Since the 1980s, one of the largest concentrations of greenhouses in the world has developed on a coastal plain near the city of Almeria, spanning over 30,000 hectares (74,000 acres) in a "sea of plastic" seen from space.
The region is so dry and barren that it was used to film dozens of "spaghetti western" films in the 1960s but with the advent of hydroponic systems that drip-feed fertilisers into grow-bags it now produces several tonnes of fruits and vegetables annually.
After decades of rapid development, though, export growth has stalled and growing numbers of people question the viability of this agricultural model.
"We produce over 65 percent of the tomatoes, 80 percent of the cucumbers and 94 percent of the eggplants sold in Europe," said Francisco Vargas, the head of the ASAJA young farmers' association.
"But look at the prices we are paid. They are below production costs."
He blames a war between large retailers who try to hold on to clients by offering the lowest possible prices.
"Multinationals are strangling us," said Miguel Rubio, 60, who struggles to make ends meet with the produce he grows on four hectares of land in the "sea of plastic".
He said farmers were forced to boost output because of the low prices paid by chains to try to make more money, which in turn creates bigger surpluses and pushes prices down even further.
"The system makes no sense," said Rubio.
'Last link in chain'
Antonio Fernandez, meanwhile, talked with pride of the "sweet taste" of the red peppers he produces that are exported to northern Europe, and the progress made in recent years to reduce the use of pesticides.
"But the price of everything increases - plastic sheets, seeds, power - except the price paid by supermarkets for produce," he said as water drip-dropped in the background from his automatic irrigation system.
Over 1,000 farmers protested in Almeria on February 4th to demand a "fair" price for their fruits and vegetables and allow them to work "with dignity".
Demonstration in Almeria on February 4th. Photo: AFP
But with profit margins squeezed, some farms have started exploiting staff that work in the greenhouses, mainly legal and illegal immigrants from Africa and Eastern Europe who toil as day workers, said University of Almeria anthropologist Francisco Checa.
At night, they stream out of the greenhouses on their bikes, back to the packed, basic homes they share with other workers.
"I work 25 days a month but on my pay slip only 10 days are recorded," said Adama, a 34-year-old from Mali who has worked in the greenhouses since 2008.
He said he was owed two months wages but was reluctant to complain - even though he has legal status in Spain - out of fear that his bosses would fire his colleagues who are in the country illegally.
Most bosses do not pay farm workers overtime and they ignore a collective labour agreement that sets wages for day workers at €46 ($51) for eight hours of work, Checa said.
The provincial branch of the SAT workers' union receives daily complaints from farm labourers, many of whom live in two shanty towns located near the greenhouses.
Tensions between Spanish residents and immigrant workers boiled over in the region in 2000 after a Spanish woman was stabbed to death, sparking clashes in the farming town of El Ejido.
"Conditions of pure exploitation of immigrants have since worsened," said Spitou Mendy, the spokesman for SAT in the province of Almeria.
Mohamed, a 32-year-old Moroccan who studied economics before crossing illegally into Spain, lives in a shack made of wood and plastic with other farm workers in one of the shanty towns near the greenhouses.
"I earn 35 euros for eight hours of work, but others only get 30 euros," he said.
Farmers and officials, however, say cases of abuse are not the norm.
"These are one-off cases, not at all the general situation of the 60,000 greenhouse workers," said Jose Antonio Aliaga, chief of agricultural services in Almeria for the regional government.
Fernandez, the farmer who exports red peppers, said "it is not fair to say that all farmers here are seen as slave drivers."
The Romanian couple he employees describe him as a model boss who pays them a monthly salary of 800 euros for five days a week of work and provides them with free accommodation in a house with a garden.
But for the anthropologist Checa, it is all due to the slim margins earned by farmers.
"Growers can only put pressure on the last link in the chain," he said.
By Laurence Boutreux / AFP