When the night comes, a ragged army of men and women sharpen their machetes to harvest the raw material for Brazil's "white gold."
With machinelike precision, the cane cutters gather five 2.5-meter (8-foot) tall stalks in the crook of one arm, bend over and cut them down with three swift machete whacks - a process they will repeat over and over again for as long as 12 hours a day.
"By the end of the day your entire body hurts so much you think you are going to die" says cane cutter Raimundo Gomes da Silva. "But it is all we know how to do, so we will continue doing the same thing, day after day, until we drop dead."
Brazil's pioneering use of sugarcane-based ethanol, which fuels about 30 percent of the country's automobiles, has made Latin America's largest country a global leader alternative energy.
Getting less attention is the squalid labor conditions of nearly half a million people who toil in the fields six days a week to supply the cane to the nation and a growing export market.
Brazil is already the world's No. 1 exporter of ethanol, shipping 3.4 billion liters (900 million gallons) of the fuel additive abroad in 2006 - up from 2.6 billion liters (690 million gallons- in 2005 - and generating revenues of US$1.6 billion (1.13 billion EUR).
Exports have risen due mostly to increased demand from European countries that find it cheaper to import the product from Brazil than to make it from wheat and sugar beets.
"Ethanol is making a lot of people in this country very rich," said Miguel Ferreira, president of the union representing cane cutters in Batatais, a town in Sao Paulo state's vast sugarcane belt. "But all the cane cutters have seen are long hours of backbreaking work for very little pay."
The most productive cutters can earn a meager US$420 (297 EUR) a month. Many earn even less. Paid by the ton, they've seen their quotas nearly double in recent years to meet the rising demand.
"In the 1980s cane cutters had to cut some six to eight tons of cane a day. Today, many plantation owners are demanding 10 to 12 tons a day and those who do not meet their production targets are fired," said Maria Cristina Gonzaga, a researcher in the Labor Ministry's Occupational Safety and Health Center.
Aside from long hours in the hot sun, cane cutters suffer a litany of bone and muscle injuries and machete cuts. Their eyes and lungs are punished by ash as they labor through fields recently burned to facilitate cutting and to kill off rats, snakes and scorpions.
Some 18 cane cutters died of exhaustion in the past three years in Sao Paulo state alone, according to the Catholic Church's Migrant Workers Pastoral, which monitors working conditions. Countless others have been injured.
And while dozens of sugar mills have been fined for violating labor laws, Gonzaga says the Labor Ministry lacks the resources to solve the problem.
The ministry has an elite unit dedicated to freeing workers from debt slavery, a common practice in the Amazon region, where ranchers and farmers force workers to pay exorbitant prices for basic goods and transportation, ensnaring them in ever-deepening debt.
But the unit shut down last month protesting "political interference" after lawmakers challenged its raid on Para Pastoril e Agricola SA, a leading ethanol producer. The raid in the northern state of Para it found more than 1,000 cutters working 13-hour days in what the unit said were slave-like conditions.
The company has denied abusing workers. It was slapped with a US$1.1 million (771,000 EUR) fine and its directors charged with "submitting workers to conditions analogous to slavery."
If found guilty, they could be sentenced to up to 15 years in jail, said Fabio Borges, a Labor Ministry spokesman.
The unit's shutdown leaves Brazil without an effective enforcement tool for conditions in the cane fields, the ministry says.
Labor ministry inspectors stationed in regional offices will try to take up the slack but they do not have the elite group's training to deal with debt slavery cases, Borges said.
"Sweat, blood and death bathe the sugar and alcohol made in Brazil," Gonzaga said.
Still, there's no shortage of labor.
Most cane cutters in Batatais migrated from Brazil's impoverished drought-ridden northeast, attracted by wages they would never dream of earning back home. With average wages of some US$330 (230 EUR) a month, cane cutters in the state of Sao Paulo earn more than the country's minimum wage of US$209 (146 EUR).
"I cut some eight tons of cane every day and make about 600 reals (US$315;223 EUR) a month" said one such internal migrant, 27-year-old Jose Dalmir. "I used to make half as much as an assistant stonemason."
UNICA, the country's association of sugar and ethanol producers acknowledges working conditions in the cane fields have caused an image problem that could lead the European Union and the United States to refuse to import Brazilian ethanol until labor conditions are improved.
To address this problem, they have committed to shorter working hours and to provide bettermeals and more and better health and educational benefits for the workers and their families, UNICA's president Marcos Sawaya Jank said in an interview.
The EU is already considering ways to certify that imported Brazilian ethanol is produced with good labor and environmental practices. Jank would support such efforts as long as they also apply to ethanol made from corn and sugar beets in other countries - and don't amount to a barrier against Brazilian products.
"We definitely favor international certification attesting to the social, environmental and labor sustainability of our ethanol," Jank said.
But Jank also noted that machines are taking over the harvests. Currently, about 40 percent of Brazil's sugarcane is harvested by machine, but that should rise to 70 percent by 2010 and 100 percent by 2015, he said. And even though UNICA says it is committed to retraining the workers as machine operators and truck drivers, many cutters will be out of work.
"Unemployment among cane cutters is inevitable," he said. "It is a problem we, the government and trade unions will have to deal with."