Lucas tears at the vine stalk; dry leaves crunch, stems crackle and grapes bleed under the force of his hands, but the stalk won’t snap off. The extra effort makes his tired arms shake, his bent legs cramp and another trickle of sweat roll down from his sun cap to the spine of his neck. It’s 36°C (96.8°F). He pulls his scissors out of his side pocket and cuts the bunch of black berries, cupping it in his hand and dropping it into the bucket below piled with grapes. He grabs another bunch. Cut. Drop. Cut. Drop. Cut. Drop.

He sees Juan next to him ripping off bunches two at a time with his hands. It’s twice as quick, but Lucas got told off by the vineyard manager yesterday for not using his scissors, and as the harvest comes to an end and work opportunities dry up he doesn’t want to risk losing a day’s work. He needs to take money home.

It has been a tough three months of harvest and by now Lucas’s back is agony, not helped by the hard floor he sleeps on each night. Last night he was hoping he’d get more sleep but Mario woke him and the others up as he stumbled into the house steaming drunk at 3 a.m., waking everyone except the one he intended to arouse – his half-deaf, snoring wife, Maria-Lucia.

“House” is an overstatement for the place where Lucas lives. It is a squalid, mud-brick shack in rural Ugarteche. When he arrived in Mendoza from his home town in Bolivia three months ago, he had a contact his brother had given him for somewhere cheap to live during the harvest. At first, it was just him and six others in the three-bedroomed “house,” but now more than 15 bodies are crammed in and sometimes the men bring back girls. Sweaty, musty, fatigued bodies lie on overlapping mattresses and blankets, with creaking hammocks above.

Lucas often takes his blanket outside to the yard to sleep, where the air is cleaner and free of Mario’s grunts. Lucas thinks about five years ago, when he and other pickers would sleep in the vineyards in tents. Sometimes he thinks that was better than their hidden, dark existence now.

Waking at dawn, as he did this morning, sometimes has its benefits. Lucas made it to the street corner before any of the pickers he lives with, and was at the top of the pecking order when the cuadrilleros [vineyard supervisors] came to bid for workers.

Two cuadrilleros with their battered minivan trucks fought over how much they could pay the pickers. Lucas went with the one who offered him the most he’s been paid all harvest: $4.20 pesos (96 cents) per bucket, in high-yielding vines where they should be able to pick at least 30 buckets a day. He thought the cuadrillero was stupid for mentioning the yield. This year almost every picker he knows has been on strike at least once, demanding more money because of smaller bundles or lower-yield grapes. Lucas doesn’t want anyone to have an excuse for further strikes; he just wants to cash in his chips and go home.

Lucas has always been a traveling harvester. He has little talent for handcrafts and is too old to cut sugar canes at home. The money he earns during five months of fruit and grape harvesting in Argentina is enough to sustain him for the rest of the year in his small town in southern Bolivia.

Cut. Drop. Cut. Drop. With his bucket full, he hauls it onto his shoulder and forces his sapped legs to run down the vines to make up the time lost to scissor cutting. He pours his 20kg load into a clean black crate and the vineyard-owner’s wife throws a chip in his sticky, glucose-sodden bucket. His purple-stained hands fish around for the silver chip, which promptly turns a grimy grey. He pushes it deep into his right-hand pocket with the rest.

Running back down the vines he smiles at Diego Jr. as he passes. Diego Jr. is only a teenager, but even at 16 he keeps being told by his father that he is too late to learn to pick and that his hands are lazy. Diego Sr. began working in his grandfather’s vineyard at the age of six and keeps reminding his son – and everyone else who picks with him – of that fact. Lucas wonders to himself why Diego Sr. doesn’t still have that family vineyard if he’s such a good picker.

No one really speaks during the pick. Occasionally, someone makes a lewd joke about the vineyard-owner’s wife, but generally they keep their heads down. Lucas isn’t much of a talker, anyway, and he’s never really understood Argentine Spanish. At home, he speaks Quechua, an indigenous language of Bolivia.

A sharp pain sears his right thumb and Lucas sees bright blood drip from his calloused digit. He lifts it to his mouth, but his tongue is as dry as a cowhide from all the dust. He asks one of the women working next to him if she has anything to stop the bleeding. She doesn’t, but her daughter produces a swath of cloth doused in vinegar. Lucas wraps it around his thumb. An old man bends over to grab the buckets from his daughter and wife, and throws the grapes over either shoulder, looking sternly at Lucas. Lucas moves away to his vine and starts to pick again. Lift thumb. Cut. Drop. Lift thumb. Cut. Drop.

* All names have been changed to protect the identity and security of the grape-pickers. Lucas's account is an amalgamation of the stories of a number of workers Amanda Barnes interviewed.