes and a posh hotel.
On the road we had heard about people who had been murdered for speaking out about the illegal logging
The hotel dining room was full of businessmen from the south. You could tell from their accents, and their complexions: ruddy, fair-skinned.
They were here to buy land, now that the road was going to be paved.
The next day we visited the offices of the federal environment agency, Ibama. The staff, young and keen, are trying to control the illegal logging of the rainforest, stopping lorries, embargoing logging areas and fining the loggers.
It is a gigantic task, and it is dangerous too.
The loggers, used to doing as they like, are angry at this interference. A few days earlier they had delivered a letter, threatening "imminent conflict".
On the road we had heard about people who had been murdered for speaking out about the illegal logging and land-grabbing that is going on in the region.
Full steam ahead
Little, it seems, will stand in the way of the soybean farmers and profit
We decided we had had enough of the road. We would do the last stretch by riverboat.
The boat was packed because it was the eve of a holiday, but we found a space and hung our hammocks.
As the sun was setting we chugged out into the middle of the wide Tapajos river.
The moon was full, there was a light breeze and the hammocks swayed backwards and forwards together. People ate and drank, chatted and sang.
Fourteen hours later as we approached Santarem - the port at the end of the road - we passed a giant grain terminal.
It is ready for the day that the fleets of lorries carrying soybeans start coming up the road.
From Our Own Correspondent was broadcast on Saturday, 8 January, 2005 at 1130 GMT on BBC Radio 4. Please check the programme schedules for World Service transmission times.